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This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
This is libmicrohttpd.info, produced by makeinfo version 6.6 from
libmicrohttpd.texi.
This manual is for GNU libmicrohttpd (version 0.9.64, 9 June 2019), a
library for embedding an HTTP(S) server into C applications.
Copyright © 2007–2017 Christian Grothoff
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, no Front-Cover Texts, and
no Back-Cover Texts. A copy of the license is included in the
section entitled "GNU Free Documentation License".
INFO-DIR-SECTION Software libraries
START-INFO-DIR-ENTRY
* libmicrohttpd: (libmicrohttpd). Embedded HTTP server library.
END-INFO-DIR-ENTRY

File: libmicrohttpd.info, Node: Top, Next: microhttpd-intro, Up: (dir)
The GNU libmicrohttpd Library
*****************************
This manual is for GNU libmicrohttpd (version 0.9.64, 9 June 2019), a
library for embedding an HTTP(S) server into C applications.
Copyright © 2007–2017 Christian Grothoff
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, no Front-Cover Texts, and
no Back-Cover Texts. A copy of the license is included in the
section entitled "GNU Free Documentation License".
* Menu:
* microhttpd-intro:: Introduction.
* microhttpd-const:: Constants.
* microhttpd-struct:: Structures type definition.
* microhttpd-cb:: Callback functions definition.
* microhttpd-init:: Starting and stopping the server.
* microhttpd-inspect:: Implementing external ‘select’.
* microhttpd-requests:: Handling requests.
* microhttpd-responses:: Building responses to requests.
* microhttpd-flow:: Flow control.
* microhttpd-dauth:: Utilizing Authentication.
* microhttpd-post:: Adding a ‘POST’ processor.
* microhttpd-info:: Obtaining and modifying status information.
* microhttpd-util:: Utilities.
Appendices
* GNU-LGPL:: The GNU Lesser General Public License says how you
can copy and share almost all of ‘libmicrohttpd’.
* GNU GPL with eCos Extension:: The GNU General Public License with eCos extension says how you
can copy and share some parts of ‘libmicrohttpd’.
* GNU-FDL:: The GNU Free Documentation License says how you
can copy and share the documentation of ‘libmicrohttpd’.
Indices
* Concept Index:: Index of concepts and programs.
* Function and Data Index:: Index of functions, variables and data types.
* Type Index:: Index of data types.

File: libmicrohttpd.info, Node: microhttpd-intro, Next: microhttpd-const, Prev: Top, Up: Top
1 Introduction
**************
All symbols defined in the public API start with ‘MHD_’. MHD is a small
HTTP daemon library. As such, it does not have any API for logging
errors (you can only enable or disable logging to stderr). Also, it may
not support all of the HTTP features directly, where applicable,
portions of HTTP may have to be handled by clients of the library.
The library is supposed to handle everything that it must handle
(because the API would not allow clients to do this), such as basic
connection management. However, detailed interpretations of headers,
such as range requests, are left to the main application. In
particular, if an application developer wants to support range requests,
he needs to explicitly indicate support in responses and also explicitly
parse the range header and generate a response (for example, using the
‘MHD_create_response_from_fd_at_offset’ call to serve ranges from a
file). MHD does understands headers that control connection management
(specifically, ‘Connection: close’ and ‘Expect: 100 continue’ are
understood and handled automatically). ‘Connection: upgrade’ is
supported by passing control over the socket (or something that behaves
like the real socket in the case of TLS) to the application (after
sending the desired HTTP response header).
MHD largely ignores the semantics of the different HTTP methods, so
clients are left to handle those. One exception is that MHD does
understand ‘HEAD’ and will only send the headers of the response and not
the body, even if the client supplied a body. (In fact, clients do need
to construct a response with the correct length, even for ‘HEAD’
request.)
MHD understands ‘POST’ data and is able to decode certain formats (at
the moment only ‘application/x-www-form-urlencoded’ and
‘multipart/form-data’) using the post processor API. The data stream of
a POST is also provided directly to the main application, so unsupported
encodings could still be processed, just not conveniently by MHD.
The header file defines various constants used by the HTTP protocol.
This does not mean that MHD actually interprets all of these values.
The provided constants are exported as a convenience for users of the
library. MHD does not verify that transmitted HTTP headers are part of
the standard specification; users of the library are free to define
their own extensions of the HTTP standard and use those with MHD.
All functions are guaranteed to be completely reentrant and
thread-safe. MHD checks for allocation failures and tries to recover
gracefully (for example, by closing the connection). Additionally,
clients can specify resource limits on the overall number of
connections, number of connections per IP address and memory used per
connection to avoid resource exhaustion.
1.1 Scope
=========
MHD is currently used in a wide range of implementations. Examples
based on reports we’ve received from developers include:
• Embedded HTTP server on a cortex M3 (128 KB code space)
• Large-scale multimedia server (reportedly serving at the simulator
limit of 7.5 GB/s)
• Administrative console (via HTTP/HTTPS) for network appliances
1.2 Thread modes and event loops
================================
MHD supports four basic thread modes and up to three event loop styles.
The four basic thread modes are external sockets polling (MHD creates
no threads, event loop is fully managed by the application), internal
polling (MHD creates one thread for all connections), polling in thread
pool (MHD creates a thread pool which is used to process all
connections) and thread-per-connection (MHD creates one thread for
listen sockets and then one thread per accepted connection).
These thread modes are then combined with the evet loop styles
(polling function type). MHD support select, poll and epoll. select is
available on all platforms, epoll and poll may not be available on some
platforms. Note that it is possible to combine MHD using epoll with an
external select-based event loop.
The default (if no other option is passed) is “external select”. The
highest performance can typically be obtained with a thread pool using
‘epoll’. Apache Benchmark (ab) was used to compare the performance of
‘select’ and ‘epoll’ when using a thread pool and a large number of
connections. *note Figure 1.1: fig:performance. shows the resulting
plot from the ‘benchmark.c’ example, which measures the latency between
an incoming request and the completion of the transmission of the
response. In this setting, the ‘epoll’ thread pool with four threads
was able to handle more than 45,000 connections per second on loopback
(with Apache Benchmark running three processes on the same machine).
[image src="libmicrohttpd_performance_data.png" alt="Data"]
Figure 1.1: Performance measurements for select vs. epoll (with
thread-pool).
Not all combinations of thread modes and event loop styles are
supported. This is partially to keep the API simple, and partially
because some combinations simply make no sense as others are strictly
superior. Note that the choice of style depends first of all on the
application logic, and then on the performance requirements.
Applications that perform a blocking operation while handling a request
within the callbacks from MHD must use a thread per connection. This is
typically rather costly. Applications that do not support threads or
that must run on embedded devices without thread-support must use the
external mode. Using ‘epoll’ is only supported on some platform, thus
portable applications must at least have a fallback option available.
*note Table 1.1: tbl:supported. lists the sane combinations.
select poll epoll
external yes no yes
internal yes yes yes
thread pool yes yes yes
thread-per-connection yes yes no
Table 1.1: Supported combinations of event styles and thread modes.
1.3 Compiling GNU libmicrohttpd
===============================
MHD uses the standard GNU system where the usual build process involves
running
$ ./configure
$ make
$ make install
MHD supports various options to be given to configure to tailor the
binary to a specific situation. Note that some of these options will
remove portions of the MHD code that are required for
binary-compatibility. They should only be used on embedded systems with
tight resource constraints and no concerns about library versioning.
Standard distributions including MHD are expected to always ship with
all features enabled, otherwise unexpected incompatibilities can arise!
Here is a list of MHD-specific options that can be given to configure
(canonical configure options such as “–prefix” are also supported, for a
full list of options run “./configure –help”):
‘``--disable-curl''’
disable running testcases using libcurl
‘``--disable-largefile''’
disable support for 64-bit files
‘``--disable-messages''’
disable logging of error messages (smaller binary size, not so much
fun for debugging)
‘``--disable-https''’
disable HTTPS support, even if GNUtls is found; this option must be
used if eCOS license is desired as an option (in all cases the
resulting binary falls under a GNU LGPL-only license)
‘``--disable-postprocessor''’
do not include the post processor API (results in binary
incompatibility)
‘``--disable-dauth''’
do not include the authentication APIs (results in binary
incompatibility)
‘``--disable-httpupgrade''’
do not build code for HTTP “Upgrade” (smaller binary size, binary
incompatible library)
‘``--disable-epoll''’
do not include epoll support, even if it supported (minimally
smaller binary size, good for portability testing)
‘``--enable-coverage''’
set flags for analysis of code-coverage with gcc/gcov (results in
slow, large binaries)
‘``--with-threads=posix,w32,none,auto''’
sets threading library to use. With use “none” to not support
threads. In this case, MHD will only support the “external”
threading modes and not perform any locking of data structures!
Use ‘MHD_is_feature_supported(MHD_FEATURE_THREADS)’ to test if
threads are available. Default is “auto”.
‘``--with-gcrypt=PATH''’
specifies path to libgcrypt installation
‘``--with-gnutls=PATH''’
specifies path to libgnutls installation
1.4 Validity of pointers
========================
MHD will give applications access to its internal data structures via
pointers via arguments and return values from its API. This creates the
question as to how long those pointers are assured to stay valid.
Most MHD data structures are associated with the connection of an
HTTP client. Thus, pointers associated with a connection are typically
valid until the connection is finished, at which point MHD will call the
‘MHD_RequestCompletedCallback’ if one is registered. Applications that
have such a callback registered may assume that keys and values from the
‘MHD_KeyValueIterator’, return values from ‘MHD_lookup_connection_value’
and the ‘url’, ‘method’ and ‘version’ arguments to the
‘MHD_AccessHandlerCallback’ will remain valid until the respective
‘MHD_RequestCompletedCallback’ is invoked.
In contrast, the ‘upload_data’ argument of
‘MHD_RequestCompletedCallback’ as well as all pointers from the
‘MHD_PostDataIterator’ are only valid for the duration of the callback.
Pointers returned from ‘MHD_get_response_header’ are valid as long as
the response itself is valid.
1.5 Including the microhttpd.h header
=====================================
Ideally, before including "microhttpd.h" you should add the necessary
includes to define the ‘uint64_t’, ‘size_t’, ‘fd_set’, ‘socklen_t’ and
‘struct sockaddr’ data types. Which specific headers are needed may
depend on your platform and your build system might include some tests
to provide you with the necessary conditional operations. For possible
suggestions consult ‘platform.h’ and ‘configure.ac’ in the MHD
distribution.
Once you have ensured that you manually (!) included the right
headers for your platform before "microhttpd.h", you should also add a
line with ‘#define MHD_PLATFORM_H’ which will prevent the "microhttpd.h"
header from trying (and, depending on your platform, failing) to include
the right headers.
If you do not define MHD_PLATFORM_H, the "microhttpd.h" header will
automatically include headers needed on GNU/Linux systems (possibly
causing problems when porting to other platforms).
1.6 SIGPIPE
===========
MHD does not install a signal handler for SIGPIPE. On platforms where
this is possible (such as GNU/Linux), it disables SIGPIPE for its I/O
operations (by passing MSG_NOSIGNAL or similar). On other platforms,
SIGPIPE signals may be generated from network operations by MHD and will
cause the process to die unless the developer explicitly installs a
signal handler for SIGPIPE.
Hence portable code using MHD must install a SIGPIPE handler or
explicitly block the SIGPIPE signal. MHD does not do so in order to
avoid messing with other parts of the application that may need to
handle SIGPIPE in a particular way. You can make your application
handle SIGPIPE by calling the following function in ‘main’:
static void
catcher (int sig)
{
}
static void
ignore_sigpipe ()
{
struct sigaction oldsig;
struct sigaction sig;
sig.sa_handler = &catcher;
sigemptyset (&sig.sa_mask);
#ifdef SA_INTERRUPT
sig.sa_flags = SA_INTERRUPT; /* SunOS */
#else
sig.sa_flags = SA_RESTART;
#endif
if (0 != sigaction (SIGPIPE, &sig, &oldsig))
fprintf (stderr,
"Failed to install SIGPIPE handler: %s\n", strerror (errno));
}
1.7 MHD_UNSIGNED_LONG_LONG
==========================
Some platforms do not support ‘long long’. Hence MHD defines a macro
‘MHD_UNSIGNED LONG_LONG’ which will default to ‘unsigned long long’.
For standard desktop operating systems, this is all you need to know.
However, if your platform does not support ‘unsigned long long’, you
should change "platform.h" to define ‘MHD_LONG_LONG’ and
‘MHD_UNSIGNED_LONG_LONG’ to an appropriate alternative type and also
define ‘MHD_LONG_LONG_PRINTF’ and ‘MHD_UNSIGNED_LONG_LONG_PRINTF’ to the
corresponding format string for printing such a data type. Note that
the “signed” versions are deprecated. Also, for historical reasons,
‘MHD_LONG_LONG_PRINTF’ is without the percent sign, whereas
‘MHD_UNSIGNED_LONG_LONG_PRINTF’ is with the percent sign. Newly written
code should only use the unsigned versions. However, you need to define
both in "platform.h" if you need to change the definition for the
specific platform.
1.8 Portability to W32
======================
libmicrohttpd in general ported well to W32. Most libmicrohttpd
features are supported. W32 do not support some functions, like epoll
and corresponding MHD features are not available on W32.
1.9 Portability to z/OS
=======================
To compile MHD on z/OS, extract the archive and run
iconv -f UTF-8 -t IBM-1047 contrib/ascebc > /tmp/ascebc.sh
chmod +x /tmp/ascebc.sh
for n in `find * -type f`
do
/tmp/ascebc.sh $n
done
to convert all source files to EBCDIC. Note that you must run
‘configure’ from the directory where the configure script is located.
Otherwise, configure will fail to find the ‘contrib/xcc’ script (which
is a wrapper around the z/OS c89 compiler).

