mrambossekandClaude Opus 5
7b676e666e
- stun: RFC 5389 binding responder + RFC 5780 attributes (OTHER-ADDRESS,
RESPONSE-ORIGIN, CHANGE-REQUEST) on a primary/alt-port socket grid per
address; advertises stun-5780 with >=2 same-family addrs, else
stun-basic. Unmodified framing for tooling interop. Tested.
- tcpecho: JSON greeting with observed src + TCP_INFO MSS/options
(Linux getsockopt; zeroed elsewhere via build tags), then byte echo.
- session: per-packet UDP observations + connect-back results, ByID lookup.
- control: GET /v1/sessions/{id}/observations, POST .../actions
(delayed_echo → DELAYED_ECHO at the observed data-plane source;
connect_back → dial the control-plane source, record connected/refused/
timeout+rtt). Capabilities computed from what is actually wired.
- config/main: comma-separated STUN listeners; all planes bind explicit
addresses; graceful shutdown of the new listeners.
Full flow smoke-tested; go test green (stun binding/change-port,
dataplane wire format).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
70 lines
1.5 KiB
Go
70 lines
1.5 KiB
Go
// SPDX-FileCopyrightText: 2026 Echolot contributors
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// SPDX-License-Identifier: GPL-3.0-or-later
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//go:build linux
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package tcpecho
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import (
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"encoding/binary"
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"net"
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"syscall"
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"unsafe"
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)
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type connInfo struct {
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MSS int
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Options []string
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}
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// tcpInfo reads TCP_INFO via getsockopt. Only the head of struct tcp_info is
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// needed: 8 header bytes (state..wscale flags) then u32 rto, ato, snd_mss,
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// rcv_mss — layout is part of the kernel ABI and stable.
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func tcpInfo(conn net.Conn) connInfo {
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tc, ok := conn.(*net.TCPConn)
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if !ok {
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return connInfo{}
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}
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raw, err := tc.SyscallConn()
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if err != nil {
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return connInfo{}
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}
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var buf [104]byte
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var got bool
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_ = raw.Control(func(fd uintptr) {
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l := uint32(len(buf))
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_, _, errno := syscall.Syscall6(syscall.SYS_GETSOCKOPT, fd,
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uintptr(syscall.SOL_TCP), uintptr(syscall.TCP_INFO),
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uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&l)), 0)
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got = errno == 0 && l >= 24
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})
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if !got {
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return connInfo{}
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}
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// tcpi_options bit flags (include/uapi/linux/tcp.h)
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const (
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optTimestamps = 1
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optSACK = 2
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optWscale = 4
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optECN = 8
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)
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var opts []string
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ob := buf[5]
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if ob&optTimestamps != 0 {
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opts = append(opts, "timestamps")
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}
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if ob&optSACK != 0 {
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opts = append(opts, "sack")
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}
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if ob&optWscale != 0 {
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opts = append(opts, "wscale")
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}
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if ob&optECN != 0 {
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opts = append(opts, "ecn")
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}
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return connInfo{
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MSS: int(binary.LittleEndian.Uint32(buf[16:20])), // tcpi_snd_mss
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Options: opts,
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}
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}
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