//throwBytes chucks bytes at the remote server then listens for a response
func throwBytes(conn io.ReadWriter, count uint64) error {
var writeBytes uint64
var b []byte
buff := make([]byte, 128)
for writeBytes < count {
if (count - writeBytes) >= uint64(len(dataBlock)) {
b = dataBlock
} else {
b = dataBlock[0:(count - writeBytes)]
}
n, err := conn.Write(b)
if err != nil {
return err
}
writeBytes += uint64(n)
}
//read the response
n, err := conn.Read(buff)
if err != nil {
return err
}
if n == 0 {
return fmt.Errorf("Failed to get OK on upload")
}
if !strings.HasPrefix(string(buff[0:n]), "OK ") {
return fmt.Errorf("Failed to get OK on upload")
}
return nil
}
func (r *Receiver) handleTransfer(conn io.ReadWriter) (
transfer.TransferResults, error,
) {
if _, err := conn.Write([]byte("ok")); err != nil {
return transfer.TransferResults{}, err
}
res := transfer.TransferResults{}
buffer := make([]byte, 1024)
startTime := time.Now()
for {
n, err := conn.Read(buffer)
if err != nil { // done reading
break
}
res.BytesSent += uint32(n)
res.Checksum = crc32.Update(res.Checksum, crc32.IEEETable, buffer)
}
endTime := time.Now()
res.Duration = endTime.Sub(startTime)
return res, nil
}
func ClientHandshake(stream io.ReadWriter, local Certificate) (*Transport, error) {
pub, priv, err := GenerateExchangeKey()
if err != nil {
return nil, err
}
if _, err = stream.Write(pub); err != nil {
return nil, err
}
theirkey := make([]byte, PublicKeySize)
if _, err = stream.Read(theirkey); err != nil {
return nil, err
}
cipher1, cipher2, err := CreateExchangedCipher(theirkey, priv)
if err != nil {
return nil, err
}
macKey, err := GenerateMACKey()
if err != nil {
return nil, err
}
encryptedMACKey := make([]byte, MACSize)
cipher1.XORKeyStream(encryptedMACKey, macKey)
if _, err = stream.Write(encryptedMACKey); err != nil {
return nil, err
}
transport := new(Transport)
transport.stream = stream
transport.macKey = macKey
transport.readCipher = cipher2
transport.writeCipher = cipher1
if err := sendCertificate(transport, local); err != nil {
return nil, err
}
remote, err := requireCertificate(transport)
if err != nil {
return nil, err
}
transport.local = local
transport.remote = remote
return transport, nil
}
// dnsRoundTripUDP implements the dnsRoundTrip interface for RFC 1035's
// "UDP usage" transport mechanism. c should be a packet-oriented connection,
// such as a *UDPConn.
func dnsRoundTripUDP(c io.ReadWriter, query *dnsMsg) (*dnsMsg, error) {
b, ok := query.Pack()
if !ok {
return nil, errors.New("cannot marshal DNS message")
}
if _, err := c.Write(b); err != nil {
return nil, err
}
b = make([]byte, 512) // see RFC 1035
for {
n, err := c.Read(b)
if err != nil {
return nil, err
}
resp := &dnsMsg{}
if !resp.Unpack(b[:n]) || !resp.IsResponseTo(query) {
// Ignore invalid responses as they may be malicious
// forgery attempts. Instead continue waiting until
// timeout. See golang.org/issue/13281.
