ping: use a constant stanza ID

src/ping.c

@@ -28,7 +28,7 @@ void xmppipe_ping(xmppipe_state_t *state) {
   iq = xmppipe_stanza_new(state->ctx);
   xmppipe_stanza_set_name(iq, "iq");
   xmppipe_stanza_set_type(iq, "get");
-  xmppipe_stanza_set_id(iq, "c2s1");
+  xmppipe_stanza_set_id(iq, XMPPIPE_KEEPALIVE_ID);
   xmppipe_stanza_set_attribute(iq, "from",
                                xmpp_conn_get_bound_jid(state->conn));
 

src/xmppipe.c

@@ -354,7 +354,8 @@ int xmppipe_stream_init(xmppipe_state_t *state) {
   xmpp_handler_add(state->conn, handle_iq, NULL, "iq", "result", state);
   xmpp_handler_add(state->conn, handle_pong, "urn:xmpp:ping", "iq", "get",
                    state);
-  xmpp_id_handler_add(state->conn, handle_ping_reply, "c2s1", state);
+  xmpp_id_handler_add(state->conn, handle_ping_reply, XMPPIPE_KEEPALIVE_ID,
+                      state);
 
   xmpp_handler_add(state->conn, handle_disco_items,
                    "http://jabber.org/protocol/disco#items", "iq", "result",

src/xmppipe.h

@@ -28,6 +28,7 @@
 
 #define XMPPIPE_VERSION "0.15.0"
 #define XMPPIPE_RESOURCE "xmppipe"
+#define XMPPIPE_KEEPALIVE_ID "xmppipe_keepalive"
 
 #define XMPPIPE_STREQ(a, b) (strcmp((a), (b)) == 0)
 #define XMPPIPE_STRNEQ(a, b) (strcmp((a), (b)) != 0)