Add stateless=true metadata option to UDP listener/handler for raw
datagram forwarding without per-client session tracking, similar to
NGINX Stream Module behavior.
- udp.NewListener: add Stateless field to ListenConfig; branch in
NewListener/Accept to skip connPool/listenLoop when stateless
- datagramConn: lightweight net.Conn+PacketConn wrapping a single
UDP datagram — no channels, mutexes, or pool logic
- forward handler: add handleRawDatagram for single request-response
cycle; extract dialTarget to share hop selection/dial/proxyproto
preamble with handleRawForwarding
Usage: gost -L "udp://:10000/127.0.0.1:2000?stateless=true"
Extract Handle into handleRawForwarding, handleSniffedProtocol, SnifferBuilder,
newRecorderObject, and checkRateLimit across forward.go, sniffing.go, and
util.go. Replace redundant x509.ParseCertificate with tlsCert.Leaf (already
populated by tls.LoadX509KeyPair since Go 1.23).
- Return clear error when Router is nil instead of panicking
- Capture and log sniffing.Sniff and xnet.Pipe errors at Debug level
- Move dial closure and Sniffer construction into HTTP/TLS switch branch
to avoid unnecessary allocation on non-HTTP/TLS traffic
- Merge ProtoHTTP and ProtoTLS cases, branch internally on proto
- Add doc comments on NewHandler and Handle
- Add comment explaining nil hop is valid (no forwarder config)
- Pass readTimeout to xnet.Pipe via WithReadTimeout
ginuerzh