File: libmicrohttpd.info, Node: microhttpd-const, Next: microhttpd-struct, Prev: microhttpd-intro, Up: Top
2 Constants
***********
-- Enumeration: MHD_FLAG
Options for the MHD daemon.
Note that MHD will run automatically in background thread(s) only
if ‘MHD_USE_INTERNAL_POLLING_THREAD’ is used. Otherwise caller
(application) must use ‘MHD_run’ or ‘MHD_run_from_select’ to have
MHD processed network connections and data.
Starting the daemon may also fail if a particular option is not
implemented or not supported on the target platform (i.e. no
support for TLS, threads or IPv6). TLS support generally depends
on options given during MHD compilation.
‘MHD_NO_FLAG’
No options selected.
‘MHD_USE_ERROR_LOG’
If this flag is used, the library should print error messages
and warnings to stderr (or to custom error printer if it’s
specified by options). Note that for this run-time option to
have any effect, MHD needs to be compiled with messages
enabled. This is done by default except you ran configure
with the ‘--disable-messages’ flag set.
‘MHD_USE_DEBUG’
Currently the same as ‘MHD_USE_ERROR_LOG’.
‘MHD_USE_TLS’
Run in HTTPS-mode. If you specify ‘MHD_USE_TLS’ and MHD was
compiled without SSL support, ‘MHD_start_daemon’ will return
NULL.
‘MHD_USE_THREAD_PER_CONNECTION’
Run using one thread per connection.
‘MHD_USE_INTERNAL_POLLING_THREAD’
Run using an internal thread doing ‘SELECT’.
‘MHD_USE_IPv6’
Run using the IPv6 protocol (otherwise, MHD will just support
IPv4). If you specify ‘MHD_USE_IPV6’ and the local platform
does not support it, ‘MHD_start_daemon’ will return NULL.
If you want MHD to support IPv4 and IPv6 using a single
socket, pass MHD_USE_DUAL_STACK, otherwise, if you only pass
this option, MHD will try to bind to IPv6-only (resulting in
no IPv4 support).
‘MHD_USE_DUAL_STACK’
Use a single socket for IPv4 and IPv6. Note that this will
mean that IPv4 addresses are returned by MHD in the
IPv6-mapped format (the ’struct sockaddr_in6’ format will be
used for IPv4 and IPv6).
‘MHD_USE_PEDANTIC_CHECKS’
Deprecated (use ‘MHD_OPTION_STRICT_FOR_CLIENT’). Be pedantic
about the protocol. Specifically, at the moment, this flag
causes MHD to reject HTTP 1.1 connections without a ‘Host’
header. This is required by the standard, but of course in
violation of the “be as liberal as possible in what you
accept” norm. It is recommended to turn this *ON* if you are
testing clients against MHD, and *OFF* in production.
‘MHD_USE_POLL’
Use ‘poll()’ instead of ‘select()’. This allows sockets with
descriptors ‘>= FD_SETSIZE’. This option currently only works
in conjunction with ‘MHD_USE_INTERNAL_POLLING_THREAD’ (at this
point). If you specify ‘MHD_USE_POLL’ and the local platform
does not support it, ‘MHD_start_daemon’ will return NULL.
‘MHD_USE_EPOLL’
Use ‘epoll()’ instead of ‘poll()’ or ‘select()’. This allows
sockets with descriptors ‘>= FD_SETSIZE’. This option is only
available on some systems and does not work in conjunction
with ‘MHD_USE_THREAD_PER_CONNECTION’ (at this point). If you
specify ‘MHD_USE_EPOLL’ and the local platform does not
support it, ‘MHD_start_daemon’ will return NULL. Using
‘epoll()’ instead of ‘select()’ or ‘poll()’ can in some
situations result in significantly higher performance as the
system call has fundamentally lower complexity (O(1) for
‘epoll()’ vs. O(n) for ‘select()’/‘poll()’ where n is the
number of open connections).
‘MHD_USE_TURBO’
Enable optimizations to aggressively improve performance.
Currently, the optimizations this option enables are based on
opportunistic reads and writes. Bascially, MHD will simply
try to read or write or accept on a socket before checking
that the socket is ready for IO using the event loop
mechanism. As the sockets are non-blocking, this may fail (at
a loss of performance), but generally MHD does this in
situations where the operation is likely to succeed, in which
case performance is improved. Setting the flag should
generally be safe (even though the code is slightly more
experimental). You may want to benchmark your application to
see if this makes any difference for you.
‘MHD_USE_SUPPRESS_DATE_NO_CLOCK’
Suppress (automatically) adding the ’Date:’ header to HTTP
responses. This option should ONLY be used on systems that do
not have a clock and that DO provide other mechanisms for
cache control. See also RFC 2616, section 14.18 (exception
3).
‘MHD_USE_NO_LISTEN_SOCKET’
Run the HTTP server without any listen socket. This option
only makes sense if ‘MHD_add_connection’ is going to be used
exclusively to connect HTTP clients to the HTTP server. This
option is incompatible with using a thread pool; if it is
used, ‘MHD_OPTION_THREAD_POOL_SIZE’ is ignored.
‘MHD_USE_ITC’
Force MHD to use a signal inter-thread communication channel
to notify the event loop (of threads) of our shutdown and
other events. This is required if an application uses
‘MHD_USE_INTERNAL_POLLING_THREAD’ and then performs
‘MHD_quiesce_daemon’ (which eliminates our ability to signal
termination via the listen socket). In these modes,
‘MHD_quiesce_daemon’ will fail if this option was not set.
Also, use of this option is automatic (as in, you do not even
have to specify it), if ‘MHD_USE_NO_LISTEN_SOCKET’ is
specified. In "external" select mode, this option is always
simply ignored.
Using this option also guarantees that MHD will not call
‘shutdown()’ on the listen socket, which means a parent
process can continue to use the socket.
‘MHD_ALLOW_SUSPEND_RESUME’
Enables using ‘MHD_suspend_connection’ and
‘MHD_resume_connection’, as performing these calls requires
some additional inter-thred communication channels to be
created, and code not using these calls should not pay the
cost.
‘MHD_USE_TCP_FASTOPEN’
Enable TCP_FASTOPEN on the listen socket. TCP_FASTOPEN is
currently supported on Linux >= 3.6. On other systems using
this option with cause ‘MHD_start_daemon’ to fail.
‘MHD_ALLOW_UPGRADE’
This option must be set if you want to upgrade connections
(via “101 Switching Protocols” responses). This requires MHD
to allocate additional resources, and hence we require this
special flag so we only use the resources that are really
needed.
‘MHD_USE_AUTO’
Automatically select best event loop style (polling function)
depending on requested mode by other MHD flags and functions
available on platform. If application doesn’t have
requirements for any specific polling function, it’s
recommended to use this flag. This flag is very convenient
for multiplatform applications.
‘MHD_USE_POST_HANDSHAKE_AUTH_SUPPORT’
Tell the TLS library to support post handshake client
authentication. Only useful in combination with
‘MHD_USE_TLS’.
This option will only work if the underyling TLS library
supports it (i.e. GnuTLS after 3.6.3). If the TLS library
does not support it, MHD may ignore the option and proceed
without supporting this features.
‘MHD_USE_INSECURE_TLS_EARLY_DATA’
Tell the TLS library to support TLS v1.3 early data (0-RTT)
with the resulting security drawbacks. Only enable this if
you really know what you are doing. MHD currently does NOT
enforce that this only affects GET requests! You have been
warned.
This option will only work if the underyling TLS library
supports it (i.e. GnuTLS after 3.6.3). If the TLS library
does not support it, MHD may ignore the option and proceed
without supporting this features.
-- Enumeration: MHD_OPTION
MHD options. Passed in the varargs portion of
‘MHD_start_daemon()’.
‘MHD_OPTION_END’
No more options / last option. This is used to terminate the
VARARGs list.
‘MHD_OPTION_CONNECTION_MEMORY_LIMIT’
Maximum memory size per connection (followed by a ‘size_t’).
The default is 32 kB (32*1024 bytes) as defined by the
internal constant ‘MHD_POOL_SIZE_DEFAULT’. Values above 128k
are unlikely to result in much benefit, as half of the memory
will be typically used for IO, and TCP buffers are unlikely to
support window sizes above 64k on most systems.
‘MHD_OPTION_CONNECTION_MEMORY_INCREMENT’
Increment to use for growing the read buffer (followed by a
‘size_t’). The default is 1024 (bytes). Increasing this
value will make MHD use memory for reading more aggressively,
which can reduce the number of ‘recvfrom’ calls but may
increase the number of ‘sendto’ calls. The given value must
fit within MHD_OPTION_CONNECTION_MEMORY_LIMIT.
‘MHD_OPTION_CONNECTION_LIMIT’
Maximum number of concurrent connections to accept (followed
by an ‘unsigned int’). The default is ‘FD_SETSIZE - 4’ (the
maximum number of file descriptors supported by ‘select’ minus
four for ‘stdin’, ‘stdout’, ‘stderr’ and the server socket).
In other words, the default is as large as possible.
If the connection limit is reached, MHD’s behavior depends a
bit on other options. If ‘MHD_USE_ITC’ was given, MHD will
stop accepting connections on the listen socket. This will
cause the operating system to queue connections (up to the
‘listen()’ limit) above the connection limit. Those
connections will be held until MHD is done processing at least
one of the active connections. If ‘MHD_USE_ITC’ is not set,
then MHD will continue to ‘accept()’ and immediately ‘close()’
these connections.
Note that if you set a low connection limit, you can easily
get into trouble with browsers doing request pipelining. For
example, if your connection limit is “1”, a browser may open a
first connection to access your “index.html” file, keep it
open but use a second connection to retrieve CSS files, images
and the like. In fact, modern browsers are typically by
default configured for up to 15 parallel connections to a
single server. If this happens, MHD will refuse to even
accept the second connection until the first connection is
closed — which does not happen until timeout. As a result,
the browser will fail to render the page and seem to hang. If
you expect your server to operate close to the connection
limit, you should first consider using a lower timeout value
and also possibly add a “Connection: close” header to your
response to ensure that request pipelining is not used and
connections are closed immediately after the request has
completed:
MHD_add_response_header (response,
MHD_HTTP_HEADER_CONNECTION,
"close");
‘MHD_OPTION_CONNECTION_TIMEOUT’
After how many seconds of inactivity should a connection
automatically be timed out? (followed by an ‘unsigned int’;
use zero for no timeout). The default is zero (no timeout).
‘MHD_OPTION_NOTIFY_COMPLETED’
Register a function that should be called whenever a request
has been completed (this can be used for application-specific
clean up). Requests that have never been presented to the
application (via ‘MHD_AccessHandlerCallback()’) will not
result in notifications.
This option should be followed by *TWO* pointers. First a
pointer to a function of type ‘MHD_RequestCompletedCallback()’
and second a pointer to a closure to pass to the request
completed callback. The second pointer maybe ‘NULL’.
‘MHD_OPTION_NOTIFY_CONNECTION’
Register a function that should be called when the TCP
connection to a client is opened or closed. Note that
‘MHD_OPTION_NOTIFY_COMPLETED’ and the ‘con_cls’ argument to
the ‘MHD_AccessHandlerCallback’ are per HTTP request (and
there can be multiple HTTP requests per TCP connection). The
registered callback is called twice per TCP connection, with
‘MHD_CONNECTION_NOTIFY_STARTED’ and
‘MHD_CONNECTION_NOTIFY_CLOSED’ respectively. An additional
argument can be used to store TCP connection specific
information, which can be retrieved using
‘MHD_CONNECTION_INFO_SOCKET_CONTEXT’ during the lifetime of
the TCP connection. The respective location is not the same
as the HTTP-request-specific ‘con_cls’ from the
‘MHD_AccessHandlerCallback’.
This option should be followed by *TWO* pointers. First a
pointer to a function of type ‘MHD_NotifyConnectionCallback()’
and second a pointer to a closure to pass to the request
completed callback. The second pointer maybe ‘NULL’.
‘MHD_OPTION_PER_IP_CONNECTION_LIMIT’
Limit on the number of (concurrent) connections made to the
server from the same IP address. Can be used to prevent one
IP from taking over all of the allowed connections. If the
same IP tries to establish more than the specified number of
connections, they will be immediately rejected. The option
should be followed by an ‘unsigned int’. The default is zero,
which means no limit on the number of connections from the
same IP address.
‘MHD_OPTION_LISTEN_BACKLOG_SIZE’
Set the size of the ‘listen()’ back log queue of the TCP
socket. Takes an ‘unsigned int’ as the argument. Default is
the platform-specific value of ‘SOMAXCONN’.
‘MHD_OPTION_STRICT_FOR_CLIENT’
Specify how strict we should enforce the HTTP protocol. Takes
an ‘int’ as the argument. Default is zero.
If set to 1, MHD will be strict about the protocol.
Specifically, at the moment, this flag uses MHD to reject HTTP
1.1 connections without a "Host" header. This is required by
the standard, but of course in violation of the "be as liberal
as possible in what you accept" norm. It is recommended to
set this to 1 if you are testing clients against MHD, and 0 in
production.
If set to -1 MHD will be permissive about the protocol,
allowing slight deviations that are technically not allowed by
the RFC. Specifically, at the moment, this flag causes MHD to
allow spaces in header field names. This is disallowed by the
standard.
It is not recommended to set it to -1 on publicly available
servers as it may potentially lower level of protection.
‘MHD_OPTION_SOCK_ADDR’
Bind daemon to the supplied socket address. This option
should be followed by a ‘struct sockaddr *’. If
‘MHD_USE_IPv6’ is specified, the ‘struct sockaddr*’ should
point to a ‘struct sockaddr_in6’, otherwise to a ‘struct
sockaddr_in’. If this option is not specified, the daemon
will listen to incoming connections from anywhere. If you use
this option, the ’port’ argument from ‘MHD_start_daemon’ is
ignored and the port from the given ‘struct sockaddr *’ will
be used instead.
‘MHD_OPTION_URI_LOG_CALLBACK’
Specify a function that should be called before parsing the
URI from the client. The specified callback function can be
used for processing the URI (including the options) before it
is parsed. The URI after parsing will no longer contain the
options, which maybe inconvenient for logging. This option
should be followed by two arguments, the first one must be of
the form
void * my_logger(void * cls, const char * uri, struct MHD_Connection *con)
where the return value will be passed as ‘*con_cls’ in calls
to the ‘MHD_AccessHandlerCallback’ when this request is
processed later; returning a value of ‘NULL’ has no special
significance; (however, note that if you return non-‘NULL’,
you can no longer rely on the first call to the access handler
having ‘NULL == *con_cls’ on entry) ‘cls’ will be set to the
second argument following MHD_OPTION_URI_LOG_CALLBACK.
Finally, ‘uri’ will be the 0-terminated URI of the request.
Note that during the time of this call, most of the
connection’s state is not initialized (as we have not yet
parsed he headers). However, information about the connecting
client (IP, socket) is available.
‘MHD_OPTION_HTTPS_MEM_KEY’
Memory pointer to the private key to be used by the HTTPS
daemon. This option should be followed by an "const char*"
argument. This should be used in conjunction with
’MHD_OPTION_HTTPS_MEM_CERT’.
‘MHD_OPTION_HTTPS_KEY_PASSWORD’
Memory pointer to the password that decrypts the private key
to be used by the HTTPS daemon. This option should be
followed by an "const char*" argument. This should be used in
conjunction with ’MHD_OPTION_HTTPS_MEM_KEY’.
The password (or passphrase) is only used immediately during
‘MHD_start_daemon()’. Thus, the application may want to erase
it from memory afterwards for additional security.
‘MHD_OPTION_HTTPS_MEM_CERT’
Memory pointer to the certificate to be used by the HTTPS
daemon. This option should be followed by an "const char*"
argument. This should be used in conjunction with
’MHD_OPTION_HTTPS_MEM_KEY’.
‘MHD_OPTION_HTTPS_MEM_TRUST’
Memory pointer to the CA certificate to be used by the HTTPS
daemon to authenticate and trust clients certificates. This
option should be followed by an "const char*" argument. The
presence of this option activates the request of certificate
to the client. The request to the client is marked optional,
and it is the responsibility of the server to check the
presence of the certificate if needed. Note that most
browsers will only present a client certificate only if they
have one matching the specified CA, not sending any
certificate otherwise.
‘MHD_OPTION_HTTPS_CRED_TYPE’
Daemon credentials type. Either certificate or anonymous,
this option should be followed by one of the values listed in
"enum gnutls_credentials_type_t".
‘MHD_OPTION_HTTPS_PRIORITIES’
SSL/TLS protocol version and ciphers. This option must be
followed by an "const char *" argument specifying the SSL/TLS
protocol versions and ciphers that are acceptable for the
application. The string is passed unchanged to
gnutls_priority_init. If this option is not specified,
“NORMAL” is used.
‘MHD_OPTION_HTTPS_CERT_CALLBACK’
Use a callback to determine which X.509 certificate should be
used for a given HTTPS connection. This option should be
followed by a argument of type
"gnutls_certificate_retrieve_function2 *". This option
provides an alternative to MHD_OPTION_HTTPS_MEM_KEY and
MHD_OPTION_HTTPS_MEM_CERT. You must use this version if
multiple domains are to be hosted at the same IP address using
TLS’s Server Name Indication (SNI) extension. In this case,
the callback is expected to select the correct certificate
based on the SNI information provided. The callback is
expected to access the SNI data using
gnutls_server_name_get(). Using this option requires GnuTLS
3.0 or higher.
‘MHD_OPTION_GNUTLS_PSK_CRED_HANDLER’
Use pre-shared key for TLS credentials. Pass a pointer to
callback of type ‘MHD_PskServerCredentialsCallback’ and a
closure. The function will be called to retrieve the shared
key for a given username.
‘MHD_OPTION_DIGEST_AUTH_RANDOM’
Digest Authentication nonce’s seed.
This option should be followed by two arguments. First an
integer of type "size_t" which specifies the size of the
buffer pointed to by the second argument in bytes. Note that
the application must ensure that the buffer of the second
argument remains allocated and unmodified while the daemon is
running. For security, you SHOULD provide a fresh random
nonce when using MHD with Digest Authentication.
‘MHD_OPTION_NONCE_NC_SIZE’
Size of an array of nonce and nonce counter map. This option
must be followed by an "unsigned int" argument that have the
size (number of elements) of a map of a nonce and a
nonce-counter. If this option is not specified, a default
value of 4 will be used (which might be too small for servers
handling many requests). If you do not use digest
authentication at all, you can specify a value of zero to save
some memory.
You should calculate the value of NC_SIZE based on the number
of connections per second multiplied by your expected session
duration plus a factor of about two for hash table collisions.
For example, if you expect 100 digest-authenticated
connections per second and the average user to stay on your
site for 5 minutes, then you likely need a value of about
60000. On the other hand, if you can only expect only 10
digest-authenticated connections per second, tolerate browsers
getting a fresh nonce for each request and expect a HTTP
request latency of 250 ms, then a value of about 5 should be
fine.
‘MHD_OPTION_LISTEN_SOCKET’
Listen socket to use. Pass a listen socket for MHD to use
(systemd-style). If this option is used, MHD will not open
its own listen socket(s). The argument passed must be of type
"int" and refer to an existing socket that has been bound to a
port and is listening.
‘MHD_OPTION_EXTERNAL_LOGGER’
Use the given function for logging error messages. This
option must be followed by two arguments; the first must be a
pointer to a function of type ’void fun(void * arg, const char
* fmt, va_list ap)’ and the second a pointer of type ’void*’
which will be passed as the "arg" argument to "fun".
Note that MHD will not generate any log messages without the
MHD_USE_ERROR_LOG flag set and if MHD was compiled with the
"–disable-messages" flag.
‘MHD_OPTION_THREAD_POOL_SIZE’
Number (unsigned int) of threads in thread pool. Enable
thread pooling by setting this value to to something greater
than 1. Currently, thread mode must be
MHD_USE_INTERNAL_POLLING_THREAD if thread pooling is enabled
(‘MHD_start_daemon’ returns ‘NULL’ for an unsupported thread
mode).
‘MHD_OPTION_ARRAY’
This option can be used for initializing MHD using options
from an array. A common use for this is writing an FFI for
MHD. The actual options given are in an array of ’struct
MHD_OptionItem’, so this option requires a single argument of
type ’struct MHD_OptionItem’. The array must be terminated
with an entry ‘MHD_OPTION_END’.
An example for code using MHD_OPTION_ARRAY is:
struct MHD_OptionItem ops[] = {
{ MHD_OPTION_CONNECTION_LIMIT, 100, NULL },
{ MHD_OPTION_CONNECTION_TIMEOUT, 10, NULL },
{ MHD_OPTION_END, 0, NULL }
};
d = MHD_start_daemon(0, 8080, NULL, NULL, dh, NULL,
MHD_OPTION_ARRAY, ops,
MHD_OPTION_END);
For options that expect a single pointer argument, the second
member of the ‘struct MHD_OptionItem’ is ignored. For options
that expect two pointer arguments, the first argument must be
cast to ‘intptr_t’.
‘MHD_OPTION_UNESCAPE_CALLBACK’
Specify a function that should be called for unescaping escape
sequences in URIs and URI arguments. Note that this function
will NOT be used by the MHD_PostProcessor. If this option is
not specified, the default method will be used which decodes
escape sequences of the form "%HH". This option should be
followed by two arguments, the first one must be of the form
size_t my_unescaper(void * cls, struct MHD_Connection *c, char *s)
where the return value must be ‘strlen(s)’ and ‘s’ should be
updated. Note that the unescape function must not lengthen
‘s’ (the result must be shorter than the input and still be
0-terminated). ‘cls’ will be set to the second argument
following MHD_OPTION_UNESCAPE_CALLBACK.
‘MHD_OPTION_THREAD_STACK_SIZE’
Maximum stack size for threads created by MHD. This option
must be followed by a ‘size_t’). Not specifying this option
or using a value of zero means using the system default (which
is likely to differ based on your platform).
‘MHD_OPTION_TCP_FASTQUEUE_QUEUE_SIZE’
When the flag ‘MHD_USE_TCP_FASTOPEN’ is used, this option sets
the connection handshake queue size for the TCP FASTOPEN
connections. Note that a TCP FASTOPEN connection handshake
occupies more resources than a TCP handshake as the SYN
packets also contain DATA which is kept in the associate state
until handshake is completed. If this option is not given the
queue size is set to a default value of 10. This option must
be followed by a ‘unsigned int’.
‘MHD_OPTION_HTTPS_MEM_DHPARAMS’
Memory pointer for the Diffie-Hellman parameters (dh.pem) to
be used by the HTTPS daemon for key exchange. This option
must be followed by a ‘const char *’ argument. The argument
would be a zero-terminated string with a PEM encoded PKCS3 DH
parameters structure suitable for passing to
‘gnutls_dh_parms_import_pkcs3’.
‘MHD_OPTION_LISTENING_ADDRESS_REUSE’
This option must be followed by a ‘unsigned int’ argument. If
this option is present and true (nonzero) parameter is given,
allow reusing the address:port of the listening socket (using
‘SO_REUSEPORT’ on most platforms, and ‘SO_REUSEADDR’ on
Windows). If a false (zero) parameter is given, disallow
reusing the the address:port of the listening socket (this
usually requires no special action, but ‘SO_EXCLUSIVEADDRUSE’
is needed on Windows). If this option is not present
‘SO_REUSEADDR’ is used on all platforms except Windows so
reusing of address:port is disallowed.
-- C Struct: MHD_OptionItem
Entry in an MHD_OPTION_ARRAY. See the ‘MHD_OPTION_ARRAY’ option
argument for its use.
The ‘option’ member is used to specify which option is specified in
the array. The other members specify the respective argument.
Note that for options taking only a single pointer, the ‘ptr_value’
member should be set. For options taking two pointer arguments,
the first pointer must be cast to ‘intptr_t’ and both the ‘value’
and the ‘ptr_value’ members should be used to pass the two
pointers.
-- Enumeration: MHD_ValueKind
The ‘MHD_ValueKind’ specifies the source of the key-value pairs in
the HTTP protocol.
‘MHD_HEADER_KIND’
HTTP header.
‘MHD_COOKIE_KIND’
Cookies. Note that the original HTTP header containing the
cookie(s) will still be available and intact.
‘MHD_POSTDATA_KIND’
‘POST’ data. This is available only if a content encoding
supported by MHD is used (currently only URL encoding), and
only if the posted content fits within the available memory
pool. Note that in that case, the upload data given to the
‘MHD_AccessHandlerCallback()’ will be empty (since it has
already been processed).
‘MHD_GET_ARGUMENT_KIND’
‘GET’ (URI) arguments.
‘MHD_FOOTER_KIND’
HTTP footer (only for http 1.1 chunked encodings).
-- Enumeration: MHD_RequestTerminationCode
The ‘MHD_RequestTerminationCode’ specifies reasons why a request
has been terminated (or completed).
‘MHD_REQUEST_TERMINATED_COMPLETED_OK’
We finished sending the response.
‘MHD_REQUEST_TERMINATED_WITH_ERROR’
Error handling the connection (resources exhausted, other side
closed connection, application error accepting request, etc.)
‘MHD_REQUEST_TERMINATED_TIMEOUT_REACHED’
No activity on the connection for the number of seconds
specified using ‘MHD_OPTION_CONNECTION_TIMEOUT’.
‘MHD_REQUEST_TERMINATED_DAEMON_SHUTDOWN’
We had to close the session since MHD was being shut down.
-- Enumeration: MHD_ResponseMemoryMode
The ‘MHD_ResponeMemoryMode’ specifies how MHD should treat the
memory buffer given for the response in
‘MHD_create_response_from_buffer’.
‘MHD_RESPMEM_PERSISTENT’
Buffer is a persistent (static/global) buffer that won’t
change for at least the lifetime of the response, MHD should
just use it, not free it, not copy it, just keep an alias to
it.
‘MHD_RESPMEM_MUST_FREE’
Buffer is heap-allocated with ‘malloc’ (or equivalent) and
should be freed by MHD after processing the response has
concluded (response reference counter reaches zero).
‘MHD_RESPMEM_MUST_COPY’
Buffer is in transient memory, but not on the heap (for
example, on the stack or non-malloc allocated) and only valid
during the call to ‘MHD_create_response_from_buffer’. MHD
must make its own private copy of the data for processing.
-- Enumeration: MHD_ResponseFlags
Response-specific flags. Passed as an argument to
‘MHD_set_response_options()’.
‘MHD_RF_NONE’
No special handling.
‘MHD_RF_HTTP_VERSION_1_0_ONLY’
Only respond in conservative HTTP 1.0-mode. In particular, do
not (automatically) sent "Connection" headers and always close
the connection after generating the response.
By default, MHD will respond using the same HTTP version which
was set in the request. You can also set the
‘MHD_RF_HTTP_VERSION_1_0_RESPONSE’ flag to force version 1.0
in the response.
‘MHD_RF_HTTP_VERSION_1_0_RESPONSE’
Only respond in HTTP 1.0-mode. Contrary to the
‘MHD_RF_HTTP_VERSION_1_0_ONLY’ flag, the response’s HTTP
version will always be set to 1.0 and “Connection” headers are
still supported.
You can even combine this option with
MHD_RF_HTTP_VERSION_1_0_ONLY to change the response’s HTTP
version while maintaining strict compliance with HTTP 1.0
regarding connection management.
This solution is not perfect as this flag is set on the
response which is created after header processing. So MHD
will behave as a HTTP 1.1 server until the response is queued.
It means that an invalid HTTP 1.1 request will fail even if
the response is sent with HTTP 1.0 and the request would be
valid if interpreted with this version. For example, this
request will fail in strict mode:
GET / HTTP/1.1
as the “Host” header is missing and is mandatory in HTTP 1.1,
but it should succeed when interpreted with HTTP 1.0.
-- Enumeration: MHD_ResponseOptions
Response-specific options. Passed in the varargs portion of
‘MHD_set_response_options()’.
‘MHD_RO_END’
No more options / last option. This is used to terminate the
VARARGs list.

