net/base/mime_util.cc

// 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 <algorithm>
#include <iterator>
#include <map>
#include <string>

#include "base/containers/hash_tables.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/stl_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "build/build_config.h"
#include "net/base/mime_util.h"
#include "net/base/platform_mime_util.h"
#include "net/http/http_util.h"

using std::string;

namespace net {

// Singleton utility class for mime types.
class MimeUtil : public PlatformMimeUtil {
 public:
  bool GetMimeTypeFromExtension(const base::FilePath::StringType& ext,
                                std::string* mime_type) const;

  bool GetMimeTypeFromFile(const base::FilePath& file_path,
                           std::string* mime_type) const;

  bool GetWellKnownMimeTypeFromExtension(const base::FilePath::StringType& ext,
                                         std::string* mime_type) const;

  bool MatchesMimeType(const std::string &mime_type_pattern,
                       const std::string &mime_type) const;

  bool ParseMimeTypeWithoutParameter(const std::string& type_string,
                                     std::string* top_level_type,
                                     std::string* subtype) const;

  bool IsValidTopLevelMimeType(const std::string& type_string) const;

 private:
  friend struct base::DefaultLazyInstanceTraits<MimeUtil>;

  MimeUtil();

  bool GetMimeTypeFromExtensionHelper(const base::FilePath::StringType& ext,
                                      bool include_platform_types,
                                      std::string* mime_type) const;
};  // class MimeUtil

// This variable is Leaky because we need to access it from WorkerPool threads.
static base::LazyInstance<MimeUtil>::Leaky g_mime_util =
    LAZY_INSTANCE_INITIALIZER;

static const MimeInfo primary_mappings[] = {
  { "text/html", "html,htm,shtml,shtm" },
  { "text/css", "css" },
  { "text/xml", "xml" },
  { "image/gif", "gif" },
  { "image/jpeg", "jpeg,jpg" },
  { "image/webp", "webp" },
  { "image/png", "png" },
  { "video/mp4", "mp4,m4v" },
  { "audio/x-m4a", "m4a" },
  { "audio/mp3", "mp3" },
  { "video/ogg", "ogv,ogm" },
  { "audio/ogg", "ogg,oga,opus" },
  { "video/webm", "webm" },
  { "audio/webm", "webm" },
  { "audio/wav", "wav" },
  { "application/xhtml+xml", "xhtml,xht,xhtm" },
  { "application/x-chrome-extension", "crx" },
  { "multipart/related", "mhtml,mht" }
};

static const MimeInfo secondary_mappings[] = {
  { "application/octet-stream", "exe,com,bin" },
  { "application/gzip", "gz" },
  { "application/pdf", "pdf" },
  { "application/postscript", "ps,eps,ai" },
  { "application/javascript", "js" },
  { "application/font-woff", "woff" },
  { "image/bmp", "bmp" },
  { "image/x-icon", "ico" },
  { "image/vnd.microsoft.icon", "ico" },
  { "image/jpeg", "jfif,pjpeg,pjp" },
  { "image/tiff", "tiff,tif" },
  { "image/x-xbitmap", "xbm" },
  { "image/svg+xml", "svg,svgz" },
  { "image/x-png", "png"},
  { "message/rfc822", "eml" },
  { "text/plain", "txt,text" },
  { "text/html", "ehtml" },
  { "application/rss+xml", "rss" },
  { "application/rdf+xml", "rdf" },
  { "text/xml", "xsl,xbl,xslt" },
  { "application/vnd.mozilla.xul+xml", "xul" },
  { "application/x-shockwave-flash", "swf,swl" },
  { "application/pkcs7-mime", "p7m,p7c,p7z" },
  { "application/pkcs7-signature", "p7s" },
  { "application/x-mpegurl", "m3u8" },
};

