Sticky server does not work with H2 client (#7261)

(cherry picked from commit d285211)

Author: shinrich

doc/admin-guide/files/records.config.en.rst

@@ -977,7 +977,9 @@ mptcp
 .. ts:cv:: CONFIG proxy.config.http.attach_server_session_to_client INT 0
    :overridable:
 
-   Control the re-use of an server session by a user agent (client) session.
+   Control the re-use of an server session by a user agent (client) session. Currently only applies to user
+   agents using HTTP/1.0 or HTTP/1.1. For other HTTP versions, the origin connection is always returned to the
+   session sharing pool or closed.
 
    If a user agent performs more than one HTTP transaction on its connection to |TS| a server session must be
    obtained for the second (and subsequent) transaction as for the first. This settings affects how that server session

proxy/ProxySession.cc

@@ -200,9 +200,10 @@ ProxySession::connection_id() const
   return con_id;
 }
 
-void
+bool
 ProxySession::attach_server_session(Http1ServerSession *ssession, bool transaction_done)
 {
+  return false;
 }
 
 Http1ServerSession *

proxy/ProxySession.h

@@ -89,7 +89,7 @@ class ProxySession : public VConnection, public PluginUserArgs<TS_USER_ARGS_SSN>
   // Virtual Methods
   virtual void new_connection(NetVConnection *new_vc, MIOBuffer *iobuf, IOBufferReader *reader) = 0;
   virtual void start()                                                                          = 0;
-  virtual void attach_server_session(Http1ServerSession *ssession, bool transaction_done = true);
+  virtual bool attach_server_session(Http1ServerSession *ssession, bool transaction_done = true);
 
   virtual void release(ProxyTransaction *trans) = 0;
 

proxy/ProxyTransaction.cc

@@ -56,10 +56,10 @@ ProxyTransaction::new_transaction(bool from_early_data)
   _sm->attach_client_session(this, _reader);
 }
 
-void
+bool
 ProxyTransaction::attach_server_session(Http1ServerSession *ssession, bool transaction_done)
 {
-  _proxy_ssn->attach_server_session(ssession, transaction_done);
+  return _proxy_ssn->attach_server_session(ssession, transaction_done);
 }
 
 void

proxy/ProxyTransaction.h

@@ -38,7 +38,7 @@ class ProxyTransaction : public VConnection
   /// Virtual Methods
   //
   virtual void new_transaction(bool from_early_data = false);
-  virtual void attach_server_session(Http1ServerSession *ssession, bool transaction_done = true);
+  virtual bool attach_server_session(Http1ServerSession *ssession, bool transaction_done = true);
   Action *adjust_thread(Continuation *cont, int event, void *data);
   virtual void release(IOBufferReader *r) = 0;
   virtual void transaction_done();

proxy/http/Http1ClientSession.cc

@@ -460,7 +460,7 @@ Http1ClientSession::new_transaction()
   trans.new_transaction(read_from_early_data > 0 ? true : false);
 }
 
-void
+bool
 Http1ClientSession::attach_server_session(Http1ServerSession *ssession, bool transaction_done)
 {
   if (ssession) {
@@ -499,6 +499,7 @@ Http1ClientSession::attach_server_session(Http1ServerSession *ssession, bool tra
     bound_ss     = nullptr;
     slave_ka_vio = nullptr;
   }
+  return true;
 }
 
 void

proxy/http/Http1ClientSession.h

@@ -60,7 +60,7 @@ class Http1ClientSession : public ProxySession
   void destroy() override;
   void free() override;
 
-  void attach_server_session(Http1ServerSession *ssession, bool transaction_done = true) override;
+  bool attach_server_session(Http1ServerSession *ssession, bool transaction_done = true) override;
 
   // Implement VConnection interface.
   void do_io_close(int lerrno = -1) override;

proxy/http/HttpSM.cc

@@ -3113,10 +3113,14 @@ HttpSM::tunnel_handler_server(int event, HttpTunnelProducer *p)
     // server session to so the next ka request can use it.  Server sessions will
     // be placed into the shared pool if the next incoming request is for a different
     // origin server
+    bool release_origin_connection = true;
     if (t_state.txn_conf->attach_server_session_to_client == 1 && ua_txn && t_state.client_info.keep_alive == HTTP_KEEPALIVE) {
       Debug("http", "attaching server session to the client");
-      ua_txn->attach_server_session(server_session);
-    } else {
+      if (ua_txn->attach_server_session(server_session)) {
+        release_origin_connection = false;
+      }
+    }
+    if (release_origin_connection) {
       // Release the session back into the shared session pool
       server_session->get_netvc()->set_inactivity_timeout(HRTIME_SECONDS(t_state.txn_conf->keep_alive_no_activity_timeout_out));
       server_session->release();