<div class="content"><p> </p><p>The <b>R_DhcpEnumMScopeClients</b> method enumerates all
MADCAP clients serviced from the specified IPv4 multicast subnet. The caller of
this function can free the memory pointed to by the <i>ClientInfo</i> parameter
and other client parameters by calling the function <b>midl_user_free</b>
(section <span><a href="a7e5f2d1-04b7-4363-bdc0-76a1099664eb" data-linktype="relative-path">3</a></span>).</p><dl>
<dd>
<div><pre> DWORD R_DhcpEnumMScopeClients(
   [in, unique, string] DHCP_SRV_HANDLE ServerIpAddress,
   [in, ref, string] LPWSTR* MScopeName,
   [in, out] DHCP_RESUME_HANDLE* ResumeHandle,
   [in] DWORD PreferredMaximum,
   [out] LPDHCP_MCLIENT_INFO_ARRAY* ClientInfo,
   [out] DWORD* ClientsRead,
   [out] DWORD* ClientsTotal
 );
</pre></div>
</dd></dl><p><b>ServerIpAddress: </b>The IP address/host name of
the MADCAP server. This parameter is unused.</p><p><b>MScopeName: </b>This is a pointer to a Unicode
string that contains the name of the multicast subnet from which IPv4 multicast
subnet elements are enumerated. There is no restriction on the length of this
field.</p><p><b>ResumeHandle: </b>This is a pointer of type <span><a href="a6e4cdc0-4f71-4922-ade1-7a5392f9e920" data-linktype="relative-path">DHCP_RESUME_HANDLE (section 2.2.1.2.6)</a></span>
that identifies the enumeration operation. Initially, this value MUST be set to
zero, with a successful call returning the handle value used for subsequent
enumeration requests. This field contains the last IPv4 multicast address
retrieved.</p><p><b>PreferredMaximum: </b>This is of type <span><a href="../ms-dtyp/262627d8-3418-4627-9218-4ffe110850b2" data-linktype="relative-path">DWORD</a></span>,
specifying the preferred maximum number of bytes to return. The minimum value
is 1,024 bytes (1 kilobyte), and the maximum value is 65,536 bytes (64
kilobytes). If the input value is greater or less than this range, it MUST be
set to the maximum or minimum value, respectively. To retrieve all the MADCAP
clients serviced by a specific multicast scope, 0xFFFFFFFF is specified.</p><p><b>ClientInfo: </b>This is a pointer of type <span><a href="d418cd55-97bd-4e05-bb79-9c47cf09b6f4" data-linktype="relative-path">LPDHCP_MCLIENT_INFO_ARRAY</a></span>
that points to the location that contains the MADCAP lease record array.</p><p><b>ClientsRead: </b>This is a pointer to a DWORD that
specifies the number of MADCAP client lease records read in <i>ClientInfo</i>.
The caller MUST allocate memory for this parameter equal to the size of a DWORD
data type. </p><p><b>ClientsTotal: </b>This is a pointer to a DWORD
that specifies the number of MADCAP client lease records remaining from the
current position. The caller MUST allocate memory for this parameter equal to
the size of a DWORD data type. For example, if there are 100 MADCAP lease
record clients for an IPv4 multicast subnet, and if 10 MADCAP lease records are
enumerated per call, then for the first time this would have a value of 90.<a id="Appendix_A_Target_47"></a><a aria-label="Product behavior note 47" href="afab0546-79ae-4764-8dab-27a85cca5145#Appendix_A_47" data-linktype="relative-path">&lt;47&gt;</a></p><p><b>Return Values: </b>A 32-bit unsigned integer value
that indicates return status. A return value of ERROR_SUCCESS (0x00000000)
indicates that the operation was completed successfully, else it contains a
Win32 error code, as specified in <span><a href="../ms-erref/1bc92ddf-b79e-413c-bbaa-99a5281a6c90" data-linktype="relative-path">[MS-ERREF]</a></span>.
This error code value can correspond to a DHCP-specific failure, which takes a
value between 20000 and 20099, or any generic failure.</p><dl>
<dd>
<table><thead>
  <tr>
   <th>
   <p>Return value/code</p>
   </th>
   <th>
   <p>Description</p>
   </th>
  </tr>
 </thead><tbody><tr>
  <td>
  <p>0x00000000</p>
  <p>ERROR_SUCCESS</p>
  </td>
  <td>
  <p>The call was successful.</p>
  </td>
 </tr><tr>
  <td>
  <p>0x000000EA</p>
  <p>ERROR_MORE_DATA</p>
  </td>
  <td>
  <p>There are more elements available to enumerate.</p>
  </td>
 </tr><tr>
  <td>
  <p>0x00000103</p>
  <p>ERROR_NO_MORE_ITEMS</p>
  </td>
  <td>
  <p>There are no more elements left to enumerate.</p>
  </td>
 </tr><tr>
  <td>
  <p>0x00004E25</p>
  <p>ERROR_DHCP_SUBNET_NOT_PRESENT</p>
  </td>
  <td>
  <p>The specified IPv4 subnet does not exist.</p>
  </td>
 </tr><tr>
  <td>
  <p>0x00004E2D</p>
  <p>ERROR_DHCP_JET_ERROR</p>
  </td>
  <td>
  <p>An error occurred while accessing the MADCAP server
  database.</p>
  </td>
 </tr></tbody></table>
</dd></dl><p>The opnum field value for this method is 13.</p><p>When processing this call, the MADCAP server MUST do the
following:</p><ul><li><p><span><span> 
</span></span>Validate if this method is authorized for read access per section
<span><a href="baec2112-1146-4c42-b77e-b706e170a590" data-linktype="relative-path">3.5.4</a></span>.
