1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "net/base/filename_util.h" 6 7 #include "base/file_util.h" 8 #include "base/files/file_path.h" 9 #include "base/path_service.h" 10 #include "base/strings/string_util.h" 11 #include "base/strings/sys_string_conversions.h" 12 #include "base/strings/utf_string_conversions.h" 13 #include "base/threading/thread_restrictions.h" 14 #include "net/base/escape.h" 15 #include "net/base/filename_util_internal.h" 16 #include "net/base/mime_util.h" 17 #include "net/base/net_string_util.h" 18 #include "net/http/http_content_disposition.h" 19 #include "url/gurl.h" 20 21 namespace net { 22 23 void SanitizeGeneratedFileName(base::FilePath::StringType* filename, 24 bool replace_trailing) { 25 const base::FilePath::CharType kReplace[] = FILE_PATH_LITERAL("-"); 26 if (filename->empty()) 27 return; 28 if (replace_trailing) { 29 // Handle CreateFile() stripping trailing dots and spaces on filenames 30 // http://support.microsoft.com/kb/115827 31 size_t length = filename->size(); 32 size_t pos = filename->find_last_not_of(FILE_PATH_LITERAL(" .")); 33 filename->resize((pos == std::string::npos) ? 0 : (pos + 1)); 34 base::TrimWhitespace(*filename, base::TRIM_TRAILING, filename); 35 if (filename->empty()) 36 return; 37 size_t trimmed = length - filename->size(); 38 if (trimmed) 39 filename->insert(filename->end(), trimmed, kReplace[0]); 40 } 41 base::TrimString(*filename, FILE_PATH_LITERAL("."), filename); 42 if (filename->empty()) 43 return; 44 // Replace any path information by changing path separators. 45 ReplaceSubstringsAfterOffset(filename, 0, FILE_PATH_LITERAL("/"), kReplace); 46 ReplaceSubstringsAfterOffset(filename, 0, FILE_PATH_LITERAL("\\"), kReplace); 47 } 48 49 // Returns the filename determined from the last component of the path portion 50 // of the URL. Returns an empty string if the URL doesn't have a path or is 51 // invalid. If the generated filename is not reliable, 52 // |should_overwrite_extension| will be set to true, in which case a better 53 // extension should be determined based on the content type. 54 std::string GetFileNameFromURL(const GURL& url, 55 const std::string& referrer_charset, 56 bool* should_overwrite_extension) { 57 // about: and data: URLs don't have file names, but esp. data: URLs may 58 // contain parts that look like ones (i.e., contain a slash). Therefore we 59 // don't attempt to divine a file name out of them. 60 if (!url.is_valid() || url.SchemeIs("about") || url.SchemeIs("data")) 61 return std::string(); 62 63 const std::string unescaped_url_filename = UnescapeURLComponent( 64 url.ExtractFileName(), 65 UnescapeRule::SPACES | UnescapeRule::URL_SPECIAL_CHARS); 66 67 // The URL's path should be escaped UTF-8, but may not be. 68 std::string decoded_filename = unescaped_url_filename; 69 if (!base::IsStringUTF8(decoded_filename)) { 70 // TODO(jshin): this is probably not robust enough. To be sure, we need 71 // encoding detection. 72 base::string16 utf16_output; 73 if (!referrer_charset.empty() && 74 net::ConvertToUTF16( 75 unescaped_url_filename, referrer_charset.c_str(), &utf16_output)) { 76 decoded_filename = base::UTF16ToUTF8(utf16_output); 77 } else { 78 decoded_filename = 79 base::WideToUTF8(base::SysNativeMBToWide(unescaped_url_filename)); 80 } 81 } 82 // If the URL contains a (possibly empty) query, assume it is a generator, and 83 // allow the determined extension to be overwritten. 84 *should_overwrite_extension = !decoded_filename.empty() && url.has_query(); 85 86 return decoded_filename; 87 } 88 89 // Returns whether the specified extension is automatically integrated into the 90 // windows shell. 91 bool IsShellIntegratedExtension(const base::FilePath::StringType& extension) { 92 base::FilePath::StringType extension_lower = StringToLowerASCII(extension); 93 94 // http://msdn.microsoft.com/en-us/library/ms811694.aspx 95 // Right-clicking on shortcuts can be magical. 96 if ((extension_lower == FILE_PATH_LITERAL("local")) || 97 (extension_lower == FILE_PATH_LITERAL("lnk"))) 98 return true; 99 100 // http://www.juniper.net/security/auto/vulnerabilities/vuln2612.html 101 // Files become magical if they end in a CLSID, so block such extensions. 