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/*
* Copyright 2013 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "p2p/base/async_stun_tcp_socket.h"
#include <errno.h>
#include <stdint.h>
#include <string.h>
#include "api/transport/stun.h"
#include "rtc_base/byte_order.h"
#include "rtc_base/checks.h"
#include "rtc_base/network/sent_packet.h"
#include "rtc_base/time_utils.h"
namespace cricket {
static const size_t kMaxPacketSize = 64 * 1024;
typedef uint16_t PacketLength;
static const size_t kPacketLenSize = sizeof(PacketLength);
static const size_t kPacketLenOffset = 2;
static const size_t kBufSize = kMaxPacketSize + kStunHeaderSize;
static const size_t kTurnChannelDataHdrSize = 4;
inline bool IsStunMessage(uint16_t msg_type) {
// The first two bits of a channel data message are 0b01.
return (msg_type & 0xC000) ? false : true;
}
// AsyncStunTCPSocket
// Binds and connects `socket` and creates AsyncTCPSocket for
// it. Takes ownership of `socket`. Returns NULL if bind() or
// connect() fail (`socket` is destroyed in that case).
AsyncStunTCPSocket* AsyncStunTCPSocket::Create(
rtc::Socket* socket,
const rtc::SocketAddress& bind_address,
const rtc::SocketAddress& remote_address) {
return new AsyncStunTCPSocket(
AsyncTCPSocketBase::ConnectSocket(socket, bind_address, remote_address));
}
AsyncStunTCPSocket::AsyncStunTCPSocket(rtc::Socket* socket)
: rtc::AsyncTCPSocketBase(socket, kBufSize) {}
int AsyncStunTCPSocket::Send(const void* pv,
size_t cb,
const rtc::PacketOptions& options) {
if (cb > kBufSize || cb < kPacketLenSize + kPacketLenOffset) {
SetError(EMSGSIZE);
return -1;
}
// If we are blocking on send, then silently drop this packet
if (!IsOutBufferEmpty())
return static_cast<int>(cb);
int pad_bytes;
size_t expected_pkt_len = GetExpectedLength(pv, cb, &pad_bytes);
// Accepts only complete STUN/ChannelData packets.
if (cb != expected_pkt_len)
return -1;
AppendToOutBuffer(pv, cb);
RTC_DCHECK(pad_bytes < 4);
char padding[4] = {0};
AppendToOutBuffer(padding, pad_bytes);
int res = FlushOutBuffer();
if (res <= 0) {
// drop packet if we made no progress
ClearOutBuffer();
return res;
}
rtc::SentPacket sent_packet(options.packet_id, rtc::TimeMillis());
SignalSentPacket(this, sent_packet);
// We claim to have sent the whole thing, even if we only sent partial
return static_cast<int>(cb);
}
void AsyncStunTCPSocket::ProcessInput(char* data, size_t* len) {
rtc::SocketAddress remote_addr(GetRemoteAddress());
// STUN packet - First 4 bytes. Total header size is 20 bytes.
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |0 0| STUN Message Type | Message Length |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TURN ChannelData
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Channel Number | Length |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
while (true) {
// We need at least 4 bytes to read the STUN or ChannelData packet length.
if (*len < kPacketLenOffset + kPacketLenSize)
return;
int pad_bytes;
size_t expected_pkt_len = GetExpectedLength(data, *len, &pad_bytes);
size_t actual_length = expected_pkt_len + pad_bytes;
if (*len < actual_length) {
return;
}
SignalReadPacket(this, data, expected_pkt_len, remote_addr,
rtc::TimeMicros());
*len -= actual_length;
if (*len > 0) {
memmove(data, data + actual_length, *len);
}
}
}
size_t AsyncStunTCPSocket::GetExpectedLength(const void* data,
size_t len,
int* pad_bytes) {
*pad_bytes = 0;
PacketLength pkt_len =
rtc::GetBE16(static_cast<const char*>(data) + kPacketLenOffset);
size_t expected_pkt_len;
uint16_t msg_type = rtc::GetBE16(data);
if (IsStunMessage(msg_type)) {
// STUN message.
expected_pkt_len = kStunHeaderSize + pkt_len;
} else {
// TURN ChannelData message.
expected_pkt_len = kTurnChannelDataHdrSize + pkt_len;
// From RFC 5766 section 11.5
// Over TCP and TLS-over-TCP, the ChannelData message MUST be padded to
// a multiple of four bytes in order to ensure the alignment of
// subsequent messages. The padding is not reflected in the length
// field of the ChannelData message, so the actual size of a ChannelData
// message (including padding) is (4 + Length) rounded up to the nearest
// multiple of 4. Over UDP, the padding is not required but MAY be
// included.
if (expected_pkt_len % 4)
*pad_bytes = 4 - (expected_pkt_len % 4);
}
return expected_pkt_len;
}
} // namespace cricket
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