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https://github.com/bolkedebruin/rdpgw.git
synced 2025-07-27 12:56:09 +02:00
Websocket refactor
This commit is contained in:
Bolke de Bruin
parent
2f78a7fd8e
commit
33290f59e6
4 changed files with 380 additions and 93 deletions
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@ -6,10 +6,28 @@ import (
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"errors"
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"github.com/bolkedebruin/rdpgw/transport"
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"io"
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"log"
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"net"
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"strconv"
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"time"
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)
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// When should the client disconnect when idle in minutes
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var IdleTimeout = 0
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type VerifyPAACookieFunc func(string) (bool, error)
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type VerifyTunnelAuthFunc func(string) (bool, error)
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type VerifyServerFunc func(string) (bool, error)
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type Handler struct {
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Transport transport.Transport
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Transport transport.Transport
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VerifyPAACookieFunc VerifyPAACookieFunc
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VerifyTunnelAuthFunc VerifyTunnelAuthFunc
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VerifyServerFunc VerifyServerFunc
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SmartCardAuth bool
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TokenAuth bool
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ClientName string
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Remote net.Conn
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}
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func NewHandler(t transport.Transport) *Handler {
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@ -19,15 +37,73 @@ func NewHandler(t transport.Transport) *Handler {
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return h
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}
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func (p *Handler) ReadMessage() (pt int, n int, msg []byte, err error) {
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func (h *Handler) Process() error {
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for {
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pt, sz, pkt, err := h.ReadMessage()
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if err != nil {
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log.Printf("Cannot read message from stream %s", err)
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return err
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}
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switch pt {
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case PKT_TYPE_HANDSHAKE_REQUEST:
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major, minor, _, auth := readHandshake(pkt)
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msg := h.handshakeResponse(major, minor, auth)
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h.Transport.WritePacket(msg)
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case PKT_TYPE_TUNNEL_CREATE:
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_, cookie := readCreateTunnelRequest(pkt)
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if h.VerifyPAACookieFunc != nil {
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if ok, _ := h.VerifyPAACookieFunc(cookie); ok == false {
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log.Printf("Invalid PAA cookie: %s", cookie)
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return errors.New("invalid PAA cookie")
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}
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}
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msg := createTunnelResponse()
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h.Transport.WritePacket(msg)
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case PKT_TYPE_TUNNEL_AUTH:
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h.readTunnelAuthRequest(pkt)
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msg := h.createTunnelAuthResponse()
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h.Transport.WritePacket(msg)
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case PKT_TYPE_CHANNEL_CREATE:
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server, port := readChannelCreateRequest(pkt)
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log.Printf("Establishing connection to RDP server: %s on port %d (%x)", server, port, server)
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h.Remote, err = net.DialTimeout(
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"tcp",
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net.JoinHostPort(server, strconv.Itoa(int(port))),
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time.Second*15)
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if err != nil {
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log.Printf("Error connecting to %s, %d, %s", server, port, err)
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return err
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}
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log.Printf("Connection established")
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msg := createChannelCreateResponse()
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h.Transport.WritePacket(msg)
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// Make sure to start the flow from the RDP server first otherwise connections
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// might hang eventually
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go h.sendDataPacket()
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case PKT_TYPE_DATA:
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h.forwardDataPacket(pkt)
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case PKT_TYPE_KEEPALIVE:
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// avoid concurrency issues
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// p.Transport.Write(createPacket(PKT_TYPE_KEEPALIVE, []byte{}))
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case PKT_TYPE_CLOSE_CHANNEL:
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h.Transport.Close()
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default:
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log.Printf("Unknown packet (size %d): %x", sz, pkt)
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}
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}
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}
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func (h *Handler) ReadMessage() (pt int, n int, msg []byte, err error) {
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fragment := false
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index := 0
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buf := make([]byte, 4096)
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for {
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size, pkt, err := p.Transport.ReadPacket()
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size, pkt, err := h.Transport.ReadPacket()
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if err != nil {
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return 0, 0, []byte{0,0}, err
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return 0, 0, []byte{0, 0}, err
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}
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// check for fragments
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@ -48,7 +124,7 @@ func (p *Handler) ReadMessage() (pt int, n int, msg []byte, err error) {
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pt, sz, msg, err = readHeader(append(buf[:index], pkt[:size]...))