continue
}
return resp, nil
}
}
func verifyPipe(t *testing.T, a, b io.ReadWriter) {
mes := make([]byte, 1024)
rand.Read(mes)
go func() {
b.Write(mes)
a.Write(mes)
}()
buf := make([]byte, len(mes))
n, err := a.Read(buf)
if err != nil {
t.Fatal(err)
}
if n != len(buf) {
t.Fatal("failed to read enough")
}
if string(buf) != string(mes) {
t.Fatal("somehow read wrong message")
}
n, err = b.Read(buf)
if err != nil {
t.Fatal(err)
}
if n != len(buf) {
t.Fatal("failed to read enough")
}
if string(buf) != string(mes) {
t.Fatal("somehow read wrong message")
}
}
func negotiateMethod(c Context, rw io.ReadWriter) {
rw.Write(methodRequest(proxy.MethodNoPassword))
if _, err := rw.Read(make([]byte, 3)); err != nil {
c.Error(err)
}
return
}
func echoOnce(rw io.ReadWriter) error {
buf := make([]byte, 256)
n, err := rw.Read(buf)
if err != nil {
return err
}
_, err = rw.Write(buf[:n])
return err
}
func ServerHandshake(stream io.ReadWriter, local Certificate) (*Transport, error) {
pub, priv, err := GenerateExchangeKey()
if err != nil {
return nil, err
}
theirkey := make([]byte, PublicKeySize)
if _, err = stream.Read(theirkey); err != nil {
return nil, err
}
if _, err = stream.Write(pub); err != nil {
return nil, err
}
cipher1, cipher2, err := CreateExchangedCipher(theirkey, priv)
if err != nil {
return nil, err
}
macKey := make([]byte, MACSize)
if n, err := stream.Read(macKey); err != nil {
return nil, err
} else if n < MACSize {
return nil, MacKeyTooSmallError
}
cipher1.XORKeyStream(macKey, macKey)
transport := new(Transport)
transport.stream = stream
transport.macKey = macKey
transport.readCipher = cipher1
transport.writeCipher = cipher2
remote, err := requireCertificate(transport)
if err != nil {
return nil, err
}
if err := sendCertificate(transport, local); err != nil {
return nil, err
}
transport.local = local
transport.remote = remote
return transport, nil
}
// exchangeKeys performs a key exchange with a remote peer
// and returns peer's public key after successfull exchange.
func exchangeKeys(conn io.ReadWriter, pub *[32]byte) (*[32]byte, error) {
var ppub [32]byte
if _, err := conn.Write(pub[:]); err != nil {
return nil, err
}
if _, err := conn.Read(ppub[:]); err != nil {
return nil, err
}
return &ppub, nil
}
// exchangeKeys performs the exchange of the keys
// by writing the public key into the data stream first and
// then reading the shared key from the data stream.
func exchangeKeys(pub, peerPub *[32]byte, rw io.ReadWriter) error {
if _, err := rw.Write(pub[:]); err != nil {
return err
}
if _, err := rw.Read(peerPub[:]); err != nil {
return err
}
return nil
}
func (p *Proxy) pipe(src, dst io.ReadWriter) {
islocal := src == p.lconn
var dataDirection string
if islocal {
dataDirection = ">>> %d bytes sent%s"
} else {
dataDirection = "<<< %d bytes recieved%s"
}
var byteFormat string
if p.OutputHex {
byteFormat = "%x"
} else {
byteFormat = "%s"
}
//directional copy (64k buffer)
buff := make([]byte, 0xffff)
for {
n, err := src.Read(buff)
if err != nil {
p.err("Read failed '%s'\n", err)
return
}
b := buff[:n]
//execute match
if p.Matcher != nil {
p.Matcher(b)
}
//execute replace
if p.Replacer != nil {
b = p.Replacer(b)
}
//show output
p.Log.Debug(dataDirection, n, "")
p.Log.Trace(byteFormat, b)
//write out result
n, err = dst.Write(b)
if err != nil {
p.err("Write failed '%s'\n", err)
return
}
if islocal {
p.sentBytes += uint64(n)
} else {
p.receivedBytes += uint64(n)
}
}
}
// CopyToWebsocket copies pipe data to/from a websocket. It blocks.
func (p *pipe) CopyToWebsocket(end io.ReadWriter, conn *websocket.Conn) error {
p.mtx.Lock()
if p.closed {
p.mtx.Unlock()
return nil
}
p.wg.Add(1)
p.mtx.Unlock()
defer p.wg.Done()
errors := make(chan error, 1)
// Read-from-UI loop
go func() {
for {
_, buf, err := conn.ReadMessage() // TODO type should be binary message
if err != nil {
errors <- err
return
}
if _, err := end.Write(buf); err != nil {
errors <- err
return
}
}
}()
// Write-to-UI loop
go func() {
buf := make([]byte, 1024)
for {
n, err := end.Read(buf)
if err != nil {
errors <- err
return
}
if err := conn.WriteMessage(websocket.BinaryMessage, buf[:n]); err != nil {
errors <- err
return
}
}
}()
// block until one of the goroutines exits
// this convoluted mechanism is to ensure we only close the websocket once.
