Add some basic support for offering ice-lite using rtpproxy's

module with the same name.

sippy/Rtp_proxy_session.py

@@ -29,6 +29,7 @@
 from hashlib import md5
 from random import random
 from time import time
+from urllib.parse import unquote
 try:
     from _thread import get_ident
 except ImportError:
@@ -45,6 +46,12 @@
 DTLS_ATTRS = ('setup', 'fingerprint', 'rtcp', 'ssrc')
 DTLS_ATTRS_RM = tuple([a for a in DTLS_ATTRS if a != 'ssrc'])
 
+ICE_ATTRS = ('ice-ufrag', 'ice-pwd')
+ICE_ATTRS_RM = ICE_ATTRS + ('candidate', 'ice-options', 'rtcp-mux',
+  'end-of-candidates', 'ice-options')
+ICE_ATTRS_RM += ('extmap', 'extmap-allow-mixed', 'msid',
+  'msid-semantic', 'mid', 'group', 'rtcp-fb')
+
 try:
     strtypes = (str, unicode)
 except NameError:
@@ -217,6 +224,64 @@ def sdp_sect_fin(self, sdp_bc, sect):
         sect.addHeader('a', F'setup:{self.dtls_mode}')
         sect.addHeader('a', F'fingerprint:{self.dtls_fingerprint}')
 
+class subcommand_ice(subcommand):
+    name = 'ICE'
+    ice_lufrag: str
+    ice_lpwd: str
+    ice_candidates: list
+    i_mod = subcommand.mod_2_i_mod['ice_lite']
+
+    def __init__(self):
+        super().__init__(f'{self.i_mod} S')
+
+    def handle_results(self, results, ur):
+        if ex:=super().handle_results(results, ur): return ex
+        ice_res = results[0].split()
+        if len(ice_res) < 3:
+            return RtpProxyError(f'RTPProxy errored: {self.name}: {results=}')
+        self.ice_lufrag, self.ice_lpwd = ice_res[:2]
+        self.ice_candidates = [unquote(r[2:]) for r in ice_res[2:]]
+        ur.sdp_sect_fins.append(self.sdp_sect_fin)
+        return None
+
+    def sdp_sect_fin(self, sdp_bc, sect):
+        self._sdp_attrs_rm(sdp_bc, sect, ICE_ATTRS_RM)
+        sect.addHeader('a', 'rtcp-mux')
+        sect.addHeader('a', 'ice-lite')
+        sect.addHeader('a', F'ice-ufrag:{self.ice_lufrag}')
+        sect.addHeader('a', F'ice-pwd:{self.ice_lpwd}')
+        for cand in self.ice_candidates:
+            sect.addHeader('a', F'candidate:{cand}')
+        sect.m_header.transport = 'UDP/TLS/RTP/SAVP'
+
+class subcommand_deice(subcommand):
+    name = 'deICE'
+    i_mod = subcommand.mod_2_i_mod['ice_lite']
+
+    def __init__(self, sdp_bc, sect):
+        adict = dict([(x.name, x.value) for x in sect.a_headers
+                        if x.name in ICE_ATTRS])
+        for rattr in ('ice-ufrag', 'ice-pwd'):
+            if rattr not in adict:
+                raise SdpParseError(f'Missing ICE {rattr} parameter')
+        super().__init__(f'{self.i_mod} A {adict["ice-ufrag"]} {adict["ice-pwd"]}')
+        for cand in (x.value for x in sect.a_headers
+                        if x.name == 'candidate'):
+            pts = cand.split(None, 4)
+            if pts[2].lower() != 'udp':
+                continue
+            self.append(f'{self.i_mod} C {cand}')
+
+    def handle_results(self, results, ur):
+        if ex:=super().handle_results(results, ur): return ex
+        if any(true for r in results if r != '0'):
+            return RtpProxyError(f'RTPProxy errored: {self.name}: {results=}')
+        ur.sdp_sect_fins.append(self.sdp_sect_fin)
+        return None
+
+    def sdp_sect_fin(self, sdp_bc, sect):
+        self._sdp_attrs_rm(sdp_bc, sect, ICE_ATTRS_RM)
+
 class subcommand_dedtls(subcommand):
     name = 'deDTLS'
     i_mod = subcommand.mod_2_i_mod['dtls_gw']
@@ -276,6 +341,7 @@ class _rtpps_side(object):
     oh_remote = None
     repacketize = None
     gateway_dtls = 'pass'
+    deice = False
     soft_repacketize = False
     after_sdp_change = None
     needs_new_port = False
@@ -416,8 +482,12 @@ def _on_sdp_change(self, rtpps, sdp_body, result_callback, en_excpt):
             up.index = si
             if otherside.gateway_dtls == 'dtls':
                 up.subcommands.append(subcommand_dtls())
+            if otherside.deice:
+                up.subcommands.append(subcommand_ice())
             if self.gateway_dtls == 'dtls' and sect.m_header.transport in DTLS_TRANSPORTS:
                 up.subcommands.append(subcommand_dedtls(sdp_bc, sect))
+            if self.deice:
+                up.subcommands.append(subcommand_deice(sdp_bc, sect))
             up.result_callback = partial(self._sdp_change_finish, sdp_body, sect, sects, result_callback)
             self.update(up)
         return