const char* FindMimeType(const MimeInfo* mappings,
                         size_t mappings_len,
                         const std::string& ext) {
  for (size_t i = 0; i < mappings_len; ++i) {
    const char* extensions = mappings[i].extensions;
    for (;;) {
      size_t end_pos = strcspn(extensions, ",");
      if (end_pos == ext.size() &&
          base::strncasecmp(extensions, ext.data(), ext.size()) == 0)
        return mappings[i].mime_type;
      extensions += end_pos;
      if (!*extensions)
        break;
      extensions += 1;  // skip over comma
    }
  }
  return NULL;
}

bool MimeUtil::GetMimeTypeFromExtension(const base::FilePath::StringType& ext,
                                        string* result) const {
  return GetMimeTypeFromExtensionHelper(ext, true, result);
}

bool MimeUtil::GetWellKnownMimeTypeFromExtension(
    const base::FilePath::StringType& ext,
    string* result) const {
  return GetMimeTypeFromExtensionHelper(ext, false, result);
}

bool MimeUtil::GetMimeTypeFromFile(const base::FilePath& file_path,
                                   string* result) const {
  base::FilePath::StringType file_name_str = file_path.Extension();
  if (file_name_str.empty())
    return false;
  return GetMimeTypeFromExtension(file_name_str.substr(1), result);
}

bool MimeUtil::GetMimeTypeFromExtensionHelper(
    const base::FilePath::StringType& ext,
    bool include_platform_types,
    string* result) const {
  // Avoids crash when unable to handle a long file path. See crbug.com/48733.
  const unsigned kMaxFilePathSize = 65536;
  if (ext.length() > kMaxFilePathSize)
    return false;

  // Reject a string which contains null character.
  base::FilePath::StringType::size_type nul_pos =
      ext.find(FILE_PATH_LITERAL('\0'));
  if (nul_pos != base::FilePath::StringType::npos)
    return false;

  // We implement the same algorithm as Mozilla for mapping a file extension to
  // a mime type.  That is, we first check a hard-coded list (that cannot be
  // overridden), and then if not found there, we defer to the system registry.
  // Finally, we scan a secondary hard-coded list to catch types that we can
  // deduce but that we also want to allow the OS to override.

  base::FilePath path_ext(ext);
  const string ext_narrow_str = path_ext.AsUTF8Unsafe();
  const char* mime_type = FindMimeType(
      primary_mappings, arraysize(primary_mappings), ext_narrow_str);
  if (mime_type) {
    *result = mime_type;
    return true;
  }

  if (include_platform_types && GetPlatformMimeTypeFromExtension(ext, result))
    return true;

  mime_type = FindMimeType(secondary_mappings, arraysize(secondary_mappings),
                           ext_narrow_str);
  if (mime_type) {
    *result = mime_type;
    return true;
  }

  return false;
}

MimeUtil::MimeUtil() {
}

// Tests for MIME parameter equality. Each parameter in the |mime_type_pattern|
// must be matched by a parameter in the |mime_type|. If there are no
// parameters in the pattern, the match is a success.
//
// According rfc2045 keys of parameters are case-insensitive, while values may
// or may not be case-sensitive, but they are usually case-sensitive. So, this
// function matches values in *case-sensitive* manner, however note that this
// may produce some false negatives.
bool MatchesMimeTypeParameters(const std::string& mime_type_pattern,
                               const std::string& mime_type) {
  typedef std::map<std::string, std::string> StringPairMap;

  const std::string::size_type semicolon = mime_type_pattern.find(';');
  const std::string::size_type test_semicolon = mime_type.find(';');
  if (semicolon != std::string::npos) {
    if (test_semicolon == std::string::npos)
      return false;

    base::StringPairs pattern_parameters;
    base::SplitStringIntoKeyValuePairs(mime_type_pattern.substr(semicolon + 1),
                                       '=', ';', &pattern_parameters);
    base::StringPairs test_parameters;
    base::SplitStringIntoKeyValuePairs(mime_type.substr(test_semicolon + 1),
                                       '=', ';', &test_parameters);

    // Put the parameters to maps with the keys converted to lower case.
    StringPairMap pattern_parameter_map;
    for (const auto& pair : pattern_parameters) {
      pattern_parameter_map[base::StringToLowerASCII(pair.first)] = pair.second;
    }