102 if (!extension_lower.empty() && 103 (extension_lower[0] == FILE_PATH_LITERAL('{')) && 104 (extension_lower[extension_lower.length() - 1] == FILE_PATH_LITERAL('}'))) 105 return true; 106 return false; 107 } 108 109 // Returns whether the specified file name is a reserved name on windows. 110 // This includes names like "com2.zip" (which correspond to devices) and 111 // desktop.ini and thumbs.db which have special meaning to the windows shell. 112 bool IsReservedName(const base::FilePath::StringType& filename) { 113 // This list is taken from the MSDN article "Naming a file" 114 // http://msdn2.microsoft.com/en-us/library/aa365247(VS.85).aspx 115 // I also added clock$ because GetSaveFileName seems to consider it as a 116 // reserved name too. 117 static const char* const known_devices[] = { 118 "con", "prn", "aux", "nul", "com1", "com2", "com3", "com4", 119 "com5", "com6", "com7", "com8", "com9", "lpt1", "lpt2", "lpt3", 120 "lpt4", "lpt5", "lpt6", "lpt7", "lpt8", "lpt9", "clock$"}; 121 #if defined(OS_WIN) 122 std::string filename_lower = StringToLowerASCII(base::WideToUTF8(filename)); 123 #elif defined(OS_POSIX) 124 std::string filename_lower = StringToLowerASCII(filename); 125 #endif 126 127 for (size_t i = 0; i < arraysize(known_devices); ++i) { 128 // Exact match. 129 if (filename_lower == known_devices[i]) 130 return true; 131 // Starts with "DEVICE.". 132 if (filename_lower.find(std::string(known_devices[i]) + ".") == 0) 133 return true; 134 } 135 136 static const char* const magic_names[] = { 137 // These file names are used by the "Customize folder" feature of the shell. 138 "desktop.ini", 139 "thumbs.db", 140 }; 141 142 for (size_t i = 0; i < arraysize(magic_names); ++i) { 143 if (filename_lower == magic_names[i]) 144 return true; 145 } 146 147 return false; 148 } 149 150 // Examines the current extension in |file_name| and modifies it if necessary in 151 // order to ensure the filename is safe. If |file_name| doesn't contain an 152 // extension or if |ignore_extension| is true, then a new extension will be 153 // constructed based on the |mime_type|. 154 // 155 // We're addressing two things here: 156 // 157 // 1) Usability. If there is no reliable file extension, we want to guess a 158 // reasonable file extension based on the content type. 159 // 160 // 2) Shell integration. Some file extensions automatically integrate with the 161 // shell. We block these extensions to prevent a malicious web site from 162 // integrating with the user's shell. 163 void EnsureSafeExtension(const std::string& mime_type, 164 bool ignore_extension, 165 base::FilePath* file_name) { 166 // See if our file name already contains an extension. 167 base::FilePath::StringType extension = file_name->Extension(); 168 if (!extension.empty()) 169 extension.erase(extension.begin()); // Erase preceding '.'. 170 171 if ((ignore_extension || extension.empty()) && !mime_type.empty()) { 172 base::FilePath::StringType preferred_mime_extension; 173 std::vector<base::FilePath::StringType> all_mime_extensions; 174 net::GetPreferredExtensionForMimeType(mime_type, &preferred_mime_extension); 175 net::GetExtensionsForMimeType(mime_type, &all_mime_extensions); 176 // If the existing extension is in the list of valid extensions for the 177 // given type, use it. This avoids doing things like pointlessly renaming 178 // "foo.jpg" to "foo.jpeg". 179 if (std::find(all_mime_extensions.begin(), 180 all_mime_extensions.end(), 181 extension) != all_mime_extensions.end()) { 182 // leave |extension| alone 183 } else if (!preferred_mime_extension.empty()) { 184 extension = preferred_mime_extension; 185 } 186 } 187 188 #if defined(OS_WIN) 189 static const base::FilePath::CharType default_extension[] = 190 FILE_PATH_LITERAL("download"); 191 192 // Rename shell-integrated extensions. 193 // TODO(asanka): Consider stripping out the bad extension and replacing it 194 // with the preferred extension for the MIME type if one is available. 