url/url_util.cc

   1 // Copyright 2013 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 "url/url_util.h"
   6
   7 #include <string.h>
   8 #include <vector>
   9
  10 #include "base/logging.h"
  11 #include "url/url_canon_internal.h"
  12 #include "url/url_file.h"
  13 #include "url/url_util_internal.h"
  14
  15 namespace url_util {
  16
  17 const char kFileScheme[] = "file";
  18 const char kFileSystemScheme[] = "filesystem";
  19 const char kMailtoScheme[] = "mailto";
  20
  21 namespace {
  22
  23 // ASCII-specific tolower.  The standard library's tolower is locale sensitive,
  24 // so we don't want to use it here.
  25 template <class Char> inline Char ToLowerASCII(Char c) {
  26   return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c;
  27 }
  28
  29 // Backend for LowerCaseEqualsASCII.
  30 template<typename Iter>
  31 inline bool DoLowerCaseEqualsASCII(Iter a_begin, Iter a_end, const char* b) {
  32   for (Iter it = a_begin; it != a_end; ++it, ++b) {
  33     if (!*b || ToLowerASCII(*it) != *b)
  34       return false;
  35   }
  36   return *b == 0;
  37 }
  38
  39 const int kNumStandardURLSchemes = 8;
  40 const char* kStandardURLSchemes[kNumStandardURLSchemes] = {
  41   "http",
  42   "https",
  43   kFileScheme,  // Yes, file urls can have a hostname!
  44   "ftp",
  45   "gopher",
  46   "ws",  // WebSocket.
  47   "wss",  // WebSocket secure.
  48   kFileSystemScheme,
  49 };
  50
  51 // List of the currently installed standard schemes. This list is lazily
  52 // initialized by InitStandardSchemes and is leaked on shutdown to prevent
  53 // any destructors from being called that will slow us down or cause problems.
  54 std::vector<const char*>* standard_schemes = NULL;
  55
  56 // See the LockStandardSchemes declaration in the header.
  57 bool standard_schemes_locked = false;
  58
  59 // Ensures that the standard_schemes list is initialized, does nothing if it
  60 // already has values.
  61 void InitStandardSchemes() {
  62   if (standard_schemes)
  63     return;
  64   standard_schemes = new std::vector<const char*>;
  65   for (int i = 0; i < kNumStandardURLSchemes; i++)
  66     standard_schemes->push_back(kStandardURLSchemes[i]);
  67 }
  68
  69 // Given a string and a range inside the string, compares it to the given
  70 // lower-case |compare_to| buffer.
  71 template<typename CHAR>
  72 inline bool DoCompareSchemeComponent(const CHAR* spec,
  73                                      const url_parse::Component& component,
  74                                      const char* compare_to) {
  75   if (!component.is_nonempty())
  76     return compare_to[0] == 0;  // When component is empty, match empty scheme.
  77   return LowerCaseEqualsASCII(&spec[component.begin],
  78                               &spec[component.end()],
  79                               compare_to);
  80 }
  81
  82 // Returns true if the given scheme identified by |scheme| within |spec| is one
  83 // of the registered "standard" schemes.
  84 template<typename CHAR>
  85 bool DoIsStandard(const CHAR* spec, const url_parse::Component& scheme) {
  86   if (!scheme.is_nonempty())
  87     return false;  // Empty or invalid schemes are non-standard.
  88
  89   InitStandardSchemes();
  90   for (size_t i = 0; i < standard_schemes->size(); i++) {
  91     if (LowerCaseEqualsASCII(&spec[scheme.begin], &spec[scheme.end()],
  92                              standard_schemes->at(i)))
  93       return true;
  94   }
  95   return false;
  96 }
  97
  98 template<typename CHAR>
  99 bool DoFindAndCompareScheme(const CHAR* str,
 100                             int str_len,
 101                             const char* compare,
 102                             url_parse::Component* found_scheme) {
 103   // Before extracting scheme, canonicalize the URL to remove any whitespace.
 104   // This matches the canonicalization done in DoCanonicalize function.
 105   url_canon::RawCanonOutputT<CHAR> whitespace_buffer;
 106   int spec_len;
 107   const CHAR* spec = RemoveURLWhitespace(str, str_len,
 108                                          &whitespace_buffer, &spec_len);
 109
 110   url_parse::Component our_scheme;
 111   if (!url_parse::ExtractScheme(spec, spec_len, &our_scheme)) {
 112     // No scheme.
