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- // Copyright 2013 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.
- // Canonicalizer functions for working with and resolving relative URLs.
- #include <algorithm>
- #include <ostream>
- #include "base/check_op.h"
- #include "base/strings/string_util.h"
- #include "url/url_canon.h"
- #include "url/url_canon_internal.h"
- #include "url/url_constants.h"
- #include "url/url_file.h"
- #include "url/url_parse_internal.h"
- #include "url/url_util.h"
- #include "url/url_util_internal.h"
- namespace url {
- namespace {
- // Firefox does a case-sensitive compare (which is probably wrong--Mozilla bug
- // 379034), whereas IE is case-insensitive.
- //
- // We choose to be more permissive like IE. We don't need to worry about
- // unescaping or anything here: neither IE or Firefox allow this. We also
- // don't have to worry about invalid scheme characters since we are comparing
- // against the canonical scheme of the base.
- //
- // The base URL should always be canonical, therefore it should be ASCII.
- template<typename CHAR>
- bool AreSchemesEqual(const char* base,
- const Component& base_scheme,
- const CHAR* cmp,
- const Component& cmp_scheme) {
- if (base_scheme.len != cmp_scheme.len)
- return false;
- for (int i = 0; i < base_scheme.len; i++) {
- // We assume the base is already canonical, so we don't have to
- // canonicalize it.
- if (CanonicalSchemeChar(cmp[cmp_scheme.begin + i]) !=
- base[base_scheme.begin + i])
- return false;
- }
- return true;
- }
- #ifdef WIN32
- // Here, we also allow Windows paths to be represented as "/C:/" so we can be
- // consistent about URL paths beginning with slashes. This function is like
- // DoesBeginWindowsDrivePath except that it also requires a slash at the
- // beginning.
- template<typename CHAR>
- bool DoesBeginSlashWindowsDriveSpec(const CHAR* spec, int start_offset,
- int spec_len) {
- if (start_offset >= spec_len)
- return false;
- return IsURLSlash(spec[start_offset]) &&
- DoesBeginWindowsDriveSpec(spec, start_offset + 1, spec_len);
- }
- #endif // WIN32
- template <typename CHAR>
- bool IsValidScheme(const CHAR* url, const Component& scheme) {
- // Caller should ensure that the |scheme| is not empty.
- DCHECK_NE(0, scheme.len);
- // From https://url.spec.whatwg.org/#scheme-start-state:
- // scheme start state:
- // 1. If c is an ASCII alpha, append c, lowercased, to buffer, and set
- // state to scheme state.
- // 2. Otherwise, if state override is not given, set state to no scheme
- // state, and decrease pointer by one.
- // 3. Otherwise, validation error, return failure.
- // Note that both step 2 and step 3 mean that the scheme was not valid.
- if (!base::IsAsciiAlpha(url[scheme.begin]))
- return false;
- // From https://url.spec.whatwg.org/#scheme-state:
- // scheme state:
- // 1. If c is an ASCII alphanumeric, U+002B (+), U+002D (-), or U+002E
- // (.), append c, lowercased, to buffer.
- // 2. Otherwise, if c is U+003A (:), then [...]
- //
- // We begin at |scheme.begin + 1|, because the character at |scheme.begin| has
- // already been checked by base::IsAsciiAlpha above.
- int scheme_end = scheme.end();
- for (int i = scheme.begin + 1; i < scheme_end; i++) {
- if (!CanonicalSchemeChar(url[i]))
- return false;
- }
- return true;
- }
- // See IsRelativeURL in the header file for usage.
- template<typename CHAR>
- bool DoIsRelativeURL(const char* base,
- const Parsed& base_parsed,
- const CHAR* url,
- int url_len,
- bool is_base_hierarchical,
- bool* is_relative,
- Component* relative_component) {
- *is_relative = false; // So we can default later to not relative.
- // Trim whitespace and construct a new range for the substring.
- int begin = 0;
- TrimURL(url, &begin, &url_len);
- if (begin >= url_len) {
- // Empty URLs are relative, but do nothing.
- if (!is_base_hierarchical) {
- // Don't allow relative URLs if the base scheme doesn't support it.
- return false;
- }
- *relative_component = Component(begin, 0);
- *is_relative = true;
- return true;
- }
- #ifdef WIN32
- // We special case paths like "C:\foo" so they can link directly to the
- // file on Windows (IE compatibility). The security domain stuff should
- // prevent a link like this from actually being followed if its on a
- // web page.
- //
- // We treat "C:/foo" as an absolute URL. We can go ahead and treat "/c:/"
- // as relative, as this will just replace the path when the base scheme
- // is a file and the answer will still be correct.
