diff options
Diffstat (limited to 'transports/obfs4/packet.go')
| -rw-r--r-- | transports/obfs4/packet.go | 176 |
1 files changed, 0 insertions, 176 deletions
diff --git a/transports/obfs4/packet.go b/transports/obfs4/packet.go deleted file mode 100644 index ac3028a..0000000 --- a/transports/obfs4/packet.go +++ /dev/null @@ -1,176 +0,0 @@ -/* - * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org> - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are met: - * - * * Redistributions of source code must retain the above copyright notice, - * this list of conditions and the following disclaimer. - * - * * Redistributions in binary form must reproduce the above copyright notice, - * this list of conditions and the following disclaimer in the documentation - * and/or other materials provided with the distribution. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" - * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE - * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE - * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR - * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF - * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS - * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN - * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) - * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE - * POSSIBILITY OF SUCH DAMAGE. - */ - -package obfs4 - -import ( - "crypto/sha256" - "encoding/binary" - "fmt" - "io" - - "github.com/OperatorFoundation/obfs4/common/drbg" - "github.com/OperatorFoundation/obfs4/transports/obfs4/framing" -) - -const ( - packetOverhead = 2 + 1 - maxPacketPayloadLength = framing.MaximumFramePayloadLength - packetOverhead - maxPacketPaddingLength = maxPacketPayloadLength - seedPacketPayloadLength = seedLength - - consumeReadSize = framing.MaximumSegmentLength * 16 -) - -const ( - packetTypePayload = iota - packetTypePrngSeed -) - -// InvalidPacketLengthError is the error returned when decodePacket detects a -// invalid packet length/ -type InvalidPacketLengthError int - -func (e InvalidPacketLengthError) Error() string { - return fmt.Sprintf("packet: Invalid packet length: %d", int(e)) -} - -// InvalidPayloadLengthError is the error returned when decodePacket rejects the -// payload length. -type InvalidPayloadLengthError int - -func (e InvalidPayloadLengthError) Error() string { - return fmt.Sprintf("packet: Invalid payload length: %d", int(e)) -} - -var zeroPadBytes [maxPacketPaddingLength]byte - -func (conn *obfs4Conn) makePacket(w io.Writer, pktType uint8, data []byte, padLen uint16) error { - var pkt [framing.MaximumFramePayloadLength]byte - - if len(data)+int(padLen) > maxPacketPayloadLength { - panic(fmt.Sprintf("BUG: makePacket() len(data) + padLen > maxPacketPayloadLength: %d + %d > %d", - len(data), padLen, maxPacketPayloadLength)) - } - - // Packets are: - // uint8_t type packetTypePayload (0x00) - // uint16_t length Length of the payload (Big Endian). - // uint8_t[] payload Data payload. - // uint8_t[] padding Padding. - pkt[0] = pktType - binary.BigEndian.PutUint16(pkt[1:], uint16(len(data))) - if len(data) > 0 { - copy(pkt[3:], data[:]) - } - copy(pkt[3+len(data):], zeroPadBytes[:padLen]) - - pktLen := packetOverhead + len(data) + int(padLen) - - // Encode the packet in an AEAD frame. - var frame [framing.MaximumSegmentLength]byte - frameLen, err := conn.encoder.Encode(frame[:], pkt[:pktLen]) - if err != nil { - // All encoder errors are fatal. - return err - } - wrLen, err := w.Write(frame[:frameLen]) - if err != nil { - return err - } else if wrLen < frameLen { - return io.ErrShortWrite - } - - return nil -} - -func (conn *obfs4Conn) readPackets() (err error) { - // Attempt to read off the network. - var buf [consumeReadSize]byte - rdLen, rdErr := conn.Conn.Read(buf[:]) - conn.receiveBuffer.Write(buf[:rdLen]) - - var decoded [framing.MaximumFramePayloadLength]byte - for conn.receiveBuffer.Len() > 0 { - // Decrypt an AEAD frame. - decLen := 0 - decLen, err = conn.decoder.Decode(decoded[:], conn.receiveBuffer) - if err == framing.ErrAgain { - break - } else if err != nil { - break - } else if decLen < packetOverhead { - err = InvalidPacketLengthError(decLen) - break - } - - // Decode the packet. - pkt := decoded[0:decLen] - pktType := pkt[0] - payloadLen := binary.BigEndian.Uint16(pkt[1:]) - if int(payloadLen) > len(pkt)-packetOverhead { - err = InvalidPayloadLengthError(int(payloadLen)) - break - } - payload := pkt[3 : 3+payloadLen] - - switch pktType { - case packetTypePayload: - if payloadLen > 0 { - conn.receiveDecodedBuffer.Write(payload) - } - case packetTypePrngSeed: - // Only regenerate the distribution if we are the client. - if len(payload) == seedPacketPayloadLength && !conn.isServer { - var seed *drbg.Seed - seed, err = drbg.SeedFromBytes(payload) - if err != nil { - break - } - conn.lenDist.Reset(seed) - if conn.iatDist != nil { - iatSeedSrc := sha256.Sum256(seed.Bytes()[:]) - iatSeed, err := drbg.SeedFromBytes(iatSeedSrc[:]) - if err != nil { - break - } - conn.iatDist.Reset(iatSeed) - } - } - default: - // Ignore unknown packet types. - } - } - - // Read errors (all fatal) take priority over various frame processing - // errors. - if rdErr != nil { - return rdErr - } - - return -} |