select {
case err := <-errors:
return err
case <-p.quit:
return nil
}
}
func (us *UnixSock) processBuffer(fd io.ReadWriter) {
var buf [1024]byte
for {
n, err := fd.Read(buf[0:])
if err != nil || n == 0 {
break
}
us.data <- pipe.NewSimpleChunk(buf[0:n])
}
}
func runEcho(fd io.ReadWriter, done chan<- int) {
var buf [1024]byte
for {
n, err := fd.Read(buf[0:])
if err != nil || n == 0 || string(buf[:n]) == "END" {
break
}
fd.Write(buf[0:n])
}
done <- 1
}
func runEcho(fd io.ReadWriter, done chan<- int) {
var buf [1024]byte;
for {
n, err := fd.Read(&buf);
if err != nil || n == 0 {
break
}
fd.Write(buf[0:n]);
}
done <- 1;
}
func exchangeKeys(pub *[32]byte, conn io.ReadWriter) (*[32]byte, error) {
_, err := conn.Write(pub[:])
if err != nil {
return nil, err
}
otherPub := [32]byte{}
_, err = conn.Read(otherPub[:])
if err != nil {
return nil, err
}
return &otherPub, nil
}
// submitTPMRequest sends a structure to the TPM device file and gets results
// back, interpreting them as a new provided structure.
func submitTPMRequest(rw io.ReadWriter, tag uint16, ord uint32, in []interface{}, out []interface{}) (uint32, error) {
if rw == nil {
return 0, errors.New("nil TPM handle")
}
ch := commandHeader{tag, 0, ord}
inb, err := packWithHeader(ch, in)
if err != nil {
return 0, err
}
if _, err := rw.Write(inb); err != nil {
return 0, err
}
// Try to read the whole thing, but handle the case where it's just a
// ResponseHeader and not the body, since that's what happens in the error
// case.
var rh responseHeader
rhSize := binary.Size(rh)
outb := make([]byte, maxTPMResponse)
outlen, err := rw.Read(outb)
if err != nil {
return 0, err
}
// Resize the buffer to match the amount read from the TPM.
outb = outb[:outlen]
if err := unpack(outb[:rhSize], []interface{}{&rh}); err != nil {
return 0, err
}
// Check success before trying to read the rest of the result.
// Note that the command tag and its associated response tag differ by 3,
// e.g., tagRQUCommand == 0x00C1, and tagRSPCommand == 0x00C4.
if rh.Res != 0 {
return rh.Res, tpmError(rh.Res)
}
if rh.Tag != ch.Tag+3 {
return 0, errors.New("inconsistent tag returned by TPM. Expected " + strconv.Itoa(int(ch.Tag+3)) + " but got " + strconv.Itoa(int(rh.Tag)))
}
if rh.Size > uint32(rhSize) {
if err := unpack(outb[rhSize:], out); err != nil {
return 0, err
}
}
return rh.Res, nil
}
// DefaultInteractive is the default server selection prompt for users during
// session forward.