    StringPairMap test_parameter_map;
    for (const auto& pair : test_parameters) {
      test_parameter_map[base::StringToLowerASCII(pair.first)] = pair.second;
    }

    if (pattern_parameter_map.size() > test_parameter_map.size())
      return false;

    for (const auto& parameter_pair : pattern_parameter_map) {
      const auto& test_parameter_pair_it =
          test_parameter_map.find(parameter_pair.first);
      if (test_parameter_pair_it == test_parameter_map.end())
        return false;
      if (parameter_pair.second != test_parameter_pair_it->second)
        return false;
    }
  }

  return true;
}

// This comparison handles absolute maching and also basic
// wildcards.  The plugin mime types could be:
//      application/x-foo
//      application/*
//      application/*+xml
//      *
// Also tests mime parameters -- all parameters in the pattern must be present
// in the tested type for a match to succeed.
bool MimeUtil::MatchesMimeType(const std::string& mime_type_pattern,
                               const std::string& mime_type) const {
  if (mime_type_pattern.empty())
    return false;

  std::string::size_type semicolon = mime_type_pattern.find(';');
  const std::string base_pattern(mime_type_pattern.substr(0, semicolon));
  semicolon = mime_type.find(';');
  const std::string base_type(mime_type.substr(0, semicolon));

  if (base_pattern == "*" || base_pattern == "*/*")
    return MatchesMimeTypeParameters(mime_type_pattern, mime_type);

  const std::string::size_type star = base_pattern.find('*');
  if (star == std::string::npos) {
    if (base_pattern.size() == base_type.size() &&
        base::strncasecmp(base_pattern.data(), base_type.data(),
                          base_pattern.size()) == 0) {
      return MatchesMimeTypeParameters(mime_type_pattern, mime_type);
    } else {
      return false;
    }
  }

  // Test length to prevent overlap between |left| and |right|.
  if (base_type.length() < base_pattern.length() - 1)
    return false;

  const std::string left(base_pattern.substr(0, star));
  const std::string right(base_pattern.substr(star + 1));

  if (!StartsWithASCII(base_type, left, false))
    return false;

  if (!right.empty() && !EndsWith(base_type, right, false))
    return false;

  return MatchesMimeTypeParameters(mime_type_pattern, mime_type);
}

// See http://www.iana.org/assignments/media-types/media-types.xhtml
static const char* const legal_top_level_types[] = {
  "application",
  "audio",
  "example",
  "image",
  "message",
  "model",
  "multipart",
  "text",
  "video",
};

bool MimeUtil::ParseMimeTypeWithoutParameter(
    const std::string& type_string,
    std::string* top_level_type,
    std::string* subtype) const {
  std::vector<std::string> components;
  base::SplitString(type_string, '/', &components);
  if (components.size() != 2 ||
      !HttpUtil::IsToken(components[0]) ||
      !HttpUtil::IsToken(components[1]))
    return false;

  if (top_level_type)
    *top_level_type = components[0];
  if (subtype)
    *subtype = components[1];
  return true;
}

bool MimeUtil::IsValidTopLevelMimeType(const std::string& type_string) const {
  std::string lower_type = base::StringToLowerASCII(type_string);
  for (size_t i = 0; i < arraysize(legal_top_level_types); ++i) {
    if (lower_type.compare(legal_top_level_types[i]) == 0)
      return true;
  }

  return type_string.size() > 2 && StartsWithASCII(type_string, "x-", false);
}

//----------------------------------------------------------------------------
// Wrappers for the singleton
//----------------------------------------------------------------------------

bool GetMimeTypeFromExtension(const base::FilePath::StringType& ext,
                              std::string* mime_type) {
  return g_mime_util.Get().GetMimeTypeFromExtension(ext, mime_type);
}

bool GetMimeTypeFromFile(const base::FilePath& file_path,
                         std::string* mime_type) {
  return g_mime_util.Get().GetMimeTypeFromFile(file_path, mime_type);
}

