url/url_parse_file.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 "base/logging.h"
   6 #include "url/url_file.h"
   7 #include "url/url_parse.h"
   8 #include "url/url_parse_internal.h"
   9
  10 // Interesting IE file:isms...
  11 //
  12 //  INPUT                      OUTPUT
  13 //  =========================  ==============================
  14 //  file:/foo/bar              file:///foo/bar
  15 //      The result here seems totally invalid!?!? This isn't UNC.
  16 //
  17 //  file:/
  18 //  file:// or any other number of slashes
  19 //      IE6 doesn't do anything at all if you click on this link. No error:
  20 //      nothing. IE6's history system seems to always color this link, so I'm
  21 //      guessing that it maps internally to the empty URL.
  22 //
  23 //  C:\                        file:///C:/
  24 //      When on a file: URL source page, this link will work. When over HTTP,
  25 //      the file: URL will appear in the status bar but the link will not work
  26 //      (security restriction for all file URLs).
  27 //
  28 //  file:foo/                  file:foo/     (invalid?!?!?)
  29 //  file:/foo/                 file:///foo/  (invalid?!?!?)
  30 //  file://foo/                file://foo/   (UNC to server "foo")
  31 //  file:///foo/               file:///foo/  (invalid, seems to be a file)
  32 //  file:////foo/              file://foo/   (UNC to server "foo")
  33 //      Any more than four slashes is also treated as UNC.
  34 //
  35 //  file:C:/                   file://C:/
  36 //  file:/C:/                  file://C:/
  37 //      The number of slashes after "file:" don't matter if the thing following
  38 //      it looks like an absolute drive path. Also, slashes and backslashes are
  39 //      equally valid here.
  40
  41 namespace url_parse {
  42
  43 namespace {
  44
  45 // A subcomponent of DoInitFileURL, the input of this function should be a UNC
  46 // path name, with the index of the first character after the slashes following
  47 // the scheme given in |after_slashes|. This will initialize the host, path,
  48 // query, and ref, and leave the other output components untouched
  49 // (DoInitFileURL handles these for us).
  50 template<typename CHAR>
  51 void DoParseUNC(const CHAR* spec,
  52                 int after_slashes,
  53                 int spec_len,
  54                Parsed* parsed) {
  55   int next_slash = FindNextSlash(spec, after_slashes, spec_len);
  56   if (next_slash == spec_len) {
  57     // No additional slash found, as in "file://foo", treat the text as the
  58     // host with no path (this will end up being UNC to server "foo").
  59     int host_len = spec_len - after_slashes;
  60     if (host_len)
  61       parsed->host = Component(after_slashes, host_len);
  62     else
  63       parsed->host.reset();
  64     parsed->path.reset();
  65     return;
  66   }
  67
  68 #ifdef WIN32
  69   // See if we have something that looks like a path following the first
  70   // component. As in "file://localhost/c:/", we get "c:/" out. We want to
  71   // treat this as a having no host but the path given. Works on Windows only.
  72   if (DoesBeginWindowsDriveSpec(spec, next_slash + 1, spec_len)) {
  73     parsed->host.reset();
  74     ParsePathInternal(spec, MakeRange(next_slash, spec_len),
  75                       &parsed->path, &parsed->query, &parsed->ref);
  76     return;
  77   }
  78 #endif
  79
  80   // Otherwise, everything up until that first slash we found is the host name,
  81   // which will end up being the UNC host. For example "file://foo/bar.txt"
  82   // will get a server name of "foo" and a path of "/bar". Later, on Windows,
  83   // this should be treated as the filename "\\foo\bar.txt" in proper UNC
  84   // notation.
  85   int host_len = next_slash - after_slashes;
  86   if (host_len)
  87     parsed->host = MakeRange(after_slashes, next_slash);
  88   else
  89     parsed->host.reset();
  90   if (next_slash < spec_len) {
  91     ParsePathInternal(spec, MakeRange(next_slash, spec_len),
  92                       &parsed->path, &parsed->query, &parsed->ref);
  93   } else {
  94     parsed->path.reset();
  95   }
  96 }
  97
  98 // A subcomponent of DoParseFileURL, the input should be a local file, with the
  99 // beginning of the path indicated by the index in |path_begin|. This will
 100 // initialize the host, path, query, and ref, and leave the other output
 101 // components untouched (DoInitFileURL handles these for us).
 102 template<typename CHAR>
 103 void DoParseLocalFile(const CHAR* spec,
 104                       int path_begin,
 105                       int spec_len,
 106                       Parsed* parsed) {
 107   parsed->host.reset();
 108   ParsePathInternal(spec, MakeRange(path_begin, spec_len),
 109                     &parsed->path, &parsed->query, &parsed->ref);
 110 }
 111
 112 // Backend for the external functions that operates on either char type.
 113 // Handles cases where there is a scheme, but also when handed the first
 114 // character following the "file:" at the beginning of the spec. If so,
 115 // this is usually a slash, but needn't be; we allow paths like "file:c:\foo".
