We need to set up the pion/webrtc logger to write output to the
snowflake log, otherwise the warnings we are getting from the pion
library are being lost.

Note: this requires go version 1.13 and later in order to use the
`log.Writer()` function.

Modified the snowflake client to use pion/webrtc as the webrtc library.
This involved a few small changes to match function signatures as well
as several larger ones:
- OnNegotiationNeeded is no longer supported, so CreateOffer and
SetLocalDescription have been moved to a go routine called after the
other peer connection callbacks are set
- We need our own deserialize/serialize functions
- We need to use a SettingEngine in order to access the
OnICEGatheringStateChange callback

Amounts to the same thing as currently implemented in go-webrtc

Removed raw bytes of ICE answers from broker logs and the SDP stanzas
from the client logs

From https://trac.torproject.org/projects/tor/ticket/21312#comment:33

 * From https://github.com/keroserene/go-webrtc/pull/59

 - stabilize rest of WebRTCPeer
 - use uid for the datachannel label
 - store a consistent WebRTC config in the dialer

copy-paste rendezvous works again, but with new interface allowing seamless recovery for the first time

to more sensible locations

maxedChan

Serene Han authored 8 years ago and Arlo Breault committed 8 years ago

webRTCConn close as part of its reset, instead of depending on external deferred close after receiving reset channel, allows valid disconnections even before use

Serene Han authored 9 years ago and Arlo Breault committed 8 years ago

replace webrtcRemote with webrtcRemotes map & indexing, client multiplexing remotes confirmed working (#31)

defer conn.Close for simplicity and remove unnecessary goroutines, improve error handling (close #12)

 * This will induce the tor client to establish a new SocksConn,
   which in turn will dial a new WebRTC connection.

   To be improved upon.

 * Part of #12

retry client offers immediately instead of reset, combine sendOffer and receiveAnswer into exchangeSDP

only flush datachannel with nonzero bytes, which prevents Tor from marking the SOCKS for close (#12)

remove webRTCConn SendLoop and simplify Write without additional channel, as net.Conn is already safe

clean up ice candidate log message.
still need to debug the copy loop break.