Forwarder output: fix segfault when sending IPFIX Templates

src/plugins/output/forwarder/src/Forwarder.h

@@ -59,7 +59,7 @@ struct Client;
 struct Odid
 {
     Odid() {} // Default constructor needed because of std::map
-    
+
     Odid(Session &session, uint32_t odid)
     : session(&session)
     , odid(odid)
@@ -73,7 +73,7 @@ struct Odid
     std::time_t last_templates_send_time = 0;
     unsigned bytes_since_templates_sent = 0;
 
-    std::string 
+    std::string
     str();
 
     void
@@ -93,7 +93,7 @@ struct Session
     , client(client)
     , ident(ident)
     {}
-    
+
     Connection &connection;
     Client &client;
     std::string ident;
@@ -117,17 +117,17 @@ struct Client
     std::string name;
     std::map<const ipx_session *, std::unique_ptr<Session>> sessions;
 
-    std::string 
+    std::string
     str()
     {
         return name;
     }
 };
 
-std::string 
+std::string
 Odid::str()
 {
-    return session->ident + "(" + std::to_string(odid) + ") -> " + session->client.name; 
+    return session->ident + "(" + std::to_string(odid) + ") -> " + session->client.name;
 }
 
 std::string
@@ -137,37 +137,37 @@ Session::str()
 }
 
 class Forwarder
-{    
+{
 public:
     Forwarder(ipx_ctx_t *log_ctx)
     : log_ctx(log_ctx)
     {}
 
-    void 
+    void
     set_transport_protocol(TransProto transport_protocol)
     {
         this->transport_protocol = transport_protocol;
     }
 
-    void 
+    void
     set_forward_mode(ForwardMode forward_mode)
     {
         this->forward_mode = forward_mode;
     }
 
-    void 
+    void
     set_connection_buffer_size(long number_of_bytes)
     {
         connection_manager.set_connection_buffer_size(number_of_bytes);
     }
 
-    void 
+    void
     set_template_refresh_interval_secs(int number_of_seconds)
     {
         this->template_refresh_interval_secs = number_of_seconds;
     }
 
-    void 
+    void
     set_template_refresh_interval_bytes(int number_of_bytes)
     {
         this->template_refresh_interval_bytes = number_of_bytes;
@@ -275,7 +275,7 @@ class Forwarder
         client.sessions[session_info] = std::move(session_ptr);
     }
 
-    void 
+    void
     close_session(Client &client, const ipx_session *session_info)
     {
         auto &session = *client.sessions[session_info];
@@ -295,7 +295,7 @@ class Forwarder
         }
     }
 
-    void 
+    void
     forward_round_robin(IPFIXMessage &message)
     {
         int i = 0;
@@ -331,7 +331,7 @@ class Forwarder
     /// through the session connection and update the state accordingly
     ///
     /// \return true if there was enough space in the connection buffer, false otherwise
-    bool 
+    bool
     send_templates(Session &session, Odid &odid, IPFIXMessage &message)
     {
         auto templates_snapshot = message.get_templates_snapshot();
@@ -342,19 +342,19 @@ class Forwarder
         MessageBuilder builder;
         builder.begin_message(header);
 
-        fds_tsnapshot_for(templates_snapshot, 
+        fds_tsnapshot_for(templates_snapshot,
             [](const fds_template *tmplt, void *data) -> bool {
                 auto &builder = *(MessageBuilder *)data;
                 builder.write_template(tmplt);
                 return true;
             }, &builder);
-        
+
         builder.finalize_message();
 
         auto lock = session.connection.begin_write();
         if (builder.message_length() > session.connection.writeable()) {
-            // IPX_CTX_WARNING(log_ctx, 
-            //     "[%s] Cannot send templates because buffer is full! (need %dB, have %ldB)", 
+            // IPX_CTX_WARNING(log_ctx,
+            //     "[%s] Cannot send templates because buffer is full! (need %dB, have %ldB)",
             //     odid.str().c_str(), builder.message_length(), session.connection.writeable());
             return false;
         }
@@ -371,18 +371,18 @@ class Forwarder
         return true;
     }
 
-    bool 
+    bool
     should_refresh_templates(Odid &odid)
     {
         if (transport_protocol != TransProto::Udp) {
             return false;
         }
         auto time_since = (std::time(NULL) - odid.last_templates_send_time);
-        return (time_since > (unsigned)template_refresh_interval_secs) 
+        return (time_since > (unsigned)template_refresh_interval_secs)
             || (odid.bytes_since_templates_sent > (unsigned)template_refresh_interval_bytes);
     }
 
-    bool 
+    bool
     templates_changed(Odid &odid, IPFIXMessage &message)
     {
         auto templates_snapshot = message.get_templates_snapshot();
@@ -392,7 +392,7 @@ class Forwarder
     /// Forward message to the client, including templates update if needed
     ///
     /// \return true if there was enough space in the connection buffer, false otherwise
-    bool 
+    bool
     forward_message(Client &client, IPFIXMessage &message)
     {
         auto &session = *client.sessions[message.session()];
@@ -409,17 +409,17 @@ class Forwarder
             IPX_CTX_INFO(log_ctx, "[%s] Seen new ODID %u", session.str().c_str(), message.odid());
         }
         auto &odid = session.odids[message.odid()];
-        
+
         if (should_refresh_templates(odid) || templates_changed(odid, message)) {
-            if (!send_templates(session, odid, message)) {
+            if (message.get_templates_snapshot() != nullptr && !send_templates(session, odid, message)) {
                 return false;
             }
         }
-        
+
         auto lock = session.connection.begin_write();
         if (message.length() > session.connection.writeable()) {
-            // IPX_CTX_WARNING(log_ctx, 
-            //     "[%s] Cannot forward message because buffer is full! (need %dB, have %ldB)", 
+            // IPX_CTX_WARNING(log_ctx,
+            //     "[%s] Cannot forward message because buffer is full! (need %dB, have %ldB)",
             //     odid.str().c_str(), message.length(), session.connection.writeable());
             return false;
         }