File: libmicrohttpd.info, Node: microhttpd-struct, Next: microhttpd-cb, Prev: microhttpd-const, Up: Top
3 Structures type definition
****************************
-- C Struct: MHD_Daemon
Handle for the daemon (listening on a socket for HTTP traffic).
-- C Struct: MHD_Connection
Handle for a connection / HTTP request. With HTTP/1.1, multiple
requests can be run over the same connection. However, MHD will
only show one request per TCP connection to the client at any given
time.
-- C Struct: MHD_Response
Handle for a response.
-- C Struct: MHD_PostProcessor
Handle for ‘POST’ processing.
-- C Union: MHD_ConnectionInfo
Information about a connection.
-- C Union: MHD_DaemonInfo
Information about an MHD daemon.

File: libmicrohttpd.info, Node: microhttpd-cb, Next: microhttpd-init, Prev: microhttpd-struct, Up: Top
4 Callback functions definition
*******************************
-- Function Pointer: int *MHD_AcceptPolicyCallback (void *cls, const
struct sockaddr * addr, socklen_t addrlen)
Invoked in the context of a connection to allow or deny a client to
connect. This callback return ‘MHD_YES’ if connection is allowed,
‘MHD_NO’ if not.
CLS
custom value selected at callback registration time;
ADDR
address information from the client;
ADDRLEN
length of the address information.
-- Function Pointer: int *MHD_AccessHandlerCallback (void *cls, struct
MHD_Connection * connection, const char *url, const char
*method, const char *version, const char *upload_data, size_t
*upload_data_size, void **con_cls)
Invoked in the context of a connection to answer a request from the
client. This callback must call MHD functions (example: the
‘MHD_Response’ ones) to provide content to give back to the client
and return an HTTP status code (i.e. ‘200’ for OK, ‘404’, etc.).
*note microhttpd-post::, for details on how to code this callback.
Must return ‘MHD_YES’ if the connection was handled successfully,
‘MHD_NO’ if the socket must be closed due to a serious error while
handling the request
CLS
custom value selected at callback registration time;
URL
the URL requested by the client;
METHOD
the HTTP method used by the client (‘GET’, ‘PUT’, ‘DELETE’,
‘POST’, etc.);
VERSION
the HTTP version string (i.e. ‘HTTP/1.1’);
UPLOAD_DATA
the data being uploaded (excluding headers):
‘POST’ data *will* be made available incrementally in
UPLOAD_DATA; even if ‘POST’ data is available, the first time
the callback is invoked there won’t be upload data, as this is
done just after MHD parses the headers. If supported by the
client and the HTTP version, the application can at this point
queue an error response to possibly avoid the upload entirely.
If no response is generated, MHD will (if required)
automatically send a 100 CONTINUE reply to the client.
Afterwards, POST data will be passed to the callback to be
processed incrementally by the application. The application
may return ‘MHD_NO’ to forcefully terminate the TCP connection
without generating a proper HTTP response. Once all of the
upload data has been provided to the application, the
application will be called again with 0 bytes of upload data.
At this point, a response should be queued to complete the
handling of the request.
UPLOAD_DATA_SIZE
set initially to the size of the UPLOAD_DATA provided; this
callback must update this value to the number of bytes *NOT*
processed; unless external select is used, the callback maybe
required to process at least some data. If the callback fails
to process data in multi-threaded or internal-select mode and
if the read-buffer is already at the maximum size that MHD is
willing to use for reading (about half of the maximum amount
of memory allowed for the connection), then MHD will abort
handling the connection and return an internal server error to
the client. In order to avoid this, clients must be able to
process upload data incrementally and reduce the value of
‘upload_data_size’.
CON_CLS
reference to a pointer, initially set to ‘NULL’, that this
callback can set to some address and that will be preserved by
MHD for future calls for this request;
since the access handler may be called many times (i.e., for a
‘PUT’/‘POST’ operation with plenty of upload data) this allows
the application to easily associate some request-specific
state;
if necessary, this state can be cleaned up in the global
‘MHD_RequestCompletedCallback’ (which can be set with the
‘MHD_OPTION_NOTIFY_COMPLETED’).
-- Function Pointer: void *MHD_RequestCompletedCallback (void *cls,
struct MHD_Connectionconnection, void **con_cls, enum
MHD_RequestTerminationCode toe)
Signature of the callback used by MHD to notify the application
about completed requests.
CLS
custom value selected at callback registration time;
CONNECTION
connection handle;
CON_CLS
value as set by the last call to the
‘MHD_AccessHandlerCallback’;
TOE
reason for request termination see
‘MHD_OPTION_NOTIFY_COMPLETED’.
-- Function Pointer: int *MHD_KeyValueIterator (void *cls, enum
MHD_ValueKind kind, const char *key, const char *value, size_t
value_size)
Iterator over key-value pairs. This iterator can be used to
iterate over all of the cookies, headers, or ‘POST’-data fields of
a request, and also to iterate over the headers that have been
added to a response.
CLS
custom value specified when iteration was triggered;
KIND
kind of the header we are looking at
KEY
key for the value, can be an empty string
VALUE
value corresponding value, can be NULL
VALUE_SIZE
number of bytes in ‘value’. This argument was introduced in
‘MHD_VERSION’ 0x00096301 to allow applications to use binary
zeros in values. Applications using this argument must ensure
that they are using a sufficiently recent version of MHD, i.e.
by testing ‘MHD_get_version()’ for values above or equal to
0.9.64. Applications that do not need zeros in values and
that want to compile without warnings against newer versions
of MHD should not declare this argument and cast the function
pointer argument to ‘MHD_KeyValueIterator’.
Return ‘MHD_YES’ to continue iterating, ‘MHD_NO’ to abort the
iteration.
-- Function Pointer: int *MHD_ContentReaderCallback (void *cls,
uint64_t pos, char *buf, size_t max)
Callback used by MHD in order to obtain content. The callback has
to copy at most MAX bytes of content into BUF. The total number of
bytes that has been placed into BUF should be returned.
Note that returning zero will cause MHD to try again. Thus,
returning zero should only be used in conjunction with
‘MHD_suspend_connection()’ to avoid busy waiting.
While usually the callback simply returns the number of bytes
written into BUF, there are two special return value:
‘MHD_CONTENT_READER_END_OF_STREAM’ (-1) should be returned for the
regular end of transmission (with chunked encoding, MHD will then
terminate the chunk and send any HTTP footers that might be
present; without chunked encoding and given an unknown response
size, MHD will simply close the connection; note that while
returning ‘MHD_CONTENT_READER_END_OF_STREAM’ is not technically
legal if a response size was specified, MHD accepts this and treats
it just as ‘MHD_CONTENT_READER_END_WITH_ERROR’.
‘MHD_CONTENT_READER_END_WITH_ERROR’ (-2) is used to indicate a
server error generating the response; this will cause MHD to simply
close the connection immediately. If a response size was given or
if chunked encoding is in use, this will indicate an error to the
client. Note, however, that if the client does not know a response
size and chunked encoding is not in use, then clients will not be
able to tell the difference between
‘MHD_CONTENT_READER_END_WITH_ERROR’ and
‘MHD_CONTENT_READER_END_OF_STREAM’. This is not a limitation of
MHD but rather of the HTTP protocol.
CLS
custom value selected at callback registration time;
POS
position in the datastream to access; note that if an
‘MHD_Response’ object is re-used, it is possible for the same
content reader to be queried multiple times for the same data;
however, if an ‘MHD_Response’ is not re-used, MHD guarantees
that POS will be the sum of all non-negative return values
obtained from the content reader so far.
Return ‘-1’ on error (MHD will no longer try to read content and
instead close the connection with the client).
-- Function Pointer: void *MHD_ContentReaderFreeCallback (void *cls)
This method is called by MHD if we are done with a content reader.
It should be used to free resources associated with the content
reader.
-- Function Pointer: int *MHD_PostDataIterator (void *cls, enum
MHD_ValueKind kind, const char *key, const char *filename,
const char *content_type, const char *transfer_encoding, const
char *data, uint64_t off, size_t size)
Iterator over key-value pairs where the value maybe made available
in increments and/or may not be zero-terminated. Used for
processing ‘POST’ data.
CLS
custom value selected at callback registration time;
KIND
type of the value;
KEY
zero-terminated key for the value;
FILENAME
name of the uploaded file, ‘NULL’ if not known;
CONTENT_TYPE
mime-type of the data, ‘NULL’ if not known;
TRANSFER_ENCODING
encoding of the data, ‘NULL’ if not known;
DATA
pointer to size bytes of data at the specified offset;
OFF
offset of data in the overall value;
SIZE
number of bytes in data available.
Return ‘MHD_YES’ to continue iterating, ‘MHD_NO’ to abort the
iteration.

