Add SSH sniffer

common/sniff/ssh.go

@@ -0,0 +1,26 @@
+package sniff
+
+import (
+	"bufio"
+	"context"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/sagernet/sing-box/adapter"
+	C "github.com/sagernet/sing-box/constant"
+)
+
+func SSH(_ context.Context, metadata *adapter.InboundContext, reader io.Reader) error {
+	scanner := bufio.NewScanner(reader)
+	if !scanner.Scan() {
+		return os.ErrInvalid
+	}
+	fistLine := scanner.Text()
+	if !strings.HasPrefix(fistLine, "SSH-2.0-") {
+		return os.ErrInvalid
+	}
+	metadata.Protocol = C.ProtocolSSH
+	metadata.Client = fistLine[8:]
+	return nil
+}

common/sniff/ssh_test.go

@@ -0,0 +1,26 @@
+package sniff_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/hex"
+	"testing"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/sniff"
+	C "github.com/sagernet/sing-box/constant"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSniffSSH(t *testing.T) {
+	t.Parallel()
+
+	pkt, err := hex.DecodeString("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")
+	require.NoError(t, err)
+	var metadata adapter.InboundContext
+	err = sniff.SSH(context.TODO(), &metadata, bytes.NewReader(pkt))
+	require.NoError(t, err)
+	require.Equal(t, C.ProtocolSSH, metadata.Protocol)
+	require.Equal(t, "dropbear", metadata.Client)
+}