mrambossekandClaude Opus 5
1472a86508
A connection opening with a TLS handshake (first byte 0x16) and ALPN elt-echo gets the ClientHello it sent back raw (b64) and as a JA4 fingerprint (sec.clienthello_echo), then a TLS byte-echo; plain connections are unchanged. One port, multiplexed by a timed peek: plain echo is server-speaks-first, so a silent client (peek timeout) is greeted, while a TLS client's immediate ClientHello (0x16) routes to the TLS path — 500ms tolerates ~1s RTT before misdetection. JA4 (FoxIO): full ClientHello parser (ciphers, extensions, ALPN, supported_versions, sig algs) with GREASE exclusion; a_b_c fingerprint, unit-tested for structure + GREASE invariance. Live-verified: elt-echo negotiated, JA4 t13d1712eo computed, 1530-byte ClientHello returned. Capability tls-echo. This completes spec §4. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
54 lines
1.2 KiB
Go
54 lines
1.2 KiB
Go
// SPDX-FileCopyrightText: 2026 Echolot contributors
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// SPDX-License-Identifier: GPL-3.0-or-later
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package tcpecho
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import (
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"bufio"
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"encoding/json"
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"net"
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"testing"
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"time"
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)
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// Plain echo must be server-speaks-first: a client that sends nothing still
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// gets the greeting (via the peek timeout), then its bytes are echoed.
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func TestPlainEchoServerSpeaksFirst(t *testing.T) {
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ln, err := net.Listen("tcp", "127.0.0.1:0")
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if err != nil {
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t.Fatal(err)
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}
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defer ln.Close()
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go (&Server{}).Serve(ln)
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c, err := net.Dial("tcp", ln.Addr().String())
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if err != nil {
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t.Fatal(err)
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}
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defer c.Close()
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c.SetDeadline(time.Now().Add(3 * time.Second))
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line, err := bufio.NewReader(c).ReadBytes('\n')
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if err != nil {
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t.Fatalf("no greeting: %v", err)
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}
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var g struct {
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TLS bool `json:"tls"`
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Src string `json:"observed_src"`
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}
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if err := json.Unmarshal(line, &g); err != nil {
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t.Fatal(err)
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}
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if g.TLS {
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t.Fatal("plain connection reported tls=true")
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}
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if g.Src == "" {
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t.Fatal("greeting missing observed_src")
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}
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c.Write([]byte("xyz"))
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buf := make([]byte, 3)
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if _, err := c.Read(buf); err != nil || string(buf) != "xyz" {
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t.Fatalf("echo failed: %q %v", buf, err)
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}
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}
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