File: libmicrohttpd.info, Node: microhttpd-init, Next: microhttpd-inspect, Prev: microhttpd-cb, Up: Top
5 Starting and stopping the server
**********************************
-- Function: void MHD_set_panic_func (MHD_PanicCallback cb, void *cls)
Set a handler for fatal errors.
CB
function to call if MHD encounters a fatal internal error. If
no handler was set explicitly, MHD will call ‘abort’.
CLS
closure argument for cb; the other arguments are the name of
the source file, line number and a string describing the
nature of the fatal error (which can be ‘NULL’)
-- Function: struct MHD_Daemon * MHD_start_daemon (unsigned int flags,
unsigned short port, MHD_AcceptPolicyCallback apc, void
*apc_cls, MHD_AccessHandlerCallback dh, void *dh_cls, ...)
Start a webserver on the given port.
FLAGS
OR-ed combination of ‘MHD_FLAG’ values;
PORT
port to bind to;
APC
callback to call to check which clients will be allowed to
connect; you can pass ‘NULL’ in which case connections from
any IP will be accepted;
APC_CLS
extra argument to APC;
DH
default handler for all URIs;
DH_CLS
extra argument to DH.
Additional arguments are a list of options (type-value pairs,
terminated with ‘MHD_OPTION_END’). It is mandatory to use
‘MHD_OPTION_END’ as last argument, even when there are no
additional arguments.
Return ‘NULL’ on error, handle to daemon on success.
-- Function: int MHD_quiesce_daemon (struct MHD_Daemon *daemon)
Stop accepting connections from the listening socket. Allows
clients to continue processing, but stops accepting new
connections. Note that the caller is responsible for closing the
returned socket; however, if MHD is run using threads (anything but
external select mode), it must not be closed until AFTER
‘MHD_stop_daemon’ has been called (as it is theoretically possible
that an existing thread is still using it).
This function is useful in the special case that a listen socket is
to be migrated to another process (i.e. a newer version of the
HTTP server) while existing connections should continue to be
processed until they are finished.
Return ‘-1’ on error (daemon not listening), the handle to the
listen socket otherwise.
-- Function: void MHD_stop_daemon (struct MHD_Daemon *daemon)
Shutdown an HTTP daemon.
-- Function: int MHD_run (struct MHD_Daemon *daemon)
Run webserver operations (without blocking unless in client
callbacks). This method should be called by clients in combination
with ‘MHD_get_fdset()’ if the client-controlled ‘select’-method is
used.
This function will work for external ‘poll’ and ‘select’ mode.
However, if using external ‘select’ mode, you may want to instead
use ‘MHD_run_from_select’, as it is more efficient.
DAEMON
daemon to process connections of
Return ‘MHD_YES’ on success, ‘MHD_NO’ if this daemon was not
started with the right options for this call.
-- Function: int MHD_run_from_select (struct MHD_Daemon *daemon, const
fd_set *read_fd_set, const fd_set *write_fd_set, const fd_set
*except_fd_set)
Run webserver operations given sets of ready socket handles.
This method should be called by clients in combination with
‘MHD_get_fdset’ if the client-controlled (external) select method
is used.
You can use this function instead of ‘MHD_run’ if you called
‘select’ on the result from ‘MHD_get_fdset’. File descriptors in
the sets that are not controlled by MHD will be ignored. Calling
this function instead of ‘MHD_run’ is more efficient as MHD will
not have to call ‘select’ again to determine which operations are
ready.
DAEMON
daemon to process connections of
READ_FD_SET
set of descriptors that must be ready for reading without
blocking
WRITE_FD_SET
set of descriptors that must be ready for writing without
blocking
EXCEPT_FD_SET
ignored, can be NULL
Return ‘MHD_YES’ on success, ‘MHD_NO’ on serious internal errors.
-- Function: void MHD_add_connection (struct MHD_Daemon *daemon, int
client_socket, const struct sockaddr *addr, socklen_t addrlen)
Add another client connection to the set of connections managed by
MHD. This API is usually not needed (since MHD will accept inbound
connections on the server socket). Use this API in special cases,
for example if your HTTP server is behind NAT and needs to connect
out to the HTTP client, or if you are building a proxy.
If you use this API in conjunction with a internal select or a
thread pool, you must set the option ‘MHD_USE_ITC’ to ensure that
the freshly added connection is immediately processed by MHD.
The given client socket will be managed (and closed!) by MHD after
this call and must no longer be used directly by the application
afterwards.
DAEMON
daemon that manages the connection
CLIENT_SOCKET
socket to manage (MHD will expect to receive an HTTP request
from this socket next).
ADDR
IP address of the client
ADDRLEN
number of bytes in addr
This function will return ‘MHD_YES’ on success, ‘MHD_NO’ if this
daemon could not handle the connection (i.e. malloc failed, etc).
The socket will be closed in any case; ’errno’ is set to indicate
further details about the error.

File: libmicrohttpd.info, Node: microhttpd-inspect, Next: microhttpd-requests, Prev: microhttpd-init, Up: Top
6 Implementing external ‘select’
********************************
-- Function: int MHD_get_fdset (struct MHD_Daemon *daemon, fd_set *
read_fd_set, fd_set * write_fd_set, fd_set * except_fd_set,
int *max_fd)
Obtain the ‘select()’ sets for this daemon. The daemon’s socket is
added to READ_FD_SET. The list of currently existent connections
is scanned and their file descriptors added to the correct set.
When calling this function, FD_SETSIZE is assumed to be platform’s
default. If you changed FD_SETSIZE for your application, you
should use ‘MHD_get_fdset2()’ instead.
This function should only be called in when MHD is configured to
use external select with ‘select()’ or with ‘epoll()’. In the
latter case, it will only add the single ‘epoll()’ file descriptor
used by MHD to the sets.
After the call completed successfully: the variable referenced by
MAX_FD references the file descriptor with highest integer
identifier. The variable must be set to zero before invoking this
function.
Return ‘MHD_YES’ on success, ‘MHD_NO’ if: the arguments are invalid
(example: ‘NULL’ pointers); this daemon was not started with the
right options for this call.
-- Function: int MHD_get_fdset2 (struct MHD_Daemon *daemon, fd_set *
read_fd_set, fd_set * write_fd_set, fd_set * except_fd_set,
int *max_fd, unsigned int fd_setsize)
Like ‘MHD_get_fdset()’, except that you can manually specify the
value of FD_SETSIZE used by your application.
-- Function: int MHD_get_timeout (struct MHD_Daemon *daemon, unsigned
long long *timeout)
Obtain timeout value for select for this daemon (only needed if
connection timeout is used). The returned value is how many
milliseconds ‘select’ should at most block, not the timeout value
set for connections. This function must not be called if the
‘MHD_USE_THREAD_PER_CONNECTION’ mode is in use (since then it is
not meaningful to ask for a timeout, after all, there is
concurrenct activity). The function must also not be called by
user-code if ‘MHD_USE_INTERNAL_POLLING_THREAD’ is in use. In the
latter case, the behavior is undefined.
DAEMON
which daemon to obtain the timeout from.
TIMEOUT
will be set to the timeout (in milliseconds).
Return ‘MHD_YES’ on success, ‘MHD_NO’ if timeouts are not used (or
no connections exist that would necessiate the use of a timeout
right now).

File: libmicrohttpd.info, Node: microhttpd-requests, Next: microhttpd-responses, Prev: microhttpd-inspect, Up: Top
7 Handling requests
*******************
-- Function: int MHD_get_connection_values (struct MHD_Connection
*connection, enum MHD_ValueKind kind, MHD_KeyValueIterator
iterator, void *iterator_cls)
Get all the headers matching KIND from the request. The KIND
argument can be a bitmask, ORing the various header kinds that are
requested.
The ITERATOR callback is invoked once for each header, with
ITERATOR_CLS as first argument. After version 0.9.19, the headers
are iterated in the same order as they were received from the
network; previous versions iterated over the headers in reverse
order.
‘MHD_get_connection_values’ returns the number of entries iterated
over; this can be less than the number of headers if, while
iterating, ITERATOR returns ‘MHD_NO’.
ITERATOR can be ‘NULL’: in this case this function just counts and
returns the number of headers.
In the case of ‘MHD_GET_ARGUMENT_KIND’, the VALUE argument will be
‘NULL’ if the URL contained a key without an equals operator. For
example, for a HTTP request to the URL “http://foo/bar?key”, the
VALUE argument is ‘NULL’; in contrast, a HTTP request to the URL
“http://foo/bar?key=”, the VALUE argument is the empty string. The
normal case is that the URL contains “http://foo/bar?key=value” in
which case VALUE would be the string “value” and KEY would contain
the string “key”.
-- Function: int MHD_set_connection_value (struct MHD_Connection
*connection, enum MHD_ValueKind kind, const char *key, const
char *value)
This function can be used to append an entry to the list of HTTP
headers of a connection (so that the ‘MHD_get_connection_values
function’ will return them – and the MHD PostProcessor will also
see them). This maybe required in certain situations (see Mantis
#1399) where (broken) HTTP implementations fail to supply values
needed by the post processor (or other parts of the application).
This function MUST only be called from within the
MHD_AccessHandlerCallback (otherwise, access maybe improperly
synchronized). Furthermore, the client must guarantee that the key
and value arguments are 0-terminated strings that are NOT freed
until the connection is closed. (The easiest way to do this is by
passing only arguments to permanently allocated strings.).
CONNECTION is the connection for which the entry for KEY of the
given KIND should be set to the given VALUE.
The function returns ‘MHD_NO’ if the operation could not be
performed due to insufficient memory and ‘MHD_YES’ on success.
-- Function: const char * MHD_lookup_connection_value (struct
MHD_Connection *connection, enum MHD_ValueKind kind, const
char *key)
Get a particular header value. If multiple values match the KIND,
return one of them (the “first”, whatever that means). KEY must
reference a zero-terminated ASCII-coded string representing the
header to look for: it is compared against the headers using
‘strcasecmp()’, so case is ignored. A value of ‘NULL’ for KEY can
be used to lookup ’trailing’ values without a key, for example if a
URI is of the form “http://example.com/?trailer”, a KEY of ‘NULL’
can be used to access “tailer" The function returns ‘NULL’ if no
matching item was found.

File: libmicrohttpd.info, Node: microhttpd-responses, Next: microhttpd-flow, Prev: microhttpd-requests, Up: Top
8 Building responses to requests
********************************
Response objects handling by MHD is asynchronous with respect to the
application execution flow. Instances of the ‘MHD_Response’ structure
are not associated to a daemon and neither to a client connection: they
are managed with reference counting.
In the simplest case: we allocate a new ‘MHD_Response’ structure for
each response, we use it once and finally we destroy it.
MHD allows more efficient resources usages.
Example: we allocate a new ‘MHD_Response’ structure for each response
*kind*, we use it every time we have to give that response and we
finally destroy it only when the daemon shuts down.
* Menu:
* microhttpd-response enqueue:: Enqueuing a response.
* microhttpd-response create:: Creating a response object.
* microhttpd-response headers:: Adding headers to a response.
* microhttpd-response options:: Setting response options.
* microhttpd-response inspect:: Inspecting a response object.
* microhttpd-response upgrade:: Creating a response for protocol upgrades.

File: libmicrohttpd.info, Node: microhttpd-response enqueue, Next: microhttpd-response create, Up: microhttpd-responses
8.1 Enqueuing a response
========================
-- Function: int MHD_queue_response (struct MHD_Connection *connection,
unsigned int status_code, struct MHD_Response *response)
Queue a response to be transmitted to the client as soon as
possible but only after MHD_AccessHandlerCallback returns. This
function checks that it is legal to queue a response at this time
for the given connection. It also increments the internal
reference counter for the response object (the counter will be
decremented automatically once the response has been transmitted).
CONNECTION
the connection identifying the client;
STATUS_CODE
HTTP status code (i.e. ‘200’ for OK);
RESPONSE
response to transmit.
Return ‘MHD_YES’ on success or if message has been queued. Return
‘MHD_NO’: if arguments are invalid (example: ‘NULL’ pointer); on
error (i.e. reply already sent).
-- Function: void MHD_destroy_response (struct MHD_Response *response)
Destroy a response object and associated resources (decrement the
reference counter). Note that MHD may keep some of the resources
around if the response is still in the queue for some clients, so
the memory may not necessarily be freed immediately.
An explanation of reference counting(1):
1. a ‘MHD_Response’ object is allocated:
struct MHD_Response * response = MHD_create_response_from_buffer(...);
/* here: reference counter = 1 */
2. the ‘MHD_Response’ object is enqueued in a ‘MHD_Connection’:
MHD_queue_response(connection, , response);
/* here: reference counter = 2 */
3. the creator of the response object discharges responsibility for
it:
MHD_destroy_response(response);
/* here: reference counter = 1 */
4. the daemon handles the connection sending the response’s data to
the client then decrements the reference counter by calling
‘MHD_destroy_response()’: the counter’s value drops to zero and the
‘MHD_Response’ object is released.
---------- Footnotes ----------
(1) Note to readers acquainted to the Tcl API: reference counting on
‘MHD_Connection’ structures is handled in the same way as Tcl handles
‘Tcl_Obj’ structures through ‘Tcl_IncrRefCount()’ and
‘Tcl_DecrRefCount()’.

File: libmicrohttpd.info, Node: microhttpd-response create, Next: microhttpd-response headers, Prev: microhttpd-response enqueue, Up: microhttpd-responses
8.2 Creating a response object
==============================
-- Function: struct MHD_Response * MHD_create_response_from_callback
(uint64_t size, size_t block_size, MHD_ContentReaderCallback
crc, void *crc_cls, MHD_ContentReaderFreeCallback crfc)
Create a response object. The response object can be extended with
header information and then it can be used any number of times.
SIZE
size of the data portion of the response, ‘-1’ for unknown;
BLOCK_SIZE
preferred block size for querying CRC (advisory only, MHD may
still call CRC using smaller chunks); this is essentially the
buffer size used for IO, clients should pick a value that is
appropriate for IO and memory performance requirements;
CRC
callback to use to obtain response data;
CRC_CLS
extra argument to CRC;
CRFC
callback to call to free CRC_CLS resources.
Return ‘NULL’ on error (i.e. invalid arguments, out of memory).
-- Function: struct MHD_Response * MHD_create_response_from_fd
(uint64_t size, int fd)
Create a response object. The response object can be extended with
header information and then it can be used any number of times.
SIZE
size of the data portion of the response (should be smaller or
equal to the size of the file)
FD
file descriptor referring to a file on disk with the data;
will be closed when response is destroyed; note that ’fd’ must
be an actual file descriptor (not a pipe or socket) since MHD
might use ’sendfile’ or ’seek’ on it. The descriptor should
be in blocking-IO mode.
Return ‘NULL’ on error (i.e. invalid arguments, out of memory).
-- Function: struct MHD_Response *
MHD_create_response_from_fd_at_offset (size_t size, int fd,
off_t offset)
Create a response object. The response object can be extended with
header information and then it can be used any number of times.
Note that you need to be a bit careful about ‘off_t’ when writing
this code. Depending on your platform, MHD is likely to have been
compiled with support for 64-bit files. When you compile your own
application, you must make sure that ‘off_t’ is also a 64-bit
value. If not, your compiler may pass a 32-bit value as ‘off_t’,
which will result in 32-bits of garbage.
If you use the autotools, use the ‘AC_SYS_LARGEFILE’ autoconf macro
and make sure to include the generated ‘config.h’ file before
‘microhttpd.h’ to avoid problems. If you do not have a build
system and only want to run on a GNU/Linux system, you could also
use
#define _FILE_OFFSET_BITS 64
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <microhttpd.h>
to ensure 64-bit ‘off_t’. Note that if your operating system does
not support 64-bit files, MHD will be compiled with a 32-bit
‘off_t’ (in which case the above would be wrong).
SIZE
size of the data portion of the response (number of bytes to
transmit from the file starting at offset).
FD
file descriptor referring to a file on disk with the data;
will be closed when response is destroyed; note that ’fd’ must
be an actual file descriptor (not a pipe or socket) since MHD
might use ’sendfile’ or ’seek’ on it. The descriptor should
be in blocking-IO mode.
OFFSET
offset to start reading from in the file
Return ‘NULL’ on error (i.e. invalid arguments, out of memory).
-- Function: struct MHD_Response * MHD_create_response_from_buffer
(size_t size, void *data, enum MHD_ResponseMemoryMode mode)
Create a response object. The response object can be extended with
header information and then it can be used any number of times.
SIZE
size of the data portion of the response;
BUFFER
the data itself;
MODE
memory management options for buffer; use
MHD_RESPMEM_PERSISTENT if the buffer is static/global memory,
use MHD_RESPMEM_MUST_FREE if the buffer is heap-allocated and
should be freed by MHD and MHD_RESPMEM_MUST_COPY if the buffer
is in transient memory (i.e. on the stack) and must be copied
by MHD;
Return ‘NULL’ on error (i.e. invalid arguments, out of memory).
-- Function: struct MHD_Response *
MHD_create_response_from_buffer_with_free_callback (size_t
size, void *data, MHD_ContentReaderFreeCallback crfc)
Create a response object. The buffer at the end must be free’d by
calling the CRFC function.
SIZE
size of the data portion of the response;
BUFFER
the data itself;
CRFC
function to call at the end to free memory allocated at
BUFFER.
Return ‘NULL’ on error (i.e. invalid arguments, out of memory).
-- Function: struct MHD_Response * MHD_create_response_from_data
(size_t size, void *data, int must_free, int must_copy)
Create a response object. The response object can be extended with
header information and then it can be used any number of times.
This function is deprecated, use ‘MHD_create_response_from_buffer’
instead.
SIZE
size of the data portion of the response;
DATA
the data itself;
MUST_FREE
if true: MHD should free data when done;
MUST_COPY
if true: MHD allocates a block of memory and use it to make a
copy of DATA embedded in the returned ‘MHD_Response’
structure; handling of the embedded memory is responsibility
of MHD; DATA can be released anytime after this call returns.
Return ‘NULL’ on error (i.e. invalid arguments, out of memory).
Example: create a response from a statically allocated string:
const char * data = "<html><body><p>Error!</p></body></html>";
struct MHD_Connection * connection = ...;
struct MHD_Response * response;
response = MHD_create_response_from_buffer (strlen(data), data,
MHD_RESPMEM_PERSISTENT);
MHD_queue_response(connection, 404, response);
MHD_destroy_response(response);

