Ephemeral port range control

[richardklafter]

Essentially just converted aiortc/aioice#63 PR into a monkey patch. It could use a bit more testing.

Should fix your last issue in #4 ?

[kristiankielhofner]

Crashing with:

RTC: Created for 76.14.83.52
INFO:     76.14.83.52:57203 - "POST /api/rtc/asr?model=large HTTP/1.1" 500 Internal Server Error
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/uvicorn/protocols/http/httptools_impl.py", line 419, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/usr/local/lib/python3.8/dist-packages/uvicorn/middleware/proxy_headers.py", line 78, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.8/dist-packages/fastapi/applications.py", line 270, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/applications.py", line 124, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/middleware/errors.py", line 184, in __call__
    raise exc
  File "/usr/local/lib/python3.8/dist-packages/starlette/middleware/errors.py", line 162, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/middleware/exceptions.py", line 79, in __call__
    raise exc
  File "/usr/local/lib/python3.8/dist-packages/starlette/middleware/exceptions.py", line 68, in __call__
    await self.app(scope, receive, sender)
  File "/usr/local/lib/python3.8/dist-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
    raise e
  File "/usr/local/lib/python3.8/dist-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/routing.py", line 706, in __call__
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/routing.py", line 276, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/routing.py", line 66, in app
    response = await func(request)
  File "/usr/local/lib/python3.8/dist-packages/fastapi/routing.py", line 237, in app
    raw_response = await run_endpoint_function(
  File "/usr/local/lib/python3.8/dist-packages/fastapi/routing.py", line 163, in run_endpoint_function
    return await dependant.call(**values)
  File "/app/./main.py", line 455, in rtc_asr
    response = await rtc_offer(request, model, beam_size, task, detect_language, return_language)
  File "/app/./main.py", line 421, in rtc_offer
    await pc.setRemoteDescription(offer)
  File "/usr/local/lib/python3.8/dist-packages/aiortc/rtcpeerconnection.py", line 978, in setRemoteDescription
    await asyncio.gather(*coros)
  File "/usr/local/lib/python3.8/dist-packages/aiortc/rtcpeerconnection.py", line 176, in add_remote_candidates
    await asyncio.gather(*coros)
  File "/usr/local/lib/python3.8/dist-packages/aiortc/rtcicetransport.py", line 293, in addRemoteCandidate
    await self._connection.add_remote_candidate(
  File "/usr/local/lib/python3.8/dist-packages/aioice/ice.py", line 367, in add_remote_candidate
    mdns_protocol = await get_or_create_mdns_protocol()
  File "/usr/local/lib/python3.8/dist-packages/aioice/ice.py", line 39, in get_or_create_mdns_protocol
    _mdns.protocol = await mdns.create_mdns_protocol()
  File "/usr/local/lib/python3.8/dist-packages/aioice/mdns.py", line 158, in create_mdns_protocol
    tx_transport, _ = await loop.create_datagram_endpoint(
  File "/app/./main.py", line 73, in create_datagram_endpoint
    protocol_factory, local_addr=(local_addr[0], port), **kwargs
TypeError: 'NoneType' object is not subscriptable