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// header is corrupted even after defragmenting
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if err != nil {
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return 0, 0, []byte{0,0}, err
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return 0, 0, []byte{0, 0}, err
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}
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}
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if !fragment {
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@ -57,6 +133,27 @@ func (p *Handler) ReadMessage() (pt int, n int, msg []byte, err error) {
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}
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}
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// Creates a packet the is a response to a handshake request
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// HTTP_EXTENDED_AUTH_SSPI_NTLM is not supported in Linux
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// but could be in Windows. However the NTLM protocol is insecure
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func (h *Handler) handshakeResponse(major byte, minor byte, auth uint16) []byte {
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var caps uint16
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if h.SmartCardAuth {
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caps = caps | HTTP_EXTENDED_AUTH_PAA
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}
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if h.TokenAuth {
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caps = caps | HTTP_EXTENDED_AUTH_PAA
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}
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buf := new(bytes.Buffer)
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binary.Write(buf, binary.LittleEndian, uint32(0)) // error_code
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buf.Write([]byte{major, minor})
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binary.Write(buf, binary.LittleEndian, uint16(0)) // server version
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binary.Write(buf, binary.LittleEndian, uint16(caps)) // extended auth
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return createPacket(PKT_TYPE_HANDSHAKE_RESPONSE, buf.Bytes())
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}
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func readHeader(data []byte) (packetType uint16, size uint32, packet []byte, err error) {
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// header needs to be 8 min
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if len(data) < 8 {
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@ -71,3 +168,188 @@ func readHeader(data []byte) (packetType uint16, size uint32, packet []byte, err
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}
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return packetType, size, data[8:], nil
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}
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func readHandshake(data []byte) (major byte, minor byte, version uint16, extAuth uint16) {
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r := bytes.NewReader(data)
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binary.Read(r, binary.LittleEndian, &major)
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binary.Read(r, binary.LittleEndian, &minor)
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binary.Read(r, binary.LittleEndian, &version)
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binary.Read(r, binary.LittleEndian, &extAuth)
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log.Printf("major: %d, minor: %d, version: %d, ext auth: %d", major, minor, version, extAuth)
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return
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}
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func readCreateTunnelRequest(data []byte) (caps uint32, cookie string) {
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var fields uint16
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r := bytes.NewReader(data)
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binary.Read(r, binary.LittleEndian, &caps)
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binary.Read(r, binary.LittleEndian, &fields)
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r.Seek(2, io.SeekCurrent)
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if fields == HTTP_TUNNEL_PACKET_FIELD_PAA_COOKIE {
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var size uint16
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binary.Read(r, binary.LittleEndian, &size)
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cookieB := make([]byte, size)
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r.Read(cookieB)
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cookie, _ = DecodeUTF16(cookieB)
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}
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log.Printf("Create tunnel caps: %d, cookie: %s", caps, cookie)
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return
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}
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func createTunnelResponse() []byte {
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buf := new(bytes.Buffer)
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binary.Write(buf, binary.LittleEndian, uint16(0)) // server version
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binary.Write(buf, binary.LittleEndian, uint32(0)) // error code
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binary.Write(buf, binary.LittleEndian, uint16(HTTP_TUNNEL_RESPONSE_FIELD_TUNNEL_ID|HTTP_TUNNEL_RESPONSE_FIELD_CAPS)) // fields present
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binary.Write(buf, binary.LittleEndian, uint16(0)) // reserved
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binary.Write(buf, binary.LittleEndian, uint16(0)) // reserved
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// tunnel id ?
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binary.Write(buf, binary.LittleEndian, uint32(15))
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// caps ?
