Set ice candidates server (#285)

* Add code

* Add code

* Code

backend/fastrtc/webrtc_connection_mixin.py

@@ -9,6 +9,7 @@ from collections import defaultdict
 from collections.abc import AsyncGenerator, Callable
 from dataclasses import dataclass, field
 from typing import (
+    Any,
     Literal,
     ParamSpec,
     TypeVar,
@@ -16,11 +17,14 @@ from typing import (
 )
 
 from aiortc import (
+    RTCConfiguration,
     RTCIceCandidate,
+    RTCIceServer,
     RTCPeerConnection,
     RTCSessionDescription,
 )
 from aiortc.contrib.media import MediaRelay  # type: ignore
+from anyio.to_thread import run_sync
 from fastapi.responses import JSONResponse
 
 from fastrtc.tracks import (
@@ -37,6 +41,7 @@ from fastrtc.tracks import (
 from fastrtc.utils import (
     AdditionalOutputs,
     Context,
+    RTCConfigurationCallable,
     create_message,
     webrtc_error_handler,
 )
@@ -80,12 +85,32 @@ class WebRTCConnectionMixin:
         self.modality: Literal["video", "audio", "audio-video"]
         self.mode: Literal["send", "receive", "send-receive"]
         self.allow_extra_tracks: bool
+        self.rtc_configuration: dict[str, Any] | None | RTCConfigurationCallable | None
+        self.server_rtc_configuration: RTCConfiguration | None
 
     @staticmethod
     async def wait_for_time_limit(pc: RTCPeerConnection, time_limit: float):
         await asyncio.sleep(time_limit)
         await pc.close()
 
+    @staticmethod
+    def convert_to_aiortc_format(
+        rtc_configuration: dict[str, Any] | None,
+    ) -> RTCConfiguration | None:
+        rtc_config = rtc_configuration
+        if rtc_config is not None:
+            rtc_config = RTCConfiguration(
+                iceServers=[
+                    RTCIceServer(
+                        urls=server["urls"],
+                        username=server.get("username"),
+                        credential=server.get("credential"),
+                    )
+                    for server in rtc_config.get("iceServers", [])
+                ]
+            )
+        return rtc_config
+
     async def connection_timeout(
         self,
         pc: RTCPeerConnection,
@@ -148,6 +173,15 @@ class WebRTCConnectionMixin:
 
         return set_outputs
 
+    async def resolve_rtc_configuration(self) -> dict[str, Any] | None:
+        if inspect.isfunction(self.rtc_configuration):
+            if inspect.iscoroutinefunction(self.rtc_configuration):
+                return await self.rtc_configuration()
+            else:
+                return await run_sync(self.rtc_configuration)
+        else:
+            return cast(dict[str, Any], self.rtc_configuration) or {}
+
     async def handle_offer(self, body, set_outputs):
         logger.debug("Starting to handle offer")
         logger.debug("Offer body %s", body)
@@ -169,13 +203,9 @@ class WebRTCConnectionMixin:
             pc = self.pcs[webrtc_id]
             if pc.connectionState != "closed":
                 try:
-                    # Parse the candidate string from the browser
                     candidate_str = body["candidate"].get("candidate", "")
 
                     # Example format: "candidate:2393089663 1 udp 2122260223 192.168.86.60 63692 typ host generation 0 ufrag LkZb network-id 1 network-cost 10"
-                    # We need to parse this string to extract the required fields
-
-                    # Parse the candidate string
                     parts = candidate_str.split()
                     if len(parts) >= 10 and parts[0].startswith("candidate:"):
                         foundation = parts[0].split(":", 1)[1]
@@ -253,7 +283,7 @@ class WebRTCConnectionMixin:
 
         offer = RTCSessionDescription(sdp=body["sdp"], type=body["type"])
 
-        pc = RTCPeerConnection()
+        pc = RTCPeerConnection(configuration=self.server_rtc_configuration)
         self.pcs[body["webrtc_id"]] = pc
 
         if isinstance(self.event_handler, StreamHandlerImpl):