File: libmicrohttpd.info, Node: microhttpd-response headers, Next: microhttpd-response options, Prev: microhttpd-response create, Up: microhttpd-responses
8.3 Adding headers to a response
================================
-- Function: int MHD_add_response_header (struct MHD_Response
*response, const char *header, const char *content)
Add a header line to the response. The strings referenced by
HEADER and CONTENT must be zero-terminated and they are duplicated
into memory blocks embedded in RESPONSE.
Notice that the strings must not hold newlines, carriage returns or
tab chars.
MHD_add_response_header() prevents applications from setting a
“Transfer-Encoding” header to values other than “identity” or
“chunked” as other transfer encodings are not supported by MHD.
Note that usually MHD will pick the transfer encoding correctly
automatically, but applications can use the header to force a
particular behavior.
MHD_add_response_header() also prevents applications from setting a
“Content-Length” header. MHD will automatically set a correct
“Content-Length” header if it is possible and allowed.
Return ‘MHD_NO’ on error (i.e. invalid header or content format or
memory allocation error).
-- Function: int MHD_add_response_footer (struct MHD_Response
*response, const char *footer, const char *content)
Add a footer line to the response. The strings referenced by
FOOTER and CONTENT must be zero-terminated and they are duplicated
into memory blocks embedded in RESPONSE.
Notice that the strings must not hold newlines, carriage returns or
tab chars. You can add response footers at any time before
signalling the end of the response to MHD (not just before calling
’MHD_queue_response’). Footers are useful for adding cryptographic
checksums to the reply or to signal errors encountered during data
generation. This call was introduced in MHD 0.9.3.
Return ‘MHD_NO’ on error (i.e. invalid header or content format or
memory allocation error).
-- Function: int MHD_del_response_header (struct MHD_Response
*response, const char *header, const char *content)
Delete a header (or footer) line from the response. Return
‘MHD_NO’ on error (arguments are invalid or no such header known).

File: libmicrohttpd.info, Node: microhttpd-response options, Next: microhttpd-response inspect, Prev: microhttpd-response headers, Up: microhttpd-responses
8.4 Setting response options
============================
-- Function: int MHD_set_response_options (struct MHD_Response
*response, enum MHD_ResponseFlags flags, ...)
Set special flags and options for a response.
Calling this functions sets the given flags and options for the
response.
RESPONSE
which response should be modified;
FLAGS
flags to set for the response;
Additional arguments are a list of options (type-value pairs,
terminated with ‘MHD_RO_END’). It is mandatory to use ‘MHD_RO_END’
as last argument, even when there are no additional arguments.
Return ‘MHD_NO’ on error, ‘MHD_YES’ on success.

File: libmicrohttpd.info, Node: microhttpd-response inspect, Next: microhttpd-response upgrade, Prev: microhttpd-response options, Up: microhttpd-responses
8.5 Inspecting a response object
================================
-- Function: int MHD_get_response_headers (struct MHD_Response
*response, MHD_KeyValueIterator iterator, void *iterator_cls)
Get all of the headers added to a response.
Invoke the ITERATOR callback for each header in the response, using
ITERATOR_CLS as first argument. Return number of entries iterated
over. ITERATOR can be ‘NULL’: in this case the function just
counts headers.
ITERATOR should not modify the its key and value arguments, unless
we know what we are doing.
-- Function: const char * MHD_get_response_header (struct MHD_Response
*response, const char *key)
Find and return a pointer to the value of a particular header from
the response. KEY must reference a zero-terminated string
representing the header to look for. The search is case sensitive.
Return ‘NULL’ if header does not exist or KEY is ‘NULL’.
We should not modify the value, unless we know what we are doing.

File: libmicrohttpd.info, Node: microhttpd-response upgrade, Prev: microhttpd-response inspect, Up: microhttpd-responses
8.6 Creating a response for protocol upgrades
=============================================
With RFC 2817 a mechanism to switch protocols within HTTP was
introduced. Here, a client sends a request with a “Connection: Upgrade”
header. The server responds with a “101 Switching Protocols” response
header, after which the two parties begin to speak a different
(non-HTTP) protocol over the TCP connection.
This mechanism is used for upgrading HTTP 1.1 connections to HTTP2 or
HTTPS, as well as for implementing WebSockets. Which protocol upgrade
is performed is negotiated between server and client in additional
headers, in particular the “Upgrade” header.
MHD supports switching protocols using this mechanism only if the
‘MHD_ALLOW_SUSPEND_RESUME’ flag has been set when starting the daemon.
If this flag has been set, applications can upgrade a connection by
queueing a response (using the ‘MHD_HTTP_SWITCHING_PROTOCOLS’ status
code) which must have been created with the following function:
-- Function: int MHD_create_response_for_upgrade (MHD_UpgradeHandler
upgrade_handler, void *upgrade_handler_cls)
Create a response suitable for switching protocols. Returns
‘MHD_YES’ on success. ‘upgrade_handler’ must not be ‘NULL’.
When creating this type of response, the “Connection: Upgrade”
header will be set automatically for you. MHD requires that you
additionally set an “Upgrade:” header. The “Upgrade” header must
simply exist, the specific value is completely up to the
application.
The ‘upgrade_handler’ argument to the above has the following type:
-- Function Pointer: void *MHD_UpgradeHandler (void *cls, struct
MHD_Connection *connection, const char *extra_in, size_t
extra_in_size, MHD_socket sock, struct
MHD_UpgradeResponseHandle *urh)
This function will be called once MHD has transmitted the header of
the response to the connection that is being upgraded. At this
point, the application is expected to take over the socket ‘sock’
and speak the non-HTTP protocol to which the connection was
upgraded. MHD will no longer use the socket; this includes
handling timeouts. The application must call ‘MHD_upgrade_action’
with an upgrade action of ‘MHD_UPGRADE_ACTION_CLOSE’ when it is
done processing the connection to close the socket. The
application must not call ‘MHD_stop_daemon’ on the respective
daemon as long as it is still handling the connection. The
arguments given to the ‘upgrade_handler’ have the following
meaning:
CLS
matches the ‘upgrade_handler_cls’ that was given to
‘MHD_create_response_for_upgrade’
CONNECTION
identifies the connection that is being upgraded;
CON_CLS
last value left in ‘*con_cls‘ in the
‘MHD_AccessHandlerCallback‘
EXTRA_IN
buffer of bytes MHD read “by accident” from the socket
already. This can happen if the client eagerly transmits more
than just the HTTP request. The application should treat
these as if it had read them from the socket.
EXTRA_IN_SIZE
number of bytes in ‘extra_in’
SOCK
the socket which the application can now use directly for some
bi-directional communication with the client. The application
can henceforth use ‘recv()’ and ‘send()’ or ‘read()’ and
‘write()’ system calls on the socket. However, ‘ioctl()’ and
‘setsockopt()’ functions will not work as expected when using
HTTPS. Such operations may be supported in the future via
‘MHD_upgrade_action’. Most importantly, the application must
never call ‘close()’ on this socket. Closing the socket must
be done using ‘MHD_upgrade_action’. However, while close is
forbidden, the application may call ‘shutdown()’ on the
socket.
URH
argument for calls to ‘MHD_upgrade_action’. Applications must
eventually use this function to perform the ‘close()’ action
on the socket.
-- Function: int MHD_upgrade_action (struct MHD_UpgradeResponseHandle
*urh, enum MHD_UpgradeAction action, ...)
Perform special operations related to upgraded connections.
URH
identifies the upgraded connection to perform an action on
ACTION
specifies the action to perform; further arguments to the
function depend on the specifics of the action.
-- Enumeration: MHD_UpgradeAction
Set of actions to be performed on upgraded connections. Passed as
an argument to ‘MHD_upgrade_action()’.
‘MHD_UPGRADE_ACTION_CLOSE’
Closes the connection. Must be called once the application is
done with the client. Takes no additional arguments.

File: libmicrohttpd.info, Node: microhttpd-flow, Next: microhttpd-dauth, Prev: microhttpd-responses, Up: Top
9 Flow control.
***************
Sometimes it may be possible that clients upload data faster than an
application can process it, or that an application needs an extended
period of time to generate a response. If
‘MHD_USE_THREAD_PER_CONNECTION’ is used, applications can simply deal
with this by performing their logic within the thread and thus
effectively blocking connection processing by MHD. In all other modes,
blocking logic must not be placed within the callbacks invoked by MHD as
this would also block processing of other requests, as a single thread
may be responsible for tens of thousands of connections.
Instead, applications using thread modes other than
‘MHD_USE_THREAD_PER_CONNECTION’ should use the following functions to
perform flow control.
-- Function: int MHD_suspend_connection (struct MHD_Connection
*connection)
Suspend handling of network data for a given connection. This can
be used to dequeue a connection from MHD’s event loop (external
select, internal select or thread pool; not applicable to
thread-per-connection!) for a while.
If you use this API in conjunction with a internal select or a
thread pool, you must set the option ‘MHD_ALLOW_SUSPEND_RESUME’ to
ensure that a resumed connection is immediately processed by MHD.
Suspended connections continue to count against the total number of
connections allowed (per daemon, as well as per IP, if such limits
are set). Suspended connections will NOT time out; timeouts will
restart when the connection handling is resumed. While a
connection is suspended, MHD will not detect disconnects by the
client.
The only safe time to suspend a connection is from the
‘MHD_AccessHandlerCallback’ or from the respective
‘MHD_ContentReaderCallback’ (but in this case the response object
must not be shared among multiple connections).
Finally, it is an API violation to call ‘MHD_stop_daemon’ while
having suspended connections (this will at least create memory and
socket leaks or lead to undefined behavior). You must explicitly
resume all connections before stopping the daemon.
CONNECTION
the connection to suspend
-- Function: int MHD_resume_connection (struct MHD_Connection
*connection)
Resume handling of network data for suspended connection. It is
safe to resume a suspended connection at any time. Calling this
function on a connection that was not previously suspended will
result in undefined behavior.
If you are using this function in “external” select mode, you must
make sure to run ‘MHD_run’ afterwards (before again calling
‘MHD_get_fdset’), as otherwise the change may not be reflected in
the set returned by ‘MHD_get_fdset’ and you may end up with a
connection that is stuck until the next network activity.
You can check whether a connection is currently suspended using
‘MHD_get_connection_info’ by querying for
‘MHD_CONNECTION_INFO_CONNECTION_SUSPENDED’.
CONNECTION
the connection to resume

File: libmicrohttpd.info, Node: microhttpd-dauth, Next: microhttpd-post, Prev: microhttpd-flow, Up: Top
10 Utilizing Authentication
***************************
MHD support three types of client authentication.
Basic authentication uses a simple authentication method based on
BASE64 algorithm. Username and password are exchanged in clear between
the client and the server, so this method must only be used for
non-sensitive content or when the session is protected with https. When
using basic authentication MHD will have access to the clear password,
possibly allowing to create a chained authentication toward an external
authentication server.
Digest authentication uses a one-way authentication method based on
MD5 hash algorithm. Only the hash will transit over the network, hence
protecting the user password. The nonce will prevent replay attacks.
This method is appropriate for general use, especially when https is not
used to encrypt the session.
Client certificate authentication uses a X.509 certificate from the
client. This is the strongest authentication mechanism but it requires
the use of HTTPS. Client certificate authentication can be used
simultaneously with Basic or Digest Authentication in order to provide a
two levels authentication (like for instance separate machine and user
authentication). A code example for using client certificates is
presented in the MHD tutorial.
* Menu:
* microhttpd-dauth basic:: Using Basic Authentication.
* microhttpd-dauth digest:: Using Digest Authentication.

File: libmicrohttpd.info, Node: microhttpd-dauth basic, Next: microhttpd-dauth digest, Up: microhttpd-dauth
10.1 Using Basic Authentication
===============================
-- Function: void MHD_free (void *ptr)
Free the memory given at ‘ptr’. Used to free data structures
allocated by MHD. Calls ‘free(ptr)’.
-- Function: char * MHD_basic_auth_get_username_password (struct
MHD_Connection *connection, char** password)
Get the username and password from the basic authorization header
sent by the client. Return ‘NULL’ if no username could be found, a
pointer to the username if found. If returned value is not ‘NULL’,
the value must be ‘MHD_free()’’ed.
PASSWORD reference a buffer to store the password. It can be
‘NULL’. If returned value is not ‘NULL’, the value must be
‘MHD_free()’’ed.
-- Function: int MHD_queue_basic_auth_fail_response (struct
MHD_Connection *connection, const char *realm, struct
MHD_Response *response)
Queues a response to request basic authentication from the client.
Return ‘MHD_YES’ if successful, otherwise ‘MHD_NO’.
REALM must reference to a zero-terminated string representing the
realm.
RESPONSE a response structure to specify what shall be presented to
the client with a 401 HTTP status.