 113     if (found_scheme)
 114       *found_scheme = url_parse::Component();
 115     return false;
 116   }
 117   if (found_scheme)
 118     *found_scheme = our_scheme;
 119   return DoCompareSchemeComponent(spec, our_scheme, compare);
 120 }
 121
 122 template<typename CHAR>
 123 bool DoCanonicalize(const CHAR* in_spec, int in_spec_len,
 124                     url_canon::CharsetConverter* charset_converter,
 125                     url_canon::CanonOutput* output,
 126                     url_parse::Parsed* output_parsed) {
 127   // Remove any whitespace from the middle of the relative URL, possibly
 128   // copying to the new buffer.
 129   url_canon::RawCanonOutputT<CHAR> whitespace_buffer;
 130   int spec_len;
 131   const CHAR* spec = RemoveURLWhitespace(in_spec, in_spec_len,
 132                                          &whitespace_buffer, &spec_len);
 133
 134   url_parse::Parsed parsed_input;
 135 #ifdef WIN32
 136   // For Windows, we allow things that look like absolute Windows paths to be
 137   // fixed up magically to file URLs. This is done for IE compatability. For
 138   // example, this will change "c:/foo" into a file URL rather than treating
 139   // it as a URL with the protocol "c". It also works for UNC ("\\foo\bar.txt").
 140   // There is similar logic in url_canon_relative.cc for
 141   //
 142   // For Max & Unix, we don't do this (the equivalent would be "/foo/bar" which
 143   // has no meaning as an absolute path name. This is because browsers on Mac
 144   // & Unix don't generally do this, so there is no compatibility reason for
 145   // doing so.
 146   if (url_parse::DoesBeginUNCPath(spec, 0, spec_len, false) ||
 147       url_parse::DoesBeginWindowsDriveSpec(spec, 0, spec_len)) {
 148     url_parse::ParseFileURL(spec, spec_len, &parsed_input);
 149     return url_canon::CanonicalizeFileURL(spec, spec_len, parsed_input,
 150                                           charset_converter,
 151                                           output, output_parsed);
 152   }
 153 #endif
 154
 155   url_parse::Component scheme;
 156   if (!url_parse::ExtractScheme(spec, spec_len, &scheme))
 157     return false;
 158
 159   // This is the parsed version of the input URL, we have to canonicalize it
 160   // before storing it in our object.
 161   bool success;
 162   if (DoCompareSchemeComponent(spec, scheme, kFileScheme)) {
 163     // File URLs are special.
 164     url_parse::ParseFileURL(spec, spec_len, &parsed_input);
 165     success = url_canon::CanonicalizeFileURL(spec, spec_len, parsed_input,
 166                                              charset_converter, output,
 167                                              output_parsed);
 168   } else if (DoCompareSchemeComponent(spec, scheme, kFileSystemScheme)) {
 169     // Filesystem URLs are special.
 170     url_parse::ParseFileSystemURL(spec, spec_len, &parsed_input);
 171     success = url_canon::CanonicalizeFileSystemURL(spec, spec_len,
 172                                                    parsed_input,
 173                                                    charset_converter,
 174                                                    output, output_parsed);
 175
 176   } else if (DoIsStandard(spec, scheme)) {
 177     // All "normal" URLs.
 178     url_parse::ParseStandardURL(spec, spec_len, &parsed_input);
 179     success = url_canon::CanonicalizeStandardURL(spec, spec_len, parsed_input,
 180                                                  charset_converter,
 181                                                  output, output_parsed);
 182
 183   } else if (DoCompareSchemeComponent(spec, scheme, kMailtoScheme)) {
 184     // Mailto are treated like a standard url with only a scheme, path, query
 185     url_parse::ParseMailtoURL(spec, spec_len, &parsed_input);
 186     success = url_canon::CanonicalizeMailtoURL(spec, spec_len, parsed_input,
 187                                                output, output_parsed);
 188
 189   } else {
 190     // "Weird" URLs like data: and javascript:
 191     url_parse::ParsePathURL(spec, spec_len, &parsed_input);
 192     success = url_canon::CanonicalizePathURL(spec, spec_len, parsed_input,
 193                                              output, output_parsed);
 194   }
 195   return success;
 196 }
 197
 198 template<typename CHAR>
 199 bool DoResolveRelative(const char* base_spec,
 200                        int base_spec_len,
 201                        const url_parse::Parsed& base_parsed,
 202                        const CHAR* in_relative,
 203                        int in_relative_length,
 204                        url_canon::CharsetConverter* charset_converter,
 205                        url_canon::CanonOutput* output,
 206                        url_parse::Parsed* output_parsed) {
 207   // Remove any whitespace from the middle of the relative URL, possibly
 208   // copying to the new buffer.
