Repo created

TMessagesProj/jni/voip/webrtc/media/base/turn_utils.cc

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+/*
+ *  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 "media/base/turn_utils.h"
+
+#include "api/transport/stun.h"
+#include "rtc_base/byte_order.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