File: libmicrohttpd.info, Node: microhttpd-dauth digest, Prev: microhttpd-dauth basic, Up: microhttpd-dauth
10.2 Using Digest Authentication
================================
MHD supports MD5 (deprecated by IETF) and SHA-256 hash algorithms for
digest authentication. The ‘MHD_DigestAuthAlgorithm’ enumeration is
used to specify which algorithm should be used.
-- Enumeration: MHD_DigestAuthAlgorithm
Which digest algorithm should be used. Must be used consistently.
‘MHD_DIGEST_ALG_AUTO’
Have MHD pick an algorithm currently considered secure. For
now defaults to SHA-256.
‘MHD_DIGEST_ALG_MD5’
Force use of (deprecated, ancient, insecure) MD5.
‘MHD_DIGEST_ALG_SHA256’
Force use of SHA-256.
-- Function: char * MHD_digest_auth_get_username (struct MHD_Connection
*connection)
Find and return a pointer to the username value from the request
header. Return ‘NULL’ if the value is not found or header does not
exist. If returned value is not ‘NULL’, the value must be
‘MHD_free()’’ed.
-- Function: int MHD_digest_auth_check2 (struct MHD_Connection
*connection, const char *realm, const char *username, const
char *password, unsigned int nonce_timeout, enum
MHD_DigestAuthAlgorithm algo)
Checks if the provided values in the WWW-Authenticate header are
valid and sound according to RFC2716. If valid return ‘MHD_YES’,
otherwise return ‘MHD_NO’.
REALM must reference to a zero-terminated string representing the
realm.
USERNAME must reference to a zero-terminated string representing
the username, it is usually the returned value from
MHD_digest_auth_get_username.
PASSWORD must reference to a zero-terminated string representing
the password, most probably it will be the result of a lookup of
the username against a local database.
NONCE_TIMEOUT is the amount of time in seconds for a nonce to be
invalid. Most of the time it is sound to specify 300 seconds as
its values.
ALGO which digest algorithm should we use.
-- Function: int MHD_digest_auth_check (struct MHD_Connection
*connection, const char *realm, const char *username, const
char *password, unsigned int nonce_timeout)
Checks if the provided values in the WWW-Authenticate header are
valid and sound according to RFC2716. If valid return ‘MHD_YES’,
otherwise return ‘MHD_NO’. Deprecated, use
‘MHD_digest_auth_check2’ instead.
REALM must reference to a zero-terminated string representing the
realm.
USERNAME must reference to a zero-terminated string representing
the username, it is usually the returned value from
MHD_digest_auth_get_username.
PASSWORD must reference to a zero-terminated string representing
the password, most probably it will be the result of a lookup of
the username against a local database.
NONCE_TIMEOUT is the amount of time in seconds for a nonce to be
invalid. Most of the time it is sound to specify 300 seconds as
its values.
-- Function: int MHD_digest_auth_check_digest2 (struct MHD_Connection
*connection, const char *realm, const char *username, const
uint8_t *digest, unsigned int nonce_timeout, enum
MHD_DigestAuthAlgorithm algo)
Checks if the provided values in the WWW-Authenticate header are
valid and sound according to RFC2716. If valid return ‘MHD_YES’,
otherwise return ‘MHD_NO’.
REALM must reference to a zero-terminated string representing the
realm.
USERNAME must reference to a zero-terminated string representing
the username, it is usually the returned value from
MHD_digest_auth_get_username.
DIGEST pointer to the binary MD5 sum for the precalculated hash
value “userame:realm:password”. The size must match the selected
ALGO!
NONCE_TIMEOUT is the amount of time in seconds for a nonce to be
invalid. Most of the time it is sound to specify 300 seconds as
its values.
ALGO digest authentication algorithm to use.
-- Function: int MHD_digest_auth_check_digest (struct MHD_Connection
*connection, const char *realm, const char *username, const
unsigned char digest[MHD_MD5_DIGEST_SIZE], unsigned int
nonce_timeout)
Checks if the provided values in the WWW-Authenticate header are
valid and sound according to RFC2716. If valid return ‘MHD_YES’,
otherwise return ‘MHD_NO’. Deprecated, use
‘MHD_digest_auth_check_digest2’ instead.
REALM must reference to a zero-terminated string representing the
realm.
USERNAME must reference to a zero-terminated string representing
the username, it is usually the returned value from
MHD_digest_auth_get_username.
DIGEST pointer to the binary MD5 sum for the precalculated hash
value “userame:realm:password” of ‘MHD_MD5_DIGEST_SIZE’ bytes.
NONCE_TIMEOUT is the amount of time in seconds for a nonce to be
invalid. Most of the time it is sound to specify 300 seconds as
its values.
-- Function: int MHD_queue_auth_fail_response2 (struct MHD_Connection
*connection, const char *realm, const char *opaque, struct
MHD_Response *response, int signal_stale, enum
MHD_DigestAuthAlgorithm algo)
Queues a response to request authentication from the client, return
‘MHD_YES’ if successful, otherwise ‘MHD_NO’.
REALM must reference to a zero-terminated string representing the
realm.
OPAQUE must reference to a zero-terminated string representing a
value that gets passed to the client and expected to be passed
again to the server as-is. This value can be a hexadecimal or
base64 string.
RESPONSE a response structure to specify what shall be presented to
the client with a 401 HTTP status.
SIGNAL_STALE a value that signals "stale=true" in the response
header to indicate the invalidity of the nonce and no need to ask
for authentication parameters and only a new nonce gets generated.
‘MHD_YES’ to generate a new nonce, ‘MHD_NO’ to ask for
authentication parameters.
ALGO which digest algorithm should we use. The same algorithm must
then be selected when checking digests received from clients!
-- Function: int MHD_queue_auth_fail_response (struct MHD_Connection
*connection, const char *realm, const char *opaque, struct
MHD_Response *response, int signal_stale)
Queues a response to request authentication from the client, return
‘MHD_YES’ if successful, otherwise ‘MHD_NO’.
REALM must reference to a zero-terminated string representing the
realm.
OPAQUE must reference to a zero-terminated string representing a
value that gets passed to the client and expected to be passed
again to the server as-is. This value can be a hexadecimal or
base64 string.
RESPONSE a response structure to specify what shall be presented to
the client with a 401 HTTP status.
SIGNAL_STALE a value that signals "stale=true" in the response
header to indicate the invalidity of the nonce and no need to ask
for authentication parameters and only a new nonce gets generated.
‘MHD_YES’ to generate a new nonce, ‘MHD_NO’ to ask for
authentication parameters.
Example: handling digest authentication requests and responses.
#define PAGE "<html><head><title>libmicrohttpd demo</title></head><body>Access granted</body></html>"
#define DENIED "<html><head><title>libmicrohttpd demo</title></head><body>Access denied</body></html>"
#define OPAQUE "11733b200778ce33060f31c9af70a870ba96ddd4"
static int
ahc_echo (void *cls,
struct MHD_Connection *connection,
const char *url,
const char *method,
const char *version,
const char *upload_data, size_t *upload_data_size, void **ptr)
{
struct MHD_Response *response;
char *username;
const char *password = "testpass";
const char *realm = "test@example.com";
int ret;
username = MHD_digest_auth_get_username (connection);
if (username == NULL)
{
response = MHD_create_response_from_buffer(strlen (DENIED),
DENIED,
MHD_RESPMEM_PERSISTENT);
ret = MHD_queue_auth_fail_response2 (connection,
realm,
OPAQUE,
response,
MHD_NO,
MHD_DIGEST_ALG_SHA256);
MHD_destroy_response(response);
return ret;
}
ret = MHD_digest_auth_check2 (connection,
realm,
username,
password,
300,
MHD_DIGEST_ALG_SHA256);
free(username);
if ( (ret == MHD_INVALID_NONCE) ||
(ret == MHD_NO) )
{
response = MHD_create_response_from_buffer(strlen (DENIED),
DENIED,
MHD_RESPMEM_PERSISTENT);
if (NULL == response)
return MHD_NO;
ret = MHD_queue_auth_fail_response2 (connection,
realm,
OPAQUE,
response,
(ret == MHD_INVALID_NONCE) ? MHD_YES : MHD_NO,
MHD_DIGEST_ALG_SHA256);
MHD_destroy_response(response);
return ret;
}
response = MHD_create_response_from_buffer (strlen(PAGE),
PAGE,
MHD_RESPMEM_PERSISTENT);
ret = MHD_queue_response (connection,
MHD_HTTP_OK,
response);
MHD_destroy_response(response);
return ret;
}

File: libmicrohttpd.info, Node: microhttpd-post, Next: microhttpd-info, Prev: microhttpd-dauth, Up: Top
11 Adding a ‘POST’ processor
****************************
* Menu:
* microhttpd-post api:: Programming interface for the
‘POST’ processor.
MHD provides the post processor API to make it easier for applications
to parse the data of a client’s ‘POST’ request: the
‘MHD_AccessHandlerCallback’ will be invoked multiple times to process
data as it arrives; at each invocation a new chunk of data must be
processed. The arguments UPLOAD_DATA and UPLOAD_DATA_SIZE are used to
reference the chunk of data.
When ‘MHD_AccessHandlerCallback’ is invoked for a new connection: its
‘*CON_CLS’ argument is set to ‘NULL’. When ‘POST’ data comes in the
upload buffer it is *mandatory* to use the CON_CLS to store a reference
to per-connection data. The fact that the pointer was initially ‘NULL’
can be used to detect that this is a new request.
One method to detect that a new connection was established is to set
‘*con_cls’ to an unused integer:
int
access_handler (void *cls,
struct MHD_Connection * connection,
const char *url,
const char *method, const char *version,
const char *upload_data, size_t *upload_data_size,
void **con_cls)
{
static int old_connection_marker;
int new_connection = (NULL == *con_cls);
if (new_connection)
{
/* new connection with POST */
*con_cls = &old_connection_marker;
}
...
}
In contrast to the previous example, for ‘POST’ requests in particular,
it is more common to use the value of ‘*con_cls’ to keep track of actual
state used during processing, such as the post processor (or a struct
containing a post processor):
int
access_handler (void *cls,
struct MHD_Connection * connection,
const char *url,
const char *method, const char *version,
const char *upload_data, size_t *upload_data_size,
void **con_cls)
{
struct MHD_PostProcessor * pp = *con_cls;
if (pp == NULL)
{
pp = MHD_create_post_processor(connection, ...);
*con_cls = pp;
return MHD_YES;
}
if (*upload_data_size)
{
MHD_post_process(pp, upload_data, *upload_data_size);
*upload_data_size = 0;
return MHD_YES;
}
else
{
MHD_destroy_post_processor(pp);
return MHD_queue_response(...);
}
}
Note that the callback from ‘MHD_OPTION_NOTIFY_COMPLETED’ should be
used to destroy the post processor. This cannot be done inside of the
access handler since the connection may not always terminate normally.

File: libmicrohttpd.info, Node: microhttpd-post api, Up: microhttpd-post
11.1 Programming interface for the ‘POST’ processor
===================================================
-- Function: struct MHD_PostProcessor * MHD_create_post_processor
(struct MHD_Connection *connection, size_t buffer_size,
MHD_PostDataIterator iterator, void *iterator_cls)
Create a PostProcessor. A PostProcessor can be used to
(incrementally) parse the data portion of a ‘POST’ request.
CONNECTION
the connection on which the ‘POST’ is happening (used to
determine the ‘POST’ format);
BUFFER_SIZE
maximum number of bytes to use for internal buffering (used
only for the parsing, specifically the parsing of the keys).
A tiny value (256-1024) should be sufficient; do *NOT* use a
value smaller than 256; for good performance, use 32k or 64k
(i.e. 65536).
ITERATOR
iterator to be called with the parsed data; must *NOT* be
‘NULL’;
ITERATOR_CLS
custom value to be used as first argument to ITERATOR.
Return ‘NULL’ on error (out of memory, unsupported encoding),
otherwise a PP handle.
-- Function: int MHD_post_process (struct MHD_PostProcessor *pp, const
char *post_data, size_t post_data_len)
Parse and process ‘POST’ data. Call this function when ‘POST’ data
is available (usually during an ‘MHD_AccessHandlerCallback’) with
the UPLOAD_DATA and UPLOAD_DATA_SIZE. Whenever possible, this will
then cause calls to the ‘MHD_IncrementalKeyValueIterator’.
PP
the post processor;
POST_DATA
POST_DATA_LEN bytes of ‘POST’ data;
POST_DATA_LEN
length of POST_DATA.
Return ‘MHD_YES’ on success, ‘MHD_NO’ on error (out-of-memory,
iterator aborted, parse error).
-- Function: int MHD_destroy_post_processor (struct MHD_PostProcessor
*pp)
Release PostProcessor resources. After this function is being
called, the PostProcessor is guaranteed to no longer call its
iterator. There is no special call to the iterator to indicate the
end of the post processing stream. After destroying the
PostProcessor, the programmer should perform any necessary work to
complete the processing of the iterator.
Return ‘MHD_YES’ if processing completed nicely, ‘MHD_NO’ if there
were spurious characters or formatting problems with the post
request. It is common to ignore the return value of this function.

File: libmicrohttpd.info, Node: microhttpd-info, Next: microhttpd-util, Prev: microhttpd-post, Up: Top
12 Obtaining and modifying status information.
**********************************************
* Menu:
* microhttpd-info daemon:: State information about an MHD daemon
* microhttpd-info conn:: State information about a connection
* microhttpd-option conn:: Modify per-connection options

File: libmicrohttpd.info, Node: microhttpd-info daemon, Next: microhttpd-info conn, Up: microhttpd-info
12.1 Obtaining state information about an MHD daemon
====================================================
-- Function: const union MHD_DaemonInfo * MHD_get_daemon_info (struct
MHD_Daemon *daemon, enum MHD_DaemonInfoType infoType, ...)
Obtain information about the given daemon. This function is
currently not fully implemented.
DAEMON
the daemon about which information is desired;
INFOTYPE
type of information that is desired
...
additional arguments about the desired information (depending
on infoType)
Returns a union with the respective member (depending on infoType)
set to the desired information), or ‘NULL’ in case the desired
information is not available or applicable.
-- Enumeration: MHD_DaemonInfoType
Values of this enum are used to specify what information about a
daemon is desired.
‘MHD_DAEMON_INFO_KEY_SIZE’
Request information about the key size for a particular cipher
algorithm. The cipher algorithm should be passed as an extra
argument (of type ’enum MHD_GNUTLS_CipherAlgorithm’). No
longer supported, using this value will cause
‘MHD_get_daemon_info’ to return NULL.
‘MHD_DAEMON_INFO_MAC_KEY_SIZE’
Request information about the key size for a particular cipher
algorithm. The cipher algorithm should be passed as an extra
argument (of type ’enum MHD_GNUTLS_HashAlgorithm’). No longer
supported, using this value will cause ‘MHD_get_daemon_info’
to return NULL.
‘MHD_DAEMON_INFO_LISTEN_FD’
Request the file-descriptor number that MHD is using to listen
to the server socket. This can be useful if no port was
specified and a client needs to learn what port is actually
being used by MHD. No extra arguments should be passed.
‘MHD_DAEMON_INFO_EPOLL_FD’
Request the file-descriptor number that MHD is using for
epoll. If the build is not supporting epoll, NULL is
returned; if we are using a thread pool or this daemon was not
started with ‘MHD_USE_EPOLL’, (a pointer to) -1 is returned.
If we are using ‘MHD_USE_INTERNAL_POLLING_THREAD’ or are in
’external’ select mode, the internal epoll FD is returned.
This function must be used in external select mode with epoll
to obtain the FD to call epoll on. No extra arguments should
be passed.
‘MHD_DAEMON_INFO_CURRENT_CONNECTIONS’
Request the number of current connections handled by the
daemon. No extra arguments should be passed and a pointer to
a ‘union MHD_DaemonInfo’ value is returned, with the
‘num_connections’ member of type ‘unsigned int’ set to the
number of active connections.
Note that in multi-threaded or internal-select mode, the real
number of current connections may already be different when
‘MHD_get_daemon_info’ returns. The number of current
connections can be used (even in multi-threaded and
internal-select mode) after ‘MHD_quiesce_daemon’ to detect
whether all connections have been handled.

File: libmicrohttpd.info, Node: microhttpd-info conn, Next: microhttpd-option conn, Prev: microhttpd-info daemon, Up: microhttpd-info
12.2 Obtaining state information about a connection
===================================================
-- Function: const union MHD_ConnectionInfo * MHD_get_connection_info
(struct MHD_Connection *daemon, enum MHD_ConnectionInfoType
infoType, ...)
Obtain information about the given connection.
CONNECTION
the connection about which information is desired;
INFOTYPE
type of information that is desired
...
additional arguments about the desired information (depending
on infoType)
Returns a union with the respective member (depending on infoType)
set to the desired information), or ‘NULL’ in case the desired
information is not available or applicable.
-- Enumeration: MHD_ConnectionInfoType
Values of this enum are used to specify what information about a
connection is desired.
‘MHD_CONNECTION_INFO_CIPHER_ALGO’
What cipher algorithm is being used (HTTPS connections only).
‘NULL’ is returned for non-HTTPS connections.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_PROTOCOL,’
Allows finding out the TLS/SSL protocol used (HTTPS
connections only). ‘NULL’ is returned for non-HTTPS
connections.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_CLIENT_ADDRESS’
Returns information about the address of the client. Returns
essentially a ‘struct sockaddr **’ (since the API returns a
‘union MHD_ConnectionInfo *’ and that union contains a ‘struct
sockaddr *’).
Takes no extra arguments.
‘MHD_CONNECTION_INFO_GNUTLS_SESSION,’
Takes no extra arguments. Allows access to the underlying
GNUtls session, including access to the underlying GNUtls
client certificate (HTTPS connections only). Takes no extra
arguments. ‘NULL’ is returned for non-HTTPS connections.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_GNUTLS_CLIENT_CERT,’
Dysfunctional (never implemented, deprecated). Use
MHD_CONNECTION_INFO_GNUTLS_SESSION to get the
‘gnutls_session_t’ and then call
‘gnutls_certificate_get_peers()’.
‘MHD_CONNECTION_INFO_DAEMON’
Returns information about ‘struct MHD_Daemon’ which manages
this connection.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_CONNECTION_FD’
Returns the file descriptor (usually a TCP socket) associated
with this connection (in the “connect-fd” member of the
returned struct). Note that manipulating the descriptor
directly can have problematic consequences (as in, break
HTTP). Applications might use this access to manipulate TCP
options, for example to set the “TCP-NODELAY” option for
COMET-like applications. Note that MHD will set TCP-CORK
after sending the HTTP header and clear it after finishing the
footers automatically (if the platform supports it). As the
connection callbacks are invoked in between, those might be
used to set different values for TCP-CORK and TCP-NODELAY in
the meantime.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_CONNECTION_SUSPENDED’
Returns pointer to an integer that is ‘MHD_YES’ if the
connection is currently suspended (and thus can be safely
resumed) and ‘MHD_NO’ otherwise.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_SOCKET_CONTEXT’
Returns the client-specific pointer to a ‘void *’ that was
(possibly) set during a ‘MHD_NotifyConnectionCallback’ when
the socket was first accepted. Note that this is NOT the same
as the ‘con_cls’ argument of the ‘MHD_AccessHandlerCallback’.
The ‘con_cls’ is fresh for each HTTP request, while the
‘socket_context’ is fresh for each socket.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_CONNECTION_TIMEOUT’
Returns pointer to an ‘unsigned int’ that is the current
timeout used for the connection (in seconds, 0 for no
timeout). Note that while suspended connections will not
timeout, the timeout value returned for suspended connections
will be the timeout that the connection will use after it is
resumed, and thus might not be zero.
Takes no extra arguments.
‘MHD_CONNECTION_INFO_REQUEST_HEADER_SIZE’
Returns pointer to an ‘size_t’ that represents the size of the
HTTP header received from the client. Only valid after the
first callback to the access handler.
Takes no extra arguments.