- //
- // We require strict backslashes when detecting UNC since two forward
- // slashes should be treated a a relative URL with a hostname.
- if (DoesBeginWindowsDriveSpec(url, begin, url_len) ||
- DoesBeginUNCPath(url, begin, url_len, true))
- return true;
- #endif // WIN32
- // See if we've got a scheme, if not, we know this is a relative URL.
- // BUT, just because we have a scheme, doesn't make it absolute.
- // "http:foo.html" is a relative URL with path "foo.html". If the scheme is
- // empty, we treat it as relative (":foo"), like IE does.
- Component scheme;
- const bool scheme_is_empty =
- !ExtractScheme(url, url_len, &scheme) || scheme.len == 0;
- if (scheme_is_empty) {
- if (url[begin] == '#') {
- // |url| is a bare fragment (e.g. "#foo"). This can be resolved against
- // any base. Fall-through.
- } else if (!is_base_hierarchical) {
- // Don't allow relative URLs if the base scheme doesn't support it.
- return false;
- }
- *relative_component = MakeRange(begin, url_len);
- *is_relative = true;
- return true;
- }
- // If the scheme isn't valid, then it's relative.
- if (!IsValidScheme(url, scheme)) {
- if (!is_base_hierarchical) {
- // Don't allow relative URLs if the base scheme doesn't support it.
- return false;
- }
- *relative_component = MakeRange(begin, url_len);
- *is_relative = true;
- return true;
- }
- // If the scheme is not the same, then we can't count it as relative.
- if (!AreSchemesEqual(base, base_parsed.scheme, url, scheme))
- return true;
- // When the scheme that they both share is not hierarchical, treat the
- // incoming scheme as absolute (this way with the base of "data:foo",
- // "data:bar" will be reported as absolute.
- if (!is_base_hierarchical)
- return true;
- int colon_offset = scheme.end();
- // If it's a filesystem URL, the only valid way to make it relative is not to
- // supply a scheme. There's no equivalent to e.g. http:index.html.
- if (CompareSchemeComponent(url, scheme, kFileSystemScheme))
- return true;
- // ExtractScheme guarantees that the colon immediately follows what it
- // considers to be the scheme. CountConsecutiveSlashes will handle the
- // case where the begin offset is the end of the input.
- int num_slashes = CountConsecutiveSlashes(url, colon_offset + 1, url_len);
- if (num_slashes == 0 || num_slashes == 1) {
- // No slashes means it's a relative path like "http:foo.html". One slash
- // is an absolute path. "http:/home/foo.html"
- *is_relative = true;
- *relative_component = MakeRange(colon_offset + 1, url_len);
- return true;
- }
- // Two or more slashes after the scheme we treat as absolute.
- return true;
- }
- // Copies all characters in the range [begin, end) of |spec| to the output,
- // up until and including the last slash. There should be a slash in the
- // range, if not, nothing will be copied.
- //
- // For stardard URLs the input should be canonical, but when resolving relative
- // URLs on a non-standard base (like "data:") the input can be anything.
- void CopyToLastSlash(const char* spec,
- int begin,
- int end,
- CanonOutput* output) {
- // Find the last slash.
- int last_slash = -1;
- for (int i = end - 1; i >= begin; i--) {
- if (spec[i] == '/' || spec[i] == '\\') {
- last_slash = i;
- break;
- }
- }
- if (last_slash < 0)
- return; // No slash.
- // Copy.
- for (int i = begin; i <= last_slash; i++)
- output->push_back(spec[i]);
- }
- // Copies a single component from the source to the output. This is used
- // when resolving relative URLs and a given component is unchanged. Since the
- // source should already be canonical, we don't have to do anything special,
- // and the input is ASCII.
- void CopyOneComponent(const char* source,
- const Component& source_component,
- CanonOutput* output,
- Component* output_component) {
- if (source_component.len < 0) {
- // This component is not present.
- *output_component = Component();
- return;
- }
- output_component->begin = output->length();
- int source_end = source_component.end();
- for (int i = source_component.begin; i < source_end; i++)
- output->push_back(source[i]);
- output_component->len = output->length() - output_component->begin;
- }
- #ifdef WIN32
- // Called on Windows when the base URL is a file URL, this will copy the "C:"
- // to the output, if there is a drive letter and if that drive letter is not
- // being overridden by the relative URL. Otherwise, do nothing.
- //
- // It will return the index of the beginning of the next character in the
- // base to be processed: if there is a "C:", the slash after it, or if
- // there is no drive letter, the slash at the beginning of the path, or
- // the end of the base. This can be used as the starting offset for further
- // path processing.
