Release v0.45.0

docs-src/config.toml

@@ -4,7 +4,7 @@ langs = ["en", "ja"]
 
 [site]
 title = "cpp-httplib"
-version = "0.44.0"
+version = "0.45.0"
 hostname = "https://yhirose.github.io"
 base_path = "/cpp-httplib"
 footer_message = "© 2026 Yuji Hirose. All rights reserved."

httplib.h

@@ -8,8 +8,8 @@
 #ifndef CPPHTTPLIB_HTTPLIB_H
 #define CPPHTTPLIB_HTTPLIB_H
 
-#define CPPHTTPLIB_VERSION "0.44.0"
-#define CPPHTTPLIB_VERSION_NUM "0x002c00"
+#define CPPHTTPLIB_VERSION "0.45.0"
+#define CPPHTTPLIB_VERSION_NUM "0x002d00"
 
 #ifdef _WIN32
 #if defined(_WIN32_WINNT) && _WIN32_WINNT < 0x0A00
@@ -8578,17 +8578,24 @@ write_multipart_ranges_data(Stream &strm, const Request &req, Response &res,
       });
 }
 
+inline bool has_framed_body(const Request &req) {
+  return is_chunked_transfer_encoding(req.headers) ||
+         req.get_header_value_u64("Content-Length") > 0;
+}
+
+inline bool is_connection_persistent(const Request &req) {
+  auto conn = req.get_header_value("Connection");
+  if (conn == "close") { return false; }
+  if (req.version == "HTTP/1.0" && conn != "Keep-Alive") { return false; }
+  return true;
+}
+
 inline bool expect_content(const Request &req) {
   if (req.method == "POST" || req.method == "PUT" || req.method == "PATCH" ||
       req.method == "DELETE") {
     return true;
   }
-  if (req.has_header("Content-Length") &&
-      req.get_header_value_u64("Content-Length") > 0) {
-    return true;
-  }
-  if (is_chunked_transfer_encoding(req.headers)) { return true; }
-  return false;
+  return has_framed_body(req);
 }
 
 #ifdef _WIN32
@@ -11304,29 +11311,18 @@ inline bool Server::read_content_core(
                      size_t /*len*/) { return receiver(buf, n); };
   }
 
-  // RFC 7230 Section 3.3.3: If this is a request message and none of the above
-  // are true (no Transfer-Encoding and no Content-Length), then the message
-  // body length is zero (no message body is present).
-  //
-  // For non-SSL builds, detect clients that send a body without a
-  // Content-Length header (raw HTTP over TCP). Check both the stream's
-  // internal read buffer (data already read from the socket during header
-  // parsing) and the socket itself for pending data. If data is found and
-  // exceeds the configured payload limit, reject with 413.
-  // For SSL builds we cannot reliably peek the decrypted application bytes,
-  // so keep the original behaviour.
+  // RFC 9112 §6: no Transfer-Encoding and no Content-Length means no body.
+  // For non-SSL builds we still scan non-persistent connections for stray
+  // body bytes so the payload limit is enforced (413). On keep-alive,
+  // pending bytes may be the next request (issue #2450), so skip.
 #if !defined(CPPHTTPLIB_SSL_ENABLED)
   if (!req.has_header("Content-Length") &&
       !detail::is_chunked_transfer_encoding(req.headers)) {
-    // Only check if payload_max_length is set to a finite value
-    if (payload_max_length_ > 0 &&
+    if (!detail::is_connection_persistent(req) && payload_max_length_ > 0 &&
         payload_max_length_ < (std::numeric_limits<size_t>::max)()) {
-      // Check if there is data already buffered in the stream (read during
-      // header parsing) or pending on the socket. Use a non-blocking socket
-      // check to avoid deadlock when the client sends no body.
-      bool has_data = strm.is_readable();
+      auto has_data = strm.is_readable();
       if (!has_data) {
-        socket_t s = strm.socket();
+        auto s = strm.socket();
         if (s != INVALID_SOCKET) {
           has_data = detail::select_read(s, 0, 0) > 0;
         }
@@ -11888,6 +11884,11 @@ get_client_ip(const std::string &x_forwarded_for,
                   ip_list.emplace_back(std::string(b + r.first, b + r.second));
                 });
 
+  // A malformed X-Forwarded-For (empty, comma-only, whitespace-only) yields
+  // no segments. Signal "no client IP derived" with an empty string so the
+  // caller can fall back to the connection-level remote address.
+  if (ip_list.empty()) { return std::string(); }
+
   for (size_t i = 0; i < ip_list.size(); ++i) {
     auto ip = ip_list[i];
 
@@ -11978,7 +11979,8 @@ Server::process_request(Stream &strm, const std::string &remote_addr,
 
   if (!trusted_proxies_.empty() && req.has_header("X-Forwarded-For")) {
     auto x_forwarded_for = req.get_header_value("X-Forwarded-For");
-    req.remote_addr = get_client_ip(x_forwarded_for, trusted_proxies_);
+    auto derived = get_client_ip(x_forwarded_for, trusted_proxies_);
+    req.remote_addr = derived.empty() ? remote_addr : derived;
   } else {
     req.remote_addr = remote_addr;
   }
@@ -12180,15 +12182,14 @@ Server::process_request(Stream &strm, const std::string &remote_addr,
     ret = write_response(strm, close_connection, req, res);
   }
 
