Add client and service

v3_conn.go

@@ -0,0 +1,171 @@
+package shadowtls
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/binary"
+	"hash"
+	"io"
+	"net"
+
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/bufio"
+	E "github.com/sagernet/sing/common/exceptions"
+	N "github.com/sagernet/sing/common/network"
+)
+
+type verifiedConn struct {
+	net.Conn
+	writer     N.VectorisedWriter
+	hmacAdd    hash.Hash
+	hmacVerify hash.Hash
+	hmacIgnore hash.Hash
+
+	buffer *buf.Buffer
+}
+
+func newVerifiedConn(
+	conn net.Conn,
+	hmacAdd hash.Hash,
+	hmacVerify hash.Hash,
+	hmacIgnore hash.Hash,
+) *verifiedConn {
+	return &verifiedConn{
+		Conn:       conn,
+		writer:     bufio.NewVectorisedWriter(conn),
+		hmacAdd:    hmacAdd,
+		hmacVerify: hmacVerify,
+		hmacIgnore: hmacIgnore,
+	}
+}
+
+func (c *verifiedConn) Read(b []byte) (n int, err error) {
+	if c.buffer != nil {
+		if !c.buffer.IsEmpty() {
+			return c.buffer.Read(b)
+		}
+		c.buffer.Release()
+		c.buffer = nil
+	}
+	for {
+		var tlsHeader [tlsHeaderSize]byte
+		_, err = io.ReadFull(c.Conn, tlsHeader[:])
+		if err != nil {
+			sendAlert(c.Conn)
+			return
+		}
+		length := int(binary.BigEndian.Uint16(tlsHeader[3:tlsHeaderSize]))
+		c.buffer = buf.NewSize(tlsHeaderSize + length)
+		common.Must1(c.buffer.Write(tlsHeader[:]))
+		_, err = c.buffer.ReadFullFrom(c.Conn, length)
+		if err != nil {
+			return
+		}
+		buffer := c.buffer.Bytes()
+		switch buffer[0] {
+		case alert:
+			err = E.Cause(net.ErrClosed, "remote alert")
+			return
+		case applicationData:
+			if c.hmacIgnore != nil {
+				if verifyApplicationData(buffer, c.hmacIgnore, false) {
+					c.buffer.Release()
+					c.buffer = nil
+					continue
+				} else {
+					c.hmacIgnore = nil
+				}
+			}
+			if !verifyApplicationData(buffer, c.hmacVerify, true) {
+				sendAlert(c.Conn)
+				err = E.New("application data verification failed")
+				return
+			}
+			c.buffer.Advance(tlsHmacHeaderSize)
+		default:
+			sendAlert(c.Conn)
+			err = E.New("unexpected TLS record type: ", buffer[0])
+			return
+		}
+		return c.buffer.Read(b)
+	}
+}
+
+func (c *verifiedConn) Write(p []byte) (n int, err error) {
+	pTotal := len(p)
+	for len(p) > 0 {
+		var pWrite []byte
+		if len(p) > 16384 {
+			pWrite = p[:16384]
+			p = p[16384:]
+		} else {
+			pWrite = p
+			p = nil
+		}
+		_, err = c.write(pWrite)
+	}
+	if err == nil {
+		n = pTotal
+	}
+	return
+}
+
+func (c *verifiedConn) write(p []byte) (n int, err error) {
+	var header [tlsHmacHeaderSize]byte
+	header[0] = applicationData
+	header[1] = 3
+	header[2] = 3
+	binary.BigEndian.PutUint16(header[3:tlsHeaderSize], hmacSize+uint16(len(p)))
+	c.hmacAdd.Write(p)
+	hmacHash := c.hmacAdd.Sum(nil)[:hmacSize]
+	c.hmacAdd.Write(hmacHash)
+	copy(header[tlsHeaderSize:], hmacHash)
+	_, err = bufio.WriteVectorised(c.writer, [][]byte{common.Dup(header[:]), p})
+	if err == nil {
+		n = len(p)
+	}
+	return
+}
+
+func (c *verifiedConn) WriteVectorised(buffers []*buf.Buffer) error {
+	var header [tlsHmacHeaderSize]byte
+	header[0] = applicationData
+	header[1] = 3
+	header[2] = 3
+	binary.BigEndian.PutUint16(header[3:tlsHeaderSize], hmacSize+uint16(buf.LenMulti(buffers)))
+	for _, buffer := range buffers {
+		c.hmacAdd.Write(buffer.Bytes())
+	}
+	c.hmacAdd.Write(c.hmacAdd.Sum(nil)[:hmacSize])
+	copy(header[tlsHeaderSize:], c.hmacAdd.Sum(nil)[:hmacSize])
+	return c.writer.WriteVectorised(append([]*buf.Buffer{buf.As(header[:])}, buffers...))
+}
+
+func verifyApplicationData(frame []byte, hmac hash.Hash, update bool) bool {
+	if frame[1] != 3 || frame[2] != 3 || len(frame) < tlsHmacHeaderSize {
+		return false
+	}
+	hmac.Write(frame[tlsHmacHeaderSize:])
+	hmacHash := hmac.Sum(nil)[:hmacSize]
+	if update {
+		hmac.Write(hmacHash)
+	}
+	return bytes.Equal(frame[tlsHeaderSize:tlsHeaderSize+hmacSize], hmacHash)
+}
+
+func sendAlert(writer io.Writer) {
+	const recordSize = 31
+	record := [recordSize]byte{
+		alert,
+		3,
+		3,
+		0,
+		recordSize - tlsHeaderSize,
+	}
+	_, err := rand.Read(record[tlsHeaderSize:])
+	if err != nil {
+		return
+	}
+	writer.Write(record[:])
+}