File: libmicrohttpd.info, Node: microhttpd-option conn, Prev: microhttpd-info conn, Up: microhttpd-info
12.3 Setting custom options for an individual connection
========================================================
-- Function: int MHD_set_connection_option (struct MHD_Connection
*daemon, enum MHD_CONNECTION_OPTION option, ...)
Set a custom option for the given connection.
CONNECTION
the connection for which an option should be set or modified;
OPTION
option to set
...
additional arguments for the option (depending on option)
Returns ‘MHD_YES’ on success, ‘MHD_NO’ for errors (i.e. option
argument invalid or option unknown).
-- Enumeration: MHD_CONNECTION_OPTION
Values of this enum are used to specify which option for a
connection should be changed.
‘MHD_CONNECTION_OPTION_TIMEOUT’
Set a custom timeout for the given connection. Specified as
the number of seconds, given as an ‘unsigned int’. Use zero
for no timeout.

File: libmicrohttpd.info, Node: microhttpd-util, Next: GNU-LGPL, Prev: microhttpd-info, Up: Top
13 Utility functions.
*********************
* Menu:
* microhttpd-util feature:: Test supported MHD features
* microhttpd-util unescape:: Unescape strings

File: libmicrohttpd.info, Node: microhttpd-util feature, Next: microhttpd-util unescape, Up: microhttpd-util
13.1 Testing for supported MHD features
=======================================
-- Enumeration: MHD_FEATURE
Values of this enum are used to specify what information about a
daemon is desired.
‘MHD_FEATURE_MESSAGES’
Get whether messages are supported. If supported then in
debug mode messages can be printed to stderr or to external
logger.
‘MHD_FEATURE_SSL’
Get whether HTTPS is supported. If supported then flag
MHD_USE_SSL and options MHD_OPTION_HTTPS_MEM_KEY,
MHD_OPTION_HTTPS_MEM_CERT, MHD_OPTION_HTTPS_MEM_TRUST,
MHD_OPTION_HTTPS_MEM_DHPARAMS, MHD_OPTION_HTTPS_CRED_TYPE,
MHD_OPTION_HTTPS_PRIORITIES can be used.
‘MHD_FEATURE_HTTPS_CERT_CALLBACK’
Get whether option #MHD_OPTION_HTTPS_CERT_CALLBACK is
supported.
‘MHD_FEATURE_IPv6’
Get whether IPv6 is supported. If supported then flag
MHD_USE_IPv6 can be used.
‘MHD_FEATURE_IPv6_ONLY’
Get whether IPv6 without IPv4 is supported. If not supported
then IPv4 is always enabled in IPv6 sockets and flag
MHD_USE_DUAL_STACK if always used when MHD_USE_IPv6 is
specified.
‘MHD_FEATURE_POLL’
Get whether ‘poll()’ is supported. If supported then flag
MHD_USE_POLL can be used.
‘MHD_FEATURE_EPOLL’
Get whether ‘epoll()’ is supported. If supported then Flags
MHD_USE_EPOLL and MHD_USE_EPOLL_INTERNAL_THREAD can be used.
‘MHD_FEATURE_SHUTDOWN_LISTEN_SOCKET’
Get whether shutdown on listen socket to signal other threads
is supported. If not supported flag MHD_USE_ITC is
automatically forced.
‘MHD_FEATURE_SOCKETPAIR’
Get whether a ‘socketpair()’ is used internally instead of a
‘pipe()’ to signal other threads.
‘MHD_FEATURE_TCP_FASTOPEN’
Get whether TCP Fast Open is supported. If supported then
flag MHD_USE_TCP_FASTOPEN and option
MHD_OPTION_TCP_FASTOPEN_QUEUE_SIZE can be used.
‘MHD_FEATURE_BASIC_AUTH’
Get whether HTTP Basic authorization is supported. If
supported then functions
‘MHD_basic_auth_get_username_password()’ and
‘MHD_queue_basic_auth_fail_response()’ can be used.
‘MHD_FEATURE_DIGEST_AUTH’
Get whether HTTP Digest authorization is supported. If
supported then options MHD_OPTION_DIGEST_AUTH_RANDOM,
MHD_OPTION_NONCE_NC_SIZE and functions
‘MHD_digest_auth_check()’, can be used.
‘MHD_FEATURE_POSTPROCESSOR’
Get whether postprocessor is supported. If supported then
functions ‘MHD_create_post_processor()’, ‘MHD_post_process()’,
‘MHD_destroy_post_processor()’ can be used.
‘MHD_FEATURE_SENDFILE’
Get whether ‘sendfile()’ is supported.
-- Function: int MHD_is_feature_supported (enum MHD_FEATURE feature)
Get information about supported MHD features. Indicate that MHD
was compiled with or without support for particular feature. Some
features require additional support by the kernel. However, kernel
support is not checked by this function.
FEATURE
type of requested information
Returns ‘MHD_YES’ if the feature is supported, and ‘MHD_NO’ if not.

File: libmicrohttpd.info, Node: microhttpd-util unescape, Prev: microhttpd-util feature, Up: microhttpd-util
13.2 Unescape strings
=====================
-- Function: size_t MHD_http_unescape (char *val)
Process escape sequences (’%HH’) Updates val in place; the result
should be UTF-8 encoded and cannot be larger than the input. The
result must also still be 0-terminated.
VAL
value to unescape (modified in the process), must be a
0-terminated UTF-8 string.
Returns length of the resulting val (‘strlen(val)’ may be shorter
afterwards due to elimination of escape sequences).

File: libmicrohttpd.info, Node: GNU-LGPL, Next: GNU GPL with eCos Extension, Prev: microhttpd-util, Up: Top
GNU-LGPL
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File: libmicrohttpd.info, Node: GNU GPL with eCos Extension, Next: GNU-FDL, Prev: GNU-LGPL, Up: Top
GNU GPL with eCos Extension
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Preamble
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cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a
medium customarily used for software interchange; or,
c. Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with
such an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete
source code means all the source code for all modules it contains,
plus any associated interface definition files, plus the scripts
used to control compilation and installation of the executable.
However, as a special exception, the source code distributed need
not include anything that is normally distributed (in either source
or binary form) with the major components (compiler, kernel, and so
on) of the operating system on which the executable runs, unless
that component itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
5. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this
License. However, parties who have received copies, or rights,
from you under this License will not have their licenses terminated
so long as such parties remain in full compliance.
6. You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify
or distribute the Program or its derivative works. These actions
are prohibited by law if you do not accept this License.
Therefore, by modifying or distributing the Program (or any work
based on the Program), you indicate your acceptance of this License
to do so, and all its terms and conditions for copying,
distributing or modifying the Program or works based on it.
7. Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject
to these terms and conditions. You may not impose any further
restrictions on the recipients’ exercise of the rights granted
herein. You are not responsible for enforcing compliance by third
parties to this License.
8. If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent
issues), conditions are imposed on you (whether by court order,
agreement or otherwise) that contradict the conditions of this
License, they do not excuse you from the conditions of this
License. If you cannot distribute so as to satisfy simultaneously
your obligations under this License and any other pertinent
obligations, then as a consequence you may not distribute the
Program at all. For example, if a patent license would not permit
royalty-free redistribution of the Program by all those who receive
copies directly or indirectly through you, then the only way you
could satisfy both it and this License would be to refrain entirely
from distribution of the Program.
If any portion of this section is held invalid or unenforceable
under any particular circumstance, the balance of the section is
intended to apply and the section as a whole is intended to apply
in other circumstances.
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of
any such claims; this section has the sole purpose of protecting
the integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is
willing to distribute software through any other system and a
licensee cannot impose that choice.
This section is intended to make thoroughly clear what is believed
to be a consequence of the rest of this License.
9. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces,
the original copyright holder who places the Program under this
License may add an explicit geographical distribution limitation
excluding those countries, so that distribution is permitted only
in or among countries not thus excluded. In such case, this
License incorporates the limitation as if written in the body of
this License.
10. The Free Software Foundation may publish revised and/or new
versions of the General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the
Program specifies a version number of this License which applies to
it and “any later version”, you have the option of following the
terms and conditions either of that version or of any later version
published by the Free Software Foundation. If the Program does not
specify a version number of this License, you may choose any
version ever published by the Free Software Foundation.
11. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the
author to ask for permission. For software which is copyrighted by
the Free Software Foundation, write to the Free Software
Foundation; we sometimes make exceptions for this. Our decision
will be guided by the two goals of preserving the free status of
all derivatives of our free software and of promoting the sharing
and reuse of software generally.
NO WARRANTY
12. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS
AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY
OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND
PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE
DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR
OR CORRECTION.
13. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
ECOS EXTENSION
14. As a special exception, if other files instantiate templates or
use macros or inline functions from this file, or you compile this
file and link it with other works to produce a work based on this
file, this file does not by itself cause the resulting work to be
covered by the GNU General Public License. However the source code
for this file must still be made available in accordance with
section (3) of the GNU General Public License v2.
This exception does not invalidate any other reasons why a work
based on this file might be covered by the GNU General Public
License.
END OF TERMS AND CONDITIONS
---------------------------
How to Apply These Terms to Your New Programs
=============================================
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least the
“copyright” line and a pointer to where the full notice is found.
ONE LINE TO GIVE THE PROGRAM'S NAME AND AN IDEA OF WHAT IT DOES.
Copyright (C) 19YY NAME OF AUTHOR
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Also add information on how to contact you by electronic and paper
mail.
If the program is interactive, make it output a short notice like
this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'. This is free software, and you are welcome
to redistribute it under certain conditions; type `show c'
for details.
The hypothetical commands ‘show w’ and ‘show c’ should show the
appropriate parts of the General Public License. Of course, the
commands you use may be called something other than ‘show w’ and ‘show
c’; they could even be mouse-clicks or menu items—whatever suits your
program.
You should also get your employer (if you work as a programmer) or
your school, if any, to sign a “copyright disclaimer” for the program,
if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written
by James Hacker.
SIGNATURE OF TY COON, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your
program into proprietary programs. If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
GNU Library General Public License instead of this License.

File: libmicrohttpd.info, Node: GNU-FDL, Next: Concept Index, Prev: GNU GPL with eCos Extension, Up: Top
GNU-FDL
*******
Version 1.3, 3 November 2008
Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other
functional and useful document “free” in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not
being considered responsible for modifications made by others.
This License is a kind of “copyleft”, which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.
We have designed this License in order to use it for manuals for
free software, because free software needs free documentation: a
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book. We
recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
that contains a notice placed by the copyright holder saying it can
be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
“Document”, below, refers to any such manual or work. Any member
of the public is a licensee, and is addressed as “you”. You accept
the license if you copy, modify or distribute the work in a way
requiring permission under copyright law.
A “Modified Version” of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
A “Secondary Section” is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document’s overall
subject (or to related matters) and contains nothing that could
fall directly within that overall subject. (Thus, if the Document
is in part a textbook of mathematics, a Secondary Section may not
explain any mathematics.) The relationship could be a matter of
historical connection with the subject or with related matters, or
of legal, commercial, philosophical, ethical or political position
regarding them.
The “Invariant Sections” are certain Secondary Sections whose
titles are designated, as being those of Invariant Sections, in the
notice that says that the Document is released under this License.
If a section does not fit the above definition of Secondary then it
is not allowed to be designated as Invariant. The Document may
contain zero Invariant Sections. If the Document does not identify
any Invariant Sections then there are none.
The “Cover Texts” are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
that says that the Document is released under this License. A
Front-Cover Text may be at most 5 words, and a Back-Cover Text may
be at most 25 words.
A “Transparent” copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed
of pixels) generic paint programs or (for drawings) some widely
available drawing editor, and that is suitable for input to text
formatters or for automatic translation to a variety of formats
suitable for input to text formatters. A copy made in an otherwise
Transparent file format whose markup, or absence of markup, has
been arranged to thwart or discourage subsequent modification by
readers is not Transparent. An image format is not Transparent if
used for any substantial amount of text. A copy that is not
“Transparent” is called “Opaque”.
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
SGML or XML using a publicly available DTD, and standard-conforming
simple HTML, PostScript or PDF designed for human modification.
Examples of transparent image formats include PNG, XCF and JPG.
Opaque formats include proprietary formats that can be read and
edited only by proprietary word processors, SGML or XML for which
the DTD and/or processing tools are not generally available, and
the machine-generated HTML, PostScript or PDF produced by some word
processors for output purposes only.
The “Title Page” means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
material this License requires to appear in the title page. For
works in formats which do not have any title page as such, “Title
Page” means the text near the most prominent appearance of the
work’s title, preceding the beginning of the body of the text.
The “publisher” means any person or entity that distributes copies
of the Document to the public.
A section “Entitled XYZ” means a named subunit of the Document
whose title either is precisely XYZ or contains XYZ in parentheses
following text that translates XYZ in another language. (Here XYZ
stands for a specific section name mentioned below, such as
“Acknowledgements”, “Dedications”, “Endorsements”, or “History”.)
To “Preserve the Title” of such a section when you modify the
Document means that it remains a section “Entitled XYZ” according
to this definition.
The Document may include Warranty Disclaimers next to the notice
which states that this License applies to the Document. These
Warranty Disclaimers are considered to be included by reference in
this License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and
has no effect on the meaning of this License.
2. VERBATIM COPYING
You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License
applies to the Document are reproduced in all copies, and that you
add no other conditions whatsoever to those of this License. You
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However,
you may accept compensation in exchange for copies. If you
distribute a large enough number of copies you must also follow the
conditions in section 3.
You may also lend copies, under the same conditions stated above,
and you may publicly display copies.
3. COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly
have printed covers) of the Document, numbering more than 100, and
the Document’s license notice requires Cover Texts, you must
enclose the copies in covers that carry, clearly and legibly, all
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The
front cover must present the full title with all words of the title
equally prominent and visible. You may add other material on the
covers in addition. Copying with changes limited to the covers, as
long as they preserve the title of the Document and satisfy these
conditions, can be treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto
adjacent pages.
If you publish or distribute Opaque copies of the Document
numbering more than 100, you must either include a machine-readable
Transparent copy along with each Opaque copy, or state in or with
each Opaque copy a computer-network location from which the general
network-using public has access to download using public-standard
network protocols a complete Transparent copy of the Document, free
of added material. If you use the latter option, you must take
reasonably prudent steps, when you begin distribution of Opaque
copies in quantity, to ensure that this Transparent copy will
remain thus accessible at the stated location until at least one
year after the last time you distribute an Opaque copy (directly or
through your agents or retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of
the Document well before redistributing any large number of copies,
to give them a chance to provide you with an updated version of the
Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
release the Modified Version under precisely this License, with the
Modified Version filling the role of the Document, thus licensing
distribution and modification of the Modified Version to whoever
possesses a copy of it. In addition, you must do these things in
the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
distinct from that of the Document, and from those of previous
versions (which should, if there were any, be listed in the
History section of the Document). You may use the same title
as a previous version if the original publisher of that
version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
the Modified Version, together with at least five of the
principal authors of the Document (all of its principal
authors, if it has fewer than five), unless they release you
from this requirement.
C. State on the Title page the name of the publisher of the
Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license
notice giving the public permission to use the Modified
Version under the terms of this License, in the form shown in
the Addendum below.
G. Preserve in that license notice the full lists of Invariant
Sections and required Cover Texts given in the Document’s
license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled “History”, Preserve its Title,
and add to it an item stating at least the title, year, new
authors, and publisher of the Modified Version as given on the
Title Page. If there is no section Entitled “History” in the
Document, create one stating the title, year, authors, and
publisher of the Document as given on its Title Page, then add
an item describing the Modified Version as stated in the
previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
previous versions it was based on. These may be placed in the
“History” section. You may omit a network location for a work
that was published at least four years before the Document
itself, or if the original publisher of the version it refers
to gives permission.
K. For any section Entitled “Acknowledgements” or “Dedications”,
Preserve the Title of the section, and preserve in the section
all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document, unaltered
in their text and in their titles. Section numbers or the
equivalent are not considered part of the section titles.
M. Delete any section Entitled “Endorsements”. Such a section
may not be included in the Modified Version.
N. Do not retitle any existing section to be Entitled
“Endorsements” or to conflict in title with any Invariant
Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
material copied from the Document, you may at your option designate
some or all of these sections as invariant. To do this, add their
titles to the list of Invariant Sections in the Modified Version’s
license notice. These titles must be distinct from any other
section titles.
You may add a section Entitled “Endorsements”, provided it contains
nothing but endorsements of your Modified Version by various
parties—for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of
a standard.
You may add a passage of up to five words as a Front-Cover Text,
and a passage of up to 25 words as a Back-Cover Text, to the end of
the list of Cover Texts in the Modified Version. Only one passage
of Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity. If the Document
already includes a cover text for the same cover, previously added
by you or by arrangement made by the same entity you are acting on
behalf of, you may not add another; but you may replace the old
one, on explicit permission from the previous publisher that added
the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
assert or imply endorsement of any Modified Version.
5. COMBINING DOCUMENTS
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
modified versions, provided that you include in the combination all
of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name
but different contents, make the title of each such section unique
by adding at the end of it, in parentheses, the name of the
original author or publisher of that section if known, or else a
unique number. Make the same adjustment to the section titles in
the list of Invariant Sections in the license notice of the
combined work.
In the combination, you must combine any sections Entitled
“History” in the various original documents, forming one section
Entitled “History”; likewise combine any sections Entitled
“Acknowledgements”, and any sections Entitled “Dedications”. You
must delete all sections Entitled “Endorsements.”
6. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
rules of this License for verbatim copying of each of the documents
in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
a copy of this License into the extracted document, and follow this
License in all other respects regarding verbatim copying of that
document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of a
storage or distribution medium, is called an “aggregate” if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation’s users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
of the entire aggregate, the Document’s Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form. Otherwise they must appear on printed covers that bracket
the whole aggregate.
8. TRANSLATION
Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section
4. Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also
include the original English version of this License and the
original versions of those notices and disclaimers. In case of a
disagreement between the translation and the original version of
this License or a notice or disclaimer, the original version will
prevail.
If a section in the Document is Entitled “Acknowledgements”,
“Dedications”, or “History”, the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.
9. TERMINATION
You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void,
and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly and
finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from
that copyright holder, and you cure the violation prior to 30 days
after your receipt of the notice.
Termination of your rights under this section does not terminate
the licenses of parties who have received copies or rights from you
under this License. If your rights have been terminated and not
permanently reinstated, receipt of a copy of some or all of the
same material does not give you any rights to use it.
10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
<http://www.gnu.org/copyleft/>.
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License “or any later version” applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If the
Document does not specify a version number of this License, you may
choose any version ever published (not as a draft) by the Free
Software Foundation. If the Document specifies that a proxy can
decide which future versions of this License can be used, that
proxy’s public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
11. RELICENSING
“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server.
A “Massive Multiauthor Collaboration” (or “MMC”) contained in the
site means any set of copyrightable works thus published on the MMC
site.
“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
“Incorporate” means to publish or republish a Document, in whole or
in part, as part of another Document.
An MMC is “eligible for relicensing” if it is licensed under this
License, and if all works that were first published under this
License somewhere other than this MMC, and subsequently
incorporated in whole or in part into the MMC, (1) had no cover
texts or invariant sections, and (2) were thus incorporated prior
to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
ADDENDUM: How to use this License for your documents
====================================================
To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:
Copyright (C) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the “with...Texts.” line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
being LIST.
If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.