-  // Drain any unconsumed request body to prevent request smuggling on
-  // keep-alive connections.
-  if (!req.body_consumed_ && detail::expect_content(req)) {
-    int drain_status = 200; // required by read_content signature
+  // Drain any unconsumed framed body to prevent request smuggling on
+  // keep-alive. Without framing there is no body to drain — reading would
+  // consume the next request (issue #2450).
+  if (!req.body_consumed_ && detail::has_framed_body(req)) {
+    int dummy_status;
     if (!detail::read_content(
-            strm, req, payload_max_length_, drain_status, nullptr,
+            strm, req, payload_max_length_, dummy_status, nullptr,
             [](const char *, size_t, size_t, size_t) { return true; }, false)) {
-      // Body exceeds payload limit or read error — close the connection
-      // to prevent leftover bytes from being misinterpreted.
       connection_closed = true;
     }
   }

test/test.cc

@@ -14251,6 +14251,53 @@ TEST(ForwardedHeadersTest, HandlesWhitespaceAroundIPs) {
   EXPECT_EQ(observed_remote_addr, "203.0.113.66");
 }
 
+// An X-Forwarded-For header whose value parses to zero IP segments must not
+// crash the server (it used to call front() on an empty vector inside
+// get_client_ip). The connection-level remote address must be retained instead.
+static void run_malformed_xff_test(const std::string &xff_value) {
+  Server svr;
+  svr.set_trusted_proxies({"192.0.2.45"});
+
+  std::string observed_remote_addr;
+  svr.Get("/ip", [&](const Request &req, Response &res) {
+    observed_remote_addr = req.remote_addr;
+    res.set_content("ok", "text/plain");
+  });
+
+  int port = 0;
+  thread t = thread([&]() {
+    port = svr.bind_to_any_port(HOST);
+    svr.listen_after_bind();
+  });
+  auto se = detail::scope_exit([&] {
+    svr.stop();
+    t.join();
+    ASSERT_FALSE(svr.is_running());
+  });
+
+  svr.wait_until_ready();
+
+  Client cli(HOST, port);
+  auto res = cli.Get("/ip", {{"X-Forwarded-For", xff_value}});
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+  EXPECT_TRUE(observed_remote_addr == "::1" ||
+              observed_remote_addr == "127.0.0.1");
+}
+
+TEST(ForwardedHeadersTest, EmptyXForwardedFor_DoesNotCrash) {
+  run_malformed_xff_test("");
+}
+
+TEST(ForwardedHeadersTest, CommaOnlyXForwardedFor_DoesNotCrash) {
+  run_malformed_xff_test(",");
+}
+
+TEST(ForwardedHeadersTest, MultipleCommasXForwardedFor_DoesNotCrash) {
+  run_malformed_xff_test(", , ,");
+}
+
 #ifndef _WIN32
 TEST(ServerRequestParsingTest, RequestWithoutContentLengthOrTransferEncoding) {
   Server svr;
@@ -18157,3 +18204,63 @@ TEST(RequestSmugglingTest, ContentLengthAndTransferEncodingRejected) {
               response.substr(0, response.find("\r\n")));
   }
 }
+
+// Regression for issue #2450: a DELETE without Content-Length on a
+// keep-alive connection must not let the post-response drain consume the
+// next request's bytes.
+TEST(KeepAliveTest, DeleteWithoutContentLengthDoesNotEatNextRequest) {
+  Server svr;
+
+  std::atomic<int> delete_count(0);
+  svr.Delete("/items/:id", [&](const Request &, Response &res) {
+    delete_count++;
+    res.status = StatusCode::NoContent_204;
+  });
+
+  auto port = svr.bind_to_any_port(HOST);
+  thread t = thread([&] { svr.listen_after_bind(); });
+  auto se = detail::scope_exit([&] {
+    svr.stop();
+    t.join();
+  });
+  svr.wait_until_ready();
+
+  auto error = Error::Success;
+  auto sock = detail::create_client_socket(
+      HOST, "", port, AF_UNSPEC, false, false, nullptr,
+      /*connection_timeout_sec=*/2, 0,
+      /*read_timeout_sec=*/2, 0,
+      /*write_timeout_sec=*/2, 0, std::string(), error);
+  ASSERT_NE(INVALID_SOCKET, sock);
+  auto sock_se = detail::scope_exit([&] { detail::close_socket(sock); });
+
+  auto send_request_and_read_response = [&](const std::string &req,
+                                            std::string &out) -> bool {
+    auto sent = send(sock, req.data(), req.size(), 0);
+    if (sent != static_cast<ssize_t>(req.size())) { return false; }
+    char buf[4096];
+    for (;;) {
+      auto n = recv(sock, buf, sizeof(buf), 0);
+      if (n <= 0) { return !out.empty(); }
+      out.append(buf, static_cast<size_t>(n));
+      if (out.find("\r\n\r\n") != std::string::npos) { return true; }
+    }
+  };
+
+  std::string req1 = "DELETE /items/1 HTTP/1.1\r\n"
+                     "Host: localhost\r\n"
+                     "\r\n";
+  std::string resp1;
+  ASSERT_TRUE(send_request_and_read_response(req1, resp1));
+  EXPECT_NE(std::string::npos, resp1.find("HTTP/1.1 204"));
+
+  std::string req2 = "DELETE /items/2 HTTP/1.1\r\n"
+                     "Host: localhost\r\n"
+                     "Connection: close\r\n"
+                     "\r\n";
+  std::string resp2;
+  ASSERT_TRUE(send_request_and_read_response(req2, resp2));
+  EXPECT_NE(std::string::npos, resp2.find("HTTP/1.1 204"));
+
+  EXPECT_EQ(2, delete_count.load());
+}