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      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 #ifndef URL_URL_CANON_H_
      6 #define URL_URL_CANON_H_
      7 
      8 #include <stdlib.h>
      9 #include <string.h>
     10 
     11 #include "base/strings/string16.h"
     12 #include "url/url_export.h"
     13 #include "url/url_parse.h"
     14 
     15 namespace url {
     16 
     17 // Canonicalizer output -------------------------------------------------------
     18 
     19 // Base class for the canonicalizer output, this maintains a buffer and
     20 // supports simple resizing and append operations on it.
     21 //
     22 // It is VERY IMPORTANT that no virtual function calls be made on the common
     23 // code path. We only have two virtual function calls, the destructor and a
     24 // resize function that is called when the existing buffer is not big enough.
     25 // The derived class is then in charge of setting up our buffer which we will
     26 // manage.
     27 template<typename T>
     28 class CanonOutputT {
     29  public:
     30   CanonOutputT() : buffer_(NULL), buffer_len_(0), cur_len_(0) {
     31   }
     32   virtual ~CanonOutputT() {
     33   }
     34 
     35   // Implemented to resize the buffer. This function should update the buffer
     36   // pointer to point to the new buffer, and any old data up to |cur_len_| in
     37   // the buffer must be copied over.
     38   //
     39   // The new size |sz| must be larger than buffer_len_.
     40   virtual void Resize(int sz) = 0;
     41 
     42   // Accessor for returning a character at a given position. The input offset
     43   // must be in the valid range.
     44   inline char at(int offset) const {
     45     return buffer_[offset];
     46   }
     47 
     48   // Sets the character at the given position. The given position MUST be less
     49   // than the length().
     50   inline void set(int offset, int ch) {
     51     buffer_[offset] = ch;
     52   }
     53 
     54   // Returns the number of characters currently in the buffer.
     55   inline int length() const {
     56     return cur_len_;
     57   }
     58 
     59   // Returns the current capacity of the buffer. The length() is the number of
     60   // characters that have been declared to be written, but the capacity() is
     61   // the number that can be written without reallocation. If the caller must
     62   // write many characters at once, it can make sure there is enough capacity,
     63   // write the data, then use set_size() to declare the new length().
     64   int capacity() const {
     65     return buffer_len_;
     66   }
     67 
     68   // Called by the user of this class to get the output. The output will NOT
     69   // be NULL-terminated. Call length() to get the
     70   // length.
     71   const T* data() const {
     72     return buffer_;
     73   }
     74   T* data() {
     75     return buffer_;
     76   }
     77 
     78   // Shortens the URL to the new length. Used for "backing up" when processing
     79   // relative paths. This can also be used if an external function writes a lot
     80   // of data to the buffer (when using the "Raw" version below) beyond the end,
     81   // to declare the new length.
     82   //
     83   // This MUST NOT be used to expand the size of the buffer beyond capacity().
     84   void set_length(int new_len) {
     85     cur_len_ = new_len;
     86   }
     87 
     88   // This is the most performance critical function, since it is called for
     89   // every character.
     90   void push_back(T ch) {
     91     // In VC2005, putting this common case first speeds up execution
     92     // dramatically because this branch is predicted as taken.
     93     if (cur_len_ < buffer_len_) {
     94       buffer_[cur_len_] = ch;
     95       cur_len_++;
     96       return;
     97     }
     98 
     99     // Grow the buffer to hold at least one more item. Hopefully we won't have
    100     // to do this very often.
    101     if (!Grow(1))
    102       return;
    103 
    104     // Actually do the insertion.
    105     buffer_[cur_len_] = ch;
    106     cur_len_++;
    107   }
    108 
    109   // Appends the given string to the output.
    110   void Append(const T* str, int str_len) {
    111     if (cur_len_ + str_len > buffer_len_) {
    112       if (!Grow(cur_len_ + str_len - buffer_len_))
    113         return;
    114     }
    115     for (int i = 0; i < str_len; i++)
    116       buffer_[cur_len_ + i] = str[i];
    117     cur_len_ += str_len;
    118   }
    119 
    120  protected:
    121   // Grows the given buffer so that it can fit at least |min_additional|
    122   // characters. Returns true if the buffer could be resized, false on OOM.
    123   bool Grow(int min_additional) {
    124     static const int kMinBufferLen = 16;
    125     int new_len = (buffer_len_ == 0) ? kMinBufferLen : buffer_len_;
    126     do {
    127       if (new_len >= (1 << 30))  // Prevent overflow below.