 209   url_canon::RawCanonOutputT<CHAR> whitespace_buffer;
 210   int relative_length;
 211   const CHAR* relative = RemoveURLWhitespace(in_relative, in_relative_length,
 212                                              &whitespace_buffer,
 213                                              &relative_length);
 214   bool base_is_authority_based = false;
 215   bool base_is_hierarchical = false;
 216   if (base_spec &&
 217       base_parsed.scheme.is_nonempty()) {
 218     int after_scheme = base_parsed.scheme.end() + 1;  // Skip past the colon.
 219     int num_slashes = url_parse::CountConsecutiveSlashes(
 220         base_spec, after_scheme, base_spec_len);
 221     base_is_authority_based = num_slashes > 1;
 222     base_is_hierarchical = num_slashes > 0;
 223   }
 224
 225   bool standard_base_scheme =
 226       base_parsed.scheme.is_nonempty() &&
 227       DoIsStandard(base_spec, base_parsed.scheme);
 228
 229   bool is_relative;
 230   url_parse::Component relative_component;
 231   if (!url_canon::IsRelativeURL(base_spec, base_parsed,
 232                                 relative, relative_length,
 233                                 (base_is_hierarchical || standard_base_scheme),
 234                                 &is_relative,
 235                                 &relative_component)) {
 236     // Error resolving.
 237     return false;
 238   }
 239
 240   // Pretend for a moment that |base_spec| is a standard URL. Normally
 241   // non-standard URLs are treated as PathURLs, but if the base has an
 242   // authority we would like to preserve it.
 243   if (is_relative && base_is_authority_based && !standard_base_scheme) {
 244     url_parse::Parsed base_parsed_authority;
 245     ParseStandardURL(base_spec, base_spec_len, &base_parsed_authority);
 246     if (base_parsed_authority.host.is_nonempty()) {
 247       bool did_resolve_succeed =
 248           url_canon::ResolveRelativeURL(base_spec, base_parsed_authority,
 249                                         false, relative,
 250                                         relative_component, charset_converter,
 251                                         output, output_parsed);
 252       // The output_parsed is incorrect at this point (because it was built
 253       // based on base_parsed_authority instead of base_parsed) and needs to be
 254       // re-created.
 255       ParsePathURL(output->data(), output->length(), output_parsed);
 256       return did_resolve_succeed;
 257     }
 258   } else if (is_relative) {
 259     // Relative, resolve and canonicalize.
 260     bool file_base_scheme = base_parsed.scheme.is_nonempty() &&
 261         DoCompareSchemeComponent(base_spec, base_parsed.scheme, kFileScheme);
 262     return url_canon::ResolveRelativeURL(base_spec, base_parsed,
 263                                          file_base_scheme, relative,
 264                                          relative_component, charset_converter,
 265                                          output, output_parsed);
 266   }
 267
 268   // Not relative, canonicalize the input.
 269   return DoCanonicalize(relative, relative_length, charset_converter,
 270                         output, output_parsed);
 271 }
 272
 273 template<typename CHAR>
 274 bool DoReplaceComponents(const char* spec,
 275                          int spec_len,
 276                          const url_parse::Parsed& parsed,
 277                          const url_canon::Replacements<CHAR>& replacements,
 278                          url_canon::CharsetConverter* charset_converter,
 279                          url_canon::CanonOutput* output,
 280                          url_parse::Parsed* out_parsed) {
 281   // If the scheme is overridden, just do a simple string substitution and
 282   // reparse the whole thing. There are lots of edge cases that we really don't
 283   // want to deal with. Like what happens if I replace "http://e:8080/foo"
 284   // with a file. Does it become "file:///E:/8080/foo" where the port number
 285   // becomes part of the path? Parsing that string as a file URL says "yes"
 286   // but almost no sane rule for dealing with the components individually would
 287   // come up with that.
