Fix incorrect parsing in chan_gtalk when xmpp contains extra whitespaces

To drill into the xmpp to find the capabilities between channels, chan_gtalk 
calls iks_child() and iks_next(). iks_child() and iks_next() are functions in 
the iksemel xml parsing library that traverse xml nodes. The bug here is that 
both iks_child() and iks_next() will return the next iks_struct node 
*regardless* of type. chan_gtalk expects the next node to be of type IKS_TAG, 
which in most cases, it is, but in this case (a call being made from the 
Empathy IM client), there exists iks_struct nodes which are not IKS_TAG data 
(they are extraneous whitespaces), and chan_gtalk doesn't handle that case, 
so capabilities don't match, and a call cannot be made.

iks_first_tag() and iks_next_tag(), on the other hand, will not return the 
very next iks_struct, but will check to see if the next iks_struct is of 
type IKS_TAG. If it isn't, it will be skipped, and the next struct of type 
IKS_TAG it finds will be returned. This assures that chan_gtalk will find 
the iks_struct it is looking for.

This fix simply changes all calls to iks_child() and iks_next() to become 
calls to iks_first_tag() and iks_next_tag(), which resolves the capability 
matching.

The following is a payload listing from Empathy, which, due to the extraneous 
whitespace, will not be parsed correctly by iksemel:

<iq from='dbrooksjab@235-22-24-10/Telepathy' to='astjab@235-22-24-10/asterisk' type='set' id='542757715704'> <session xmlns='http://www.google.com/session' initiator='dbrooksjab@235-22-24-10/Telepathy' type='initiate' id='1837267342'> <description xmlns='http://www.google.com/session/phone'> <payload-type clockrate='16000' name='speex' id='96'/>
 <payload-type clockrate='8000' name='PCMA' id='8'/>
 <payload-type clockrate='8000' name='PCMU' id='0'/>
 <payload-type clockrate='90000' name='MPA' id='97'/>
 <payload-type clockrate='16000' name='SIREN' id='98'/>
 <payload-type clockrate='8000' name='telephone-event' id='99'/>
</description>
</session>
</iq>


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@185362 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_gtalk.c

@@ -649,11 +649,11 @@ static int gtalk_is_answered(struct gtalk *client, ikspak *pak)
 	}
 
 	/* codec points to the first <payload-type/> tag */
-	codec = iks_child(iks_child(iks_child(pak->x)));
+	codec = iks_first_tag(iks_first_tag(iks_first_tag(pak->x)));
 	while (codec) {
 		ast_rtp_set_m_type(tmp->rtp, atoi(iks_find_attrib(codec, "id")));
 		ast_rtp_set_rtpmap_type(tmp->rtp, atoi(iks_find_attrib(codec, "id")), "audio", iks_find_attrib(codec, "name"), 0);
-		codec = iks_next(codec);
+		codec = iks_next_tag(codec);
 	}
 	
 	/* Now gather all of the codecs that we are asked for */
@@ -1224,12 +1224,12 @@ static int gtalk_newcall(struct gtalk *client, ikspak *pak)
 	}
 
 	/* codec points to the first <payload-type/> tag */	
-	codec = iks_child(iks_child(iks_child(pak->x)));
+	codec = iks_first_tag(iks_first_tag(iks_first_tag(pak->x)));
 	
 	while (codec) {
 		ast_rtp_set_m_type(p->rtp, atoi(iks_find_attrib(codec, "id")));
 		ast_rtp_set_rtpmap_type(p->rtp, atoi(iks_find_attrib(codec, "id")), "audio", iks_find_attrib(codec, "name"), 0);
-		codec = iks_next(codec);
+		codec = iks_next_tag(codec);
 	}
 	
 	/* Now gather all of the codecs that we are asked for */
@@ -1343,11 +1343,11 @@ static int gtalk_add_candidate(struct gtalk *client, ikspak *pak)
 	traversenodes = pak->query;
 	while(traversenodes) {
 		if(!strcasecmp(iks_name(traversenodes), "session")) {
-			traversenodes = iks_child(traversenodes);
+			traversenodes = iks_first_tag(traversenodes);
 			continue;
 		}
 		if(!strcasecmp(iks_name(traversenodes), "transport")) {
-			traversenodes = iks_child(traversenodes);
+			traversenodes = iks_first_tag(traversenodes);
 			continue;
 		}
 		if(!strcasecmp(iks_name(traversenodes), "candidate")) {
@@ -1386,7 +1386,7 @@ static int gtalk_add_candidate(struct gtalk *client, ikspak *pak)
 			gtalk_update_stun(p->parent, p);
 			newcandidate = NULL;
 		}
-		traversenodes = iks_next(traversenodes);
+		traversenodes = iks_next_tag(traversenodes);
 	}
 	
 	receipt = iks_new("iq");