connection.h

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/*
  Copyright (c) 2021, 2025, Oracle and/or its affiliates.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  as designated in a particular file or component or in included license
  documentation.  The authors of MySQL hereby grant you an additional
  permission to link the program and your derivative works with the
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  the program or referenced in the documentation.
 
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
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  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef ROUTER_SRC_HTTP_INCLUDE_HTTP_BASE_CONNECTION_H_
#define ROUTER_SRC_HTTP_INCLUDE_HTTP_BASE_CONNECTION_H_
 
#include <algorithm>
#include <atomic>
#include <bitset>
#include <list>
#include <map>
#include <sstream>
#include <string>
#include <utility>
#include <vector>
 
#include "cno/core.h"
#include "http/base/connection_interface.h"
#include "http/base/connection_status_callbacks.h"
#include "http/base/details/owned_buffer.h"
#include "http/base/http_time.h"
#include "http/base/method.h"
#include "http/base/status_code.h"
#include "http/cno/buffer_sequence.h"
#include "http/cno/callback_init.h"
#include "http/cno/cno_interface.h"
#include "http/cno/error_code.h"
#include "http/cno/string.h"
 
#include "mysql/harness/net_ts/internet.h"
#include "mysql/harness/string_utils.h"
#include "mysqlrouter/http_common_export.h"
 
namespace http {
namespace base {
 
namespace impl {
 
inline void set_socket_parent(net::ip::tcp::socket *, const char *) {
  // Do nothing, net::ip::tcp::socket, is missing the custom
  // `set_parent` method.
}
 
inline net::ip::tcp::socket *get_socket(net::ip::tcp::socket *s) { return s; }
inline const net::ip::tcp::socket *get_socket(const net::ip::tcp::socket *s) {
  return s;
}
 
template <typename T>
net::ip::tcp::socket *get_socket(T *s) {
  return get_socket(&s->lower_layer());
}
 
template <typename T>
auto *get_socket1(T *s) {
  return &s->lower_layer();
}
 
template <typename T>
const net::ip::tcp::socket *get_socket(const T *s) {
  return get_socket(&s->lower_layer());
}
 
template <typename T>
void set_socket_parent(T *s, const char *parent) {
  s->set_parent(parent);
 
  set_socket_parent(get_socket1(s), parent);
}
 
}  // namespace impl
 
enum Pending {
  k_pending_none = 0,
  k_pending_closing = 1 << 1,
  k_pending_reading = 1 << 2,
  k_pending_writing = 1 << 3
};
 
template <typename IOLayer>
class Connection : public base::ConnectionInterface, public cno::CnoInterface {
 public:
  using This = Connection<IOLayer>;
  using ConnectionStatusCallbacks = http::base::ConnectionStatusCallbacks<This>;
  using Methods = base::method::Bitset;
  using Headers = http::base::Headers;
  using owned_buffer = http::base::details::owned_buffer;
  using ref_buffers = http::base::details::ref_buffers<std::list<owned_buffer>>;
  using IO = IOLayer;
 
 public:
  Connection(IOLayer s, base::method::Bitset *allowed_method,
             ConnectionStatusCallbacks *connection_handler,
             CNO_CONNECTION_KIND kind, CNO_HTTP_VERSION version)
      : socket_(std::move(s)),
        allowed_method_(allowed_method),
        connection_handler_{connection_handler} {
    std::stringstream ss;
    ss << "HTTP-" << this;
 
    socket_.set_option(net::ip::tcp::no_delay{true});
    impl::set_socket_parent(&socket_, ss.str().c_str());
    cno_init(&cno_, kind);
    cno_.disallow_h2_prior_knowledge = 1;
    cno::callback_init(&cno_, this);
    output_buffers_.emplace_back(4096);
    cno_begin(&cno_, version);
  }
 