 288   //
 289   // Why allow these crazy cases at all? Programatically, there is almost no
 290   // case for replacing the scheme. The most common case for hitting this is
 291   // in JS when building up a URL using the location object. In this case, the
 292   // JS code expects the string substitution behavior:
 293   //   http://www.w3.org/TR/2008/WD-html5-20080610/structured.html#common3
 294   if (replacements.IsSchemeOverridden()) {
 295     // Canonicalize the new scheme so it is 8-bit and can be concatenated with
 296     // the existing spec.
 297     url_canon::RawCanonOutput<128> scheme_replaced;
 298     url_parse::Component scheme_replaced_parsed;
 299     url_canon::CanonicalizeScheme(
 300         replacements.sources().scheme,
 301         replacements.components().scheme,
 302         &scheme_replaced, &scheme_replaced_parsed);
 303
 304     // We can assume that the input is canonicalized, which means it always has
 305     // a colon after the scheme (or where the scheme would be).
 306     int spec_after_colon = parsed.scheme.is_valid() ? parsed.scheme.end() + 1
 307                                                     : 1;
 308     if (spec_len - spec_after_colon > 0) {
 309       scheme_replaced.Append(&spec[spec_after_colon],
 310                              spec_len - spec_after_colon);
 311     }
 312
 313     // We now need to completely re-parse the resulting string since its meaning
 314     // may have changed with the different scheme.
 315     url_canon::RawCanonOutput<128> recanonicalized;
 316     url_parse::Parsed recanonicalized_parsed;
 317     DoCanonicalize(scheme_replaced.data(), scheme_replaced.length(),
 318                    charset_converter,
 319                    &recanonicalized, &recanonicalized_parsed);
 320
 321     // Recurse using the version with the scheme already replaced. This will now
 322     // use the replacement rules for the new scheme.
 323     //
 324     // Warning: this code assumes that ReplaceComponents will re-check all
 325     // components for validity. This is because we can't fail if DoCanonicalize
 326     // failed above since theoretically the thing making it fail could be
 327     // getting replaced here. If ReplaceComponents didn't re-check everything,
 328     // we wouldn't know if something *not* getting replaced is a problem.
 329     // If the scheme-specific replacers are made more intelligent so they don't
 330     // re-check everything, we should instead recanonicalize the whole thing
 331     // after this call to check validity (this assumes replacing the scheme is
 332     // much much less common than other types of replacements, like clearing the
 333     // ref).
 334     url_canon::Replacements<CHAR> replacements_no_scheme = replacements;
 335     replacements_no_scheme.SetScheme(NULL, url_parse::Component());
 336     return DoReplaceComponents(recanonicalized.data(), recanonicalized.length(),
 337                                recanonicalized_parsed, replacements_no_scheme,
 338                                charset_converter, output, out_parsed);
 339   }
 340
 341   // If we get here, then we know the scheme doesn't need to be replaced, so can
 342   // just key off the scheme in the spec to know how to do the replacements.
 343   if (DoCompareSchemeComponent(spec, parsed.scheme, kFileScheme)) {
 344     return url_canon::ReplaceFileURL(spec, parsed, replacements,
 345                                      charset_converter, output, out_parsed);
 346   }
 347   if (DoCompareSchemeComponent(spec, parsed.scheme, kFileSystemScheme)) {
 348     return url_canon::ReplaceFileSystemURL(spec, parsed, replacements,
 349                                            charset_converter, output,
 350                                            out_parsed);
 351   }
 352   if (DoIsStandard(spec, parsed.scheme)) {
 353     return url_canon::ReplaceStandardURL(spec, parsed, replacements,
 354                                          charset_converter, output, out_parsed);
 355   }
 356   if (DoCompareSchemeComponent(spec, parsed.scheme, kMailtoScheme)) {
 357      return url_canon::ReplaceMailtoURL(spec, parsed, replacements,
 358                                         output, out_parsed);
 359   }
 360
 361   // Default is a path URL.
 362   return url_canon::ReplacePathURL(spec, parsed, replacements,
 363                                    output, out_parsed);
 364 }
 365
 366 }  // namespace
 367
 368 void Initialize() {
 369   InitStandardSchemes();
 370 }
 371
 372 void Shutdown() {
 373   if (standard_schemes) {
 374     delete standard_schemes;
 375     standard_schemes = NULL;
 376   }
 377 }
 378
 379 void AddStandardScheme(const char* new_scheme) {
 380   // If this assert triggers, it means you've called AddStandardScheme after
 381   // LockStandardSchemes have been called (see the header file for
 382   // LockStandardSchemes for more).