- template<typename CHAR>
- int CopyBaseDriveSpecIfNecessary(const char* base_url,
- int base_path_begin,
- int base_path_end,
- const CHAR* relative_url,
- int path_start,
- int relative_url_len,
- CanonOutput* output) {
- if (base_path_begin >= base_path_end)
- return base_path_begin; // No path.
- // If the relative begins with a drive spec, don't do anything. The existing
- // drive spec in the base will be replaced.
- if (DoesBeginWindowsDriveSpec(relative_url, path_start, relative_url_len)) {
- return base_path_begin; // Relative URL path is "C:/foo"
- }
- // The path should begin with a slash (as all canonical paths do). We check
- // if it is followed by a drive letter and copy it.
- if (DoesBeginSlashWindowsDriveSpec(base_url,
- base_path_begin,
- base_path_end)) {
- // Copy the two-character drive spec to the output. It will now look like
- // "file:///C:" so the rest of it can be treated like a standard path.
- output->push_back('/');
- output->push_back(base_url[base_path_begin + 1]);
- output->push_back(base_url[base_path_begin + 2]);
- return base_path_begin + 3;
- }
- return base_path_begin;
- }
- #endif // WIN32
- // A subroutine of DoResolveRelativeURL, this resolves the URL knowning that
- // the input is a relative path or less (query or ref).
- template<typename CHAR>
- bool DoResolveRelativePath(const char* base_url,
- const Parsed& base_parsed,
- bool base_is_file,
- const CHAR* relative_url,
- const Component& relative_component,
- CharsetConverter* query_converter,
- CanonOutput* output,
- Parsed* out_parsed) {
- bool success = true;
- // We know the authority section didn't change, copy it to the output. We
- // also know we have a path so can copy up to there.
- Component path, query, ref;
- ParsePathInternal(relative_url, relative_component, &path, &query, &ref);
- // Canonical URLs always have a path, so we can use that offset. Reserve
- // enough room for the base URL, the new path, and some extra bytes for
- // possible escaped characters.
- output->ReserveSizeIfNeeded(base_parsed.path.begin +
- std::max({path.end(), query.end(), ref.end()}));
- output->Append(base_url, base_parsed.path.begin);
- if (path.len > 0) {
- // The path is replaced or modified.
- int true_path_begin = output->length();
- // For file: URLs on Windows, we don't want to treat the drive letter and
- // colon as part of the path for relative file resolution when the
- // incoming URL does not provide a drive spec. We save the true path
- // beginning so we can fix it up after we are done.
- int base_path_begin = base_parsed.path.begin;
- #ifdef WIN32
- if (base_is_file) {
- base_path_begin = CopyBaseDriveSpecIfNecessary(
- base_url, base_parsed.path.begin, base_parsed.path.end(),
- relative_url, relative_component.begin, relative_component.end(),
- output);
- // Now the output looks like either "file://" or "file:///C:"
- // and we can start appending the rest of the path. |base_path_begin|
- // points to the character in the base that comes next.
- }
- #endif // WIN32
- if (IsURLSlash(relative_url[path.begin])) {
- // Easy case: the path is an absolute path on the server, so we can
- // just replace everything from the path on with the new versions.
- // Since the input should be canonical hierarchical URL, we should
- // always have a path.
- success &= CanonicalizePath(relative_url, path,
- output, &out_parsed->path);
- } else {
- // Relative path, replace the query, and reference. We take the
- // original path with the file part stripped, and append the new path.
- // The canonicalizer will take care of resolving ".." and "."
- size_t path_begin = output->length();
- CopyToLastSlash(base_url, base_path_begin, base_parsed.path.end(),
- output);
- success &= CanonicalizePartialPathInternal(relative_url, path, path_begin,
- output);
- out_parsed->path = MakeRange(path_begin, output->length());
- // Copy the rest of the stuff after the path from the relative path.
- }
- // Finish with the query and reference part (these can't fail).
- CanonicalizeQuery(relative_url, query, query_converter,
- output, &out_parsed->query);
- CanonicalizeRef(relative_url, ref, output, &out_parsed->ref);
- // Fix the path beginning to add back the "C:" we may have written above.
- out_parsed->path = MakeRange(true_path_begin, out_parsed->path.end());
- return success;
- }
- // If we get here, the path is unchanged: copy to output.
