| /* |
| * Copyright (c) 2016 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 "webrtc/media/base/turnutils.h" |
| |
| #include "webrtc/base/byteorder.h" |
| #include "webrtc/base/checks.h" |
| #include "webrtc/p2p/base/stun.h" |
| |
| namespace cricket { |
| |
| namespace { |
| |
| const size_t kTurnChannelHeaderLength = 4; |
| |
| bool IsTurnChannelData(const uint8_t* data, size_t length) { |
| return length >= kTurnChannelHeaderLength && ((*data & 0xC0) == 0x40); |
| } |
| |
| bool IsTurnSendIndicationPacket(const uint8_t* data, size_t length) { |
| if (length < kStunHeaderSize) { |
| return false; |
| } |
| |
| uint16_t type = rtc::GetBE16(data); |
| return (type == TURN_SEND_INDICATION); |
| } |
| |
| } // namespace |
| |
| bool UnwrapTurnPacket(const uint8_t* packet, |
| size_t packet_size, |
| size_t* content_position, |
| size_t* content_size) { |
| if (IsTurnChannelData(packet, packet_size)) { |
| // Turn Channel Message header format. |
| // 0 1 2 3 |
| // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // | Channel Number | Length | |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // | | |
| // / Application Data / |
| // / / |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| size_t length = rtc::GetBE16(&packet[2]); |
| if (length + kTurnChannelHeaderLength > packet_size) { |
| return false; |
| } |
| |
| *content_position = kTurnChannelHeaderLength; |
| *content_size = length; |
| return true; |
| } |
| |
| if (IsTurnSendIndicationPacket(packet, packet_size)) { |
| // Validate STUN message length. |
| const size_t stun_message_length = rtc::GetBE16(&packet[2]); |
| if (stun_message_length + kStunHeaderSize != packet_size) { |
| return false; |
| } |
| |
| // First skip mandatory stun header which is of 20 bytes. |
| size_t pos = kStunHeaderSize; |
| // Loop through STUN attributes until we find STUN DATA attribute. |
| while (pos < packet_size) { |
| // Keep reading STUN attributes until we hit DATA attribute. |
| // Attribute will be a TLV structure. |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // | Type | Length | |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // | Value (variable) .... |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // The value in the length field MUST contain the length of the Value |
| // part of the attribute, prior to padding, measured in bytes. Since |
| // STUN aligns attributes on 32-bit boundaries, attributes whose content |
| // is not a multiple of 4 bytes are padded with 1, 2, or 3 bytes of |
| // padding so that its value contains a multiple of 4 bytes. The |
| // padding bits are ignored, and may be any value. |
| uint16_t attr_type, attr_length; |
| const int kAttrHeaderLength = sizeof(attr_type) + sizeof(attr_length); |
| |
| if (packet_size < pos + kAttrHeaderLength) { |
| return false; |
| } |
| |
| // Getting attribute type and length. |
| attr_type = rtc::GetBE16(&packet[pos]); |
| attr_length = rtc::GetBE16(&packet[pos + sizeof(attr_type)]); |
| |
| pos += kAttrHeaderLength; // Skip STUN_DATA_ATTR header. |
| |
| // Checking for bogus attribute length. |
| if (pos + attr_length > packet_size) { |
| return false; |
| } |
| |
| if (attr_type == STUN_ATTR_DATA) { |
| *content_position = pos; |
| *content_size = attr_length; |
| return true; |
| } |
| |
| pos += attr_length; |
| if ((attr_length % 4) != 0) { |
| pos += (4 - (attr_length % 4)); |
| } |
| } |
| |
| // There is no data attribute present in the message. |
| return false; |
| } |
| |
| // This is not a TURN packet. |
| *content_position = 0; |
| *content_size = packet_size; |
| return true; |
| } |
| |
| } // namespace cricket |