fix: update Route header handling in established dialogs

Author: moha-abdi

PySIP/sip_call.py

@@ -457,15 +457,16 @@ def construct_invite_message(
     def ack_generator(self, transaction):
         _, port = self.sip_core.get_extra_info("sockname")
         ip = self.my_public_ip
+        request_uri = self.dialogue.remote_contact_uri or f"sip:{self.callee}@{self.server}:{self.port};transport={self.CTS}"
 
-        msg = f"ACK sip:{self.callee}@{self.server}:{self.port};transport={self.CTS} SIP/2.0\r\n"
+        msg = f"ACK {request_uri} SIP/2.0\r\n"
         msg += f"Via: SIP/2.0/{self.CTS} {ip}:{port};rport;branch={transaction.branch_id};alias\r\n"
         msg += "Max-Forwards: 70\r\n"
         msg += f"From: sip:{self.caller_id}@{self.server};tag={self.dialogue.local_tag}\r\n"
         msg += f"To: sip:{self.callee}@{self.server};tag={self.dialogue.remote_tag}\r\n"
         msg += f"Call-ID: {self.call_id}\r\n"
         msg += f"CSeq: {transaction.cseq} ACK\r\n"
-        msg += f"Route: <sip:{self.server}:{self.port};transport={self.CTS};lr>\r\n"
+        msg += f"Route: <{request_uri};lr>\r\n"
         msg += "Content-Length: 0\r\n\r\n"
 
         return msg
@@ -476,18 +477,20 @@ def bye_generator(self):
 
         branch_id = self.sip_core.gen_branch()
         transaction = self.dialogue.add_transaction(branch_id, "BYE")
+        request_uri = self.dialogue.remote_contact_uri or f"sip:{self.callee}@{peer_ip}:{peer_port};transport={self.CTS}"
 
-        msg = f"BYE sip:{self.callee}@{peer_ip}:{peer_port};transport={self.CTS} SIP/2.0\r\n"
+        msg = f"BYE {request_uri} SIP/2.0\r\n"
         msg += (
             f"Via: SIP/2.0/{self.CTS} {self.my_public_ip}:{port};rport;"
             + f"branch={branch_id};alias\r\n"
         )
-        msg += 'Reason: Q.850;cause=16;text="normal call clearing"'
+        msg += 'Reason: Q.850;cause=16;text="normal call clearing"\r\n'
         msg += "Max-Forwards: 70\r\n"
         msg += f"From: sip:{self.caller_id}@{self.server};tag={self.dialogue.local_tag}\r\n"
         msg += f"To: sip:{self.callee}@{self.server};tag={self.dialogue.remote_tag}\r\n"
         msg += f"Call-ID: {self.call_id}\r\n"
         msg += f"CSeq: {transaction.cseq} BYE\r\n"
+        msg += f"Route: <{request_uri};lr>\r\n"
         msg += "Content-Length: 0\r\n\r\n"
 
         return msg
@@ -500,8 +503,9 @@ def refer_generator(self, refer_to_callee):
         transaction = self.dialogue.add_transaction(branch_id, "REFER")
         refer_to = f"sip:{refer_to_callee}@{self.server};transport={self.CTS}"
         referred_by = f"sip:{self.caller_id}@{self.server}"
+        request_uri= self.dialogue.remote_contact_uri or f"sip:{self.callee}@{self.server}:{self.port};transport={self.CTS}"
 
-        msg = f"REFER sip:{self.callee}@{self.server}:{self.port};transport={self.CTS} sip/2.0\r\n"
+        msg = f"REFER {request_uri} sip/2.0\r\n"
         msg += f"Via: sip/2.0/{self.CTS} {ip}:{port};rport;branch={branch_id};alias\r\n"
         msg += "Max-Forwards: 70\r\n"
         msg += f"From: sip:{self.caller_id}@{self.server};tag={self.dialogue.local_tag}\r\n"
@@ -511,6 +515,7 @@ def refer_generator(self, refer_to_callee):
         msg += f"Refer-To: {refer_to}\r\n"
         msg += f"Referred-By: {referred_by}\r\n"
         msg += f"Contact: <sip:{self.username}@{ip}:{port};transport={self.CTS}>\r\n"
+        msg += f"Route: <{request_uri};lr>\r\n"
         msg += "Content-Length: 0\r\n\r\n"
 
         return msg
@@ -668,10 +673,10 @@ async def message_handler(self, msg: SipMessage):
             transaction = self.dialogue.add_transaction(
                 self.sip_core.gen_branch(), "ACK"
             )
+            self.dialogue.update_state(msg)
             ack_message = self.ack_generator(transaction)
             self.dialogue.auth_retry_count = 0  # reset the auth counter
             await self.sip_core.send(ack_message)
-            self.dialogue.update_state(msg)
             await self.update_call_state(CallState.ANSWERED)
             return
 

PySIP/sip_core.py

@@ -420,6 +420,7 @@ def __init__(self, call_id, local_tag, remote_tag) -> None:
         self.auth_retry_count = 0
         self._local_session_info: Optional[SDPParser] = None
         self._remote_session_info: Optional[SDPParser] = None
+        self.remote_contact_uri: Optional[str] = None
 
     def matches(self, call_id, local_tag, remote_tag):
         # We now check if the provided identifiers match this dialogue's identifiers
@@ -449,6 +450,7 @@ def find_transaction(self, branch_id):
     def update_state(self, message):
         # This method should be called with each message received/sent that pertains to this dialog
         self.previous_state = self.state
+
         is_provisional_response = (str(message.status).startswith("18")) and (
             message.method == "INVITE"
         )
@@ -468,11 +470,12 @@ def update_state(self, message):
                 self._remote_session_info = SDPParser(message.body)
 
         elif (
-            self.state in [DialogState.INITIAL, DialogState.EARLY] and is_final_response
+            self.state in [DialogState.PREDIALOG, DialogState.INITIAL, DialogState.EARLY] and is_final_response
         ):
             self.state = DialogState.CONFIRMED
             if message.body is not None:
                 self._remote_session_info = SDPParser(message.body)
+                self.update_remote_contact(message.get_header("Contact"))
         elif message.method == "BYE" and message.status is SIPStatus.OK:
             self.state = DialogState.TERMINATED
         elif message.status == SIPStatus(487) and message.method == "INVITE":
@@ -483,6 +486,13 @@ def update_state(self, message):
         if self.state != self.previous_state:
             logger.log(logging.DEBUG, f"Dialog state changed to -> {self.state}")
 
+    def update_remote_contact(self, contact_header: str) -> None:
+        if contact_header:
+            match = re.search(r'<(.+?)>', contact_header)
+            if match:
+                self.remote_contact_uri = match.group(1)
+                logger.debug(f"Updated remote contact URI: {self.remote_contact_uri}")
+
     @property
     def local_session_info(self):
         return self._local_session_info

requirements.txt

@@ -2,3 +2,4 @@ pydub>=0.25.1
 requests>=2.25.1
 edge-tts>=5.0.0
 python-dotenv>=0.19.0
+scipy