func DefaultInteractive(comm io.ReadWriter, session *Session) (string, error) {
remotes := session.Remotes
fmt.Fprintf(comm, "Welcome to sshmux, %s\r\n", session.Conn.User())
for i, v := range remotes {
fmt.Fprintf(comm, " [%d] %s\r\n", i, v)
}
// Beware, nasty comm parsing loop
loop:
for {
fmt.Fprintf(comm, "Please select remote server: ")
var buf []byte
b := make([]byte, 1)
var (
n int
err error
)
for {
if err != nil {
return "", err
}
n, err = comm.Read(b)
if n == 1 {
fmt.Fprintf(comm, "%s", b)
switch b[0] {
case '\r':
fmt.Fprintf(comm, "\r\n")
res, err := strconv.ParseInt(string(buf), 10, 64)
if err != nil {
fmt.Fprintf(comm, "comm not a valid integer. Please try again\r\n")
continue loop
}
if int(res) >= len(remotes) || res < 0 {
fmt.Fprintf(comm, "No such server. Please try again\r\n")
continue loop
}
return remotes[int(res)], nil
case 0x03:
fmt.Fprintf(comm, "\r\nGoodbye\r\n")
return "", errors.New("user terminated session")
}
buf = append(buf, b[0])
}
}
}
}
func (s *Sender) handshake(conn io.ReadWriter) error {
msgBytes := make([]byte, 16)
n, err := conn.Read(msgBytes)
if err != nil {
return err
}
msg := string(msgBytes[:n])
if msg == "ok" {
return nil
} else if msg == "i-am-busy" {
return ErrBusy
} else {
return fmt.Errorf("unrecognized server response `%s`", msg)
}
}
// echo server on top of a generic io.ReadWriter. Reads from the reader,
// and writes received data back to the writer. To implement secure echo,
// rw must be composed of a secure reader and writer, as produced by
// serverHandshake.
func echo(rw io.ReadWriter) error {
var (
n int
err error
)
buf := make([]byte, msglen)
for {
if n, err = rw.Read(buf); err != nil {
return err
}
if _, err := rw.Write(buf[:n]); err != nil {
return err
}
}
}
func WriteFileHandler(parameters string, connection io.ReadWriter) {
segments := strings.Split(parameters, " ")
if len(segments) != 2 {
log.Println("Invalid put command formatting")
}
lengtha, _ := strconv.Atoi(segments[1])
fileName := segments[0]
log.Printf("Receive file '%s' (length = %d)", fileName, lengtha)
file, err := os.OpenFile(fileName, os.O_RDWR|os.O_CREATE, 0)
if err != nil {
log.Printf("Failed to open file for writing: %s\n", err)
return
}
common.WriteString(connection, "ok")
buffer := make([]byte, 1024)
for {
// Read from socket
n, err := connection.Read(buffer)
if err != nil {
log.Println("Failed to read data from socket; abandoning transfer")
break
}
// Read into buffer
_, err = file.Write(buffer[:n])
lengtha = lengtha - n
if lengtha == 0 {
log.Println("Transfer completed")
break
}
}
common.WriteString(connection, "ok")
file.Close()
}
func testRws(a, b io.ReadWriter) error {
data := []byte("ABCD")
go a.Write(data)
buf := make([]byte, 10)
n, err := b.Read(buf)
if err != nil {
return err
}
if n != 4 {
return fmt.Errorf("n must be 4, not %d", n)
}
if !bytes.Equal(buf[:n], data) {
return fmt.Errorf("invalid data received: %s", hex.EncodeToString(buf[:n]))
}
return nil
}
func (s *Sender) handshake(conn io.ReadWriter) (uint16, error) {
msgBytes := make([]byte, 16)
n, err := conn.Read(msgBytes)
if err != nil {
return 0, err
}
msg := string(msgBytes[:n])
var iperfPort uint16
_, err = fmt.Sscanf(msg, "ok - %d", &iperfPort)
if err != nil {
if msg == "i-am-busy" {
return 0, ErrBusy
} else {
return 0, fmt.Errorf("unrecognized server response `%s`: %s", msg, err)
}
}
return iperfPort, nil
}
func ModemSend(c io.ReadWriter, data []byte) error {
oBuffer := make([]byte, 1)
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] == POLL {
var blocks uint8 = uint8(len(data) / LONG_PACKET_PAYLOAD_LEN)
if len(data) > int(int(blocks)*int(LONG_PACKET_PAYLOAD_LEN)) {
blocks++
}
failed := 0
var currentBlock uint8 = 0
for currentBlock < blocks && failed < 10 {
if int(int(currentBlock+1)*int(LONG_PACKET_PAYLOAD_LEN)) > len(data) {
sendBlock(c, currentBlock+1, data[int(currentBlock)*int(LONG_PACKET_PAYLOAD_LEN):])
} else {
sendBlock(c, currentBlock+1, data[int(currentBlock)*int(LONG_PACKET_PAYLOAD_LEN):(int(currentBlock)+1)*int(LONG_PACKET_PAYLOAD_LEN)])
}
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] == ACK {
currentBlock++
} else {
failed++
}
}
if _, err := c.Write([]byte{EOT}); err != nil {
return err
}
}
return nil
}
func testSecureSessionMessage(conn1, conn2 io.ReadWriter) error {
pt := []byte("hello peer!")
