Make sure we keep the stable-id and origin-id nodes when required

See https://xmpp.org/extensions/xep-0359.html

src/xmpp/biboumi_component.cpp

@@ -286,7 +286,26 @@ void BiboumiComponent::handle_message(const Stanza& stanza)
       if (body && !body->get_inner().empty())
         {
           if (bridge->is_resource_in_chan(iid.to_tuple(), from.resource))
-            bridge->send_channel_message(iid, body->get_inner(), id);
+            {
+              // Extract some XML nodes that we must include in the
+              // reflection (if any), because XMPP says so
+              std::vector<XmlNode> nodes_to_reflect;
+              const XmlNode* origin_id = stanza.get_child("origin-id", STABLE_ID_NS);
+              if (origin_id)
+                nodes_to_reflect.push_back(*origin_id);
+              const auto own_address = std::to_string(iid) + '@' + this->served_hostname;
+              for (const XmlNode* stable_id: stanza.get_children("stable-id", STABLE_ID_NS))
+                {
+                  // Stanza ID generating entities, which encounter a
+                  // <stanza-id/> element where the 'by' attribute matches
+                  // the 'by' attribute they would otherwise set, MUST
+                  // delete that element even if they are not adding their
+                  // own stanza ID.
+                  if (stable_id->get_tag("by") != own_address)
+                    nodes_to_reflect.push_back(*stable_id);
+                }
+              bridge->send_channel_message(iid, body->get_inner(), id, std::move(nodes_to_reflect));
+            }
           else
             {
               error_type = "modify";

src/xmpp/xmpp_component.cpp

@@ -367,7 +367,7 @@ void XmppComponent::send_topic(const std::string& from, Xmpp::body&& topic, cons
   this->send_stanza(message);
 }
 
-void XmppComponent::send_muc_message(const std::string& muc_name, const std::string& nick, Xmpp::body&& xmpp_body, const std::string& jid_to, std::string uuid, std::string id)
+Stanza XmppComponent::make_muc_message(const std::string& muc_name, const std::string& nick, Xmpp::body&& xmpp_body, const std::string& jid_to, std::string uuid, std::string id)
 {
   Stanza message("message");
   message["to"] = jid_to;
@@ -399,7 +399,7 @@ void XmppComponent::send_muc_message(const std::string& muc_name, const std::str
       stanza_id["id"] = std::move(uuid);
     }
 
-  this->send_stanza(message);
+  return message;
 }
 
 #ifdef USE_DATABASE

src/xmpp/xmpp_component.hpp

@@ -135,8 +135,8 @@ public:
   /**
    * Send a (non-private) message to the MUC
    */
-  void send_muc_message(const std::string& muc_name, const std::string& nick, Xmpp::body&& body, const std::string& jid_to,
-                        std::string uuid, std::string id);
+  Stanza make_muc_message(const std::string& muc_name, const std::string& nick, Xmpp::body&& xmpp_body, const std::string& jid_to,
+                          std::string uuid, std::string id);
 #ifdef USE_DATABASE
   /**
    * Send a message, with a <delay/> element, part of a MUC history