bool GetWellKnownMimeTypeFromExtension(const base::FilePath::StringType& ext,
                                       std::string* mime_type) {
  return g_mime_util.Get().GetWellKnownMimeTypeFromExtension(ext, mime_type);
}

bool GetPreferredExtensionForMimeType(const std::string& mime_type,
                                      base::FilePath::StringType* extension) {
  return g_mime_util.Get().GetPreferredExtensionForMimeType(mime_type,
                                                            extension);
}

bool MatchesMimeType(const std::string& mime_type_pattern,
                     const std::string& mime_type) {
  return g_mime_util.Get().MatchesMimeType(mime_type_pattern, mime_type);
}

bool ParseMimeTypeWithoutParameter(const std::string& type_string,
                                   std::string* top_level_type,
                                   std::string* subtype) {
  return g_mime_util.Get().ParseMimeTypeWithoutParameter(
      type_string, top_level_type, subtype);
}

bool IsValidTopLevelMimeType(const std::string& type_string) {
  return g_mime_util.Get().IsValidTopLevelMimeType(type_string);
}

namespace {

// From http://www.w3schools.com/media/media_mimeref.asp and
// http://plugindoc.mozdev.org/winmime.php
static const char* const kStandardImageTypes[] = {
  "image/bmp",
  "image/cis-cod",
  "image/gif",
  "image/ief",
  "image/jpeg",
  "image/webp",
  "image/pict",
  "image/pipeg",
  "image/png",
  "image/svg+xml",
  "image/tiff",
  "image/vnd.microsoft.icon",
  "image/x-cmu-raster",
  "image/x-cmx",
  "image/x-icon",
  "image/x-portable-anymap",
  "image/x-portable-bitmap",
  "image/x-portable-graymap",
  "image/x-portable-pixmap",
  "image/x-rgb",
  "image/x-xbitmap",
  "image/x-xpixmap",
  "image/x-xwindowdump"
};
static const char* const kStandardAudioTypes[] = {
  "audio/aac",
  "audio/aiff",
  "audio/amr",
  "audio/basic",
  "audio/midi",
  "audio/mp3",
  "audio/mp4",
  "audio/mpeg",
  "audio/mpeg3",
  "audio/ogg",
  "audio/vorbis",
  "audio/wav",
  "audio/webm",
  "audio/x-m4a",
  "audio/x-ms-wma",
  "audio/vnd.rn-realaudio",
  "audio/vnd.wave"
};
static const char* const kStandardVideoTypes[] = {
  "video/avi",
  "video/divx",
  "video/flc",
  "video/mp4",
  "video/mpeg",
  "video/ogg",
  "video/quicktime",
  "video/sd-video",
  "video/webm",
  "video/x-dv",
  "video/x-m4v",
  "video/x-mpeg",
  "video/x-ms-asf",
  "video/x-ms-wmv"
};

struct StandardType {
  const char* const leading_mime_type;
  const char* const* standard_types;
  size_t standard_types_len;
};
static const StandardType kStandardTypes[] = {
  { "image/", kStandardImageTypes, arraysize(kStandardImageTypes) },
  { "audio/", kStandardAudioTypes, arraysize(kStandardAudioTypes) },
  { "video/", kStandardVideoTypes, arraysize(kStandardVideoTypes) },
  { NULL, NULL, 0 }
};

void GetExtensionsFromHardCodedMappings(
    const MimeInfo* mappings,
    size_t mappings_len,
    const std::string& leading_mime_type,
    base::hash_set<base::FilePath::StringType>* extensions) {
  for (size_t i = 0; i < mappings_len; ++i) {
    if (StartsWithASCII(mappings[i].mime_type, leading_mime_type, false)) {
      std::vector<string> this_extensions;
      base::SplitString(mappings[i].extensions, ',', &this_extensions);
      for (size_t j = 0; j < this_extensions.size(); ++j) {
#if defined(OS_WIN)
        base::FilePath::StringType extension(
            base::UTF8ToWide(this_extensions[j]));
#else
        base::FilePath::StringType extension(this_extensions[j]);
#endif
        extensions->insert(extension);
      }
    }
  }
}

void GetExtensionsHelper(
    const char* const* standard_types,
    size_t standard_types_len,
    const std::string& leading_mime_type,
    base::hash_set<base::FilePath::StringType>* extensions) {
  for (size_t i = 0; i < standard_types_len; ++i) {
    g_mime_util.Get().GetPlatformExtensionsForMimeType(standard_types[i],
                                                       extensions);
  }

