Correct a regression introduced in 0.8.0 that prevented socket options like TCP_NODELAY from being set. Improve documentation about how pre_init differs from init_asio. Improve documentation for the TCP pre-bind handler that is the actual solution to the issue this regression related to. references #530 fixes #812

Author: Peter Thorson

changelog.md

@@ -45,6 +45,9 @@ HEAD
   later compilers. Thank you Matus Kysel for the patch & tests. #792
 - Reliability: Add a few defensive assertions to guard against corrupted
   HTTP message reads. Thank you Oleh Derevenko for reporting. #899
+- Fix Regression: Correct a regression introduced in 0.8.0 that broke
+  functionality for setting accepted socket options like TCP_NODELAY.
+  #530 #812
 - Bug: Fix null pointer deference in proxy error handling code. Thank you
   abitmore for reporting and stkaufer for a patch. #820 #825
 - Documentation: Added language to explicitly clarify that the library

docs/handlers.dox

@@ -108,7 +108,24 @@ Close is not called for failed connections.
 Endpoint Handlers
 -----------------
 
-## Acceptance Loop End Handler
+### Socket Init Handler
+
+| Event          | Signature                                                                     | Availability         |
+| -------------- | ----------------------------------------------------------------------------- | -------------------- |
+| Listen Prebind | `lib::error_code tcp_pre_bind(lib::shared_ptr<lib::asio::ip::tcp::acceptor>)` | 0.8.0 Asio Transport |
+
+This hook is triggered during the call to `endpoint::listen` after the acceptor
+is initialized and open but before bind or listen are called. It provides an
+opportunity to make application specific configuation to the acceptor, most
+commonly setting socket options on the listening socket, such as SO_REUSEPORT
+or IPV6_ONLY.
+
+The return value of the callback will be used to determine whether to proceed
+with listening. Return an empty/0 error code to proceed, or another error code
+to fail. In the fail case, the error code will be reported back to the caller
+of `endpoint::listen`.
+
+### Acceptance Loop End Handler
 
 | Event                                 | Signature                                                             | Availability                 |
 | ------------------------------------- | --------------------------------------------------------------------- | ---------------------------- |

websocketpp/transport/asio/security/none.hpp

@@ -156,7 +156,8 @@ class connection : public lib::enable_shared_from_this<connection> {
     /// Perform one time initializations
     /**
      * init_asio is called once immediately after construction to initialize
-     * Asio components to the io_service
+     * Asio components to the io_service. At this stage the connection is
+     * speculative, the server may not have actually received a new connection.
      *
      * @param service A pointer to the endpoint's io_service
      * @param strand A shared pointer to the connection's asio strand
@@ -170,10 +171,6 @@ class connection : public lib::enable_shared_from_this<connection> {
 
         m_socket.reset(new lib::asio::ip::tcp::socket(*service));
 
-        if (m_socket_init_handler) {
-            m_socket_init_handler(m_hdl, *m_socket);
-        }
-
         m_state = READY;
 
         return lib::error_code();
@@ -194,7 +191,7 @@ class connection : public lib::enable_shared_from_this<connection> {
 
     /// Pre-initialize security policy
     /**
-     * Called by the transport after a new connection is created to initialize
+     * Called by the transport after a new connection is accepted to initialize
      * the socket component of the connection. This method is not allowed to
      * write any bytes to the wire. This initialization happens before any
      * proxies or other intermediate wrappers are negotiated.
@@ -207,6 +204,10 @@ class connection : public lib::enable_shared_from_this<connection> {
             return;
         }
 
+        if (m_socket_init_handler) {
+            m_socket_init_handler(m_hdl, *m_socket);
+        }
+
         m_state = READING;
 
         callback(lib::error_code());

websocketpp/transport/asio/security/tls.hpp

@@ -195,10 +195,6 @@ class connection : public lib::enable_shared_from_this<connection> {
         }
         m_socket.reset(new socket_type(*service, *m_context));
 
-        if (m_socket_init_handler) {
-            m_socket_init_handler(m_hdl, get_socket());
-        }
-
         m_io_service = service;
         m_strand = strand;
         m_is_server = is_server;
@@ -247,6 +243,9 @@ class connection : public lib::enable_shared_from_this<connection> {
             }
         }
 #endif
+        if (m_socket_init_handler) {
+            m_socket_init_handler(m_hdl, get_socket());
+        }
 
         callback(lib::error_code());
     }