nw, err := conn1.Write(pt)
if err != nil {
return fmt.Errorf("write error: %s", err)
}
ptr := make([]byte, len(pt))
nr, err := conn2.Read(ptr)
if err != nil {
return fmt.Errorf("read error: %s", err)
}
if nr != nw {
return fmt.Errorf("bytes read not equal to bytes written: %d != %d", nr, nw)
}
if !bytes.Equal(ptr, pt) {
return fmt.Errorf("message read not equal to message written: %q != %q", ptr, pt)
}
return nil
}
func receivePacket(c io.ReadWriter) ([]byte, error) {
oBuffer := make([]byte, 1)
dBuffer := make([]byte, LONG_PACKET_PAYLOAD_LEN)
if _, err := c.Read(oBuffer); err != nil {
return nil, err
}
pType := oBuffer[0]
if pType == EOT {
return nil, nil
}
var packetSize int
switch pType {
case SOH:
packetSize = SHORT_PACKET_PAYLOAD_LEN
break
case STX:
packetSize = LONG_PACKET_PAYLOAD_LEN
break
}
if _, err := c.Read(oBuffer); err != nil {
return nil, err
}
packetCount := oBuffer[0]
if _, err := c.Read(oBuffer); err != nil {
return nil, err
}
inverseCount := oBuffer[0]
if packetCount > inverseCount || inverseCount+packetCount != 255 {
if _, err := c.Write([]byte{NAK}); err != nil {
return nil, err
}
return nil, InvalidPacket
}
received := 0
var pData bytes.Buffer
for received < packetSize {
n, err := c.Read(dBuffer)
if err != nil {
return nil, err
}
received += n
pData.Write(dBuffer[:n])
}
var crc uint16
if _, err := c.Read(oBuffer); err != nil {
return nil, err
}
crc = uint16(oBuffer[0])
if _, err := c.Read(oBuffer); err != nil {
return nil, err
}
crc <<= 8
crc |= uint16(oBuffer[0])
// Calculate CRC
crcCalc := CRC16(pData.Bytes())
if crcCalc != crc {
if _, err := c.Write([]byte{NAK}); err != nil {
return nil, err
}
}
if _, err := c.Write([]byte{ACK}); err != nil {
return nil, err
}
return pData.Bytes(), nil
}
// HandshakeClient establishes connection with the server making sure
// they both are in sync.
func HandshakeClient(conn io.ReadWriter, debug bool) error {
if tracing {
defer trace.End(trace.Begin(""))
}
buf1byte := make([]byte, 1)
if _, err := rand.Read(buf1byte); err != nil {
log.Errorf("HandshakeClient: Could not read a random byte due to: %v", err)
}
pos := incrementByte(buf1byte[0])
// set the read deadline for timeout
// this has no effect on windows as the deadline is set at port open time
log.Debug("HandshakeClient: Sending syn.")
conn.Write([]byte{flagSyn, pos})
pos = incrementByte(pos)
if _, err := conn.Read(buf1byte); err != nil {
return err
}
if buf1byte[0] != flagAck {
if buf1byte[0] == flagNak {
log.Debugf("HandshakeClient: Server didn't accept sync. Trying one more time.")
return &HandshakeError{
msg: "Server declined handshake request",
}
}
return &HandshakeError{
msg: fmt.Sprintf("Unexpected server response: %d", buf1byte[0]),
}
}
// read response sync position.
if _, err := conn.Read(buf1byte); err != nil {
return err
}
if buf1byte[0] != pos {
log.Debugf("HandshakeClient: Unexpected byte pos for SynAck: %x, expected: %x", buf1byte[0], pos)
return &HandshakeError{
msg: fmt.Sprintf("Unexpected sync position response: %d", buf1byte[0]),
}
}
if _, err := conn.Read(buf1byte); err != nil {
return err
}
log.Debug("HandshakeClient: Sending ack.")