- CopyOneComponent(base_url, base_parsed.path, output, &out_parsed->path);
- if (query.is_valid()) {
- // Just the query specified, replace the query and reference (ignore
- // failures for refs)
- CanonicalizeQuery(relative_url, query, query_converter,
- output, &out_parsed->query);
- CanonicalizeRef(relative_url, ref, output, &out_parsed->ref);
- return success;
- }
- // If we get here, the query is unchanged: copy to output. Note that the
- // range of the query parameter doesn't include the question mark, so we
- // have to add it manually if there is a component.
- if (base_parsed.query.is_valid())
- output->push_back('?');
- CopyOneComponent(base_url, base_parsed.query, output, &out_parsed->query);
- if (ref.is_valid()) {
- // Just the reference specified: replace it (ignoring failures).
- CanonicalizeRef(relative_url, ref, output, &out_parsed->ref);
- return success;
- }
- // We should always have something to do in this function, the caller checks
- // that some component is being replaced.
- DCHECK(false) << "Not reached";
- return success;
- }
- // Resolves a relative URL that contains a host. Typically, these will
- // be of the form "//www.google.com/foo/bar?baz#ref" and the only thing which
- // should be kept from the original URL is the scheme.
- template<typename CHAR>
- bool DoResolveRelativeHost(const char* base_url,
- const Parsed& base_parsed,
- const CHAR* relative_url,
- const Component& relative_component,
- CharsetConverter* query_converter,
- CanonOutput* output,
- Parsed* out_parsed) {
- // Parse the relative URL, just like we would for anything following a
- // scheme.
- Parsed relative_parsed; // Everything but the scheme is valid.
- ParseAfterScheme(relative_url, relative_component.end(),
- relative_component.begin, &relative_parsed);
- // Now we can just use the replacement function to replace all the necessary
- // parts of the old URL with the new one.
- Replacements<CHAR> replacements;
- replacements.SetUsername(relative_url, relative_parsed.username);
- replacements.SetPassword(relative_url, relative_parsed.password);
- replacements.SetHost(relative_url, relative_parsed.host);
- replacements.SetPort(relative_url, relative_parsed.port);
- replacements.SetPath(relative_url, relative_parsed.path);
- replacements.SetQuery(relative_url, relative_parsed.query);
- replacements.SetRef(relative_url, relative_parsed.ref);
- // Length() does not include the old scheme, so make sure to add it from the
- // base URL.
- output->ReserveSizeIfNeeded(
- replacements.components().Length() +
- base_parsed.CountCharactersBefore(Parsed::USERNAME, false));
- SchemeType scheme_type = SCHEME_WITH_HOST_PORT_AND_USER_INFORMATION;
- if (!GetStandardSchemeType(base_url, base_parsed.scheme, &scheme_type)) {
- // A path with an authority section gets canonicalized under standard URL
- // rules, even though the base was not known to be standard.
- scheme_type = SCHEME_WITH_HOST_PORT_AND_USER_INFORMATION;
- }
- return ReplaceStandardURL(base_url, base_parsed, replacements, scheme_type,
- query_converter, output, out_parsed);
- }
- // Resolves a relative URL that happens to be an absolute file path. Examples
- // include: "//hostname/path", "/c:/foo", and "//hostname/c:/foo".
- template<typename CHAR>
- bool DoResolveAbsoluteFile(const CHAR* relative_url,
- const Component& relative_component,
- CharsetConverter* query_converter,
- CanonOutput* output,
- Parsed* out_parsed) {
- // Parse the file URL. The file URl parsing function uses the same logic
- // as we do for determining if the file is absolute, in which case it will
- // not bother to look for a scheme.
- Parsed relative_parsed;
- ParseFileURL(&relative_url[relative_component.begin], relative_component.len,
- &relative_parsed);
- return CanonicalizeFileURL(&relative_url[relative_component.begin],
- relative_component.len, relative_parsed,
- query_converter, output, out_parsed);
- }
- // TODO(brettw) treat two slashes as root like Mozilla for FTP?
- template<typename CHAR>
- bool DoResolveRelativeURL(const char* base_url,
- const Parsed& base_parsed,
- bool base_is_file,
- const CHAR* relative_url,
- const Component& relative_component,
- CharsetConverter* query_converter,
- CanonOutput* output,
- Parsed* out_parsed) {
- // |base_parsed| is the starting point for our output. Since we may have
- // removed whitespace from |relative_url| before entering this method, we'll
- // carry over the |potentially_dangling_markup| flag.
- bool potentially_dangling_markup = out_parsed->potentially_dangling_markup;
- *out_parsed = base_parsed;
- if (potentially_dangling_markup)
- out_parsed->potentially_dangling_markup = true;
- // Sanity check: the input should have a host or we'll break badly below.
- // We can only resolve relative URLs with base URLs that have hosts and
- // paths (even the default path of "/" is OK).
