Added TLS SNI support

src/SocketCore.cc

@@ -121,6 +121,19 @@ std::string errorMsg(int errNum)
 }
 } // namespace
 
+namespace {
+enum TlsState {
+  // TLS object is not initialized.
+  A2_TLS_NONE = 0,
+  // TLS object is initialized. Ready for handshake.
+  A2_TLS_INITIALIZED = 1,
+  // TLS object is now handshaking.
+  A2_TLS_HANDSHAKING = 2,
+  // TLS object is now connected.
+  A2_TLS_CONNECTED = 3
+};
+} // namespace
+
 int SocketCore::protocolFamily_ = AF_UNSPEC;
 
 std::vector<std::pair<sockaddr_union, socklen_t> >
@@ -152,7 +165,7 @@ SocketCore::SocketCore(sock_t sockfd, int sockType)
 void SocketCore::init()
 {
   blocking_ = true;
-  secure_ = 0;
+  secure_ = A2_TLS_NONE;
 
   wantRead_ = false;
   wantWrite_ = false;
@@ -837,16 +850,28 @@ void SocketCore::prepareSecureConnection()
                            tlsContext_->getCertCred());
     gnutls_transport_set_ptr(sslSession_, (gnutls_transport_ptr_t)sockfd_);
 #endif // HAVE_LIBGNUTLS
-    secure_ = 1;
+    secure_ = A2_TLS_INITIALIZED;
   }
 }
 
 bool SocketCore::initiateSecureConnection(const std::string& hostname)
 {
-  if(secure_ == 1) {
-    wantRead_ = false;
-    wantWrite_ = false;
+  wantRead_ = false;
+  wantWrite_ = false;
 #ifdef HAVE_OPENSSL
+  switch(secure_) {
+  case A2_TLS_INITIALIZED:
+    secure_ = A2_TLS_HANDSHAKING;
+#ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
+    if(!util::isNumericHost(hostname)) {
+      // TLS extensions: SNI.  There is not documentation about the
+      // return code for this function (actually this is macro
+      // wrapping SSL_ctrl at the time of this writing).
+      SSL_set_tlsext_host_name(ssl, hostname.c_str());
+    }
+#endif // SSL_CTRL_SET_TLSEXT_HOSTNAME
+    // Fall through
+  case A2_TLS_HANDSHAKING: {
     ERR_clear_error();
     int e = SSL_connect(ssl);
 
@@ -950,8 +975,28 @@ bool SocketCore::initiateSecureConnection(const std::string& hostname)
         throw DL_ABORT_EX(MSG_HOSTNAME_NOT_MATCH);
       }
     }
+    secure_ = A2_TLS_CONNECTED;
+    break;
+  }
+  default:
+    break;
+  }
 #endif // HAVE_OPENSSL
 #ifdef HAVE_LIBGNUTLS
+  switch(secure_) {
+  case A2_TLS_INITIALIZED:
+    secure_ = A2_TLS_HANDSHAKING;
+    if(!util::isNumericHost(hostname)) {
+      // TLS extensions: SNI
+      int ret = gnutls_server_name_set(sslSession_, GNUTLS_NAME_DNS,
+                                       hostname.c_str(), hostname.size());
+      if(ret < 0) {
+        A2_LOG_WARN(fmt("Setting hostname in SNI extension failed. Cause: %s",
+                        gnutls_strerror(ret)));
+      }
+    }
+    // Fall through
+  case A2_TLS_HANDSHAKING: {
     int ret = gnutls_handshake(sslSession_);
     if(ret == GNUTLS_E_AGAIN) {
       gnutlsRecordCheckDirection();
@@ -1056,12 +1101,14 @@ bool SocketCore::initiateSecureConnection(const std::string& hostname)
         }
       }
     }
-#endif // HAVE_LIBGNUTLS
-    secure_ = 2;
-    return true;
-  } else {
-    return true;
+    secure_ = A2_TLS_CONNECTED;
+    break;
   }
+  default:
+    break;
+  }
+#endif // HAVE_LIBGNUTLS
+  return true;
 }
 
 ssize_t SocketCore::writeData(const char* data, size_t len,