if !debug {
conn.Write([]byte{flagAck, incrementByte(buf1byte[0])})
} else {
conn.Write([]byte{flagDebugAck, incrementByte(buf1byte[0])})
// Verify packet length handling works. We're going to send a known stream
// of data to the container and it will echo it back. Verify the sent and
// received bufs are the same and we know the channel is lossless.
log.Debugf("HandshakeClient: Checking for lossiness")
txbuf := []byte("\x1b[32mhello world\x1b[39m!\n")
rxbuf := make([]byte, len(txbuf))
_, err := conn.Write(txbuf)
if err != nil {
return err
}
var n int
log.Debugf("HandshakeClient: Reading response")
n, err = io.ReadFull(conn, rxbuf)
if err != nil {
log.Error(err)
return err
}
if n != len(rxbuf) {
return fmt.Errorf("packet size mismatch (expected %d, received %d)", len(rxbuf), n)
}
if bytes.Compare(rxbuf, txbuf) != 0 {
return fmt.Errorf("HandshakeClient: lossiness check FAILED")
}
// Tell the server we're good.
if _, err = conn.Write([]byte{flagAck}); err != nil {
return err
}
log.Infof("HandshakeClient: lossiness check PASSED")
}
log.Debug("HandshakeClient: Connection established.")
return nil
}
// HandshakeServer establishes connection with the client making sure
// they both are in sync.
func HandshakeServer(conn io.ReadWriter) error {
if tracing {
defer trace.End(trace.Begin(""))
}
buf1byte := make([]byte, 1)
syncBuf := make([]byte, 4096)
if _, err := rand.Read(buf1byte); err != nil {
log.Errorf("HandshakeClient: Could not read a random byte due to: %v", err)
}
pos := incrementByte(buf1byte[0])
log.Debug("HandshakeServer: Waiting for incoming syn request...")
// Sync packet is 2 bytes, however if we read more than 2
// it means buffer is not empty and data is not trusted for this sync.
n, err := io.ReadAtLeast(conn, syncBuf, 2)
if err != nil {
return err
}
if n != 2 {
log.Debugf("HandshakeServer: Received %d bytes while awaiting for syn.", n)
}
syncBuf = syncBuf[n-2:]
if syncBuf[0] != flagSyn {
conn.Write([]byte{flagNak})
return &HandshakeError{
msg: fmt.Sprintf("Unexpected syn packet: %x", syncBuf[0]),
}
}
log.Debugf("HandshakeServer: Received Syn. Writing SynAck.")
// syncBuf[1] contains position token that needs to be incremented
// by one to send it back.
conn.Write([]byte{flagAck, incrementByte(syncBuf[1]), pos})
pos = incrementByte(pos)
if _, err := conn.Read(buf1byte); err != nil {
return err
}
ackType := buf1byte[0]
if ackType != flagAck && ackType != flagDebugAck {
conn.Write([]byte{flagNak})
return &HandshakeError{
msg: fmt.Sprintf("Not an ack packet received: %x", ackType),
}
}
if _, err := conn.Read(buf1byte); err != nil {
return err
}
if buf1byte[0] != pos {
conn.Write([]byte{flagNak})
return &HandshakeError{
msg: fmt.Sprintf(
"HandshakeServer: Unexpected position %x, expected: %x",
buf1byte[0], pos),
}
}
if ackType == flagDebugAck {
log.Debugf("HandshakeServer: Debug ACK received")
rxbuf := make([]byte, 23)
log.Debugf("HandshakeServer: Checking for lossiness")
n, err := io.ReadFull(conn, rxbuf)
if err != nil {
return err
}
if n != len(rxbuf) {
return fmt.Errorf("packet size mismatch (expected %d, received %d)", len(rxbuf), n)
}
// echo the data back
_, err = conn.Write(rxbuf)
if err != nil {
return err
}
// wait for the ack
if _, err = conn.Read(buf1byte); err != nil {
return err
}
if buf1byte[0] != flagAck {
return fmt.Errorf("lossiness check FAILED")
}
log.Infof("HandshakeServer: lossiness check PASSED")
}
log.Debug("HandshakeServer: Connection established.")
