* turn: accept PROXY protocol on the TCP listener
Behind a TLS-terminating or reverse proxy that dials from its own address,
the embedded TURN server reports the proxy's address to the client as
XOR-MAPPED-ADDRESS. Firefox rejects a loopback or wildcard mapped address
and abandons the allocation, so relay-only clients never get a relay
candidate (#4851).
Add turn.proxy_protocol. When set, the TCP listener requires a PROXY
protocol v1/v2 header on every connection and uses the client address it
carries; connections without the header are rejected. The header is read
before TLS, so it works with both the built-in TLS listener and
external_tls.
* turn: only trust PROXY headers from configured proxies
A PROXY header from any peer that can reach the port would let a direct
client claim an arbitrary source address. Add
turn.proxy_protocol_trusted_cidrs, defaulting to loopback, and close
connections from any other address before reading the header.
* Apply ttl check only when authenticate allocation creating
TTL check could reject allocation/persmission refresh in
security enhancement #4505, cause long-live session disconnect
when turn credential is expired.
Only check ttl on allocation creating to prevent abusing leaked
credential but keep long-live session work.
Sapan Diwakar