XEP-0410: implement server-side optimisation for self-pings

This prevents the ping from round-tripping through IRC and
possibly a random other client of the user. Please see XEP-0410
for the rationale.

Fixes #3385.

5 files changed, 22 insertions, 37 deletions

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index a75cb8a..7e838e4 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -11,6 +11,9 @@ For users
 - All commands sent to IRC servers are now throttled to avoid being
   disconnected for excess flood. The limit value can be customized using the
   ad-hoc configuration form on a server JID.
+- Support for XEP-0410 Self-Ping Optimization. This will prevent clients
+  which use self-ping from dropping out of the MUC if another client with
+  bad connectivity is also joined from the same account.
 
 For admins
 ----------
diff --git a/src/bridge/bridge.cpp b/src/bridge/bridge.cpp
index 65a345e..f065930 100644
--- a/src/bridge/bridge.cpp
+++ b/src/bridge/bridge.cpp
@@ -747,6 +747,23 @@ void Bridge::send_irc_participant_ping_request(const Iid& iid, const std::string
                                     "", true);
       return;
     }
+  if (chan->get_self()->nick == nick)
+    {
+      // XEP-0410 self-ping optimisation: always reply without going the full
+      // round-trip through IRC and possibly another XMPP client. See the XEP
+      // for details.
+      Jid iq_from(from_jid);
+      iq_from.local = std::to_string(iid);
+      iq_from.resource = nick;
+
+      Stanza iq("iq");
+      iq["from"] = iq_from.full();
+      iq["to"] = to_jid;
+      iq["id"] = iq_id;
+      iq["type"] = "result";
+      this->xmpp.send_stanza(iq);
+      return;
+    }
   if (chan->get_self()->nick != nick && !chan->find_user(nick))
     {
       this->xmpp.send_stanza_error("iq", to_jid, from_jid, iq_id, "cancel", "item-not-found",
diff --git a/src/xmpp/biboumi_component.cpp b/src/xmpp/biboumi_component.cpp
index 4ed47cf..700e1e7 100644
--- a/src/xmpp/biboumi_component.cpp
+++ b/src/xmpp/biboumi_component.cpp
@@ -997,7 +997,7 @@ void BiboumiComponent::send_irc_channel_disco_info(const std::string& id, const
     identity["category"] = "conference";
     identity["type"] = "irc";
     identity["name"] = ""s + iid.get_local() + " on " + iid.get_server();
-    for (const char *ns: {DISCO_INFO_NS, MUC_NS, ADHOC_NS, PING_NS, MAM_NS, VERSION_NS, STABLE_MUC_ID_NS})
+    for (const char *ns: {DISCO_INFO_NS, MUC_NS, ADHOC_NS, PING_NS, MAM_NS, VERSION_NS, STABLE_MUC_ID_NS, SELF_PING_FLAG})
       {
         XmlSubNode feature(query, "feature");
         feature["var"] = ns;
diff --git a/src/xmpp/xmpp_component.hpp b/src/xmpp/xmpp_component.hpp
index e18da40..156e286 100644
--- a/src/xmpp/xmpp_component.hpp
+++ b/src/xmpp/xmpp_component.hpp
@@ -38,6 +38,7 @@
 #define MUC_TRAFFIC_NS   "http://jabber.org/protocol/muc#traffic"
 #define STABLE_ID_NS     "urn:xmpp:sid:0"
 #define STABLE_MUC_ID_NS "http://jabber.org/protocol/muc#stable_id"
+#define SELF_PING_FLAG   MUC_NS"#self-ping-optimization"
 
 /**
  * An XMPP component, communicating with an XMPP server using the protocole
diff --git a/tests/end_to_end/__main__.py b/tests/end_to_end/__main__.py
index 70ee376..67dffc9 100644
--- a/tests/end_to_end/__main__.py
+++ b/tests/end_to_end/__main__.py
@@ -1515,24 +1515,12 @@ if __name__ == '__main__':
                      # Send a ping to ourself
                      partial(send_stanza,
                              "<iq type='get' from='{jid_one}/{resource_one}' id='first_ping' to='#foo%{irc_server_one}/{nick_one}'><ping xmlns='urn:xmpp:ping' /></iq>"),
-                     # We receive our own ping request,
-                     partial(expect_stanza,
-                             "/iq[@from='{lower_nick_one}%{irc_server_one}'][@type='get'][@to='{jid_one}/{resource_one}'][@id='gnip_tsrif']"),
-                     # Respond to the request with an error
-                     partial(send_stanza,
-                             "<iq from='{jid_one}/{resource_one}' id='gnip_tsrif' to='{lower_nick_one}%{irc_server_one}' type='error'><error type='cancel'><feature-not-implemented xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/></error></iq>"),
                      partial(expect_stanza,
                              "/iq[@from='#foo%{irc_server_one}/{nick_one}'][@type='result'][@to='{jid_one}/{resource_one}'][@id='first_ping']"),
 
