sing-box/inbound/shadowtls.go
2023-02-18 14:55:47 +08:00

277 lines
8.1 KiB
Go

package inbound
import (
"bytes"
"context"
"crypto/hmac"
"crypto/sha1"
"encoding/binary"
"encoding/hex"
"io"
"net"
"os"
"github.com/sagernet/sing-box/adapter"
"github.com/sagernet/sing-box/common/dialer"
C "github.com/sagernet/sing-box/constant"
"github.com/sagernet/sing-box/log"
"github.com/sagernet/sing-box/option"
"github.com/sagernet/sing-box/transport/shadowtls"
"github.com/sagernet/sing/common"
"github.com/sagernet/sing/common/buf"
"github.com/sagernet/sing/common/bufio"
E "github.com/sagernet/sing/common/exceptions"
M "github.com/sagernet/sing/common/metadata"
N "github.com/sagernet/sing/common/network"
"github.com/sagernet/sing/common/task"
)
type ShadowTLS struct {
myInboundAdapter
handshakeDialer N.Dialer
handshakeAddr M.Socksaddr
version int
password string
fallbackAfter int
}
func NewShadowTLS(ctx context.Context, router adapter.Router, logger log.ContextLogger, tag string, options option.ShadowTLSInboundOptions) (*ShadowTLS, error) {
inbound := &ShadowTLS{
myInboundAdapter: myInboundAdapter{
protocol: C.TypeShadowTLS,
network: []string{N.NetworkTCP},
ctx: ctx,
router: router,
logger: logger,
tag: tag,
listenOptions: options.ListenOptions,
},
handshakeDialer: dialer.New(router, options.Handshake.DialerOptions),
handshakeAddr: options.Handshake.ServerOptions.Build(),
password: options.Password,
}
inbound.version = options.Version
switch options.Version {
case 0:
fallthrough
case 1:
case 2:
if options.FallbackAfter == nil {
inbound.fallbackAfter = 2
} else {
inbound.fallbackAfter = *options.FallbackAfter
}
case 3:
default:
return nil, E.New("unknown shadowtls protocol version: ", options.Version)
}
inbound.connHandler = inbound
return inbound, nil
}
func (s *ShadowTLS) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
handshakeConn, err := s.handshakeDialer.DialContext(ctx, N.NetworkTCP, s.handshakeAddr)
if err != nil {
return err
}
switch s.version {
case 1:
var handshake task.Group
handshake.Append("client handshake", func(ctx context.Context) error {
return s.copyUntilHandshakeFinished(handshakeConn, conn)
})
handshake.Append("server handshake", func(ctx context.Context) error {
return s.copyUntilHandshakeFinished(conn, handshakeConn)
})
handshake.FastFail()
handshake.Cleanup(func() {
handshakeConn.Close()
})
err = handshake.Run(ctx)
if err != nil {
return err
}
return s.newConnection(ctx, conn, metadata)
case 2:
hashConn := shadowtls.NewHashWriteConn(conn, s.password)
go bufio.Copy(hashConn, handshakeConn)
var request *buf.Buffer
request, err = s.copyUntilHandshakeFinishedV2(ctx, handshakeConn, conn, hashConn, s.fallbackAfter)
if err == nil {
handshakeConn.Close()
return s.newConnection(ctx, bufio.NewCachedConn(shadowtls.NewConn(conn), request), metadata)
} else if err == os.ErrPermission {
s.logger.WarnContext(ctx, "fallback connection")
hashConn.Fallback()
return common.Error(bufio.Copy(handshakeConn, conn))
} else {
return err
}
default:
fallthrough
case 3:
var clientHelloFrame *buf.Buffer
clientHelloFrame, err = shadowtls.ExtractFrame(conn)
if err != nil {
return E.Cause(err, "read client handshake")
}
_, err = handshakeConn.Write(clientHelloFrame.Bytes())
if err != nil {
clientHelloFrame.Release()
return E.Cause(err, "write client handshake")
}
err = shadowtls.VerifyClientHello(clientHelloFrame.Bytes(), s.password)
if err != nil {
s.logger.WarnContext(ctx, E.Cause(err, "client hello verify failed"))
return bufio.CopyConn(ctx, conn, handshakeConn)
}
s.logger.TraceContext(ctx, "client hello verify success")
clientHelloFrame.Release()
var serverHelloFrame *buf.Buffer
serverHelloFrame, err = shadowtls.ExtractFrame(handshakeConn)
if err != nil {
return E.Cause(err, "read server handshake")
}
_, err = conn.Write(serverHelloFrame.Bytes())
if err != nil {