    128         return false;
    129       new_len *= 2;
    130     } while (new_len < buffer_len_ + min_additional);
    131     Resize(new_len);
    132     return true;
    133   }
    134 
    135   T* buffer_;
    136   int buffer_len_;
    137 
    138   // Used characters in the buffer.
    139   int cur_len_;
    140 };
    141 
    142 // Simple implementation of the CanonOutput using new[]. This class
    143 // also supports a static buffer so if it is allocated on the stack, most
    144 // URLs can be canonicalized with no heap allocations.
    145 template<typename T, int fixed_capacity = 1024>
    146 class RawCanonOutputT : public CanonOutputT<T> {
    147  public:
    148   RawCanonOutputT() : CanonOutputT<T>() {
    149     this->buffer_ = fixed_buffer_;
    150     this->buffer_len_ = fixed_capacity;
    151   }
    152   virtual ~RawCanonOutputT() {
    153     if (this->buffer_ != fixed_buffer_)
    154       delete[] this->buffer_;
    155   }
    156 
    157   virtual void Resize(int sz) {
    158     T* new_buf = new T[sz];
    159     memcpy(new_buf, this->buffer_,
    160            sizeof(T) * (this->cur_len_ < sz ? this->cur_len_ : sz));
    161     if (this->buffer_ != fixed_buffer_)
    162       delete[] this->buffer_;
    163     this->buffer_ = new_buf;
    164     this->buffer_len_ = sz;
    165   }
    166 
    167  protected:
    168   T fixed_buffer_[fixed_capacity];
    169 };
    170 
    171 // Normally, all canonicalization output is in narrow characters. We support
    172 // the templates so it can also be used internally if a wide buffer is
    173 // required.
    174 typedef CanonOutputT<char> CanonOutput;
    175 typedef CanonOutputT<base::char16> CanonOutputW;
    176 
    177 template<int fixed_capacity>
    178 class RawCanonOutput : public RawCanonOutputT<char, fixed_capacity> {};
    179 template<int fixed_capacity>
    180 class RawCanonOutputW : public RawCanonOutputT<base::char16, fixed_capacity> {};
    181 
    182 // Character set converter ----------------------------------------------------
    183 //
    184 // Converts query strings into a custom encoding. The embedder can supply an
    185 // implementation of this class to interface with their own character set
    186 // conversion libraries.
    187 //
    188 // Embedders will want to see the unit test for the ICU version.
    189 
    190 class URL_EXPORT CharsetConverter {
    191  public:
    192   CharsetConverter() {}
    193   virtual ~CharsetConverter() {}
    194 
    195   // Converts the given input string from UTF-16 to whatever output format the
    196   // converter supports. This is used only for the query encoding conversion,
    197   // which does not fail. Instead, the converter should insert "invalid
    198   // character" characters in the output for invalid sequences, and do the
    199   // best it can.
    200   //
    201   // If the input contains a character not representable in the output
    202   // character set, the converter should append the HTML entity sequence in
    203   // decimal, (such as "&#20320;") with escaping of the ampersand, number
    204   // sign, and semicolon (in the previous example it would be
    205   // "%26%2320320%3B"). This rule is based on what IE does in this situation.
    206   virtual void ConvertFromUTF16(const base::char16* input,
    207                                 int input_len,
    208                                 CanonOutput* output) = 0;
    209 };
    210 
    211 // Whitespace -----------------------------------------------------------------
    212 
    213 // Searches for whitespace that should be removed from the middle of URLs, and
    214 // removes it. Removed whitespace are tabs and newlines, but NOT spaces. Spaces
    215 // are preserved, which is what most browsers do. A pointer to the output will
    216 // be returned, and the length of that output will be in |output_len|.
    217 //
    218 // This should be called before parsing if whitespace removal is desired (which
    219 // it normally is when you are canonicalizing).
    220 //
    221 // If no whitespace is removed, this function will not use the buffer and will
    222 // return a pointer to the input, to avoid the extra copy. If modification is
    223 // required, the given |buffer| will be used and the returned pointer will
    224 // point to the beginning of the buffer.
    225 //
    226 // Therefore, callers should not use the buffer, since it may actually be empty,
    227 // use the computed pointer and |*output_len| instead.
