From 53fecaf5a2101b75f0a8dcbca2ac4a8578bd3adf Mon Sep 17 00:00:00 2001
From: defanor <defanor@uberspace.net>
Date: Thu, 4 Jun 2020 19:46:29 +0300
Subject: Implement XEP-0199: XMPP Ping

---
 README       |  1 +
 src/rexmpp.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 src/rexmpp.h |  5 +++++
 3 files changed, 50 insertions(+)

diff --git a/README b/README
index 4efc99c..3a43f2a 100644
--- a/README
+++ b/README
@@ -38,6 +38,7 @@ A rough roadmap:
 [+] "Happy Eyeballs" (RFC 8305).
 [+] XEP-0368: SRV records for XMPP over TLS.
 [+] SOCKS5 (RFC 1928) support. Implemented, though can be improved.
+[+] XEP-0199: XMPP Ping.
 
 
 - Library refinement:
diff --git a/src/rexmpp.c b/src/rexmpp.c
index 282118f..4b7a62c 100644
--- a/src/rexmpp.c
+++ b/src/rexmpp.c
@@ -198,6 +198,8 @@ xmlNodePtr rexmpp_xml_default_disco_info () {
   xmlNodePtr disco_feature =
     rexmpp_xml_feature("http://jabber.org/protocol/disco#info");
   identity->next = disco_feature;
+  xmlNodePtr ping_feature = rexmpp_xml_feature("urn:xmpp:ping");
+  disco_feature->next = ping_feature;
   return identity;
 }
 
@@ -266,6 +268,9 @@ rexmpp_err_t rexmpp_init (rexmpp_t *s, const char *jid)
   s->sasl_property_cb = NULL;
   s->xml_in_cb = NULL;
   s->xml_out_cb = NULL;
+  s->ping_delay = 600;
+  s->ping_requested = 0;
+  s->last_network_activity = 0;
 
   if (jid == NULL) {
     rexmpp_log(s, LOG_CRIT, "No initial JID is provided.");
@@ -389,6 +394,7 @@ void rexmpp_cleanup (rexmpp_t *s) {
     s->server_srv_tls_cur = NULL;
   }
   s->sm_state = REXMPP_SM_INACTIVE;
+  s->ping_requested = 0;
 }
 
 /* Frees the things that persist through reconnects. */
@@ -606,6 +612,7 @@ rexmpp_err_t rexmpp_send_continue (rexmpp_t *s)
                   0);
     }
     if (ret > 0) {
+      s->last_network_activity = time(NULL);
       s->send_buffer_sent += ret;
       if (s->send_buffer_sent == s->send_buffer_len) {
         free(s->send_buffer);
@@ -824,6 +831,7 @@ void rexmpp_recv (rexmpp_t *s) {
       chunk_raw_len = recv(s->server_socket, chunk_raw, 4096, 0);
     }
     if (chunk_raw_len > 0) {
+      s->last_network_activity = time(NULL);
       if (s->sasl_state == REXMPP_SASL_ACTIVE) {
         sasl_err = gsasl_decode(s->sasl_session, chunk_raw, chunk_raw_len,
                                 &chunk, &chunk_len);
@@ -1216,6 +1224,14 @@ void rexmpp_carbons_enabled (rexmpp_t *s,
   }
 }
 
+void rexmpp_pong (rexmpp_t *s,
+                  xmlNodePtr req,
+                  xmlNodePtr response,
+                  int success)
+{
+  s->ping_requested = 0;
+}
+
 void rexmpp_iq_discovery_info (rexmpp_t *s,
                                xmlNodePtr req,
                                xmlNodePtr response,
@@ -1464,6 +1480,8 @@ void rexmpp_process_element (rexmpp_t *s) {
         if (node != NULL) {
           free(node);
         }
+      } else if (rexmpp_xml_match(query, "urn:xmpp:ping", "ping")) {
+        rexmpp_iq_reply(s, elem, "result", NULL);
       } else {
         /* An unknown request. */
         rexmpp_iq_reply(s, elem, "error",
@@ -1917,6 +1935,22 @@ rexmpp_err_t rexmpp_run (rexmpp_t *s, fd_set *read_fds, fd_set *write_fds) {
     rexmpp_send_continue(s);
   }
 
+  /* Pinging the server. */
+  if (s->tcp_state == REXMPP_TCP_CONNECTED &&
+      s->last_network_activity + s->ping_delay <= time(NULL)) {
+    if (s->ping_requested == 0) {
+      s->ping_requested = 1;
+      xmlNodePtr ping_cmd = xmlNewNode(NULL, "ping");
+      xmlNewNs(ping_cmd, "urn:xmpp:ping", NULL);
+      rexmpp_iq_new(s, "get", jid_bare_to_host(s->initial_jid),
+                    ping_cmd, rexmpp_pong);
+    } else {
+      rexmpp_log(s, LOG_WARNING, "Ping timeout, reconnecting.");
+      rexmpp_cleanup(s);
+      rexmpp_schedule_reconnect(s);
+    }
+  }
+
   /* Receiving data. Leads to all kinds of things. */
   if (s->tcp_state == REXMPP_TCP_CONNECTED &&
       FD_ISSET(s->server_socket, read_fds) &&
@@ -2048,5 +2082,15 @@ struct timeval *rexmpp_timeout (rexmpp_t *s,
     ret = tv;
   }
 
+  if (s->tcp_state == REXMPP_TCP_CONNECTED &&
+      s->last_network_activity + s->ping_delay > now.tv_sec) {
+    time_t next_ping = s->last_network_activity + s->ping_delay - now.tv_sec;
+    if (ret == NULL || next_ping < ret->tv_sec) {
+      tv->tv_sec = next_ping;
+      tv->tv_usec = 0;
+      ret = tv;
+    }
+  }
+
   return ret;
 }
diff --git a/src/rexmpp.h b/src/rexmpp.h
index 2660877..9f748cf 100644
--- a/src/rexmpp.h
+++ b/src/rexmpp.h
@@ -272,6 +272,11 @@ struct rexmpp
   uint32_t stanzas_in_count;
   char *stream_id;
 
+  /* Server ping configuration and state. */
+  int ping_delay;
+  int ping_requested;
+  time_t last_network_activity;
+
   /* DNS-related structures. */
   ares_channel resolver_channel;
   struct ares_srv_reply *server_srv;
-- 
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