Hand-rolled RFC 5389 binding-request encoder + binding-success-response
parser. Just enough to extract XOR-MAPPED-ADDRESS from a server's reply
after socks5UDPAssociate returns a relay endpoint. Avoids pulling in
pion/stun for ~80 LOC of encoding/binary work.
Provides NewTransactionID, EncodeBindingRequest, ParseBindingResponse and
six sentinel errors (ErrSTUN*) so HintFor (T11) can match specific
failure modes. Full TLV attribute walking with bounds checks; supports
both IPv4 and IPv6 XOR-MAPPED-ADDRESS values.
Tests cover encoder layout, IPv4/IPv6 happy paths, attribute walking
past unknown attributes, all error paths, sentinel uniqueness, and a
real loopback round-trip via net.ListenPacket. 90.0% combined coverage
(socks5+stun); stun.go funcs all >= 87%.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
root
36e788402a