func getRequest(conn *ss.Conn, auth bool) (host string, ota bool, err error) {
ss.SetReadTimeout(conn)
// buf size should at least have the same size with the largest possible
// request size (when addrType is 3, domain name has at most 256 bytes)
// 1(addrType) + 1(lenByte) + 256(max length address) + 2(port) + 10(hmac-sha1)
buf := make([]byte, 270)
// read till we get possible domain length field
if _, err = io.ReadFull(conn, buf[:idType+1]); err != nil {
return
}
var reqStart, reqEnd int
addrType := buf[idType]
switch addrType & ss.AddrMask {
case typeIPv4:
reqStart, reqEnd = idIP0, idIP0+lenIPv4
case typeIPv6:
reqStart, reqEnd = idIP0, idIP0+lenIPv6
case typeDm:
if _, err = io.ReadFull(conn, buf[idType+1:idDmLen+1]); err != nil {
return
}
reqStart, reqEnd = idDm0, int(idDm0+buf[idDmLen]+lenDmBase)
default:
err = fmt.Errorf("addr type %d not supported", addrType&ss.AddrMask)
return
}
if _, err = io.ReadFull(conn, buf[reqStart:reqEnd]); err != nil {
return
}
// Return string for typeIP is not most efficient, but browsers (Chrome,
// Safari, Firefox) all seems using typeDm exclusively. So this is not a
// big problem.
switch addrType & ss.AddrMask {
case typeIPv4:
host = net.IP(buf[idIP0 : idIP0+net.IPv4len]).String()
case typeIPv6:
host = net.IP(buf[idIP0 : idIP0+net.IPv6len]).String()
case typeDm:
host = string(buf[idDm0 : idDm0+buf[idDmLen]])
}
// parse port
port := binary.BigEndian.Uint16(buf[reqEnd-2 : reqEnd])
host = net.JoinHostPort(host, strconv.Itoa(int(port)))
// if specified one time auth enabled, we should verify this
if auth || addrType&ss.OneTimeAuthMask > 0 {
ota = true
if _, err = io.ReadFull(conn, buf[reqEnd:reqEnd+lenHmacSha1]); err != nil {
return
}
iv := conn.GetIv()
key := conn.GetKey()
actualHmacSha1Buf := ss.HmacSha1(append(iv, key...), buf[:reqEnd])
if !bytes.Equal(buf[reqEnd:reqEnd+lenHmacSha1], actualHmacSha1Buf) {
err = fmt.Errorf("verify one time auth failed, iv=%v key=%v data=%v", iv, key, buf[:reqEnd])
return
}
}
return
}
func handleConnection(conn *ss.Conn, auth bool) {
var host string
connCnt++ // this maybe not accurate, but should be enough
if connCnt-nextLogConnCnt >= 0 {
// XXX There's no xadd in the atomic package, so it's difficult to log
// the message only once with low cost. Also note nextLogConnCnt maybe
// added twice for current peak connection number level.
log.Printf("Number of client connections reaches %d\n", nextLogConnCnt)
nextLogConnCnt += logCntDelta
}
// function arguments are always evaluated, so surround debug statement
// with if statement
if debug {
debug.Printf("new client %s->%s\n", conn.RemoteAddr().String(), conn.LocalAddr())
}
closed := false
defer func() {
if debug {
debug.Printf("closed pipe %s<->%s\n", conn.RemoteAddr(), host)
}
connCnt--
if !closed {
conn.Close()
}
}()
host, ota, err := getRequest(conn, auth)
if err != nil {
log.Println("error getting request", conn.RemoteAddr(), conn.LocalAddr(), err)
return
}
debug.Println("connecting", host)
remote, err := net.Dial("tcp", host)
if err != nil {
if ne, ok := err.(*net.OpError); ok && (ne.Err == syscall.EMFILE || ne.Err == syscall.ENFILE) {
// log too many open file error
// EMFILE is process reaches open file limits, ENFILE is system limit
log.Println("dial error:", err)
} else {
log.Println("error connecting to:", host, err)
}
return
}
defer func() {
if !closed {
remote.Close()
}
}()
if debug {
debug.Printf("piping %s<->%s ota=%v connOta=%v", conn.RemoteAddr(), host, ota, conn.IsOta())
}
if ota {
go ss.PipeThenCloseOta(conn, remote)
} else {
go ss.PipeThenClose(conn, remote)
}
ss.PipeThenClose(remote, conn)
closed = true
return
}