If not, return ERROR_ACCESS_DENIED.</p>
</li><li><p><span><span> 
</span></span>Retrieve the <b>DHCPv4MScope</b> ADM element entry corresponding
to the <i>MScopeName</i> parameter from the server ADM element <b>DHCPv4MScopesList</b>.
If the <b>DHCPv4MScope</b> entry is not found, return
ERROR_DHCP_SUBNET_NOT_PRESENT.</p>
</li><li><p><span><span> 
</span></span>Retrieve the <b>DHCPv4MClientsList</b> member of the <b>DHCPv4MScope</b>
entry corresponding to <i>MScopeName</i> from the server ADM element <b>DHCPv4MScopesList</b>.</p>
</li><li><p><span><span> 
</span></span>If the <i>ResumeHandle</i> parameter points to 0x00000000, the
enumeration MUST start from the first entry of the <b>DHCPv4MClientsList</b>.</p>
</li><li><p><span><span> 
</span></span>If the <i>ResumeHandle</i> parameter points to 0x00000000, and
there are no entries in <b>DHCPv4MClientsList</b> of all the <b>DHCPv4MScope</b>
entries present in the <b>DHCPv4MScopesList</b>, then return
ERROR_NO_MORE_ITEMS. If there are no entries in the <b>DHCPv4MClientsList</b>
of the <b>DHCPv4MScope</b> entry corresponding to the specified <i>MScopeName</i>,
but there are <b>DHCPv4MClient</b> entries in <b>DHCPv4MClientsList</b> of
other <b>DHCPv4MScope</b> entries configured on the server, then return
ERROR_SUCCESS.</p>
</li><li><p><span><span> 
</span></span>If the <i>ResumeHandle</i> parameter points to a nonzero value,
the server MUST continue enumeration based on the value of <i>ResumeHandle</i>.
If the IPv4 address contained in <i>ResumeHandle</i> does not match <i>ClientIpAddress</i>
of any <b>DHCPv4MClient</b> of the <b>DHCPv4MScope</b> entry corresponding to
the <i>MScopeName</i> input parameter, then return ERROR_DHCP_JET_ERROR.</p>
</li><li><p><span><span> 
</span></span>The <i>PreferredMaximum</i> parameter specifies the maximum
number of bytes that the server can allocate and return to the caller
containing the data related to the MADCAP client lease records.</p>
</li><li><p><span><span> 
</span></span>If <i>PreferredMaximum</i> is less than 1024, it is assigned
1024; and if <i>PreferredMaximum</i> is greater than 65536, it is assigned
65536.</p>
</li><li><p><span><span> 
</span></span>The actual number of records that correspond to a given <i>PreferredMaximum</i>
value can be determined only at run time.</p>
</li><li><p><span><span> 
</span></span>Allocate memory for <i>PreferredMaximum</i> number of bytes.</p>
</li><li><p><span><span> 
</span></span>Copy the <b>DHCPv4Client</b> entry from the <b>DHCPv4ClientsList</b>
entries in the allocated memory, and then proceed to the next record.</p>
</li><li><p><span><span> 
</span></span>If the retrieve operation has reached the maximum number of <b>DHCPv4MClient</b>
entries that can be accommodated in <i>PreferredMaximum</i> and there are still
more <b>DHCPv4MClient</b> entries in any <b>DHCPv4MClientsList</b>, set <i>ClientsTotal</i>
to the number of <b>DHCPv4MClient</b> entries that are not yet enumerated, and
set <i>ClientsRead</i> to the number of <b>DHCPv4MClient</b> entries that are
enumerated in this retrieve operation. Set <i>ResumeHandle</i> to the <i>ClientIpAddress</i>
member of the last <b>DHCPv4MClient</b> entry read, and return ERROR_MORE_DATA.</p>
</li><li><p><span><span> 
</span></span>If the number of bytes specified by <i>PreferredMaximum</i> is
more than the total memory occupied by <b>DHCPv4MClient</b> entries, set <i>ClientsTotal</i>
to the total number of <b>DHCPv4MClient</b> entries enumerated in that retrieve
operation and <i>ClientsRead</i> to the number of <b>DHCPv4MClient</b> entries
that are enumerated in this retrieve operation. Set <i>ResumeHandle</i> to 0,
and return ERROR_SUCCESS.</p>
</li></ul><p><b>Exceptions Thrown:</b> No exceptions are thrown beyond
those thrown by the underlying RPC protocol specified in <span><a href="../ms-rpce/290c38b1-92fe-4229-91e6-4fc376610c15" data-linktype="relative-path">[MS-RPCE]</a></span>.</p></div>