void updateHandshakeState()

in quic/server/state/ServerStateMachine.cpp [328:427]
78 lines of code
17 McCabe index (conditional complexity)

void updateHandshakeState(QuicServerConnectionState& conn) {
  // Zero RTT read cipher is available after chlo is processed with the
  // condition that early data attempt is accepted.
  auto handshakeLayer = conn.serverHandshakeLayer;
  auto zeroRttReadCipher = handshakeLayer->getZeroRttReadCipher();
  auto zeroRttHeaderCipher = handshakeLayer->getZeroRttReadHeaderCipher();
  // One RTT write cipher is available at Fizz layer after chlo is processed.
  // However, the cipher is only exported to QUIC if early data attempt is
  // accepted. Otherwise, the cipher will be available after cfin is
  // processed.
  auto oneRttWriteCipher = handshakeLayer->getOneRttWriteCipher();
  // One RTT read cipher is available after cfin is processed.
  auto oneRttReadCipher = handshakeLayer->getOneRttReadCipher();

  auto oneRttWriteHeaderCipher = handshakeLayer->getOneRttWriteHeaderCipher();
  auto oneRttReadHeaderCipher = handshakeLayer->getOneRttReadHeaderCipher();

  if (zeroRttReadCipher) {
    conn.usedZeroRtt = true;
    if (conn.qLogger) {
      conn.qLogger->addTransportStateUpdate(kDerivedZeroRttReadCipher);
    }
    conn.readCodec->setZeroRttReadCipher(std::move(zeroRttReadCipher));
  }
  if (zeroRttHeaderCipher) {
    conn.readCodec->setZeroRttHeaderCipher(std::move(zeroRttHeaderCipher));
  }
  if (oneRttWriteHeaderCipher) {
    conn.oneRttWriteHeaderCipher = std::move(oneRttWriteHeaderCipher);
  }
  if (oneRttReadHeaderCipher) {
    conn.readCodec->setOneRttHeaderCipher(std::move(oneRttReadHeaderCipher));
  }

  if (oneRttWriteCipher) {
    if (conn.qLogger) {
      conn.qLogger->addTransportStateUpdate(kDerivedOneRttWriteCipher);
    }
    if (conn.oneRttWriteCipher) {
      throw QuicTransportException(
          "Duplicate 1-rtt write cipher", TransportErrorCode::CRYPTO_ERROR);
    }
    conn.oneRttWriteCipher = std::move(oneRttWriteCipher);

    updatePacingOnKeyEstablished(conn);

    // We negotiate the transport parameters whenever we have the 1-RTT write
    // keys available.
    auto clientParams = handshakeLayer->getClientTransportParams();
    if (!clientParams) {
      throw QuicTransportException(
          "No client transport params",
          TransportErrorCode::TRANSPORT_PARAMETER_ERROR);
    }
    processClientInitialParams(conn, std::move(*clientParams));
  }
  if (oneRttReadCipher) {
    if (conn.qLogger) {
      conn.qLogger->addTransportStateUpdate(kDerivedOneRttReadCipher);
    }
    // Clear limit because CFIN is received at this point
    conn.writableBytesLimit = folly::none;
    conn.readCodec->setOneRttReadCipher(std::move(oneRttReadCipher));
  }
  auto handshakeReadCipher = handshakeLayer->getHandshakeReadCipher();
  auto handshakeReadHeaderCipher =
      handshakeLayer->getHandshakeReadHeaderCipher();
  if (handshakeReadCipher) {
    CHECK(handshakeReadHeaderCipher);
    conn.readCodec->setHandshakeReadCipher(std::move(handshakeReadCipher));
    conn.readCodec->setHandshakeHeaderCipher(
        std::move(handshakeReadHeaderCipher));
  }
  if (handshakeLayer->isHandshakeDone()) {
    CHECK(conn.oneRttWriteCipher);
    if (!conn.sentHandshakeDone) {
      sendSimpleFrame(conn, HandshakeDoneFrame());
      conn.sentHandshakeDone = true;
    }

    if (!conn.sentNewTokenFrame &&
        conn.transportSettings.retryTokenSecret.has_value()) {
      // Create NewToken struct – defaults timestamp to now
      NewToken token(conn.peerAddress.getIPAddress());

      // Encrypt two tuple -> (clientIp, curTimeInMs)
      TokenGenerator generator(conn.transportSettings.retryTokenSecret.value());
      auto encryptedToken = generator.encryptToken(token);
      CHECK(encryptedToken.has_value());

      std::string encryptedTokenStr =
          encryptedToken.value()->moveToFbString().toStdString();

      sendSimpleFrame(conn, NewTokenFrame(std::move(encryptedTokenStr)));
      QUIC_STATS(conn.statsCallback, onNewTokenIssued);

      conn.sentNewTokenFrame = true;
    }
  }
}