callagent: Manually parse the 'tag' from a to...

This should be done through the grammar instead.

callagent/SIPDialog.st

@@ -63,6 +63,7 @@ Object subclass: SIPDialog [
 
     toTag: aTag [
         <category: 'accessing'>
+        to_tag := aTag
     ]
 
     callId [
@@ -100,4 +101,26 @@ Object subclass: SIPDialog [
     destPort [
         ^ dest_port
     ]
+
+    updateFromRequest: aReq [
+        to_tag ifNil: [
+            | to pos tag|
+            to := aReq parameter: 'To' ifAbsent: [^false].
+
+            pos := to indexOf: ';tag=' matchCase: true startingAt: 1.
+            pos ifNil: [^self]. 
+
+            tag := WriteStream on: (String new).
+
+            (pos last + 1) to: to size do: [:pos |
+                (to at: pos) = $; ifTrue: [
+                    to_tag := tag contents.
+                    ^ self
+                ].
+
+                tag nextPut: (to at: pos).
+            ].
+            to_tag := tag contents.
+        ]
+    ]
 ]

callagent/SIPTransactions.st

@@ -110,6 +110,9 @@ Object subclass: SIPTransaction [
         <category: 'dispatch'>
 
         ('Found response %1 %2' % {aReq code. aReq phrase}) printNl.
+
+        dialog updateFromRequest: aReq.
+
         code := aReq code asInteger.
         code < 200 ifTrue: [
             ^ self respNotification: aReq