Index: webrtc/p2p/base/rtppacketutil.cc |
diff --git a/webrtc/p2p/base/rtppacketutil.cc b/webrtc/p2p/base/rtppacketutil.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..ee38aa1fd34cbfe0dafb75c6b1e2d5b44c30a15a |
--- /dev/null |
+++ b/webrtc/p2p/base/rtppacketutil.cc |
@@ -0,0 +1,442 @@ |
+/* |
+ * Copyright 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/p2p/base/rtppacketutil.h" |
+ |
+#include <string.h> |
+ |
+#include "webrtc/base/asyncpacketsocket.h" |
+#include "webrtc/base/byteorder.h" |
+#include "webrtc/base/checks.h" |
+#include "webrtc/base/messagedigest.h" |
+#include "webrtc/base/timeutils.h" |
+#include "webrtc/p2p/base/stun.h" |
+ |
+namespace rtc { |
+ |
+namespace { |
+ |
+const size_t kMinRtpHeaderLength = 12; |
pthatcher1
2016/01/13 23:21:33
There's a lot of overlap between this and rtputils
Sergey Ulanov
2016/01/14 06:02:21
I didn't know about rtputils.cc. Move all the code
|
+const size_t kMinRtcpHeaderLength = 8; |
+const size_t kRtpExtensionHeaderLength = 4; |
+const size_t kDtlsRecordHeaderLength = 13; |
+const size_t kTurnChannelHeaderLength = 4; |
+const size_t kAbsSendTimeExtensionLength = 3; |
+const size_t kOneByteHeaderLength = 1; |
+const size_t kMaxRtpPacketLength = 2048; |
+ |
+// Fake auth tag written by the render process if external authentication is |
pthatcher1
2016/01/13 23:21:33
Does this still make sense being here? It doesn't
Sergey Ulanov
2016/01/14 06:02:21
Updated the comment
|
+// enabled. HMAC in packet will be compared against this value before updating |
+// packet with actual HMAC value. |
+static const unsigned char kFakeAuthTag[10] = { |
+ 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd |
+}; |
+ |
+bool IsTurnChannelData(const char* data, size_t length) { |
+ return length >= kTurnChannelHeaderLength && ((*data & 0xC0) == 0x40); |
+} |
+ |
+bool IsTurnSendIndicationPacket(const char* data, size_t length) { |
+ if (length < cricket::kStunHeaderSize) { |
+ return false; |
+ } |
+ |
+ uint16_t type = rtc::GetBE16(data); |
+ return (type == cricket::TURN_SEND_INDICATION); |
+} |
pthatcher1
2016/01/13 23:21:33
The above are not RTP, and so seem awkward being i
Sergey Ulanov
2016/01/14 06:02:21
Moved to turnutils.cc
|
+ |
+bool IsRtpPacket(const char* data, size_t length) { |
+ return (length >= kMinRtpHeaderLength) && ((*data & 0xC0) == 0x80); |
+} |
+ |
+void UpdateAbsSendTimeExtensionValue(char* extension_data, |
+ size_t length, |
+ uint32_t abs_send_time) { |
+ // Absolute send time in RTP streams. |
+ // |
+ // The absolute send time is signaled to the receiver in-band using the |
+ // general mechanism for RTP header extensions [RFC5285]. The payload |
+ // of this extension (the transmitted value) is a 24-bit unsigned integer |
+ // containing the sender's current time in seconds as a fixed point number |
+ // with 18 bits fractional part. |
+ // |
+ // The form of the absolute send time extension block: |
+ // |
+ // 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 |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // | ID | len=2 | absolute send time | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ if (length != kAbsSendTimeExtensionLength) { |
+ RTC_NOTREACHED(); |
+ return; |
+ } |
+ |
+ // Now() has resolution ~1-15ms |
+ uint32_t now_second = abs_send_time; |
+ if (!now_second) { |
+ uint64_t now_us = rtc::TimeMicros(); |
+ // Convert second to 24-bit unsigned with 18 bit fractional part |
+ now_second = ((now_us << 18) / rtc::kNumMicrosecsPerSec) & 0x00FFFFFF; |
+ } |
pthatcher1
2016/01/13 23:21:33
It seems like it would be better to pass in the ti
Sergey Ulanov
2016/01/14 06:02:21
Done.