serverHelloFrame.Release()
return E.Cause(err, "write server handshake")
}
serverRandom := shadowtls.ExtractServerRandom(serverHelloFrame.Bytes())
if serverRandom == nil {
s.logger.WarnContext(ctx, "server random extract failed, will copy bidirectional")
return bufio.CopyConn(ctx, conn, handshakeConn)
}
if !shadowtls.IsServerHelloSupportTLS13(serverHelloFrame.Bytes()) {
s.logger.WarnContext(ctx, "TLS 1.3 is not supported, will copy bidirectional")
return bufio.CopyConn(ctx, conn, handshakeConn)
}
serverHelloFrame.Release()
s.logger.TraceContext(ctx, "client authenticated. server random extracted: ", hex.EncodeToString(serverRandom))
hmacWrite := hmac.New(sha1.New, []byte(s.password))
hmacWrite.Write(serverRandom)
hmacAdd := hmac.New(sha1.New, []byte(s.password))
hmacAdd.Write(serverRandom)
hmacAdd.Write([]byte("S"))
hmacVerify := hmac.New(sha1.New, []byte(s.password))
hmacVerifyReset := func() {
hmacVerify.Reset()
hmacVerify.Write(serverRandom)
hmacVerify.Write([]byte("C"))
}
var clientFirstFrame *buf.Buffer
var group task.Group
var handshakeFinished bool
group.Append("client handshake relay", func(ctx context.Context) error {
clientFrame, cErr := shadowtls.CopyByFrameUntilHMACMatches(conn, handshakeConn, hmacVerify, hmacVerifyReset)
if cErr == nil {
clientFirstFrame = clientFrame
handshakeFinished = true
handshakeConn.Close()
}
return cErr
})
group.Append("server handshake relay", func(ctx context.Context) error {
cErr := shadowtls.CopyByFrameWithModification(handshakeConn, conn, s.password, serverRandom, hmacWrite)
if E.IsClosedOrCanceled(cErr) && handshakeFinished {
return nil
}
return cErr
})
group.Cleanup(func() {
handshakeConn.Close()
})
err = group.Run(ctx)
if err != nil {
return E.Cause(err, "handshake relay")
}
s.logger.TraceContext(ctx, "handshake relay finished")
return s.newConnection(ctx, bufio.NewCachedConn(shadowtls.NewVerifiedConn(conn, hmacAdd, hmacVerify, nil), clientFirstFrame), metadata)
}
}
func (s *ShadowTLS) copyUntilHandshakeFinished(dst io.Writer, src io.Reader) error {
const handshake = 0x16
const changeCipherSpec = 0x14
var hasSeenChangeCipherSpec bool
var tlsHdr [5]byte
for {
_, err := io.ReadFull(src, tlsHdr[:])
if err != nil {
return err
}
length := binary.BigEndian.Uint16(tlsHdr[3:])
_, err = io.Copy(dst, io.MultiReader(bytes.NewReader(tlsHdr[:]), io.LimitReader(src, int64(length))))
if err != nil {
return err
}
if tlsHdr[0] != handshake {
if tlsHdr[0] != changeCipherSpec {
return E.New("unexpected tls frame type: ", tlsHdr[0])
}
if !hasSeenChangeCipherSpec {
hasSeenChangeCipherSpec = true
continue
}
}
if hasSeenChangeCipherSpec {
return nil
}
}
}
func (s *ShadowTLS) copyUntilHandshakeFinishedV2(ctx context.Context, dst net.Conn, src io.Reader, hash *shadowtls.HashWriteConn, fallbackAfter int) (*buf.Buffer, error) {
const applicationData = 0x17
var tlsHdr [5]byte
var applicationDataCount int
for {
_, err := io.ReadFull(src, tlsHdr[:])
if err != nil {
return nil, err
}
length := binary.BigEndian.Uint16(tlsHdr[3:])
if tlsHdr[0] == applicationData {
data := buf.NewSize(int(length))
_, err = data.ReadFullFrom(src, int(length))
if err != nil {
data.Release()
return nil, err
}
if hash.HasContent() && length >= 8 {
checksum := hash.Sum()
if bytes.Equal(data.To(8), checksum) {
s.logger.TraceContext(ctx, "match current hashcode")
data.Advance(8)
return data, nil
} else if hash.LastSum() != nil && bytes.Equal(data.To(8), hash.LastSum()) {
s.logger.TraceContext(ctx, "match last hashcode")
data.Advance(8)
return data, nil
}
}
_, err = io.Copy(dst, io.MultiReader(bytes.NewReader(tlsHdr[:]), data))
data.Release()
applicationDataCount++
} else {
_, err = io.Copy(dst, io.MultiReader(bytes.NewReader(tlsHdr[:]), io.LimitReader(src, int64(length))))
}
if err != nil {
return nil, err
}
if applicationDataCount > fallbackAfter {
return nil, os.ErrPermission
}
}
}