  // Also look up the extensions from hard-coded mappings in case that some
  // supported extensions are not registered in the system registry, like ogg.
  GetExtensionsFromHardCodedMappings(primary_mappings,
                                     arraysize(primary_mappings),
                                     leading_mime_type,
                                     extensions);

  GetExtensionsFromHardCodedMappings(secondary_mappings,
                                     arraysize(secondary_mappings),
                                     leading_mime_type,
                                     extensions);
}

// Note that the elements in the source set will be appended to the target
// vector.
template<class T>
void HashSetToVector(base::hash_set<T>* source, std::vector<T>* target) {
  size_t old_target_size = target->size();
  target->resize(old_target_size + source->size());
  size_t i = 0;
  for (typename base::hash_set<T>::iterator iter = source->begin();
       iter != source->end(); ++iter, ++i)
    (*target)[old_target_size + i] = *iter;
}

}  // namespace

void GetExtensionsForMimeType(
    const std::string& unsafe_mime_type,
    std::vector<base::FilePath::StringType>* extensions) {
  if (unsafe_mime_type == "*/*" || unsafe_mime_type == "*")
    return;

  const std::string mime_type = base::StringToLowerASCII(unsafe_mime_type);
  base::hash_set<base::FilePath::StringType> unique_extensions;

  if (EndsWith(mime_type, "/*", false)) {
    std::string leading_mime_type = mime_type.substr(0, mime_type.length() - 1);

    // Find the matching StandardType from within kStandardTypes, or fall
    // through to the last (default) StandardType.
    const StandardType* type = NULL;
    for (size_t i = 0; i < arraysize(kStandardTypes); ++i) {
      type = &(kStandardTypes[i]);
      if (type->leading_mime_type &&
          leading_mime_type == type->leading_mime_type)
        break;
    }
    DCHECK(type);
    GetExtensionsHelper(type->standard_types,
                        type->standard_types_len,
                        leading_mime_type,
                        &unique_extensions);
  } else {
    g_mime_util.Get().GetPlatformExtensionsForMimeType(mime_type,
                                                       &unique_extensions);

    // Also look up the extensions from hard-coded mappings in case that some
    // supported extensions are not registered in the system registry, like ogg.
    GetExtensionsFromHardCodedMappings(primary_mappings,
                                       arraysize(primary_mappings),
                                       mime_type,
                                       &unique_extensions);

    GetExtensionsFromHardCodedMappings(secondary_mappings,
                                       arraysize(secondary_mappings),
                                       mime_type,
                                       &unique_extensions);
  }

  HashSetToVector(&unique_extensions, extensions);
}

void AddMultipartValueForUpload(const std::string& value_name,
                                const std::string& value,
                                const std::string& mime_boundary,
                                const std::string& content_type,
                                std::string* post_data) {
  DCHECK(post_data);
  // First line is the boundary.
  post_data->append("--" + mime_boundary + "\r\n");
  // Next line is the Content-disposition.
  post_data->append("Content-Disposition: form-data; name=\"" +
                    value_name + "\"\r\n");
  if (!content_type.empty()) {
    // If Content-type is specified, the next line is that.
    post_data->append("Content-Type: " + content_type + "\r\n");
  }
  // Leave an empty line and append the value.
  post_data->append("\r\n" + value + "\r\n");
}

void AddMultipartFinalDelimiterForUpload(const std::string& mime_boundary,
                                         std::string* post_data) {
  DCHECK(post_data);
  post_data->append("--" + mime_boundary + "--\r\n");
}

}  // namespace net