    228 URL_EXPORT const char* RemoveURLWhitespace(const char* input, int input_len,
    229                                            CanonOutputT<char>* buffer,
    230                                            int* output_len);
    231 URL_EXPORT const base::char16* RemoveURLWhitespace(
    232     const base::char16* input,
    233     int input_len,
    234     CanonOutputT<base::char16>* buffer,
    235     int* output_len);
    236 
    237 // IDN ------------------------------------------------------------------------
    238 
    239 // Converts the Unicode input representing a hostname to ASCII using IDN rules.
    240 // The output must fall in the ASCII range, but will be encoded in UTF-16.
    241 //
    242 // On success, the output will be filled with the ASCII host name and it will
    243 // return true. Unlike most other canonicalization functions, this assumes that
    244 // the output is empty. The beginning of the host will be at offset 0, and
    245 // the length of the output will be set to the length of the new host name.
    246 //
    247 // On error, returns false. The output in this case is undefined.
    248 URL_EXPORT bool IDNToASCII(const base::char16* src,
    249                            int src_len,
    250                            CanonOutputW* output);
    251 
    252 // Piece-by-piece canonicalizers ----------------------------------------------
    253 //
    254 // These individual canonicalizers append the canonicalized versions of the
    255 // corresponding URL component to the given std::string. The spec and the
    256 // previously-identified range of that component are the input. The range of
    257 // the canonicalized component will be written to the output component.
    258 //
    259 // These functions all append to the output so they can be chained. Make sure
    260 // the output is empty when you start.
    261 //
    262 // These functions returns boolean values indicating success. On failure, they
    263 // will attempt to write something reasonable to the output so that, if
    264 // displayed to the user, they will recognise it as something that's messed up.
    265 // Nothing more should ever be done with these invalid URLs, however.
    266 
    267 // Scheme: Appends the scheme and colon to the URL. The output component will
    268 // indicate the range of characters up to but not including the colon.
    269 //
    270 // Canonical URLs always have a scheme. If the scheme is not present in the
    271 // input, this will just write the colon to indicate an empty scheme. Does not
    272 // append slashes which will be needed before any authority components for most
    273 // URLs.
    274 //
    275 // The 8-bit version requires UTF-8 encoding.
    276 URL_EXPORT bool CanonicalizeScheme(const char* spec,
    277                                    const Component& scheme,
    278                                    CanonOutput* output,
    279                                    Component* out_scheme);
    280 URL_EXPORT bool CanonicalizeScheme(const base::char16* spec,
    281                                    const Component& scheme,
    282                                    CanonOutput* output,
    283                                    Component* out_scheme);
    284 
    285 // User info: username/password. If present, this will add the delimiters so
    286 // the output will be "<username>:<password>@" or "<username>@". Empty
    287 // username/password pairs, or empty passwords, will get converted to
    288 // nonexistant in the canonical version.
    289 //
    290 // The components for the username and password refer to ranges in the
    291 // respective source strings. Usually, these will be the same string, which
    292 // is legal as long as the two components don't overlap.
    293 //
    294 // The 8-bit version requires UTF-8 encoding.
    295 URL_EXPORT bool CanonicalizeUserInfo(const char* username_source,
    296                                      const Component& username,
    297                                      const char* password_source,
    298                                      const Component& password,
    299                                      CanonOutput* output,
    300                                      Component* out_username,
    301                                      Component* out_password);
    302 URL_EXPORT bool CanonicalizeUserInfo(const base::char16* username_source,
    303                                      const Component& username,
    304                                      const base::char16* password_source,
    305                                      const Component& password,
    306                                      CanonOutput* output,
    307                                      Component* out_username,
    308                                      Component* out_password);
    309 
    310 // This structure holds detailed state exported from the IP/Host canonicalizers.
    311 // Additional fields may be added as callers require them.
    312 struct CanonHostInfo {
    313   CanonHostInfo() : family(NEUTRAL), num_ipv4_components(0), out_host() {}
    314 
    315   // Convenience function to test if family is an IP address.
    316   bool IsIPAddress() const { return family == IPV4 || family == IPV6; }
    317 
    318   // This field summarizes how the input was classified by the canonicalizer.
    319   enum Family {
    320     NEUTRAL,   // - Doesn't resemble an IP address.  As far as the IP
    321                //   canonicalizer is concerned, it should be treated as a
    322                //   hostname.
    323     BROKEN,    // - Almost an IP, but was not canonicalized.  This could be an
    324                //   IPv4 address where truncation occurred, or something
    325                //   containing the special characters :[] which did not parse
    326                //   as an IPv6 address.  Never attempt to connect to this
    327                //   address, because it might actually succeed!