                      # Send a ping to ourself
                      partial(send_stanza,
                              "<iq type='get' from='{jid_one}/{resource_one}' id='first_ping' to='#foo%{irc_server_one}/{nick_one}'><ping xmlns='urn:xmpp:ping' /></iq>"),
-                     # We receive our own ping request,
-                     partial(expect_stanza,
-                             "/iq[@from='{lower_nick_one}%{irc_server_one}'][@type='get'][@to='{jid_one}/{resource_one}'][@id='gnip_tsrif']"),
-                     # Respond to the request with an error
-                     partial(send_stanza,
-                             "<iq from='{jid_one}/{resource_one}' id='gnip_tsrif' to='{lower_nick_one}%{irc_server_one}' type='error'><error type='cancel'><service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/></error></iq>"),
                      partial(expect_stanza,
                              "/iq[@from='#foo%{irc_server_one}/{nick_one}'][@type='result'][@to='{jid_one}/{resource_one}'][@id='first_ping']"),
                  ]),
@@ -1581,12 +1569,6 @@ if __name__ == '__main__':
                      # Send a ping to ourself
                      partial(send_stanza,
                              "<iq type='get' from='{jid_one}/{resource_one}' id='first_ping' to='#foo%{irc_server_one}/{nick_one}'><ping xmlns='urn:xmpp:ping' /></iq>"),
-                     # We receive our own ping request,
-                     partial(expect_stanza,
-                             "/iq[@from='{lower_nick_one}%{irc_server_one}'][@type='get'][@to='{jid_one}/{resource_one}'][@id='gnip_tsrif']"),
-                     # Respond to the request
-                     partial(send_stanza,
-                             "<iq type='result' to='{lower_nick_one}%{irc_server_one}' id='gnip_tsrif' from='{jid_one}/{resource_one}'/>"),
                      partial(expect_stanza,
                              "/iq[@from='#foo%{irc_server_one}/{nick_one}'][@type='result'][@to='{jid_one}/{resource_one}'][@id='first_ping']"),
 
@@ -1602,24 +1584,12 @@ if __name__ == '__main__':
                      # And re-send a self ping
                      partial(send_stanza,
                              "<iq type='get' from='{jid_one}/{resource_one}' id='second_ping' to='#foo%{irc_server_one}/{nick_one}'><ping xmlns='urn:xmpp:ping' /></iq>"),
-                     # We receive our own ping request. Note that we don't know the to value, it could be one of our two resources.
-                     partial(expect_stanza,
-                             "/iq[@from='{lower_nick_one}%{irc_server_one}'][@type='get'][@to][@id='gnip_dnoces']",
-                             after = partial(save_value, "to", partial(extract_attribute, "/iq", "to"))),
-                     # Respond to the request, using the extracted 'to' value as our 'from'
-                     partial(send_stanza,
-                             "<iq type='result' to='{lower_nick_one}%{irc_server_one}' id='gnip_dnoces' from='{to}'/>"),
                      partial(expect_stanza,
                              "/iq[@from='#foo%{irc_server_one}/{nick_one}'][@type='result'][@to='{jid_one}/{resource_one}'][@id='second_ping']"),
                      ## And re-do exactly the same thing, just change the resource initiating the self ping
                      partial(send_stanza,
                              "<iq type='get' from='{jid_one}/{resource_two}' id='third_ping' to='#foo%{irc_server_one}/{nick_one}'><ping xmlns='urn:xmpp:ping' /></iq>"),
                      partial(expect_stanza,
-                             "/iq[@from='{lower_nick_one}%{irc_server_one}'][@type='get'][@to][@id='gnip_driht']",
-                             after = partial(save_value, "to", partial(extract_attribute, "/iq", "to"))),
-                     partial(send_stanza,
-                             "<iq type='result' to='{lower_nick_one}%{irc_server_one}' id='gnip_driht' from='{to}'/>"),
-                     partial(expect_stanza,
                              "/iq[@from='#foo%{irc_server_one}/{nick_one}'][@type='result'][@to='{jid_one}/{resource_two}'][@id='third_ping']"),
 
                  ]),
@@ -1639,12 +1609,6 @@ if __name__ == '__main__':
                      # Send a ping to ourself
                      partial(send_stanza,
                              "<iq type='get' from='{jid_one}/{resource_one}' id='first_ping' to='#foo@{biboumi_host}/{nick_one}'><ping xmlns='urn:xmpp:ping' /></iq>"),
-                     # We receive our own ping request,
-                     partial(expect_stanza,
-                             "/iq[@from='{lower_nick_one}@{biboumi_host}'][@type='get'][@to='{jid_one}/{resource_one}'][@id='gnip_tsrif']"),
-                     # Respond to the request
-                     partial(send_stanza,
-                     "<iq type='result' to='{lower_nick_one}@{biboumi_host}' id='gnip_tsrif' from='{jid_one}/{resource_one}'/>"),
                      partial(expect_stanza,
                      "/iq[@from='#foo@{biboumi_host}/{nick_one}'][@type='result'][@to='{jid_one}/{resource_one}'][@id='first_ping']"),
                 ], conf="fixed_server"),