195 if (IsShellIntegratedExtension(extension)) 196 extension.assign(default_extension); 197 #endif 198 199 *file_name = file_name->ReplaceExtension(extension); 200 } 201 202 bool FilePathToString16(const base::FilePath& path, base::string16* converted) { 203 #if defined(OS_WIN) 204 return base::WideToUTF16( 205 path.value().c_str(), path.value().size(), converted); 206 #elif defined(OS_POSIX) 207 std::string component8 = path.AsUTF8Unsafe(); 208 return !component8.empty() && 209 base::UTF8ToUTF16(component8.c_str(), component8.size(), converted); 210 #endif 211 } 212 213 base::string16 GetSuggestedFilenameImpl( 214 const GURL& url, 215 const std::string& content_disposition, 216 const std::string& referrer_charset, 217 const std::string& suggested_name, 218 const std::string& mime_type, 219 const std::string& default_name, 220 ReplaceIllegalCharactersCallback replace_illegal_characters_callback) { 221 // TODO: this function to be updated to match the httpbis recommendations. 222 // Talk to abarth for the latest news. 223 224 // We don't translate this fallback string, "download". If localization is 225 // needed, the caller should provide localized fallback in |default_name|. 226 static const base::FilePath::CharType kFinalFallbackName[] = 227 FILE_PATH_LITERAL("download"); 228 std::string filename; // In UTF-8 229 bool overwrite_extension = false; 230 231 // Try to extract a filename from content-disposition first. 232 if (!content_disposition.empty()) { 233 HttpContentDisposition header(content_disposition, referrer_charset); 234 filename = header.filename(); 235 } 236 237 // Then try to use the suggested name. 238 if (filename.empty() && !suggested_name.empty()) 239 filename = suggested_name; 240 241 // Now try extracting the filename from the URL. GetFileNameFromURL() only 242 // looks at the last component of the URL and doesn't return the hostname as a 243 // failover. 244 if (filename.empty()) 245 filename = GetFileNameFromURL(url, referrer_charset, &overwrite_extension); 246 247 // Finally try the URL hostname, but only if there's no default specified in 248 // |default_name|. Some schemes (e.g.: file:, about:, data:) do not have a 249 // host name. 250 if (filename.empty() && default_name.empty() && url.is_valid() && 251 !url.host().empty()) { 252 // TODO(jungshik) : Decode a 'punycoded' IDN hostname. (bug 1264451) 253 filename = url.host(); 254 } 255 256 bool replace_trailing = false; 257 base::FilePath::StringType result_str, default_name_str; 258 #if defined(OS_WIN) 259 replace_trailing = true; 260 result_str = base::UTF8ToUTF16(filename); 261 default_name_str = base::UTF8ToUTF16(default_name); 262 #else 263 result_str = filename; 264 default_name_str = default_name; 265 #endif 266 SanitizeGeneratedFileName(&result_str, replace_trailing); 267 if (result_str.find_last_not_of(FILE_PATH_LITERAL("-_")) == 268 base::FilePath::StringType::npos) { 269 result_str = !default_name_str.empty() 270 ? default_name_str 271 : base::FilePath::StringType(kFinalFallbackName); 272 overwrite_extension = false; 273 } 274 replace_illegal_characters_callback.Run(&result_str, '-'); 275 base::FilePath result(result_str); 276 GenerateSafeFileName(mime_type, overwrite_extension, &result); 277 278 base::string16 result16; 279 if (!FilePathToString16(result, &result16)) { 280 result = base::FilePath(default_name_str); 281 if (!FilePathToString16(result, &result16)) { 282 result = base::FilePath(kFinalFallbackName); 283 FilePathToString16(result, &result16); 284 } 285 } 286 return result16; 287 } 288 289 base::FilePath GenerateFileNameImpl( 290 const GURL& url, 291 const std::string& content_disposition, 292 const std::string& referrer_charset, 293 const std::string& suggested_name, 294 const std::string& mime_type, 295 const std::string& default_file_name, 296 ReplaceIllegalCharactersCallback replace_illegal_characters_callback) { 297 base::string16 file_name = 298 GetSuggestedFilenameImpl(url, 299 content_disposition, 300 referrer_charset, 301 suggested_name, 302 mime_type, 303 default_file_name, 304 replace_illegal_characters_callback); 305 306 #if defined(OS_WIN) 307 base::FilePath generated_name(file_name); 308 #else 309 base::FilePath generated_name( 310 base::SysWideToNativeMB(base::UTF16ToWide(file_name))); 311 #endif 312 313 DCHECK(!generated_name.empty()); 314 315 return generated_name; 316 } 317 318 } // namespace net 319
