Remove RtcpPacket dependency on rtcp_utility

and thus IP_PACKET_SIZE constant:
Build() use BlockLength() instead of constant IP_PACKET_SIZE for packet
capacity, adding extra checks about packet generation in tests.
Build(callback) removed as unused.
definitions reordered to follow style.

BUG=webrtc:5260

Review-Url: https://codereview.webrtc.org/2270753002
Cr-Commit-Position: refs/heads/master@{#14647}

webrtc/modules/rtp_rtcp/source/rtcp_packet.cc

@@ -11,50 +11,23 @@
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet.h"
 
 #include "webrtc/base/checks.h"
-#include "webrtc/base/logging.h"
-#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
 
 namespace webrtc {
 namespace rtcp {
-namespace {
+constexpr size_t RtcpPacket::kHeaderLength;
-void AssignUWord8(uint8_t* buffer, size_t* offset, uint8_t value) {
-  buffer[(*offset)++] = value;
-}
-void AssignUWord16(uint8_t* buffer, size_t* offset, uint16_t value) {
-  ByteWriter<uint16_t>::WriteBigEndian(buffer + *offset, value);
-  *offset += 2;
-}
-}  // namespace
 
 rtc::Buffer RtcpPacket::Build() const {
+  rtc::Buffer packet(BlockLength());
+
   size_t length = 0;
-  rtc::Buffer packet(IP_PACKET_SIZE);
+  bool created = Create(packet.data(), &length, packet.capacity(), nullptr);
+  RTC_DCHECK(created) << "Invalid packet is not supported.";
+  RTC_DCHECK_EQ(length, packet.size())
+      << "BlockLength mispredicted size used by Create";
 
-  class PacketVerifier : public PacketReadyCallback {
-   public:
-    explicit PacketVerifier(rtc::Buffer* packet)
-        : called_(false), packet_(packet) {}
-    virtual ~PacketVerifier() {}
-    void OnPacketReady(uint8_t* data, size_t length) override {
-      RTC_CHECK(!called_) << "Fragmentation not supported.";
-      called_ = true;
-      packet_->SetSize(length);
-    }
-
-   private:
-    bool called_;
-    rtc::Buffer* const packet_;
-  } verifier(&packet);
-  Create(packet.data(), &length, packet.capacity(), &verifier);
-  OnBufferFull(packet.data(), &length, &verifier);
   return packet;
 }
 
-bool RtcpPacket::Build(PacketReadyCallback* callback) const {
-  uint8_t buffer[IP_PACKET_SIZE];
-  return BuildExternalBuffer(buffer, IP_PACKET_SIZE, callback);
-}
-
 bool RtcpPacket::BuildExternalBuffer(uint8_t* buffer,
                                      size_t max_length,
                                      PacketReadyCallback* callback) const {
@@ -66,9 +39,10 @@ bool RtcpPacket::BuildExternalBuffer(uint8_t* buffer,
 
 bool RtcpPacket::OnBufferFull(uint8_t* packet,
                               size_t* index,
-                              RtcpPacket::PacketReadyCallback* callback) const {
+                              PacketReadyCallback* callback) const {
   if (*index == 0)
     return false;
+  RTC_DCHECK(callback) << "Fragmentation not supported.";
   callback->OnPacketReady(packet, *index);
   *index = 0;
   return true;
@@ -76,9 +50,10 @@ bool RtcpPacket::OnBufferFull(uint8_t* packet,
 
 size_t RtcpPacket::HeaderLength() const {
   size_t length_in_bytes = BlockLength();
-  // Length in 32-bit words minus 1.
+  RTC_DCHECK_GT(length_in_bytes, 0u);
-  assert(length_in_bytes > 0);
+  RTC_DCHECK_EQ(length_in_bytes % 4, 0u) << "Padding not supported";
-  return ((length_in_bytes + 3) / 4) - 1;
+  // Length in 32-bit words without common header.
+  return (length_in_bytes - kHeaderLength) / 4;
 }
 
