Enhance transports

[zxzxwu]

• Support IPv6 schema
• Add transport integration tests
• Add UNIX socket server

[zxzxwu]

I lost my access to this repo due to recent corp policy change 😓

Requesting access.

[barbibulle]

To properly support IPv6 addresses, we need a more robust parser to separate the host and port. (':' in param isn't sufficient, since you could have an IPv6 address that has a :, but not followed by :<port>). I think we should factor out a shared function (maybe in common.py?) that knows how to parse IPv6 addresses with ports of the form [address]:port like [2001:db8:85a3:8d3:1319:8a2e:370:7348]:8000 (i.e enclosing the address in [] is mandatory when followed by a port number).

[zxzxwu]

Though it's not very complicated to do this, I am wondering if that's necessary - because we don't allow any schema without a complete address:port pair, so even if params and ':' in params[0] returns a false positive, it will still fail later such as

# python apps/controller_info.py android-netsim::::

  File "/usr/local/google/home/joshwu/projects/bumble/bumble/transport/android_netsim.py", line 447, in open_android_netsim_transport
    port = int(port_str)
ValueError: invalid literal for int() with base 10: ''

# or
grpc.aio._call.AioRpcError: <AioRpcError of RPC that terminated with:
        status = StatusCode.UNAVAILABLE
        details = "DNS resolution failed for :::1: C-ares status is not ARES_SUCCESS qtype=AAAA name=:::1 is_balancer=0: Domain name not found"
        debug_error_string = "UNKNOWN:Error received from peer  {grpc_status:14, grpc_message:"DNS resolution failed for :::1: C-ares status is not ARES_SUCCESS qtype=AAAA name=:::1 is_balancer=0: Domain name not found"}"
>

Also this might violate metadata schema defined in open_transport

    scheme, *tail = name.split(':', 1)
    spec = tail[0] if tail else None
    metadata = None
    if spec:
        # Metadata may precede the spec
        if spec.startswith('['):
            metadata_str, *tail = spec[1:].split(']')
            spec = tail[0] if tail else None
            metadata = dict([entry.split('=') for entry in metadata_str.split(',')])

[zxzxwu]

Oh wait, I found this section is totally not neceassary, since the grpc module directly parses the port, so we can remove it here.

For other transports, I think we should keep the current schema to maintain the compatibility with transport metadata?

[barbibulle]

You're right, we always have the port explicitly specified, so it's fine to split out the portion after the last :, and not require [] around IPv6 addresses. This will keep the metadata parser simple (if we needed, we could differentiate [foo=bar] metadata from [xx:yy:zz] IPv6, but we don't need to here)

[zxzxwu]

Still, I found gRPC cannot parse such address, so as you said, we can heuristically distinguish between metadata and IPv6 address (in another PR).