    328     IPV4,      // - Successfully canonicalized as an IPv4 address.
    329     IPV6,      // - Successfully canonicalized as an IPv6 address.
    330   };
    331   Family family;
    332 
    333   // If |family| is IPV4, then this is the number of nonempty dot-separated
    334   // components in the input text, from 1 to 4.  If |family| is not IPV4,
    335   // this value is undefined.
    336   int num_ipv4_components;
    337 
    338   // Location of host within the canonicalized output.
    339   // CanonicalizeIPAddress() only sets this field if |family| is IPV4 or IPV6.
    340   // CanonicalizeHostVerbose() always sets it.
    341   Component out_host;
    342 
    343   // |address| contains the parsed IP Address (if any) in its first
    344   // AddressLength() bytes, in network order. If IsIPAddress() is false
    345   // AddressLength() will return zero and the content of |address| is undefined.
    346   unsigned char address[16];
    347 
    348   // Convenience function to calculate the length of an IP address corresponding
    349   // to the current IP version in |family|, if any. For use with |address|.
    350   int AddressLength() const {
    351     return family == IPV4 ? 4 : (family == IPV6 ? 16 : 0);
    352   }
    353 };
    354 
    355 
    356 // Host.
    357 //
    358 // The 8-bit version requires UTF-8 encoding.  Use this version when you only
    359 // need to know whether canonicalization succeeded.
    360 URL_EXPORT bool CanonicalizeHost(const char* spec,
    361                                  const Component& host,
    362                                  CanonOutput* output,
    363                                  Component* out_host);
    364 URL_EXPORT bool CanonicalizeHost(const base::char16* spec,
    365                                  const Component& host,
    366                                  CanonOutput* output,
    367                                  Component* out_host);
    368 
    369 // Extended version of CanonicalizeHost, which returns additional information.
    370 // Use this when you need to know whether the hostname was an IP address.
    371 // A successful return is indicated by host_info->family != BROKEN.  See the
    372 // definition of CanonHostInfo above for details.
    373 URL_EXPORT void CanonicalizeHostVerbose(const char* spec,
    374                                         const Component& host,
    375                                         CanonOutput* output,
    376                                         CanonHostInfo* host_info);
    377 URL_EXPORT void CanonicalizeHostVerbose(const base::char16* spec,
    378                                         const Component& host,
    379                                         CanonOutput* output,
    380                                         CanonHostInfo* host_info);
    381 
    382 // IP addresses.
    383 //
    384 // Tries to interpret the given host name as an IPv4 or IPv6 address. If it is
    385 // an IP address, it will canonicalize it as such, appending it to |output|.
    386 // Additional status information is returned via the |*host_info| parameter.
    387 // See the definition of CanonHostInfo above for details.
    388 //
    389 // This is called AUTOMATICALLY from the host canonicalizer, which ensures that
    390 // the input is unescaped and name-prepped, etc. It should not normally be
    391 // necessary or wise to call this directly.
    392 URL_EXPORT void CanonicalizeIPAddress(const char* spec,
    393                                       const Component& host,
    394                                       CanonOutput* output,
    395                                       CanonHostInfo* host_info);
    396 URL_EXPORT void CanonicalizeIPAddress(const base::char16* spec,
    397                                       const Component& host,
    398                                       CanonOutput* output,
    399                                       CanonHostInfo* host_info);
    400 
    401 // Port: this function will add the colon for the port if a port is present.
    402 // The caller can pass PORT_UNSPECIFIED as the
    403 // default_port_for_scheme argument if there is no default port.
    404 //
    405 // The 8-bit version requires UTF-8 encoding.
    406 URL_EXPORT bool CanonicalizePort(const char* spec,
    407                                  const Component& port,
    408                                  int default_port_for_scheme,
    409                                  CanonOutput* output,
    410                                  Component* out_port);
    411 URL_EXPORT bool CanonicalizePort(const base::char16* spec,
    412                                  const Component& port,
    413                                  int default_port_for_scheme,
    414                                  CanonOutput* output,
    415                                  Component* out_port);
    416 
    417 // Returns the default port for the given canonical scheme, or PORT_UNSPECIFIED
    418 // if the scheme is unknown.
    419 URL_EXPORT int DefaultPortForScheme(const char* scheme, int scheme_len);
    420 
    421 // Path. If the input does not begin in a slash (including if the input is
    422 // empty), we'll prepend a slash to the path to make it canonical.
