plugins/compress/configuration.h

/** @file

  Transforms content using gzip, deflate, brotli or zstd

  @section license License

  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
 */

#pragma once

#include <set>
#include <string>
#include <vector>

#include "ts/ts.h"
#include "tscpp/api/noncopyable.h"
#include "swoc/TextView.h"

namespace Compress
{
using StringContainer = std::vector<std::string>;

enum CompressionAlgorithm {
  ALGORITHM_DEFAULT = 0,
  ALGORITHM_DEFLATE = 1,
  ALGORITHM_GZIP    = 2,
  ALGORITHM_BROTLI  = 4,
  ALGORITHM_ZSTD    = 8
};

enum class RangeRequestCtrl : int {
  NONE                   = 0, ///< Do nothing
  NO_COMPRESSION         = 1, ///< Do NOT compress Partial Content (default)
  REMOVE_RANGE           = 2, ///< Remove Range Header
  REMOVE_ACCEPT_ENCODING = 3, ///< Remove Accept-Encoding Header
};

class HostConfiguration : private atscppapi::noncopyable
{
public:
  explicit HostConfiguration(swoc::TextView host)
    : host_(host),
      enabled_(true),
      cache_(true),
      remove_accept_encoding_(false),
      flush_(false),
      compression_algorithms_(ALGORITHM_GZIP),
      minimum_content_length_(1024),
      zlib_compression_level_(6),
      brotli_compression_level_(6),
      brotli_lgw_size_(16),
      zstd_compression_level_(12),
      content_type_ignore_parameters_(false)
  {
  }

  [[nodiscard]] bool
  content_type_ignore_parameters() const
  {
    return content_type_ignore_parameters_;
  }
  void
  set_content_type_ignore_parameters(bool x)
  {
    content_type_ignore_parameters_ = x;
  }

  [[nodiscard]] bool
  enabled()
  {
    return enabled_;
  }
  void
  set_enabled(bool x)
  {
    enabled_ = x;
  }
  [[nodiscard]] RangeRequestCtrl
  range_request_ctl()
  {
    return range_request_ctl_;
  }
  [[nodiscard]] bool
  cache()
  {
    return cache_;
  }
  void
  set_cache(bool x)
  {
    cache_ = x;
  }
  [[nodiscard]] bool
  flush()
  {
    return flush_;
  }
  void
  set_flush(bool x)
  {
    flush_ = x;
  }
  [[nodiscard]] bool
  remove_accept_encoding()
  {
    return remove_accept_encoding_;
  }
  void
  set_remove_accept_encoding(bool x)
  {
    remove_accept_encoding_ = x;
  }
  [[nodiscard]] std::string
  host()
  {
    return host_;
  }

  [[nodiscard]] bool
  has_allows() const
  {
    return !allows_.empty();
  }
  [[nodiscard]] unsigned int
  minimum_content_length() const
  {
    return minimum_content_length_;
  }
  void
  set_minimum_content_length(unsigned int x)
  {
    minimum_content_length_ = x;
  }

  [[nodiscard]] unsigned int
  zlib_compression_level() const
  {
    return zlib_compression_level_;
  }

  void
  set_gzip_compression_level(int level)
  {
    zlib_compression_level_ = level;
  }

  [[nodiscard]] unsigned int
  brotli_compression_level() const
  {
    return brotli_compression_level_;
  }
  void
  set_brotli_compression_level(int level)
  {
    brotli_compression_level_ = level;
  }

  [[nodiscard]] unsigned int
  brotli_lgw_size() const
  {
    return brotli_lgw_size_;
  }
  void
  set_brotli_lgw_size(unsigned int lgw)
  {
    brotli_lgw_size_ = lgw;
  }

  [[nodiscard]] int
  zstd_compression_level() const
  {
    return zstd_compression_level_;
  }
  void
  set_zstd_compression_level(int level)
  {
    zstd_compression_level_ = level;
  }

  void               update_defaults();
  void               add_allow(swoc::TextView allow);
  void               add_compressible_content_type(swoc::TextView content_type);
  void               add_compressible_status_codes(swoc::TextView &status_codes);
  [[nodiscard]] bool is_url_allowed(const char *url, int url_len);
  [[nodiscard]] bool is_content_type_compressible(const char *content_type, int content_type_length);
  [[nodiscard]] bool is_status_code_compressible(const TSHttpStatus status_code) const;
  void               add_compression_algorithms(swoc::TextView &algorithms);
  [[nodiscard]] int  compression_algorithms();
  void               set_range_request(swoc::TextView token);

private:
  std::string  host_;
  bool         enabled_;
  bool         cache_;
  bool         remove_accept_encoding_;
  bool         flush_;
  int          compression_algorithms_;
  unsigned int minimum_content_length_;
  unsigned int zlib_compression_level_;
  unsigned int brotli_compression_level_;
  unsigned int brotli_lgw_size_;
  int          zstd_compression_level_;
  bool         content_type_ignore_parameters_;

  RangeRequestCtrl range_request_ctl_ = RangeRequestCtrl::NO_COMPRESSION;
  StringContainer  compressible_content_types_;
  StringContainer  allows_;
  // maintain backwards compatibility/usability out of the box
  std::set<TSHttpStatus> compressible_status_codes_ = {TS_HTTP_STATUS_OK, TS_HTTP_STATUS_PARTIAL_CONTENT,
                                                       TS_HTTP_STATUS_NOT_MODIFIED};
};

using HostContainer = std::vector<HostConfiguration *>;

class Configuration : private atscppapi::noncopyable
{
  friend class HostConfiguration;

public:
  [[nodiscard]] static Configuration *Parse(const char *path);
  [[nodiscard]] HostConfiguration    *find(const char *host, int host_length);

private:
  explicit Configuration() {}
  void add_host_configuration(HostConfiguration *hc);

  HostContainer host_configurations_;

}; // class Configuration

} // namespace Compress