|
+ // TODO(mallinath): Add SetBE24 to byteorder.h. |
+ extension_data[0] = static_cast<uint8_t>(now_second >> 16); |
+ extension_data[1] = static_cast<uint8_t>(now_second >> 8); |
+ extension_data[2] = static_cast<uint8_t>(now_second); |
+} |
+ |
+// Assumes |length| is actual packet length + tag length. Updates HMAC at end of |
+// the RTP packet. |
+void UpdateRtpAuthTag(char* rtp, size_t length, const PacketOptions& options) { |
pthatcher1
2016/01/13 23:21:33
It seems like the key and len should be passed in
Sergey Ulanov
2016/01/14 06:02:21
Updated it to pass rtc::PacketTimeUpdateParams. Th
|
+ // If there is no key, return. |
+ if (options.packet_time_params.srtp_auth_key.empty()) { |
+ return; |
+ } |
+ |
+ size_t tag_length = options.packet_time_params.srtp_auth_tag_len; |
+ |
+ // ROC (rollover counter) is at the beginning of the auth tag. |
+ const size_t kRocLength = 4; |
+ if (tag_length < kRocLength || tag_length > length) { |
+ RTC_NOTREACHED(); |
+ return; |
+ } |
+ |
+ char* auth_tag = rtp + (length - tag_length); |
+ |
+ // We should have a fake HMAC value @ auth_tag. |
+ RTC_DCHECK_EQ(0, memcmp(auth_tag, kFakeAuthTag, tag_length)); |
+ |
+ // Copy ROC after end of rtp packet. |
+ memcpy(auth_tag, &options.packet_time_params.srtp_packet_index, kRocLength); |
+ // Authentication of a RTP packet will have RTP packet + ROC size. |
+ int auth_required_length = length - tag_length + kRocLength; |
+ |
+ unsigned char output[64]; |
+ |
+ size_t result = ComputeHmac( |
+ rtc::DIGEST_SHA_1, &options.packet_time_params.srtp_auth_key[0], |
+ options.packet_time_params.srtp_auth_key.size(), rtp, |
+ auth_required_length, output, sizeof(output)); |
+ |
+ if (result < tag_length) { |
+ RTC_NOTREACHED(); |
+ return; |
+ } |
+ |
+ // Copy HMAC from output to packet. This is required as auth tag length |
+ // may not be equal to the actual HMAC length. |
+ memcpy(auth_tag, output, tag_length); |
+} |
+ |
+} // namespace |
+ |
+bool IsDtlsPacket(const char* data, size_t length) { |
+ const uint8_t* u = reinterpret_cast<const uint8_t*>(data); |
+ return (length >= kDtlsRecordHeaderLength && (u[0] > 19 && u[0] < 64)); |
+} |
pthatcher1
2016/01/13 23:21:33
This doesn't seem to belong in an rtputils file ei
Sergey Ulanov
2016/01/14 06:02:21
Done.
|
+ |
+bool IsRtcpPacket(const char* data, size_t length) { |
+ if (length < kMinRtcpHeaderLength) { |
+ return false; |
+ } |
+ |
+ int type = (static_cast<uint8_t>(data[1]) & 0x7F); |
+ return (type >= 64 && type < 96); |
+} |
+ |
+bool ValidateRtpHeader(const char* rtp, size_t length, size_t* header_length) { |
+ if (header_length) { |
+ *header_length = 0; |
+ } |
+ |
+ if (length < kMinRtpHeaderLength) { |
+ return false; |
+ } |
+ |
+ size_t cc_count = rtp[0] & 0x0F; |
+ size_t header_length_without_extension = kMinRtpHeaderLength + 4 * cc_count; |
+ if (header_length_without_extension > length) { |
+ return false; |
+ } |
+ |
+ // If extension bit is not set, we are done with header processing, as input |
+ // length is verified above. |
+ if (!(rtp[0] & 0x10)) { |
+ if (header_length) |
+ *header_length = header_length_without_extension; |
+ |
+ return true; |
+ } |
+ |
+ rtp += header_length_without_extension; |
+ |
+ if (header_length_without_extension + kRtpExtensionHeaderLength > length) { |
+ return false; |
+ } |
+ |
+ // Getting extension profile length. |
+ // Length is in 32 bit words. |
+ uint16_t extension_length_in_32bits = rtc::GetBE16(rtp + 2); |
+ size_t extension_length = extension_length_in_32bits * 4; |
+ |
+ size_t rtp_header_length = extension_length + |
+ header_length_without_extension + |
+ kRtpExtensionHeaderLength; |
+ |
+ // Verify input length against total header size. |
