Move rtp header extension length check from Packet::FindExtension to ExtensionT::Parse

webrtc/modules/rtp_rtcp/source/rtp_packet.h

 /*
  *  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.
  */
 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_PACKET_H_
@@ skipping 124 matching lines @@
   struct ExtensionInfo {
     ExtensionType type;
     uint16_t offset;
     uint8_t length;
   };
 
   // Helper function for Parse. Fill header fields using data in given buffer,
   // but does not touch packet own buffer, leaving packet in invalid state.
   bool ParseBuffer(const uint8_t* buffer, size_t size);
 
-  // Find an extension based on the type field of the parameter.
-  // If found, length field would be validated, the offset field will be set
-  // and true returned,
-  // otherwise the parameter will be unchanged and false is returned.
-  bool FindExtension(ExtensionType type,
-                     uint8_t length,
-                     uint16_t* offset) const;
+  // Find an extension |type|.
+  // Returns view of the raw extension or empty view on failure.
+  rtc::ArrayView<const uint8_t> FindExtension(ExtensionType type) const;
 
   // Find or allocate an extension |type|. Returns view of size |length|
   // to write raw extension to or an empty view on failure.
   rtc::ArrayView<uint8_t> AllocateExtension(ExtensionType type, size_t length);
 
   uint8_t* WriteAt(size_t offset);
   void WriteAt(size_t offset, uint8_t byte);
 
   // Header.
   bool marker_;
   uint8_t payload_type_;
   uint8_t padding_size_;
   uint16_t sequence_number_;
   uint32_t timestamp_;
   uint32_t ssrc_;
   size_t payload_offset_;  // Match header size with csrcs and extensions.
   size_t payload_size_;
 
   ExtensionInfo extension_entries_[kMaxExtensionHeaders];
   uint16_t extensions_size_ = 0;  // Unaligned.
   rtc::CopyOnWriteBuffer buffer_;
 };
 
 template <typename Extension>
 bool Packet::HasExtension() const {
-  uint16_t offset = 0;
-  return FindExtension(Extension::kId, Extension::kValueSizeBytes, &offset);
+  return !FindExtension(Extension::kId).empty();
 }
 
 template <typename Extension, typename... Values>
 bool Packet::GetExtension(Values... values) const {
-  uint16_t offset = 0;
-  if (!FindExtension(Extension::kId, Extension::kValueSizeBytes, &offset))
+  auto raw = FindExtension(Extension::kId);
+  if (raw.empty())
     return false;
-  return Extension::Parse(data() + offset, values...);
+  return Extension::Parse(raw, values...);
 }
 
 template <typename Extension, typename... Values>
 bool Packet::SetExtension(Values... values) {
   auto buffer = AllocateExtension(Extension::kId, Extension::kValueSizeBytes);
   if (buffer.empty())
     return false;
   return Extension::Write(buffer.data(), values...);
 }
 
 template <typename Extension>
 bool Packet::ReserveExtension() {
   auto buffer = AllocateExtension(Extension::kId, Extension::kValueSizeBytes);
   if (buffer.empty())
     return false;
   memset(buffer.data(), 0, Extension::kValueSizeBytes);
   return true;
 }
 }  // namespace rtp
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_PACKET_H_