Index: channels/chan_sip.c
===================================================================
RCS file: /usr/cvsroot/asterisk/channels/chan_sip.c,v
retrieving revision 1.836
diff -u -r1.836 chan_sip.c
--- channels/chan_sip.c	2 Sep 2005 19:24:32 -0000	1.836
+++ channels/chan_sip.c	6 Sep 2005 16:24:16 -0000
@@ -2996,8 +2996,11 @@
 {
 	struct sip_pvt *p;
 	char *callid;
-	char tmp[256] = "";
+	char toheader[128] = "";
+	char fromheader[128] = "";
 	char *tag = "", *c;
+	char *fromtag = "", *totag = "";
+	int badsyntax = 0;
 
 	callid = get_header(req, "Call-ID");
 
@@ -3005,32 +3008,103 @@
 		/* In principle Call-ID's uniquely identify a call, but with a forking SIP proxy
 		   we need more to identify a branch - so we have to check branch, from
 		   and to tags to identify a call leg.
-		     For Asterisk to behave correctly, you need to turn on pedanticsipchecking
+		   For Asterisk to behave correctly, you need to turn on pedanticsipchecking
 		   in sip.conf
 		   */
+		totag = get_header(req, "To");
+		c = strcasestr(totag, ";tag=");
+		if (c) {
+			ast_copy_string(toheader, c+5 , sizeof(toheader));
+			totag = toheader;
+		} else
+			totag = NULL;
+		if (totag) {
+			if ((c = strchr(totag, ';')))
+				*c = '\0';
+		}
+		fromtag = get_header(req, "From");
+		c = strcasestr(fromtag, ";tag=");
+		if (c) {
+			ast_copy_string(fromheader, c+5, sizeof(fromheader));
+			fromtag = fromheader;
+		} else
+			fromtag = NULL;
+
+		if (fromtag) {
+			if ((c = strchr(fromtag, ';')))
+				*c = '\0';
+		}
 		if (req->method == SIP_RESPONSE)
-			ast_copy_string(tmp, get_header(req, "To"), sizeof(tmp));
+			tag = totag;
 		else
-			ast_copy_string(tmp, get_header(req, "From"), sizeof(tmp));
-		tag = strcasestr(tmp, "tag=");
-		if (tag) {
-			tag += 4;
-			c = strchr(tag, ';');
-			if (c)
-				*c = '\0';
+			tag = fromtag;
+		if (option_debug > 2) {
+			if (req->method != SIP_RESPONSE) { 		/* Request */
+				if (totag && fromtag)
+					ast_log(LOG_DEBUG, "...Request within an existing dialog\n");
+				else if (totag && !fromtag)
+					ast_log(LOG_DEBUG, "...Request with no fromtag? Bad request.\n");
+				else if (!totag && !fromtag)
+					ast_log(LOG_DEBUG, "...Request with no tags? Bad request.\n");
+				else if (option_debug > 3)	/* From tag, no to tag */
+					ast_log(LOG_DEBUG, "New SIP request coming in:  Call ID: %s (Checking %s) --From tag %s --To-tag %s  \n", callid, req->method==SIP_RESPONSE ? "To" : "From", fromtag, totag);
+			} else {					/* Response */
+				if (totag && fromtag)
+					ast_log(LOG_DEBUG, "SIP response coming in:  Call ID: %s (Checking %s) --From tag %s --To-tag %s  \n", callid, req->method==SIP_RESPONSE ? "To" : "From", fromtag, totag);
+				else if (totag && !fromtag)
+					ast_log(LOG_DEBUG, "...Response with no fromtag? Bad response on bad request.\n");
+				else if (!totag && !fromtag)
+					ast_log(LOG_DEBUG, "...Response with no tags at all? Bad response.\n");
+				else 	/* From tag, no to tag */
+					ast_log(LOG_DEBUG, "...Response with no to tag? Bad response.\n");
+					
+			}
+		}
+		if (!fromtag) {					/* Always need from tags */
+			badsyntax = 1;
+		} 
+		if (req->method == SIP_RESPONSE && !totag) {	/* Responses need to-tags also */
+			badsyntax = 1;
+		}
+		if ( badsyntax ) {
+			ast_log(LOG_WARNING, "Bad SIP %s in dialog %s. \n", req->method==SIP_RESPONSE ? "Response" : "Request", callid);
 		}
 			
 	}
+
+	if (!badsyntax && option_debug > 3)
+		ast_log(LOG_DEBUG, "===== Looking for  Call ID: %s (Checking %s) --From tag %s --To-tag %s  \n", callid, req->method==SIP_RESPONSE ? "To" : "From", fromtag, totag);
 		
 	ast_mutex_lock(&iflock);
 	p = iflist;
-	while(p) {
+	while(p && !badsyntax) {
 		int found = 0;
 		if (req->method == SIP_REGISTER)
 			found = (!strcmp(p->callid, callid));
 		else 
 			found = (!strcmp(p->callid, callid) && 
 			(!pedanticsipchecking || !tag || ast_strlen_zero(p->theirtag) || !strcmp(p->theirtag, tag))) ;
+
+		if (option_debug > 3)
+			ast_log(LOG_DEBUG, "===== %s Their Call ID: %s Their Tag %s Our tag: as%08x\n", found ? "Found" : "No match", p->callid, p->theirtag, p->tag);
+
+		/* If we get a new request within an existing to-tag - check the to tag as well */
+		if (pedanticsipchecking && found  && req->method != SIP_RESPONSE) {	/* SIP Request */
+			if (p->tag == 0 && totag) {
+				/* We have no to tag, and they have. Wrong dialog */
+				found = 0;
+			} else if (totag) {			/* Both have tags, compare them */
+				char ourtag[12];
+				sprintf(ourtag, "as%08x", p->tag);
+				if (strcmp(totag, ourtag)) {
+					found = 0;		/* This is not our packet */
+				}
+			}
+			if (!found && option_debug > 3)
+				ast_log(LOG_DEBUG, "===== This is not our match on request: Call ID: %s Ourtag <null> Totag %s Method %s\n", p->callid, totag, sip_methods[req->method].text);
+		}
+
+
 		if (found) {
 			/* Found the call */
 			ast_mutex_lock(&p->lock);