 383   //
 384   // This normally means you're trying to set up a new standard scheme too late
 385   // in your application's init process. Locate where your app does this
 386   // initialization and calls LockStandardScheme, and add your new standard
 387   // scheme there.
 388   DCHECK(!standard_schemes_locked) <<
 389       "Trying to add a standard scheme after the list has been locked.";
 390
 391   size_t scheme_len = strlen(new_scheme);
 392   if (scheme_len == 0)
 393     return;
 394
 395   // Dulicate the scheme into a new buffer and add it to the list of standard
 396   // schemes. This pointer will be leaked on shutdown.
 397   char* dup_scheme = new char[scheme_len + 1];
 398   memcpy(dup_scheme, new_scheme, scheme_len + 1);
 399
 400   InitStandardSchemes();
 401   standard_schemes->push_back(dup_scheme);
 402 }
 403
 404 void LockStandardSchemes() {
 405   standard_schemes_locked = true;
 406 }
 407
 408 bool IsStandard(const char* spec, const url_parse::Component& scheme) {
 409   return DoIsStandard(spec, scheme);
 410 }
 411
 412 bool IsStandard(const base::char16* spec, const url_parse::Component& scheme) {
 413   return DoIsStandard(spec, scheme);
 414 }
 415
 416 bool FindAndCompareScheme(const char* str,
 417                           int str_len,
 418                           const char* compare,
 419                           url_parse::Component* found_scheme) {
 420   return DoFindAndCompareScheme(str, str_len, compare, found_scheme);
 421 }
 422
 423 bool FindAndCompareScheme(const base::char16* str,
 424                           int str_len,
 425                           const char* compare,
 426                           url_parse::Component* found_scheme) {
 427   return DoFindAndCompareScheme(str, str_len, compare, found_scheme);
 428 }
 429
 430 bool Canonicalize(const char* spec,
 431                   int spec_len,
 432                   url_canon::CharsetConverter* charset_converter,
 433                   url_canon::CanonOutput* output,
 434                   url_parse::Parsed* output_parsed) {
 435   return DoCanonicalize(spec, spec_len, charset_converter,
 436                         output, output_parsed);
 437 }
 438
 439 bool Canonicalize(const base::char16* spec,
 440                   int spec_len,
 441                   url_canon::CharsetConverter* charset_converter,
 442                   url_canon::CanonOutput* output,
 443                   url_parse::Parsed* output_parsed) {
 444   return DoCanonicalize(spec, spec_len, charset_converter,
 445                         output, output_parsed);
 446 }
 447
 448 bool ResolveRelative(const char* base_spec,
 449                      int base_spec_len,
 450                      const url_parse::Parsed& base_parsed,
 451                      const char* relative,
 452                      int relative_length,
 453                      url_canon::CharsetConverter* charset_converter,
 454                      url_canon::CanonOutput* output,
 455                      url_parse::Parsed* output_parsed) {
 456   return DoResolveRelative(base_spec, base_spec_len, base_parsed,
 457                            relative, relative_length,
 458                            charset_converter, output, output_parsed);
 459 }
 460
 461 bool ResolveRelative(const char* base_spec,
 462                      int base_spec_len,
 463                      const url_parse::Parsed& base_parsed,
 464                      const base::char16* relative,
 465                      int relative_length,
 466                      url_canon::CharsetConverter* charset_converter,
 467                      url_canon::CanonOutput* output,
 468                      url_parse::Parsed* output_parsed) {
 469   return DoResolveRelative(base_spec, base_spec_len, base_parsed,
 470                            relative, relative_length,
 471                            charset_converter, output, output_parsed);
 472 }
 473
 474 bool ReplaceComponents(const char* spec,
 475                        int spec_len,
 476                        const url_parse::Parsed& parsed,
 477                        const url_canon::Replacements<char>& replacements,
 478                        url_canon::CharsetConverter* charset_converter,
 479                        url_canon::CanonOutput* output,
 480                        url_parse::Parsed* out_parsed) {
 481   return DoReplaceComponents(spec, spec_len, parsed, replacements,
 482                              charset_converter, output, out_parsed);
 483 }
 484
 485 bool ReplaceComponents(
 486       const char* spec,
 487       int spec_len,
 488       const url_parse::Parsed& parsed,
 489       const url_canon::Replacements<base::char16>& replacements,
 490       url_canon::CharsetConverter* charset_converter,
 491       url_canon::CanonOutput* output,
 492       url_parse::Parsed* out_parsed) {
 493   return DoReplaceComponents(spec, spec_len, parsed, replacements,
 494                              charset_converter, output, out_parsed);
 495 }
 496
 497 // Front-ends for LowerCaseEqualsASCII.
