network layer improvements

[Antoine Martin]

tracker ticket:

• #1504 delay SSL socket wrapping
• #1594 IPv6
• #619 better TCP_NODELAY handling: only use it when it is useful
• #639 UDP transport
• #999 catch limited bandwidth issues sooner
• #401 detect bad connection and warn the user
• #540 handle connection issues, session events, network drop outs, power events, etc
• #417 re-implement bandwidth constraint option
• #1134 websockify
• #1591 signals SA_RESTART siginterrupt etc
• #1338 html mode WebRTC transport

Other ideas:

• protocol close: split read and write so we can flush with read closed - meh
• measure: YIELD vs NO_YIELD
• remove parse and format threads from protocol: no longer needed? (python threads are expensive)

Other links:

• ​srtalliance: "making video streaming better"
• ​webrtc
• ​TCP BBR: loss-based congestion control can result in abysmal throughput because it overreacts..

Older tickets:

• #1424 html5 faster network layer
• #1271 support websockets in the python client
• #1134 websockify bottleneck
• #983 AF_VSOCK support
• #731 mdns service type
• #514 TCP_NODELAY
• #502 efficient network receive buffer management when receiving large chunks
• #418 more aggressive speed tuning when bandwidth is available
• #181 to yield or not to yield

Related tickets:

• #1454 allow named pipes over the network
• #1188 create a wireshark dissector
• #1255 smartcard api