 // From RFC 3550, RTP: A Transport Protocol for Real-Time Applications.
@@ -89,18 +64,21 @@ size_t RtcpPacket::HeaderLength() const {
 //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //  |V=2|P| RC/FMT  |      PT       |             length            |
 //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
 void RtcpPacket::CreateHeader(
     uint8_t count_or_format,  // Depends on packet type.
     uint8_t packet_type,
     size_t length,
     uint8_t* buffer,
     size_t* pos) {
-  assert(length <= 0xffff);
+  RTC_DCHECK_LE(length, 0xffffU);
-  const uint8_t kVersion = 2;
+  RTC_DCHECK_LE(count_or_format, 0x1f);
-  AssignUWord8(buffer, pos, (kVersion << 6) + count_or_format);
+  constexpr uint8_t kVersionBits = 2 << 6;
-  AssignUWord8(buffer, pos, packet_type);
+  constexpr uint8_t kNoPaddingBit = 0 << 5;
-  AssignUWord16(buffer, pos, length);
+  buffer[*pos + 0] = kVersionBits | kNoPaddingBit | count_or_format;
+  buffer[*pos + 1] = packet_type;
+  buffer[*pos + 2] = (length >> 8) & 0xff;
+  buffer[*pos + 3] = length & 0xff;
+  *pos += kHeaderLength;
 }
 
 }  // namespace rtcp

webrtc/modules/rtp_rtcp/source/rtcp_packet.h

@@ -8,12 +8,11 @@
  *  be found in the AUTHORS file in the root of the source tree.
  *
  */
-
 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_H_
 
+#include "webrtc/base/basictypes.h"
 #include "webrtc/base/buffer.h"
-#include "webrtc/modules/rtp_rtcp/source/rtcp_utility.h"
 
 namespace webrtc {
 namespace rtcp {
@@ -46,27 +45,24 @@ namespace rtcp {
 
 class RtcpPacket {
  public:
-  virtual ~RtcpPacket() {}
-
   // Callback used to signal that an RTCP packet is ready. Note that this may
   // not contain all data in this RtcpPacket; if a packet cannot fit in
   // max_length bytes, it will be fragmented and multiple calls to this
   // callback will be made.
   class PacketReadyCallback {
    public:
+    virtual void OnPacketReady(uint8_t* data, size_t length) = 0;
+
+   protected:
     PacketReadyCallback() {}
     virtual ~PacketReadyCallback() {}
-
-    virtual void OnPacketReady(uint8_t* data, size_t length) = 0;
   };
 
-  // Convenience method mostly used for test. Max length of IP_PACKET_SIZE is
+  virtual ~RtcpPacket() {}
-  // used, will cause assertion error if fragmentation occurs.
-  rtc::Buffer Build() const;
 
-  // Returns true if call to Create succeeded. A buffer of size
+  // Convenience method mostly used for test. Creates packet without
-  // IP_PACKET_SIZE will be allocated and reused between calls to callback.
+  // fragmentation using BlockLength() to allocate big enough buffer.
-  bool Build(PacketReadyCallback* callback) const;
+  rtc::Buffer Build() const;
 
   // Returns true if call to Create succeeded. Provided buffer reference
   // will be used for all calls to callback.
@@ -86,21 +82,21 @@ class RtcpPacket {
                       PacketReadyCallback* callback) const = 0;
 
  protected:
+  // Size of the rtcp common header.
+  static constexpr size_t kHeaderLength = 4;
   RtcpPacket() {}
 
   static void CreateHeader(uint8_t count_or_format,
                            uint8_t packet_type,
-                           size_t block_length,  // Size in 32bit words - 1.
+                           size_t block_length,  // Payload size in 32bit words.
                            uint8_t* buffer,
                            size_t* pos);
 
   bool OnBufferFull(uint8_t* packet,
                     size_t* index,
-                    RtcpPacket::PacketReadyCallback* callback) const;
+                    PacketReadyCallback* callback) const;
-
+  // Size of the rtcp packet as written in header.
   size_t HeaderLength() const;
-
-  static const size_t kHeaderLength = 4;
 };
 }  // namespace rtcp
 }  // namespace webrtc