+ if (rtp_header_length > length) { |
+ return false; |
+ } |
+ |
+ if (header_length) { |
+ *header_length = rtp_header_length; |
+ } |
+ return true; |
+} |
+ |
+bool ApplyPacketOptions(char* data, |
+ size_t length, |
+ const rtc::PacketOptions& options, |
+ uint32_t abs_send_time) { |
pthatcher1
2016/01/13 23:21:33
This seems like it should be UpdateRtpPacket, with
Sergey Ulanov
2016/01/14 06:02:21
Changed it to use rtc::PacketTimeUpdateParams
|
+ RTC_DCHECK(data != NULL); |
+ RTC_DCHECK(length > 0); |
+ // if there is no valid |rtp_sendtime_extension_id| and |srtp_auth_key| in |
+ // PacketOptions, nothing to be updated in this packet. |
+ if (options.packet_time_params.rtp_sendtime_extension_id == -1 && |
+ options.packet_time_params.srtp_auth_key.empty()) { |
+ return true; |
+ } |
+ |
+ RTC_DCHECK(!IsDtlsPacket(data, length)); |
+ RTC_DCHECK(!IsRtcpPacket(data, length)); |
+ |
+ // If there is a srtp auth key present then packet must be a RTP packet. |
+ // RTP packet may have been wrapped in a TURN Channel Data or |
+ // TURN send indication. |
+ size_t rtp_start_pos; |
+ size_t rtp_length; |
+ if (!GetRtpPacketStartPositionAndLength( |
+ data, length, &rtp_start_pos, &rtp_length)) { |
+ // This method should never return false. |
+ RTC_NOTREACHED(); |
+ return false; |
+ } |
+ |
+ // Skip to rtp packet. |
+ char* start = data + rtp_start_pos; |
+ // If packet option has non default value (-1) for sendtime extension id, |
+ // then we should parse the rtp packet to update the timestamp. Otherwise |
+ // just calculate HMAC and update packet with it. |
+ if (options.packet_time_params.rtp_sendtime_extension_id != -1) { |
+ UpdateRtpAbsSendTimeExtension( |
+ start, |
+ rtp_length, |
+ options.packet_time_params.rtp_sendtime_extension_id, |
+ abs_send_time); |
+ } |
+ |
+ UpdateRtpAuthTag(start, rtp_length, options); |
+ return true; |
+} |
+ |
+bool GetRtpPacketStartPositionAndLength(const char* packet, |
+ size_t length, |
+ size_t* rtp_start_pos, |
+ size_t* rtp_packet_length) { |
pthatcher1
2016/01/13 23:21:33
This is kind of a funny function. "Find an RTP pa
Sergey Ulanov
2016/01/14 06:02:21
Moved to turnutils.cc and renamed to UnwrapTurnPac
|
+ if (length < kMinRtpHeaderLength || length > kMaxRtpPacketLength) { |
+ return false; |
+ } |
+ |
+ size_t rtp_begin; |
+ size_t rtp_length = 0; |
+ if (IsTurnChannelData(packet, length)) { |
+ // 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 / |
+ // / / |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ rtp_begin = kTurnChannelHeaderLength; |
+ rtp_length = rtc::GetBE16(&packet[2]); |
+ if (length < rtp_length + kTurnChannelHeaderLength) { |
+ return false; |
+ } |
+ } else if (IsTurnSendIndicationPacket(packet, length)) { |
+ // Validate STUN message length. |
+ const size_t stun_message_length = rtc::GetBE16(&packet[2]); |
+ if (stun_message_length + cricket::kStunHeaderSize != length) { |
+ return false; |
+ } |
+ |
+ // First skip mandatory stun header which is of 20 bytes. |
+ rtp_begin = cricket::kStunHeaderSize; |
+ // Loop through STUN attributes until we find STUN DATA attribute. |
+ bool data_attr_present = false; |
+ while (rtp_begin < length) { |
+ // 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 (length < rtp_begin + kAttrHeaderLength) { |
+ return false; |
+ } |
+ |
+ // Getting attribute type and length. |
+ attr_type = rtc::GetBE16(&packet[rtp_begin]); |
+ attr_length = rtc::GetBE16( |
+ &packet[rtp_begin + sizeof(attr_type)]); |
+ |
+ rtp_begin += kAttrHeaderLength; // Skip STUN_DATA_ATTR header. |
+ |
+ // Checking for bogus attribute length. |
+ if (length < rtp_begin + attr_length) { |
+ return false; |
+ } |
+ |
+ if (attr_type != cricket::STUN_ATTR_DATA) { |
+ rtp_begin += attr_length; |