  ~Connection() override {
    cno_fini(&cno_);
    socket_.close();
  }
 
 public:  // ConnectionInterface implementation
  void shutdown(bool) override {
    socket_.shutdown(net::socket_base::shutdown_send);
  }
 
  bool send(const uint32_t *stream_id_ptr, const int status_code,
            const std::string &method, const std::string &path,
            const Headers &headers, const IOBuffer &data) override {
    cno_message_t message;
    std::vector<cno_header_t> cno_header(headers.size(), cno_header_t());
    std::vector<std::string> http2_headers_names;
    const bool only_header = 0 == data.length();
 
    if (CNO_HTTP2 == cno_.mode) {
      http2_headers_names.reserve(headers.size());
    }
 
    auto output = cno_header.data();
 
    for (const auto &entry : headers) {
      if (CNO_HTTP2 == cno_.mode) {
        auto &header_name = http2_headers_names.emplace_back(
            ::mysql_harness::make_lower(entry.first));
        output->name.size = header_name.length();
        output->name.data = header_name.c_str();
      } else {
        output->name.size = entry.first.length();
        output->name.data = entry.first.c_str();
      }
 
      output->value.size = entry.second.length();
      output->value.data = entry.second.c_str();
      ++output;
    }
 
    message.code = status_code;
    message.headers = cno_header.data();
    message.headers_len = cno_header.size();
    message.path.data = path.c_str();
    message.path.size = path.length();
    message.method.data = method.c_str();
    message.method.size = method.length();
 
    uint32_t stream_id =
        stream_id_ptr ? *stream_id_ptr : cno_next_stream(&cno_);
    if (CNO_OK != cno_write_head(&cno_, stream_id, &message, only_header)) {
      return false;
    }
 
    if (!only_header) {
      return CNO_OK == cno_write_data(&cno_, stream_id, data.get().c_str(),
                                      data.length(), true);
    }
 
    return true;
  }
 
  std::string get_peer_address() const override {
    auto *s = impl::get_socket(&socket_);
    if (auto e = s->remote_endpoint()) {
      return e->address().to_string();
    }
 
    return {};
  }
 
  uint16_t get_peer_port() const override {
    auto *s = impl::get_socket(&socket_);
    if (auto e = s->remote_endpoint()) {
      return e->port();
    }
 
    return 0;
  }
 
  IOLayer &get_socket() { return socket_; }
 
  void start() override { do_net_recv(); }
 
 protected:
  void do_net_send() {
    socket_.async_send(ref_buffers(output_buffers_),
                       [this](std::error_code error, auto size) {
                         switch (on_net_send(error, size)) {
                           case k_pending_none:
                             break;
 
                           case k_pending_reading:
                             break;
 
                           case k_pending_writing:
                             do_net_send();
                             break;
 
                           case k_pending_closing:
                             if (connection_handler_)
                               connection_handler_->on_connection_close(this);
                             break;
                         }
                       });
  }
 
  void do_net_recv() {
    reading_pending_ = true;
    socket_.async_receive(
        input_mutable_buffer_, [this](std::error_code error, auto size) {
          switch (on_net_receive(error, size)) {
            case k_pending_reading:
              do_net_recv();
              break;
 
            case k_pending_writing:
            case k_pending_none:
              reading_pending_ = false;
              break;
 
            case k_pending_closing:
              reading_pending_ = false;
              if (connection_handler_)
                connection_handler_->on_connection_close(this);
              break;
          }
        });
  }
 
  Pending on_net_receive(const std::error_code &ec,
                         std::size_t bytes_transferred) {
    if (!running_) {
      return stop_running() ? k_pending_writing : k_pending_closing;
    }
 
    if (ec) {
      connection_handler_->on_connection_io_error(this, ec);
      return stop_running() ? k_pending_writing : k_pending_closing;
    }
 
    const int result = cno_consume(
        &cno_, reinterpret_cast<char *>(input_buffer_), bytes_transferred);
 
    if (result < 0) {
      auto ec = make_error_code(cno_error());
      connection_handler_->on_connection_io_error(this, ec);
      return stop_running() ? k_pending_writing : k_pending_closing;
    }
 
    if (!keep_alive_) {
      return stop_running() ? k_pending_writing : k_pending_closing;
    }
 
    if (!running_) {
      return output_pending_ ? k_pending_writing : k_pending_closing;
    }
 
    if (suspend_) return k_pending_none;
 
