In QUIC v39, read and write integers and floating numbers in big endian.

net/quic/core/quic_framer.cc

Index: net/quic/core/quic_framer.cc
diff --git a/net/quic/core/quic_framer.cc b/net/quic/core/quic_framer.cc
index b08c020f6b256ba3c20f11aaf139a7231efcc02c..7404ebb1624bac5d7c36c8e05ea834d5be008a8a 100644
--- a/net/quic/core/quic_framer.cc
+++ b/net/quic/core/quic_framer.cc
@@ -313,7 +313,7 @@ size_t QuicFramer::BuildDataPacket(const QuicPacketHeader& header,
                                    const QuicFrames& frames,
                                    char* buffer,
                                    size_t packet_length) {
-  QuicDataWriter writer(packet_length, buffer, perspective_, HOST_BYTE_ORDER);
+  QuicDataWriter writer(packet_length, buffer, perspective_, endianness());
   if (!AppendPacketHeader(header, &writer)) {
     QUIC_BUG << "AppendPacketHeader failed";
     return 0;
@@ -427,8 +427,10 @@ std::unique_ptr<QuicEncryptedPacket> QuicFramer::BuildPublicResetPacket(
   size_t len =
       kPublicFlagsSize + PACKET_8BYTE_CONNECTION_ID + reset_serialized.length();
   std::unique_ptr<char[]> buffer(new char[len]);
+  // Endianness is not a concern here, as writer is not going to write integers
+  // or floating numbers.
   QuicDataWriter writer(len, buffer.get(), Perspective::IS_SERVER,
-                        HOST_BYTE_ORDER);
+                        NETWORK_BYTE_ORDER);
 
   uint8_t flags = static_cast<uint8_t>(PACKET_PUBLIC_FLAGS_RST |
                                        PACKET_PUBLIC_FLAGS_8BYTE_CONNECTION_ID);
@@ -458,8 +460,10 @@ std::unique_ptr<QuicEncryptedPacket> QuicFramer::BuildVersionNegotiationPacket(
   DCHECK(!versions.empty());
   size_t len = GetVersionNegotiationPacketSize(versions.size());
   std::unique_ptr<char[]> buffer(new char[len]);
+  // Endianness is not a concern here, version negotiation packet does not have
+  // integers or floating numbers.
   QuicDataWriter writer(len, buffer.get(), Perspective::IS_SERVER,
-                        HOST_BYTE_ORDER);
+                        NETWORK_BYTE_ORDER);
 
   uint8_t flags = static_cast<uint8_t>(
       PACKET_PUBLIC_FLAGS_VERSION | PACKET_PUBLIC_FLAGS_8BYTE_CONNECTION_ID |
@@ -484,7 +488,7 @@ std::unique_ptr<QuicEncryptedPacket> QuicFramer::BuildVersionNegotiationPacket(
 
 bool QuicFramer::ProcessPacket(const QuicEncryptedPacket& packet) {
   QuicDataReader reader(packet.data(), packet.length(), perspective_,
-                        HOST_BYTE_ORDER);
+                        endianness());
 
   visitor_->OnPacket();
 
@@ -510,6 +514,9 @@ bool QuicFramer::ProcessPacket(const QuicEncryptedPacket& packet) {
     }
   }
 
+  // framer's version may change, reset reader's endianness.
+  reader.set_endianness(endianness());
+
   bool rv;
   if (perspective_ == Perspective::IS_CLIENT && public_header.version_flag) {
     rv = ProcessVersionNegotiationPacket(&reader, &public_header);
@@ -573,7 +580,7 @@ bool QuicFramer::ProcessDataPacket(QuicDataReader* encrypted_reader,
   }
 
   QuicDataReader reader(decrypted_buffer, decrypted_length, perspective_,
-                        HOST_BYTE_ORDER);
+                        endianness());
 
   // Set the last packet number after we have decrypted the packet
   // so we are confident is not attacker controlled.
@@ -2161,4 +2168,8 @@ bool QuicFramer::RaiseError(QuicErrorCode error) {
   return false;
 }
 
+Endianness QuicFramer::endianness() const {
+  return quic_version_ > QUIC_VERSION_38 ? NETWORK_BYTE_ORDER : HOST_BYTE_ORDER;
+}
+
 }  // namespace net