    423 //
    424 // The 8-bit version assumes UTF-8 encoding, but does not verify the validity
    425 // of the UTF-8 (i.e., you can have invalid UTF-8 sequences, invalid
    426 // characters, etc.). Normally, URLs will come in as UTF-16, so this isn't
    427 // an issue. Somebody giving us an 8-bit path is responsible for generating
    428 // the path that the server expects (we'll escape high-bit characters), so
    429 // if something is invalid, it's their problem.
    430 URL_EXPORT bool CanonicalizePath(const char* spec,
    431                                  const Component& path,
    432                                  CanonOutput* output,
    433                                  Component* out_path);
    434 URL_EXPORT bool CanonicalizePath(const base::char16* spec,
    435                                  const Component& path,
    436                                  CanonOutput* output,
    437                                  Component* out_path);
    438 
    439 // Canonicalizes the input as a file path. This is like CanonicalizePath except
    440 // that it also handles Windows drive specs. For example, the path can begin
    441 // with "c|\" and it will get properly canonicalized to "C:/".
    442 // The string will be appended to |*output| and |*out_path| will be updated.
    443 //
    444 // The 8-bit version requires UTF-8 encoding.
    445 URL_EXPORT bool FileCanonicalizePath(const char* spec,
    446                                      const Component& path,
    447                                      CanonOutput* output,
    448                                      Component* out_path);
    449 URL_EXPORT bool FileCanonicalizePath(const base::char16* spec,
    450                                      const Component& path,
    451                                      CanonOutput* output,
    452                                      Component* out_path);
    453 
    454 // Query: Prepends the ? if needed.
    455 //
    456 // The 8-bit version requires the input to be UTF-8 encoding. Incorrectly
    457 // encoded characters (in UTF-8 or UTF-16) will be replaced with the Unicode
    458 // "invalid character." This function can not fail, we always just try to do
    459 // our best for crazy input here since web pages can set it themselves.
    460 //
    461 // This will convert the given input into the output encoding that the given
    462 // character set converter object provides. The converter will only be called
    463 // if necessary, for ASCII input, no conversions are necessary.
    464 //
    465 // The converter can be NULL. In this case, the output encoding will be UTF-8.
    466 URL_EXPORT void CanonicalizeQuery(const char* spec,
    467                                   const Component& query,
    468                                   CharsetConverter* converter,
    469                                   CanonOutput* output,
    470                                   Component* out_query);
    471 URL_EXPORT void CanonicalizeQuery(const base::char16* spec,
    472                                   const Component& query,
    473                                   CharsetConverter* converter,
    474                                   CanonOutput* output,
    475                                   Component* out_query);
    476 
    477 // Ref: Prepends the # if needed. The output will be UTF-8 (this is the only
    478 // canonicalizer that does not produce ASCII output). The output is
    479 // guaranteed to be valid UTF-8.
    480 //
    481 // This function will not fail. If the input is invalid UTF-8/UTF-16, we'll use
    482 // the "Unicode replacement character" for the confusing bits and copy the rest.
    483 URL_EXPORT void CanonicalizeRef(const char* spec,
    484                                 const Component& path,
    485                                 CanonOutput* output,
    486                                 Component* out_path);
    487 URL_EXPORT void CanonicalizeRef(const base::char16* spec,
    488                                 const Component& path,
    489                                 CanonOutput* output,
    490                                 Component* out_path);
    491 
    492 // Full canonicalizer ---------------------------------------------------------
    493 //
    494 // These functions replace any string contents, rather than append as above.
    495 // See the above piece-by-piece functions for information specific to
    496 // canonicalizing individual components.
    497 //
    498 // The output will be ASCII except the reference fragment, which may be UTF-8.
    499 //
    500 // The 8-bit versions require UTF-8 encoding.
    501 
    502 // Use for standard URLs with authorities and paths.
    503 URL_EXPORT bool CanonicalizeStandardURL(const char* spec,
    504                                         int spec_len,
    505                                         const Parsed& parsed,
    506                                         CharsetConverter* query_converter,
    507                                         CanonOutput* output,
    508                                         Parsed* new_parsed);
    509 URL_EXPORT bool CanonicalizeStandardURL(const base::char16* spec,
    510                                         int spec_len,
    511                                         const Parsed& parsed,
    512                                         CharsetConverter* query_converter,
    513                                         CanonOutput* output,
    514                                         Parsed* new_parsed);
    515 
    516 // Use for file URLs.