return nil
}
func ModemSend(c io.ReadWriter, data []byte, filename string) error {
oBuffer := make([]byte, 1)
// Wait for Poll
if _, err := c.Read(oBuffer); err != nil {
return err
}
// Send zero block with filename and size
if oBuffer[0] == POLL {
var send bytes.Buffer
send.WriteString(filename)
send.WriteByte(0x0)
send.WriteString(fmt.Sprintf("%d", len(data)))
for send.Len() < LONG_PACKET_PAYLOAD_LEN {
send.Write([]byte{0x0})
}
sendBlock(c, 0, send.Bytes())
// Wait for ACK
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] != ACK {
return errors.New("Failed to send header block")
}
}
// Wait for Poll
if _, err := c.Read(oBuffer); err != nil {
return err
}
// Send remaining data
if oBuffer[0] == POLL {
var blocks uint8 = uint8(len(data) / LONG_PACKET_PAYLOAD_LEN)
if len(data) > int(int(blocks)*int(LONG_PACKET_PAYLOAD_LEN)) {
blocks++
}
failed := 0
var currentBlock uint8 = 0
for currentBlock < blocks && failed < 10 {
if int(int(currentBlock+1)*int(LONG_PACKET_PAYLOAD_LEN)) > len(data) {
sendBlock(c, currentBlock+1, data[int(currentBlock)*int(LONG_PACKET_PAYLOAD_LEN):])
} else {
sendBlock(c, currentBlock+1, data[int(currentBlock)*int(LONG_PACKET_PAYLOAD_LEN):(int(currentBlock)+1)*int(LONG_PACKET_PAYLOAD_LEN)])
}
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] == ACK {
currentBlock++
} else {
failed++
}
}
}
// Wait for NAK and send EOT
if _, err := c.Write([]byte{EOT}); err != nil {
return err
}
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] != NAK {
return errors.New("")
}
// Send EOT again
if _, err := c.Write([]byte{EOT}); err != nil {
return err
}
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] != ACK {
return errors.New("Failed to send end block")
}
// Wait for POLL
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] != POLL {
return errors.New("Failed to send end block")
}
// Send empty block to signify end
var zero bytes.Buffer
for zero.Len() < LONG_PACKET_PAYLOAD_LEN {
zero.Write([]byte{0x0})
}
sendBlock(c, 0, zero.Bytes())
// Wait for ACK
if _, err := c.Read(oBuffer); err != nil {
return err
}
if oBuffer[0] != ACK {
return errors.New("Failed to send end block")
}
return nil
}
func ModemReceive(c io.ReadWriter) (string, []byte, error) {
var data bytes.Buffer
// Start Connection
if _, err := c.Write([]byte{POLL}); err != nil {
return "", nil, err
}
// Read file information
pktData, err := receivePacket(c)
if err != nil {
return "", nil, err
}
filenameEnd := bytes.IndexByte(pktData, 0x0)
filename := string(pktData[0:filenameEnd])
var filesize int
fmt.Sscanf(string(pktData[filenameEnd+1:]), "%d", &filesize)
if _, err := c.Write([]byte{POLL}); err != nil {
return "", nil, err
}
// Read Packets
for {
pktData, err := receivePacket(c)
if err == InvalidPacket {
continue
}
if err != nil {
return "", nil, err
}
// End of Transmission
if pktData == nil {
break
}
data.Write(pktData)
}
// Send NAK to respond to EOT
if _, err := c.Write([]byte{NAK}); err != nil {
return "", nil, err
}
oBuffer := make([]byte, 1)
if _, err := c.Read(oBuffer); err != nil {
return "", nil, err
}
// Send ACK to respond to second EOT
if oBuffer[0] != EOT {
return "", nil, err
}
if _, err := c.Write([]byte{ACK}); err != nil {
return "", nil, err
}
// Second POLL to get remaining file or close
if _, err := c.Write([]byte{POLL}); err != nil {
return "", nil, err
}
// Get remaining data ( for now assume one file )
if _, err := receivePacket(c); err != nil {
return "", nil, err
}
return filename, data.Bytes()[0:filesize], nil
}