+ if ((attr_length % 4) != 0) { |
+ rtp_begin += (4 - (attr_length % 4)); |
+ } |
+ continue; |
+ } |
+ |
+ data_attr_present = true; |
+ rtp_length = attr_length; |
+ |
+ // We found STUN_DATA_ATTR. We can skip parsing rest of the packet. |
+ break; |
+ } |
+ |
+ if (!data_attr_present) { |
+ // There is no data attribute present in the message. We can't do anything |
+ // with the message. |
+ return false; |
+ } |
+ |
+ } else { |
+ // This is a raw RTP packet. |
+ rtp_begin = 0; |
+ rtp_length = length; |
+ } |
+ |
+ // Making sure we have a valid RTP packet at the end. |
+ if (IsRtpPacket(packet + rtp_begin, rtp_length) && |
+ ValidateRtpHeader(packet + rtp_begin, rtp_length, NULL)) { |
+ *rtp_start_pos = rtp_begin; |
+ *rtp_packet_length = rtp_length; |
+ return true; |
+ } |
+ return false; |
+} |
+ |
+// ValidateRtpHeader must be called before this method to make sure, we have |
+// a sane rtp packet. |
+bool UpdateRtpAbsSendTimeExtension(char* rtp, |
+ size_t length, |
+ int extension_id, |
+ uint32_t abs_send_time) { |
+ // 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 |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // |V=2|P|X| CC |M| PT | sequence number | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // | timestamp | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // | synchronization source (SSRC) identifier | |
+ // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ |
+ // | contributing source (CSRC) identifiers | |
+ // | .... | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ |
+ // Return if extension bit is not set. |
+ if (!(rtp[0] & 0x10)) { |
+ return true; |
+ } |
+ |
+ size_t cc_count = rtp[0] & 0x0F; |
+ size_t header_length_without_extension = kMinRtpHeaderLength + 4 * cc_count; |
+ |
+ rtp += header_length_without_extension; |
+ |
+ // Getting extension profile ID and length. |
+ uint16_t profile_id = rtc::GetBE16(rtp); |
+ // Length is in 32 bit words. |
+ uint16_t extension_length_in_32bits = rtc::GetBE16(rtp + 2); |
+ size_t extension_length = extension_length_in_32bits * 4; |
+ |
+ rtp += kRtpExtensionHeaderLength; // Moving past extension header. |
+ |
+ bool found = false; |
+ // WebRTC is using one byte header extension. |
+ // TODO(mallinath) - Handle two byte header extension. |
+ if (profile_id == 0xBEDE) { // OneByte extension header |
+ // 0 |
+ // 0 1 2 3 4 5 6 7 |
+ // +-+-+-+-+-+-+-+-+ |
+ // | ID |length | |
+ // +-+-+-+-+-+-+-+-+ |
+ |
+ // 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 |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // | 0xBE | 0xDE | length=3 | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // | ID | L=0 | data | ID | L=1 | data... |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // ...data | 0 (pad) | 0 (pad) | ID | L=3 | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ // | data | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+ const char* extension_start = rtp; |
+ const char* extension_end = extension_start + extension_length; |
+ |
+ while (rtp < extension_end) { |
+ const int id = (*rtp & 0xF0) >> 4; |
+ const size_t length = (*rtp & 0x0F) + 1; |
+ if (rtp + kOneByteHeaderLength + length > extension_end) { |
+ return false; |
+ } |
+ // The 4-bit length is the number minus one of data bytes of this header |
+ // extension element following the one-byte header. |
+ if (id == extension_id) { |
+ UpdateAbsSendTimeExtensionValue( |
+ rtp + kOneByteHeaderLength, length, abs_send_time); |
+ found = true; |
+ break; |
+ } |
+ rtp += kOneByteHeaderLength + length; |
+ // Counting padding bytes. |
+ while ((rtp < extension_end) && (*rtp == 0)) { |
+ ++rtp; |
+ } |
+ } |
+ } |
+ return found; |
+} |
+ |
+} // namespace rtc |