// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/tools/quic/quic_simple_server_session.h"

#include "base/logging.h"
#include "base/stl_util.h"
#include "net/quic/proto/cached_network_parameters.pb.h"
#include "net/quic/quic_connection.h"
#include "net/quic/quic_flags.h"
#include "net/quic/quic_spdy_session.h"
#include "net/quic/reliable_quic_stream.h"
#include "net/tools/quic/quic_simple_server_stream.h"
#include "url/gurl.h"

namespace net {
namespace tools {

QuicSimpleServerSession::QuicSimpleServerSession(
    const QuicConfig& config,
    QuicConnection* connection,
    QuicServerSessionVisitor* visitor,
    const QuicCryptoServerConfig* crypto_config)
    : QuicServerSessionBase(config, connection, visitor, crypto_config),
      highest_promised_stream_id_(0) {}

QuicSimpleServerSession::~QuicSimpleServerSession() {}

QuicCryptoServerStreamBase*
QuicSimpleServerSession::CreateQuicCryptoServerStream(
    const QuicCryptoServerConfig* crypto_config) {
  return new QuicCryptoServerStream(crypto_config, this);
}

void QuicSimpleServerSession::StreamDraining(QuicStreamId id) {
  QuicSpdySession::StreamDraining(id);
  if (!IsIncomingStream(id)) {
    HandlePromisedPushRequests();
  }
}

void QuicSimpleServerSession::OnStreamFrame(const QuicStreamFrame& frame) {
  if (!IsIncomingStream(frame.stream_id)) {
    LOG(WARNING) << "Client shouldn't send data on server push stream";
    connection()->SendConnectionCloseWithDetails(
        QUIC_INVALID_STREAM_ID, "Client sent data on server push stream");
    return;
  }
  QuicSpdySession::OnStreamFrame(frame);
}

void QuicSimpleServerSession::PromisePushResources(
    const string& request_url,
    const list<QuicInMemoryCache::ServerPushInfo>& resources,
    QuicStreamId original_stream_id,
    const SpdyHeaderBlock& original_request_headers) {
  for (QuicInMemoryCache::ServerPushInfo resource : resources) {
    SpdyHeaderBlock headers = SynthesizePushRequestHeaders(
        request_url, resource, original_request_headers);
    highest_promised_stream_id_ += 2;
    SendPushPromise(original_stream_id, highest_promised_stream_id_, headers);
    promised_streams_.push_back(PromisedStreamInfo(
        headers, highest_promised_stream_id_, resource.priority));
  }

  // Procese promised push request as many as possible.
  HandlePromisedPushRequests();
}

QuicSpdyStream* QuicSimpleServerSession::CreateIncomingDynamicStream(
    QuicStreamId id) {
  if (!ShouldCreateIncomingDynamicStream(id)) {
    return nullptr;
  }

  return new QuicSimpleServerStream(id, this);
}

QuicSimpleServerStream* QuicSimpleServerSession::CreateOutgoingDynamicStream(
    SpdyPriority priority) {
  if (!ShouldCreateOutgoingDynamicStream()) {
    return nullptr;
  }

  QuicSimpleServerStream* stream =
      new QuicSimpleServerStream(GetNextOutgoingStreamId(), this);
  stream->SetPriority(priority);
  ActivateStream(stream);
  return stream;
}

void QuicSimpleServerSession::CloseStreamInner(QuicStreamId stream_id,
                                               bool locally_reset) {
  QuicSpdySession::CloseStreamInner(stream_id, locally_reset);
  HandlePromisedPushRequests();
}

void QuicSimpleServerSession::HandleFrameOnNonexistentOutgoingStream(
    QuicStreamId stream_id) {
  // If this stream is a promised but not created stream (stream_id within the
  // range of next_outgoing_stream_id_ and highes_promised_stream_id_),
  // connection shouldn't be closed.
  // Otherwise behave in the same way as base class.
  if (stream_id > highest_promised_stream_id_) {
    QuicSession::HandleFrameOnNonexistentOutgoingStream(stream_id);
  }
}

void QuicSimpleServerSession::HandleRstOnValidNonexistentStream(
    const QuicRstStreamFrame& frame) {
  QuicSession::HandleRstOnValidNonexistentStream(frame);
  if (!IsClosedStream(frame.stream_id)) {
    // If a nonexistent stream is not a closed stream and still valid, it must
    // be a locally preserved stream. Resetting this kind of stream means
    // cancelling the promised server push.
    // Since PromisedStreamInfo are queued in sequence, the corresponding
    // index for it in promised_streams_ can be calculated.
    DCHECK(frame.stream_id >= next_outgoing_stream_id());
    size_t index = (frame.stream_id - next_outgoing_stream_id()) / 2;
    DCHECK(index <= promised_streams_.size());
    promised_streams_[index].is_cancelled = true;
    connection()->SendRstStream(frame.stream_id, QUIC_RST_ACKNOWLEDGEMENT, 0);
  }
}

SpdyHeaderBlock QuicSimpleServerSession::SynthesizePushRequestHeaders(
    string request_url,
    QuicInMemoryCache::ServerPushInfo resource,
    const SpdyHeaderBlock& original_request_headers) {
  GURL push_request_url = resource.request_url;
  string path = push_request_url.path();

  SpdyHeaderBlock spdy_headers = original_request_headers;
  // :authority could be different from original request.
  spdy_headers.ReplaceOrAppendHeader(":authority", push_request_url.host());
  spdy_headers.ReplaceOrAppendHeader(":path", path);
  // Push request always use GET.
  spdy_headers.ReplaceOrAppendHeader(":method", "GET");
  spdy_headers.ReplaceOrAppendHeader("referer", request_url);
  spdy_headers.ReplaceOrAppendHeader(":scheme", push_request_url.scheme());
  // It is not possible to push a response to a request that includes a request
  // body.
  spdy_headers.ReplaceOrAppendHeader("content-length", "0");
  // Remove "host" field as push request is a directly generated HTTP2 request
  // which should use ":authority" instead of "host".
  spdy_headers.erase("host");
  return spdy_headers;
}

void QuicSimpleServerSession::SendPushPromise(QuicStreamId original_stream_id,
                                              QuicStreamId promised_stream_id,
                                              const SpdyHeaderBlock& headers) {
  DVLOG(1) << "stream " << original_stream_id
           << " send PUSH_PROMISE for promised stream " << promised_stream_id;
  headers_stream()->WritePushPromise(original_stream_id, promised_stream_id,
                                     headers, nullptr);
}

void QuicSimpleServerSession::HandlePromisedPushRequests() {
  while (!promised_streams_.empty() && ShouldCreateOutgoingDynamicStream()) {
    const PromisedStreamInfo& promised_info = promised_streams_.front();
    DCHECK_EQ(next_outgoing_stream_id(), promised_info.stream_id);

    if (promised_info.is_cancelled) {
      // This stream has been reset by client. Skip this stream id.
      promised_streams_.pop_front();
      GetNextOutgoingStreamId();
      return;
    }

    QuicSimpleServerStream* promised_stream =
        static_cast<QuicSimpleServerStream*>(
            CreateOutgoingDynamicStream(promised_info.priority));
    DCHECK(promised_stream != nullptr);
    DCHECK_EQ(promised_info.stream_id, promised_stream->id());
    DVLOG(1) << "created server push stream " << promised_stream->id();

    promised_stream->PushResponse(promised_info.request_headers);

    promised_streams_.pop_front();
  }
}

}  // namespace tools
}  // namespace net