- //
- // We allow hosts with no length so we can handle file URLs, for example.
- if (base_parsed.path.len <= 0) {
- // On error, return the input (resolving a relative URL on a non-relative
- // base = the base).
- int base_len = base_parsed.Length();
- for (int i = 0; i < base_len; i++)
- output->push_back(base_url[i]);
- return false;
- }
- if (relative_component.len <= 0) {
- // Empty relative URL, leave unchanged, only removing the ref component.
- int base_len = base_parsed.Length();
- base_len -= base_parsed.ref.len + 1;
- out_parsed->ref.reset();
- output->Append(base_url, base_len);
- return true;
- }
- int num_slashes = CountConsecutiveSlashes(
- relative_url, relative_component.begin, relative_component.end());
- #ifdef WIN32
- // On Windows, two slashes for a file path (regardless of which direction
- // they are) means that it's UNC. Two backslashes on any base scheme mean
- // that it's an absolute UNC path (we use the base_is_file flag to control
- // how strict the UNC finder is).
- //
- // We also allow Windows absolute drive specs on any scheme (for example
- // "c:\foo") like IE does. There must be no preceding slashes in this
- // case (we reject anything like "/c:/foo") because that should be treated
- // as a path. For file URLs, we allow any number of slashes since that would
- // be setting the path.
- //
- // This assumes the absolute path resolver handles absolute URLs like this
- // properly. DoCanonicalize does this.
- int after_slashes = relative_component.begin + num_slashes;
- if (DoesBeginUNCPath(relative_url, relative_component.begin,
- relative_component.end(), !base_is_file) ||
- ((num_slashes == 0 || base_is_file) &&
- DoesBeginWindowsDriveSpec(
- relative_url, after_slashes, relative_component.end()))) {
- return DoResolveAbsoluteFile(relative_url, relative_component,
- query_converter, output, out_parsed);
- }
- #else
- // Other platforms need explicit handling for file: URLs with multiple
- // slashes because the generic scheme parsing always extracts a host, but a
- // file: URL only has a host if it has exactly 2 slashes. Even if it does
- // have a host, we want to use the special host detection logic for file
- // URLs provided by DoResolveAbsoluteFile(), as opposed to the generic host
- // detection logic, for consistency with parsing file URLs from scratch.
- if (base_is_file && num_slashes >= 2) {
- return DoResolveAbsoluteFile(relative_url, relative_component,
- query_converter, output, out_parsed);
- }
- #endif
- // Any other double-slashes mean that this is relative to the scheme.
- if (num_slashes >= 2) {
- return DoResolveRelativeHost(base_url, base_parsed,
- relative_url, relative_component,
- query_converter, output, out_parsed);
- }
- // When we get here, we know that the relative URL is on the same host.
- return DoResolveRelativePath(base_url, base_parsed, base_is_file,
- relative_url, relative_component,
- query_converter, output, out_parsed);
- }
- } // namespace
- bool IsRelativeURL(const char* base,
- const Parsed& base_parsed,
- const char* fragment,
- int fragment_len,
- bool is_base_hierarchical,
- bool* is_relative,
- Component* relative_component) {
- return DoIsRelativeURL<char>(
- base, base_parsed, fragment, fragment_len, is_base_hierarchical,
- is_relative, relative_component);
- }
- bool IsRelativeURL(const char* base,
- const Parsed& base_parsed,
- const char16_t* fragment,
- int fragment_len,
- bool is_base_hierarchical,
- bool* is_relative,
- Component* relative_component) {
- return DoIsRelativeURL<char16_t>(base, base_parsed, fragment, fragment_len,
- is_base_hierarchical, is_relative,
- relative_component);
- }
- bool ResolveRelativeURL(const char* base_url,
- const Parsed& base_parsed,
- bool base_is_file,
- const char* relative_url,
- const Component& relative_component,
- CharsetConverter* query_converter,
- CanonOutput* output,
- Parsed* out_parsed) {
- return DoResolveRelativeURL<char>(
- base_url, base_parsed, base_is_file, relative_url,
- relative_component, query_converter, output, out_parsed);
- }
- bool ResolveRelativeURL(const char* base_url,
- const Parsed& base_parsed,
- bool base_is_file,
- const char16_t* relative_url,
- const Component& relative_component,
- CharsetConverter* query_converter,
- CanonOutput* output,
- Parsed* out_parsed) {
- return DoResolveRelativeURL<char16_t>(base_url, base_parsed, base_is_file,
- relative_url, relative_component,
- query_converter, output, out_parsed);
- }
- } // namespace url
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