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binary.Write(buf, binary.LittleEndian, uint32(2))
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return createPacket(PKT_TYPE_TUNNEL_RESPONSE, buf.Bytes())
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}
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func (h *Handler) readTunnelAuthRequest(data []byte) {
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buf := bytes.NewReader(data)
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var size uint16
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binary.Read(buf, binary.LittleEndian, &size)
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clData := make([]byte, size)
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binary.Read(buf, binary.LittleEndian, &clData)
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clientName, _ := DecodeUTF16(clData)
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log.Printf("Client: %s", clientName)
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}
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func (h *Handler) createTunnelAuthResponse() []byte {
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buf := new(bytes.Buffer)
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binary.Write(buf, binary.LittleEndian, uint32(0)) // error code
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binary.Write(buf, binary.LittleEndian, uint16(HTTP_TUNNEL_AUTH_RESPONSE_FIELD_REDIR_FLAGS|HTTP_TUNNEL_AUTH_RESPONSE_FIELD_IDLE_TIMEOUT)) // fields present
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binary.Write(buf, binary.LittleEndian, uint16(0)) // reserved
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// flags
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var redir uint32
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/*
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if conf.Caps.RedirectAll {
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redir = HTTP_TUNNEL_REDIR_ENABLE_ALL
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} else if conf.Caps.DisableRedirect {
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redir = HTTP_TUNNEL_REDIR_DISABLE_ALL
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} else {
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if conf.Caps.DisableClipboard {
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redir = redir | HTTP_TUNNEL_REDIR_DISABLE_CLIPBOARD
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}
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if conf.Caps.DisableDrive {
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redir = redir | HTTP_TUNNEL_REDIR_DISABLE_DRIVE
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}
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if conf.Caps.DisablePnp {
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redir = redir | HTTP_TUNNEL_REDIR_DISABLE_PNP
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}
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if conf.Caps.DisablePrinter {
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redir = redir | HTTP_TUNNEL_REDIR_DISABLE_PRINTER
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}
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if conf.Caps.DisablePort {
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redir = redir | HTTP_TUNNEL_REDIR_DISABLE_PORT
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}
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}
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*/
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redir = HTTP_TUNNEL_REDIR_ENABLE_ALL
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// idle timeout
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if IdleTimeout < 0 {
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IdleTimeout = 0
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}
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binary.Write(buf, binary.LittleEndian, uint32(redir)) // redir flags
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binary.Write(buf, binary.LittleEndian, uint32(IdleTimeout)) // timeout in minutes
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return createPacket(PKT_TYPE_TUNNEL_AUTH_RESPONSE, buf.Bytes())
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}
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func readChannelCreateRequest(data []byte) (server string, port uint16) {
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buf := bytes.NewReader(data)
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var resourcesSize byte
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var alternative byte
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var protocol uint16
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var nameSize uint16
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binary.Read(buf, binary.LittleEndian, &resourcesSize)
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binary.Read(buf, binary.LittleEndian, &alternative)
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binary.Read(buf, binary.LittleEndian, &port)
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binary.Read(buf, binary.LittleEndian, &protocol)
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binary.Read(buf, binary.LittleEndian, &nameSize)
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nameData := make([]byte, nameSize)
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binary.Read(buf, binary.LittleEndian, &nameData)
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log.Printf("Name data %q", nameData)
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server, _ = DecodeUTF16(nameData)
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log.Printf("Should connect to %s on port %d", server, port)
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return
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}
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func createChannelCreateResponse() []byte {
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buf := new(bytes.Buffer)
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binary.Write(buf, binary.LittleEndian, uint32(0)) // error code
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//binary.Write(buf, binary.LittleEndian, uint16(HTTP_CHANNEL_RESPONSE_FIELD_CHANNELID | HTTP_CHANNEL_RESPONSE_FIELD_AUTHNCOOKIE | HTTP_CHANNEL_RESPONSE_FIELD_UDPPORT)) // fields present
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binary.Write(buf, binary.LittleEndian, uint16(0)) // fields
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binary.Write(buf, binary.LittleEndian, uint16(0)) // reserved
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// optional fields
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// channel id uint32 (4)
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// udp port uint16 (2)
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// udp auth cookie 1 byte for side channel
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// length uint16
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return createPacket(PKT_TYPE_CHANNEL_RESPONSE, buf.Bytes())
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}
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func (h *Handler) forwardDataPacket(data []byte) {
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buf := bytes.NewReader(data)
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var cblen uint16
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binary.Read(buf, binary.LittleEndian, &cblen)
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pkt := make([]byte, cblen)
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binary.Read(buf, binary.LittleEndian, &pkt)
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h.Remote.Write(pkt)
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}
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func (h *Handler) sendDataPacket() {
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defer h.Remote.Close()
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b1 := new(bytes.Buffer)
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buf := make([]byte, 4086)
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for {
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n, err := h.Remote.Read(buf)
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binary.Write(b1, binary.LittleEndian, uint16(n))
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if err != nil {
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log.Printf("Error reading from conn %s", err)
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break
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}
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b1.Write(buf[:n])
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h.Transport.WritePacket(createPacket(PKT_TYPE_DATA, b1.Bytes()))
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b1.Reset()
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}
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}
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func createPacket(pktType uint16, data []byte) (packet []byte) {
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size := len(data) + 8
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buf := new(bytes.Buffer)
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binary.Write(buf, binary.LittleEndian, uint16(pktType))
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binary.Write(buf, binary.LittleEndian, uint16(0)) // reserved
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binary.Write(buf, binary.LittleEndian, uint32(size))
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buf.Write(data)
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return buf.Bytes()
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}
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