Early return in stateless reset parsing

Summary:
As in title. If we parse something as a stateless reset matching our token, return early. The code before would check if the header parsed as a short header, but that's not correct. If the token bytes match, we should treat it as a stateless reset as this is a more certain check.

See: https://www.rfc-editor.org/rfc/rfc9000.html#section-10.3.1

Reviewed By: sharmafb

Differential Revision: D56376777

fbshipit-source-id: 2a7ce041c872f296db6c4d608895c3b81e479628

quic/codec/QuicReadCodec.cpp

@@ -429,16 +429,12 @@ CodecResult QuicReadCodec::parsePacket(
                   statelessResetToken_->data(), sizeof(StatelessResetToken)))) {
         token = StatelessResetToken();
         memcpy(token->data(), tokenSource, token->size());
+        return StatelessReset(*token);
       }
     }
   }
-
-  auto maybeShortHeaderPacket = tryParseShortHeaderPacket(
+  return tryParseShortHeaderPacket(
       std::move(data), ackStates, dstConnIdSize, cursor);
-  if (token && maybeShortHeaderPacket.nothing()) {
-    return StatelessReset(*token);
-  }
-  return maybeShortHeaderPacket;
 }
 
 bool QuicReadCodec::canInitiateKeyUpdate() const {

quic/codec/test/QuicReadCodecTest.cpp

@@ -573,84 +573,6 @@ TEST_F(QuicReadCodecTest, NoOneRttCipherNoReset) {
   EXPECT_FALSE(isReset(std::move(packet)));
 }
 
-TEST_F(QuicReadCodecTest, FailToDecryptLeadsToReset) {
-  auto connId = getTestConnectionId();
-  auto aead = std::make_unique<MockAead>();
-  auto rawAead = aead.get();
-
-  StatelessResetToken tok = {
-      1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
-  auto fakeToken = std::make_unique<StatelessResetToken>(tok);
-  auto codec = makeEncryptedCodec(
-      connId,
-      std::move(aead),
-      nullptr /* 0-rtt aead */,
-      std::move(fakeToken),
-      QuicNodeType::Client);
-  EXPECT_CALL(*rawAead, _tryDecrypt(_, _, _))
-      .Times(1)
-      .WillOnce(Invoke([](auto&, const auto&, auto) { return folly::none; }));
-  PacketNum packetNum = 1;
-  StreamId streamId = 2;
-  auto data = folly::IOBuf::create(30);
-  data->append(30);
-  auto streamPacket = createStreamPacket(
-      connId,
-      connId,
-      packetNum,
-      streamId,
-      *data,
-      0 /* cipherOverhead */,
-      0 /* largestAcked */,
-      folly::none,
-      true,
-      ProtectionType::KeyPhaseZero);
-  overridePacketWithToken(streamPacket, tok);
-  AckStates ackStates;
-  auto packetQueue = bufToQueue(packetToBuf(streamPacket));
-  auto packet = codec->parsePacket(packetQueue, ackStates);
-  EXPECT_TRUE(isReset(std::move(packet)));
-}
-
-TEST_F(QuicReadCodecTest, ShortPacketAutoPaddedIsReset) {
-  auto connId = getTestConnectionId();
-  auto aead = std::make_unique<MockAead>();
-  auto rawAead = aead.get();
-  StatelessResetToken tok = {
-      1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
-  auto fakeToken = std::make_unique<StatelessResetToken>(tok);
-  auto codec = makeEncryptedCodec(
-      connId,
-      std::move(aead),
-      nullptr /* 0-rtt aead */,
-      std::move(fakeToken),
-      QuicNodeType::Client);
-
-  EXPECT_CALL(*rawAead, _tryDecrypt(_, _, _))
-      .Times(1)
-      .WillOnce(Invoke([](auto&, const auto&, auto) { return folly::none; }));
-  PacketNum packetNum = 1;
-  StreamId streamId = 2;
-  auto data = folly::IOBuf::create(3);
-  data->append(3);
-  auto streamPacket = createStreamPacket(
-      connId,
-      connId,
-      packetNum,
-      streamId,
-      *data,
-      0 /* cipherOverhead */,
-      0 /* largestAcked */,
-      folly::none,
-      true,
-      ProtectionType::KeyPhaseZero);
-  overridePacketWithToken(streamPacket, tok);
-  AckStates ackStates;
-  auto packetQueue = bufToQueue(packetToBuf(streamPacket));
-  auto packet = codec->parsePacket(packetQueue, ackStates);
-  EXPECT_TRUE(isReset(std::move(packet)));
-}
-
 TEST_F(QuicReadCodecTest, FailToDecryptLongHeaderNoReset) {
   auto connId = getTestConnectionId();
   auto aead = std::make_unique<MockAead>();