feat(tcp): add Minecraft analyzer for handshake detection

feat(tcp): implement FETAnalyzer with segment buffering feat(tcp): enhance TCP engine with window scale detection test(tcp): add tests for Minecraft and FET analyzers docs: add documentation for Minecraft analyzer and TCP evasion
2026-07-27 01:09:41 +08:00
parent 278d731b6f
commit f6342c4bcf
11 changed files with 914 additions and 8 deletions
@@ -0,0 +1,119 @@
+package tcp
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/apernet/OpenGFW/analyzer"
+)
+
+func TestMinecraftParsing_HandshakeLogin(t *testing.T) {
+	handshake := buildMinecraftHandshake(t, 767, "211.136.162.178", 25565, minecraftNextStateLogin)
+	want := analyzer.PropMap{
+		"yes":             true,
+		"candidate":       false,
+		"protocol":        767,
+		"server_addr":     "211.136.162.178",
+		"server_port":     uint16(25565),
+		"next_state":      minecraftNextStateLogin,
+		"next_state_name": "login",
+		"packet_length":   len(handshake) - 1,
+	}
+
+	u, done := newMinecraftStream(nil).Feed(false, false, false, 0, handshake)
+	if !done {
+		t.Fatal("stream not done after full handshake")
+	}
+	if !reflect.DeepEqual(u.M, want) {
+		t.Errorf("parsed = %#v, want %#v", u.M, want)
+	}
+}
+
+func TestMinecraftParsing_FragmentedHandshake(t *testing.T) {
+	handshake := buildMinecraftHandshake(t, 767, "mc.example.com", 25565, minecraftNextStateStatus)
+	s := newMinecraftStream(nil)
+
+	u, done := s.Feed(false, false, false, 0, handshake[:2])
+	if done {
+		t.Fatal("stream done on partial handshake")
+	}
+	if got := u.M.Get("candidate"); got != true {
+		t.Fatalf("candidate = %v, want true", got)
+	}
+
+	u, done = s.Feed(false, false, false, 0, handshake[2:])
+	if !done {
+		t.Fatal("stream not done after remaining handshake")
+	}
+	if got := u.M.Get("yes"); got != true {
+		t.Fatalf("yes = %v, want true", got)
+	}
+	if got := u.M.Get("server_addr"); got != "mc.example.com" {
+		t.Fatalf("server_addr = %v, want mc.example.com", got)
+	}
+}
+
+func TestMinecraftParsing_InvalidAfterCandidate(t *testing.T) {
+	s := newMinecraftStream(nil)
+	u, done := s.Feed(false, false, false, 0, []byte{0x04})
+	if done {
+		t.Fatal("stream done on partial packet")
+	}
+	if got := u.M.Get("candidate"); got != true {
+		t.Fatalf("candidate = %v, want true", got)
+	}
+
+	u, done = s.Feed(false, false, false, 0, []byte{0x01, 0x02, 0x03, 0x04})
+	if !done {
+		t.Fatal("stream not done on invalid packet")
+	}
+	if got := u.M.Get("candidate"); got != false {
+		t.Fatalf("candidate = %v, want false", got)
+	}
+	if got := u.M.Get("yes"); got != false {
+		t.Fatalf("yes = %v, want false", got)
+	}
+}
+
+func TestMinecraftParsing_RejectsInvalidUTF8Address(t *testing.T) {
+	packet := []byte{0x00}
+	packet = append(packet, encodeMinecraftVarInt(767)...)
+	packet = append(packet, 0x01, 0xff)
+	packet = append(packet, 0x63, 0xdd)
+	packet = append(packet, encodeMinecraftVarInt(minecraftNextStateLogin)...)
+	data := append(encodeMinecraftVarInt(int32(len(packet))), packet...)
+
+	u, done := newMinecraftStream(nil).Feed(false, false, false, 0, data)
+	if !done {
+		t.Fatal("stream not done on invalid UTF-8 address")
+	}
+	if got := u.M.Get("yes"); got != false {
+		t.Fatalf("yes = %v, want false", got)
+	}
+}
+
+func buildMinecraftHandshake(t *testing.T, protocol int32, addr string, port uint16, nextState int32) []byte {
+	t.Helper()
+	packet := []byte{0x00}
+	packet = append(packet, encodeMinecraftVarInt(protocol)...)
+	packet = append(packet, encodeMinecraftVarInt(int32(len(addr)))...)
+	packet = append(packet, []byte(addr)...)
+	packet = append(packet, byte(port>>8), byte(port))
+	packet = append(packet, encodeMinecraftVarInt(nextState)...)
+	return append(encodeMinecraftVarInt(int32(len(packet))), packet...)
+}
+
+func encodeMinecraftVarInt(value int32) []byte {
+	var out []byte
+	for {
+		b := byte(value & 0x7f)
+		value = int32(uint32(value) >> 7)
+		if value != 0 {
+			b |= 0x80
+		}
+		out = append(out, b)
+		if value == 0 {
+			return out
+		}
+	}
+}