res_xmpp: Fix a segfault caused by bodyless messages

(closes issue ASTERISK-20361)
Reported by: Noah Engelberth
Review: https://reviewboard.asterisk.org/r/2108/
........

Merged revisions 372984 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@372985 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_xmpp.c

@@ -2983,19 +2983,23 @@ static int xmpp_component_authenticating(struct ast_xmpp_client *client, struct
 static int xmpp_pak_message(struct ast_xmpp_client *client, struct ast_xmpp_client_config *cfg, iks *node, ikspak *pak)
 {
 	struct ast_xmpp_message *message;
+	char *body;
 	int deleted = 0;
 
 	ast_debug(3, "XMPP client '%s' received a message\n", client->name);
 
+	if (!(body = iks_find_cdata(pak->x, "body"))) {
+		/* Message contains no body, ignore it. */
+		return 0;
+	}
+
 	if (!(message = ast_calloc(1, sizeof(*message)))) {
 		return -1;
 	}
 
 	message->arrived = ast_tvnow();
 
-	if (iks_find_cdata(pak->x, "body")) {
-		message->message = ast_strdup(iks_find_cdata(pak->x, "body"));
-	}
+	message->message = ast_strdup(body);
 
 	ast_copy_string(message->id, S_OR(pak->id, ""), sizeof(message->id));
 	message->from = !ast_strlen_zero(pak->from->full) ? ast_strdup(pak->from->full) : NULL;