 116 template<typename CHAR>
 117 void DoParseFileURL(const CHAR* spec, int spec_len, Parsed* parsed) {
 118   DCHECK(spec_len >= 0);
 119
 120   // Get the parts we never use for file URLs out of the way.
 121   parsed->username.reset();
 122   parsed->password.reset();
 123   parsed->port.reset();
 124
 125   // Many of the code paths don't set these, so it's convenient to just clear
 126   // them. We'll write them in those cases we need them.
 127   parsed->query.reset();
 128   parsed->ref.reset();
 129
 130   // Strip leading & trailing spaces and control characters.
 131   int begin = 0;
 132   TrimURL(spec, &begin, &spec_len);
 133
 134   // Find the scheme, if any.
 135   int num_slashes = CountConsecutiveSlashes(spec, begin, spec_len);
 136   int after_scheme;
 137   int after_slashes;
 138 #ifdef WIN32
 139   // See how many slashes there are. We want to handle cases like UNC but also
 140   // "/c:/foo". This is when there is no scheme, so we can allow pages to do
 141   // links like "c:/foo/bar" or "//foo/bar". This is also called by the
 142   // relative URL resolver when it determines there is an absolute URL, which
 143   // may give us input like "/c:/foo".
 144   after_slashes = begin + num_slashes;
 145   if (DoesBeginWindowsDriveSpec(spec, after_slashes, spec_len)) {
 146     // Windows path, don't try to extract the scheme (for example, "c:\foo").
 147     parsed->scheme.reset();
 148     after_scheme = after_slashes;
 149   } else if (DoesBeginUNCPath(spec, begin, spec_len, false)) {
 150     // Windows UNC path: don't try to extract the scheme, but keep the slashes.
 151     parsed->scheme.reset();
 152     after_scheme = begin;
 153   } else
 154 #endif
 155   {
 156     // ExtractScheme doesn't understand the possibility of filenames with
 157     // colons in them, in which case it returns the entire spec up to the
 158     // colon as the scheme. So handle /foo.c:5 as a file but foo.c:5 as
 159     // the foo.c: scheme.
 160     if (!num_slashes &&
 161         ExtractScheme(&spec[begin], spec_len - begin, &parsed->scheme)) {
 162       // Offset the results since we gave ExtractScheme a substring.
 163       parsed->scheme.begin += begin;
 164       after_scheme = parsed->scheme.end() + 1;
 165     } else {
 166       // No scheme found, remember that.
 167       parsed->scheme.reset();
 168       after_scheme = begin;
 169     }
 170   }
 171
 172   // Handle empty specs ones that contain only whitespace or control chars,
 173   // or that are just the scheme (for example "file:").
 174   if (after_scheme == spec_len) {
 175     parsed->host.reset();
 176     parsed->path.reset();
 177     return;
 178   }
 179
 180   num_slashes = CountConsecutiveSlashes(spec, after_scheme, spec_len);
 181   after_slashes = after_scheme + num_slashes;
 182 #ifdef WIN32
 183   // Check whether the input is a drive again. We checked above for windows
 184   // drive specs, but that's only at the very beginning to see if we have a
 185   // scheme at all. This test will be duplicated in that case, but will
 186   // additionally handle all cases with a real scheme such as "file:///C:/".
 187   if (!DoesBeginWindowsDriveSpec(spec, after_slashes, spec_len) &&
 188       num_slashes != 3) {
 189     // Anything not beginning with a drive spec ("c:\") on Windows is treated
 190     // as UNC, with the exception of three slashes which always means a file.
 191     // Even IE7 treats file:///foo/bar as "/foo/bar", which then fails.
 192     DoParseUNC(spec, after_slashes, spec_len, parsed);
 193     return;
 194   }
 195 #else
 196   // file: URL with exactly 2 slashes is considered to have a host component.
 197   if (num_slashes == 2) {
 198     DoParseUNC(spec, after_slashes, spec_len, parsed);
 199     return;
 200   }
 201 #endif  // WIN32
 202
 203   // Easy and common case, the full path immediately follows the scheme
 204   // (modulo slashes), as in "file://c:/foo". Just treat everything from
 205   // there to the end as the path. Empty hosts have 0 length instead of -1.
 206   // We include the last slash as part of the path if there is one.
 207   DoParseLocalFile(spec,
 208       num_slashes > 0 ? after_scheme + num_slashes - 1 : after_scheme,
 209       spec_len, parsed);
 210 }
 211
 212 }  // namespace
 213
 214 void ParseFileURL(const char* url, int url_len, Parsed* parsed) {
 215   DoParseFileURL(url, url_len, parsed);
 216 }
 217
 218 void ParseFileURL(const base::char16* url, int url_len, Parsed* parsed) {
 219   DoParseFileURL(url, url_len, parsed);
 220 }
 221
 222 }  // namespace url_parse