[rtcp] Nack::Parse updated not to use RTCPUtility

webrtc/modules/rtp_rtcp/source/rtcp_packet/nack.cc

Index: webrtc/modules/rtp_rtcp/source/rtcp_packet/nack.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/nack.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/nack.cc
index 8b9b354a0601067d1c4811a9bd10e1dd97df60df..0c1f577f7b7ba062578af9dcd1d57a5f3f3e41f5 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/nack.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/nack.cc
@@ -15,12 +15,12 @@
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
-
-using webrtc::RTCPUtility::RtcpCommonHeader;
+#include "webrtc/modules/rtp_rtcp/source/rtcp_packet/common_header.h"
 
 namespace webrtc {
 namespace rtcp {
-
+constexpr uint8_t Nack::kFeedbackMessageType;
+constexpr size_t Nack::kNackItemLength;
 // RFC 4585: Feedback format.
 //
 // Common packet format:
@@ -45,20 +45,23 @@ namespace rtcp {
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //   |            PID                |             BLP               |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-bool Nack::Parse(const RtcpCommonHeader& header, const uint8_t* payload) {
-  RTC_DCHECK(header.packet_type == kPacketType);
-  RTC_DCHECK(header.count_or_format == kFeedbackMessageType);
+Nack::Nack() {}
+Nack::~Nack() {}
 
-  if (header.payload_size_bytes < kCommonFeedbackLength + kNackItemLength) {
-    LOG(LS_WARNING) << "Payload length " << header.payload_size_bytes
+bool Nack::Parse(const CommonHeader& packet) {
+  RTC_DCHECK_EQ(packet.type(), kPacketType);
+  RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
+
+  if (packet.payload_size_bytes() < kCommonFeedbackLength + kNackItemLength) {
+    LOG(LS_WARNING) << "Payload length " << packet.payload_size_bytes()
                     << " is too small for a Nack.";
     return false;
   }
   size_t nack_items =
-      (header.payload_size_bytes - kCommonFeedbackLength) / kNackItemLength;
+      (packet.payload_size_bytes() - kCommonFeedbackLength) / kNackItemLength;
 
-  ParseCommonFeedback(payload);
-  const uint8_t* next_nack = payload + kCommonFeedbackLength;
+  ParseCommonFeedback(packet.payload());
+  const uint8_t* next_nack = packet.payload() + kCommonFeedbackLength;
 
   packet_ids_.clear();
   packed_.resize(nack_items);
@@ -78,42 +81,44 @@ bool Nack::Create(uint8_t* packet,
                   RtcpPacket::PacketReadyCallback* callback) const {
   RTC_DCHECK(!packed_.empty());
   // If nack list can't fit in packet, try to fragment.
-  size_t nack_index = 0;
-  const size_t kCommonFbFmtLength = kHeaderLength + kCommonFeedbackLength;
-  do {
+  constexpr size_t kNackHeaderLength = kHeaderLength + kCommonFeedbackLength;
+  for (size_t nack_index = 0; nack_index < packed_.size();) {
     size_t bytes_left_in_buffer = max_length - *index;
-    if (bytes_left_in_buffer < kCommonFbFmtLength + kNackItemLength) {
+    if (bytes_left_in_buffer < kNackHeaderLength + kNackItemLength) {
       if (!OnBufferFull(packet, index, callback))
         return false;
       continue;
     }
     size_t num_nack_fields =
-        std::min((bytes_left_in_buffer - kCommonFbFmtLength) / kNackItemLength,
+        std::min((bytes_left_in_buffer - kNackHeaderLength) / kNackItemLength,
                  packed_.size() - nack_index);
 
-    size_t size_bytes =
-        (num_nack_fields * kNackItemLength) + kCommonFbFmtLength;
-    size_t header_length = ((size_bytes + 3) / 4) - 1;  // As 32bit words - 1
-    CreateHeader(kFeedbackMessageType, kPacketType, header_length, packet,
+    size_t payload_size_bytes =
+        kCommonFeedbackLength + (num_nack_fields * kNackItemLength);
+    size_t payload_size_32bits =
+        rtc::CheckedDivExact<size_t>(payload_size_bytes, 4);
+    CreateHeader(kFeedbackMessageType, kPacketType, payload_size_32bits, packet,
                  index);
+
     CreateCommonFeedback(packet + *index);
     *index += kCommonFeedbackLength;
-    size_t end_index = nack_index + num_nack_fields;
-    for (; nack_index < end_index; ++nack_index) {
-      const auto& item = packed_[nack_index];
+
+    size_t nack_end_index = nack_index + num_nack_fields;
+    for (; nack_index < nack_end_index; ++nack_index) {
+      const PackedNack& item = packed_[nack_index];
       ByteWriter<uint16_t>::WriteBigEndian(packet + *index + 0, item.first_pid);
       ByteWriter<uint16_t>::WriteBigEndian(packet + *index + 2, item.bitmask);
       *index += kNackItemLength;
     }
     RTC_DCHECK_LE(*index, max_length);
-  } while (nack_index < packed_.size());
+  }
 
   return true;
 }
 
 size_t Nack::BlockLength() const {
-  return (packed_.size() * kNackItemLength) + kCommonFeedbackLength +
-         kHeaderLength;
+  return kHeaderLength + kCommonFeedbackLength +
+         packed_.size() * kNackItemLength;
 }
 
 void Nack::WithList(const uint16_t* nack_list, size_t length) {
@@ -153,9 +158,10 @@ void Nack::Unpack() {
   for (const PackedNack& item : packed_) {
     packet_ids_.push_back(item.first_pid);
     uint16_t pid = item.first_pid + 1;
-    for (uint16_t bitmask = item.bitmask; bitmask != 0; bitmask >>= 1, ++pid)
+    for (uint16_t bitmask = item.bitmask; bitmask != 0; bitmask >>= 1, ++pid) {
       if (bitmask & 1)
         packet_ids_.push_back(pid);
+    }
   }
 }