File: libmicrohttpd.info, Node: Concept Index, Next: Function and Data Index, Prev: GNU-FDL, Up: Top
Concept Index
*************
[index]
* Menu:
* ARM: microhttpd-intro. (line 274)
* bind, restricting bind: microhttpd-const. (line 321)
* bind, restricting bind <1>: microhttpd-const. (line 546)
* cipher: microhttpd-const. (line 394)
* clock: microhttpd-const. (line 105)
* compilation: microhttpd-intro. (line 121)
* connection, limiting number of connections: microhttpd-const.
(line 209)
* connection, limiting number of connections <1>: microhttpd-info daemon.
(line 60)
* cookie: microhttpd-const. (line 578)
* cortex m3: microhttpd-intro. (line 274)
* date: microhttpd-const. (line 105)
* debugging: microhttpd-const. (line 31)
* debugging <1>: microhttpd-const. (line 332)
* deprecated: microhttpd-const. (line 61)
* DH: microhttpd-const. (line 538)
* digest auth: microhttpd-const. (line 423)
* digest auth <1>: microhttpd-const. (line 434)
* eCos, GNU General Public License with eCos Extension: GNU GPL with eCos Extension.
(line 6)
* embedded systems: microhttpd-intro. (line 121)
* embedded systems <1>: microhttpd-intro. (line 274)
* embedded systems <2>: microhttpd-const. (line 105)
* embedded systems <3>: microhttpd-const. (line 112)
* embedded systems <4>: microhttpd-const. (line 522)
* epoll: microhttpd-intro. (line 67)
* epoll <1>: microhttpd-const. (line 77)
* epoll <2>: microhttpd-info daemon.
(line 49)
* escaping: microhttpd-const. (line 505)
* FD_SETSIZE: microhttpd-const. (line 70)
* FD_SETSIZE <1>: microhttpd-const. (line 77)
* foreign-function interface: microhttpd-const. (line 483)
* GPL, GNU General Public License: GNU GPL with eCos Extension.
(line 6)
* HTTP2: microhttpd-response upgrade.
(line 6)
* IAR: microhttpd-intro. (line 274)
* internationalization: microhttpd-const. (line 505)
* IPv6: microhttpd-const. (line 45)
* IPv6 <1>: microhttpd-const. (line 55)
* license: GNU-LGPL. (line 6)
* license <1>: GNU GPL with eCos Extension.
(line 6)
* license <2>: GNU-FDL. (line 6)
* listen: microhttpd-const. (line 112)
* listen <1>: microhttpd-const. (line 143)
* listen <2>: microhttpd-const. (line 528)
* listen <3>: microhttpd-info daemon.
(line 43)
* logging: microhttpd-const. (line 332)
* logging <1>: microhttpd-const. (line 464)
* long long: microhttpd-intro. (line 274)
* memory: microhttpd-const. (line 201)
* memory, limiting memory utilization: microhttpd-const. (line 193)
* MHD_LONG_LONG: microhttpd-intro. (line 274)
* microhttpd.h: microhttpd-intro. (line 214)
* options: microhttpd-const. (line 483)
* performance: microhttpd-intro. (line 91)
* performance <1>: microhttpd-const. (line 90)
* performance <2>: microhttpd-const. (line 475)
* performance <3>: microhttpd-info conn.
(line 114)
* poll: microhttpd-intro. (line 67)
* poll <1>: microhttpd-const. (line 70)
* poll <2>: microhttpd-init. (line 74)
* portability: microhttpd-intro. (line 121)
* portability <1>: microhttpd-intro. (line 214)
* POST method: microhttpd-const. (line 582)
* POST method <1>: microhttpd-struct. (line 19)
* POST method <2>: microhttpd-cb. (line 48)
* POST method <3>: microhttpd-post. (line 6)
* POST method <4>: microhttpd-post api. (line 6)
* proxy: microhttpd-const. (line 112)
* PSK: microhttpd-const. (line 417)
* pthread: microhttpd-const. (line 522)
* PUT method: microhttpd-cb. (line 48)
* query string: microhttpd-const. (line 332)
* quiesce: microhttpd-const. (line 119)
* quiesce <1>: microhttpd-init. (line 51)
* random: microhttpd-const. (line 423)
* replay attack: microhttpd-const. (line 434)
* reusing listening address: microhttpd-const. (line 546)
* RFC2817: microhttpd-response upgrade.
(line 6)
* select: microhttpd-intro. (line 67)
* select <1>: microhttpd-const. (line 70)
* select <2>: microhttpd-const. (line 77)
* select <3>: microhttpd-init. (line 74)
* select <4>: microhttpd-init. (line 89)
* signals: microhttpd-intro. (line 235)
* SNI: microhttpd-const. (line 402)
* SSL: microhttpd-const. (line 34)
* SSL <1>: microhttpd-const. (line 355)
* SSL <2>: microhttpd-const. (line 361)
* SSL <3>: microhttpd-const. (line 371)
* SSL <4>: microhttpd-const. (line 377)
* SSL <5>: microhttpd-const. (line 389)
* SSL <6>: microhttpd-const. (line 394)
* SSL <7>: microhttpd-const. (line 402)
* SSL <8>: microhttpd-const. (line 417)
* SSL <9>: microhttpd-const. (line 538)
* stack: microhttpd-const. (line 522)
* systemd: microhttpd-const. (line 457)
* thread: microhttpd-const. (line 522)
* timeout: microhttpd-const. (line 247)
* timeout <1>: microhttpd-inspect. (line 39)
* timeout <2>: microhttpd-option conn.
(line 6)
* TLS: microhttpd-const. (line 34)
* TLS <1>: microhttpd-const. (line 355)
* TLS <2>: microhttpd-const. (line 361)
* TLS <3>: microhttpd-const. (line 371)
* TLS <4>: microhttpd-const. (line 377)
* TLS <5>: microhttpd-const. (line 389)
* TLS <6>: microhttpd-const. (line 394)
* TLS <7>: microhttpd-const. (line 402)
* TLS <8>: microhttpd-const. (line 417)
* TLS <9>: microhttpd-const. (line 538)
* upgrade: microhttpd-const. (line 148)
* Upgrade: microhttpd-response upgrade.
(line 6)
* WebSockets: microhttpd-response upgrade.
(line 6)

File: libmicrohttpd.info, Node: Function and Data Index, Next: Type Index, Prev: Concept Index, Up: Top
Function and Data Index
***********************
[index]
* Menu:
* *MHD_AcceptPolicyCallback: microhttpd-cb. (line 6)
* *MHD_AccessHandlerCallback: microhttpd-cb. (line 19)
* *MHD_ContentReaderCallback: microhttpd-cb. (line 150)
* *MHD_ContentReaderFreeCallback: microhttpd-cb. (line 197)
* *MHD_KeyValueIterator: microhttpd-cb. (line 116)
* *MHD_PostDataIterator: microhttpd-cb. (line 202)
* *MHD_RequestCompletedCallback: microhttpd-cb. (line 96)
* *MHD_UpgradeHandler: microhttpd-response upgrade.
(line 36)
* MHD_add_connection: microhttpd-init. (line 115)
* MHD_add_response_footer: microhttpd-response headers.
(line 29)
* MHD_add_response_header: microhttpd-response headers.
(line 6)
* MHD_basic_auth_get_username_password: microhttpd-dauth basic.
(line 10)
* MHD_create_post_processor: microhttpd-post api. (line 6)
* MHD_create_response_for_upgrade: microhttpd-response upgrade.
(line 23)
* MHD_create_response_from_buffer: microhttpd-response create.
(line 92)
* MHD_create_response_from_buffer_with_free_callback: microhttpd-response create.
(line 113)
* MHD_create_response_from_callback: microhttpd-response create.
(line 6)
* MHD_create_response_from_data: microhttpd-response create.
(line 131)
* MHD_create_response_from_fd: microhttpd-response create.
(line 32)
* MHD_create_response_from_fd_at_offset: microhttpd-response create.
(line 50)
* MHD_del_response_header: microhttpd-response headers.
(line 45)
* MHD_destroy_post_processor: microhttpd-post api. (line 52)
* MHD_destroy_response: microhttpd-response enqueue.
(line 28)
* MHD_digest_auth_check: microhttpd-dauth digest.
(line 55)
* MHD_digest_auth_check2: microhttpd-dauth digest.
(line 30)
* MHD_digest_auth_check_digest: microhttpd-dauth digest.
(line 103)
* MHD_digest_auth_check_digest2: microhttpd-dauth digest.
(line 78)
* MHD_digest_auth_get_username: microhttpd-dauth digest.
(line 23)
* MHD_free: microhttpd-dauth basic.
(line 6)
* MHD_get_connection_info: microhttpd-info conn.
(line 6)
* MHD_get_connection_values: microhttpd-requests. (line 6)
* MHD_get_daemon_info: microhttpd-info daemon.
(line 6)
* MHD_get_fdset: microhttpd-inspect. (line 6)
* MHD_get_fdset2: microhttpd-inspect. (line 31)
* MHD_get_response_header: microhttpd-response inspect.
(line 18)
* MHD_get_response_headers: microhttpd-response inspect.
(line 6)
* MHD_get_timeout: microhttpd-inspect. (line 37)
* MHD_http_unescape: microhttpd-util unescape.
(line 6)
* MHD_is_feature_supported: microhttpd-util feature.
(line 77)
* MHD_lookup_connection_value: microhttpd-requests. (line 58)
* MHD_post_process: microhttpd-post api. (line 33)
* MHD_queue_auth_fail_response: microhttpd-dauth digest.
(line 153)
* MHD_queue_auth_fail_response2: microhttpd-dauth digest.
(line 126)
* MHD_queue_basic_auth_fail_response: microhttpd-dauth basic.
(line 21)
* MHD_queue_response: microhttpd-response enqueue.
(line 6)
* MHD_quiesce_daemon: microhttpd-init. (line 50)
* MHD_resume_connection: microhttpd-flow. (line 51)
* MHD_run: microhttpd-init. (line 70)
* MHD_run_from_select: microhttpd-init. (line 86)
* MHD_set_connection_option: microhttpd-option conn.
(line 6)
* MHD_set_connection_value: microhttpd-requests. (line 35)
* MHD_set_panic_func: microhttpd-init. (line 6)
* MHD_set_response_options: microhttpd-response options.
(line 6)
* MHD_start_daemon: microhttpd-init. (line 18)
* MHD_stop_daemon: microhttpd-init. (line 67)
* MHD_suspend_connection: microhttpd-flow. (line 20)
* MHD_upgrade_action: microhttpd-response upgrade.
(line 90)

File: libmicrohttpd.info, Node: Type Index, Prev: Function and Data Index, Up: Top
Type Index
**********
[index]
* Menu:
* MHD_Connection: microhttpd-struct. (line 9)
* MHD_ConnectionInfo: microhttpd-struct. (line 21)
* MHD_ConnectionInfoType: microhttpd-info conn.
(line 25)
* MHD_CONNECTION_OPTION: microhttpd-option conn.
(line 22)
* MHD_Daemon: microhttpd-struct. (line 6)
* MHD_DaemonInfo: microhttpd-struct. (line 24)
* MHD_DaemonInfoType: microhttpd-info daemon.
(line 25)
* MHD_DigestAuthAlgorithm: microhttpd-dauth digest.
(line 10)
* MHD_FEATURE: microhttpd-util feature.
(line 6)
* MHD_FLAG: microhttpd-const. (line 6)
* MHD_OPTION: microhttpd-const. (line 184)
* MHD_OptionItem: microhttpd-const. (line 557)
* MHD_PostProcessor: microhttpd-struct. (line 18)
* MHD_RequestTerminationCode: microhttpd-const. (line 595)
* MHD_Response: microhttpd-struct. (line 15)
* MHD_ResponseFlags: microhttpd-const. (line 635)
* MHD_ResponseMemoryMode: microhttpd-const. (line 613)
* MHD_ResponseOptions: microhttpd-const. (line 676)
* MHD_UpgradeAction: microhttpd-response upgrade.
(line 101)
* MHD_ValueKind: microhttpd-const. (line 570)

Tag Table:
Node: Top813
Node: microhttpd-intro3034
Ref: fig:performance7951
Ref: tbl:supported8922
Node: microhttpd-const16899
Node: microhttpd-struct51615
Node: microhttpd-cb52399
Node: microhttpd-init62597
Node: microhttpd-inspect68448
Node: microhttpd-requests71192
Node: microhttpd-responses74860
Node: microhttpd-response enqueue76059
Ref: microhttpd-response enqueue-Footnote-178366
Node: microhttpd-response create78601
Node: microhttpd-response headers85271
Node: microhttpd-response options87703
Node: microhttpd-response inspect88574
Node: microhttpd-response upgrade89795
Node: microhttpd-flow94949
Node: microhttpd-dauth98243
Node: microhttpd-dauth basic99794
Node: microhttpd-dauth digest101188
Node: microhttpd-post111384
Node: microhttpd-post api114383
Node: microhttpd-info117027
Node: microhttpd-info daemon117449
Node: microhttpd-info conn120909
Node: microhttpd-option conn125964
Node: microhttpd-util127044
Node: microhttpd-util feature127315
Node: microhttpd-util unescape130901
Node: GNU-LGPL131549
Node: GNU GPL with eCos Extension159755
Node: GNU-FDL179693
Node: Concept Index204982
Node: Function and Data Index214218
Node: Type Index220741

End Tag Table

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