    return k_pending_reading;
  }
 
  Pending on_net_send(const std::error_code &ec, size_t size) {
    bool has_more = true;
    bool should_close = false;
    {
      std::unique_lock<std::mutex> lock(output_buffer_mutex_);
 
      if (!ec) {
        while (size) {
          auto &page = output_buffers_.front();
          auto size_on_page = std::min(page.size(), size);
          page += size_on_page;
          size -= size_on_page;
 
          if (page.empty()) {
            if (1 == output_buffers_.size()) {
              page.reset();
            } else {
              output_buffers_.pop_front();
            }
          }
        }
      }
 
      if (0 == output_buffers_.front().size()) {
        has_more = false;
        output_pending_ = false;
 
        if (!running_) {
          should_close = true;
        }
      }
    }
 
    if (ec) {
      stop_running();
      output_pending_ = false;
 
      connection_handler_->on_connection_io_error(this, ec);
      return reading_pending_ ? k_pending_reading : k_pending_closing;
    }
    if (has_more) return k_pending_writing;
 
    on_output_buffer_empty();
 
    if (should_close) {
      return reading_pending_ ? k_pending_reading : k_pending_closing;
    }
    if (suspend_) return k_pending_none;
 
    return k_pending_reading;
  }
 
  void resume() { suspend_ = false; }
  void suspend() { suspend_ = true; }
 
  /**
   * Mark the connection that it should stop running
   *
   * @returns information if the object may be delete
   * @retval 'false' Connection object can be removed immediately
   * @retval 'true'  Connection object must wait until IO is finished.
   */
  bool stop_running() {
    std::unique_lock<std::mutex> lock(output_buffer_mutex_);
    running_ = false;
 
    return output_pending_;
  }
 
 protected:
  virtual void on_output_buffer_empty() {}
 
 protected:  // CnoInterface implementation
  int on_cno_writev(const cno_buffer_t *buffer, size_t count) override {
    bool was_first = false;
    {
      std::unique_lock<std::mutex> lock(output_buffer_mutex_);
      cno::BufferSequence<> buffers{buffer, count};
 
      bool expected = false;
      if (impl::get_socket(&socket_)->is_open())
        was_first = output_pending_.compare_exchange_weak(expected, true);
      auto source_it = buffers.begin();
 
      while (source_it != buffers.end()) {
        // The constructor fills the output buffer with single page
        // and all algorithms that clear not used pages, leave at
        // last one page.
        // thus we do not need to check if there are no pages.
        auto &obuffer = output_buffers_.back();
 
        if (0 == source_it->size()) {
          ++source_it;
          continue;
        }
 
        if (0 == obuffer.space_left()) {
          output_buffers_.emplace_back(4096);
          continue;
        }
 
        (*source_it) += obuffer.write(
            static_cast<const uint8_t *>(source_it->data()), source_it->size());
      }
    }
 
    if (was_first) {
      do_net_send();
    }
 
    return 0;
  }
 
  int on_cno_message_tail([[maybe_unused]] const uint32_t session_id,
                          [[maybe_unused]] const cno_tail_t *tail) override {
    //    processed_request_ = true;
    return 0;
  }
 
  int on_cno_stream_start([[maybe_unused]] const uint32_t id) override {
    return 0;
  }
 
  int on_cno_close() override {
    keep_alive_ = false;
    return 0;
  }
 
 protected:
  bool keep_alive_{true};
  IOLayer socket_;
  Methods *allowed_method_;
  cno_connection_t cno_;
 
  uint8_t input_buffer_[512];
  net::mutable_buffer input_mutable_buffer_{net::buffer(input_buffer_)};
 
  std::mutex output_buffer_mutex_;
  std::list<owned_buffer> output_buffers_;
 
  std::atomic<bool> output_pending_{false};
  std::atomic<bool> reading_pending_{false};
  std::atomic<bool> running_{true};
  std::atomic<bool> suspend_{false};
 
  ConnectionStatusCallbacks *connection_handler_;
};
 
}  // namespace base
}  // namespace http
 
#endif  // ROUTER_SRC_HTTP_INCLUDE_HTTP_BASE_CONNECTION_H_