 498 bool LowerCaseEqualsASCII(const char* a_begin,
 499                           const char* a_end,
 500                           const char* b) {
 501   return DoLowerCaseEqualsASCII(a_begin, a_end, b);
 502 }
 503
 504 bool LowerCaseEqualsASCII(const char* a_begin,
 505                           const char* a_end,
 506                           const char* b_begin,
 507                           const char* b_end) {
 508   while (a_begin != a_end && b_begin != b_end &&
 509          ToLowerASCII(*a_begin) == *b_begin) {
 510     a_begin++;
 511     b_begin++;
 512   }
 513   return a_begin == a_end && b_begin == b_end;
 514 }
 515
 516 bool LowerCaseEqualsASCII(const base::char16* a_begin,
 517                           const base::char16* a_end,
 518                           const char* b) {
 519   return DoLowerCaseEqualsASCII(a_begin, a_end, b);
 520 }
 521
 522 void DecodeURLEscapeSequences(const char* input, int length,
 523                               url_canon::CanonOutputW* output) {
 524   url_canon::RawCanonOutputT<char> unescaped_chars;
 525   for (int i = 0; i < length; i++) {
 526     if (input[i] == '%') {
 527       unsigned char ch;
 528       if (url_canon::DecodeEscaped(input, &i, length, &ch)) {
 529         unescaped_chars.push_back(ch);
 530       } else {
 531         // Invalid escape sequence, copy the percent literal.
 532         unescaped_chars.push_back('%');
 533       }
 534     } else {
 535       // Regular non-escaped 8-bit character.
 536       unescaped_chars.push_back(input[i]);
 537     }
 538   }
 539
 540   // Convert that 8-bit to UTF-16. It's not clear IE does this at all to
 541   // JavaScript URLs, but Firefox and Safari do.
 542   for (int i = 0; i < unescaped_chars.length(); i++) {
 543     unsigned char uch = static_cast<unsigned char>(unescaped_chars.at(i));
 544     if (uch < 0x80) {
 545       // Non-UTF-8, just append directly
 546       output->push_back(uch);
 547     } else {
 548       // next_ch will point to the last character of the decoded
 549       // character.
 550       int next_character = i;
 551       unsigned code_point;
 552       if (url_canon::ReadUTFChar(unescaped_chars.data(), &next_character,
 553                                  unescaped_chars.length(), &code_point)) {
 554         // Valid UTF-8 character, convert to UTF-16.
 555         url_canon::AppendUTF16Value(code_point, output);
 556         i = next_character;
 557       } else {
 558         // If there are any sequences that are not valid UTF-8, we keep
 559         // invalid code points and promote to UTF-16. We copy all characters
 560         // from the current position to the end of the identified sequence.
 561         while (i < next_character) {
 562           output->push_back(static_cast<unsigned char>(unescaped_chars.at(i)));
 563           i++;
 564         }
 565         output->push_back(static_cast<unsigned char>(unescaped_chars.at(i)));
 566       }
 567     }
 568   }
 569 }
 570
 571 void EncodeURIComponent(const char* input, int length,
 572                         url_canon::CanonOutput* output) {
 573   for (int i = 0; i < length; ++i) {
 574     unsigned char c = static_cast<unsigned char>(input[i]);
 575     if (url_canon::IsComponentChar(c))
 576       output->push_back(c);
 577     else
 578       AppendEscapedChar(c, output);
 579   }
 580 }
 581
 582 bool CompareSchemeComponent(const char* spec,
 583                             const url_parse::Component& component,
 584                             const char* compare_to) {
 585   return DoCompareSchemeComponent(spec, component, compare_to);
 586 }
 587
 588 bool CompareSchemeComponent(const base::char16* spec,
 589                             const url_parse::Component& component,
 590                             const char* compare_to) {
 591   return DoCompareSchemeComponent(spec, component, compare_to);
 592 }
 593
 594 }  // namespace url_util