    517 URL_EXPORT bool CanonicalizeFileURL(const char* spec,
    518                                     int spec_len,
    519                                     const Parsed& parsed,
    520                                     CharsetConverter* query_converter,
    521                                     CanonOutput* output,
    522                                     Parsed* new_parsed);
    523 URL_EXPORT bool CanonicalizeFileURL(const base::char16* spec,
    524                                     int spec_len,
    525                                     const Parsed& parsed,
    526                                     CharsetConverter* query_converter,
    527                                     CanonOutput* output,
    528                                     Parsed* new_parsed);
    529 
    530 // Use for filesystem URLs.
    531 URL_EXPORT bool CanonicalizeFileSystemURL(const char* spec,
    532                                           int spec_len,
    533                                           const Parsed& parsed,
    534                                           CharsetConverter* query_converter,
    535                                           CanonOutput* output,
    536                                           Parsed* new_parsed);
    537 URL_EXPORT bool CanonicalizeFileSystemURL(const base::char16* spec,
    538                                           int spec_len,
    539                                           const Parsed& parsed,
    540                                           CharsetConverter* query_converter,
    541                                           CanonOutput* output,
    542                                           Parsed* new_parsed);
    543 
    544 // Use for path URLs such as javascript. This does not modify the path in any
    545 // way, for example, by escaping it.
    546 URL_EXPORT bool CanonicalizePathURL(const char* spec,
    547                                     int spec_len,
    548                                     const Parsed& parsed,
    549                                     CanonOutput* output,
    550                                     Parsed* new_parsed);
    551 URL_EXPORT bool CanonicalizePathURL(const base::char16* spec,
    552                                     int spec_len,
    553                                     const Parsed& parsed,
    554                                     CanonOutput* output,
    555                                     Parsed* new_parsed);
    556 
    557 // Use for mailto URLs. This "canonicalizes" the url into a path and query
    558 // component. It does not attempt to merge "to" fields. It uses UTF-8 for
    559 // the query encoding if there is a query. This is because a mailto URL is
    560 // really intended for an external mail program, and the encoding of a page,
    561 // etc. which would influence a query encoding normally are irrelevant.
    562 URL_EXPORT bool CanonicalizeMailtoURL(const char* spec,
    563                                       int spec_len,
    564                                       const Parsed& parsed,
    565                                       CanonOutput* output,
    566                                       Parsed* new_parsed);
    567 URL_EXPORT bool CanonicalizeMailtoURL(const base::char16* spec,
    568                                       int spec_len,
    569                                       const Parsed& parsed,
    570                                       CanonOutput* output,
    571                                       Parsed* new_parsed);
    572 
    573 // Part replacer --------------------------------------------------------------
    574 
    575 // Internal structure used for storing separate strings for each component.
    576 // The basic canonicalization functions use this structure internally so that
    577 // component replacement (different strings for different components) can be
    578 // treated on the same code path as regular canonicalization (the same string
    579 // for each component).
    580 //
    581 // A Parsed structure usually goes along with this. Those
    582 // components identify offsets within these strings, so that they can all be
    583 // in the same string, or spread arbitrarily across different ones.
    584 //
    585 // This structures does not own any data. It is the caller's responsibility to
    586 // ensure that the data the pointers point to stays in scope and is not
    587 // modified.
    588 template<typename CHAR>
    589 struct URLComponentSource {
    590   // Constructor normally used by callers wishing to replace components. This
    591   // will make them all NULL, which is no replacement. The caller would then
    592   // override the components they want to replace.
    593   URLComponentSource()
    594       : scheme(NULL),
    595         username(NULL),
    596         password(NULL),
    597         host(NULL),
    598         port(NULL),
    599         path(NULL),
    600         query(NULL),
    601         ref(NULL) {
    602   }
    603 
    604   // Constructor normally used internally to initialize all the components to
    605   // point to the same spec.
    606   explicit URLComponentSource(const CHAR* default_value)
    607       : scheme(default_value),
    608         username(default_value),
    609         password(default_value),
    610         host(default_value),
    611         port(default_value),
    612         path(default_value),
    613         query(default_value),
    614         ref(default_value) {
    615   }
    616 
    617   const CHAR* scheme;
    618   const CHAR* username;
    619   const CHAR* password;
    620   const CHAR* host;
    621   const CHAR* port;
    622   const CHAR* path;
    623   const CHAR* query;
    624   const CHAR* ref;
    625 };
    626 
    627 // This structure encapsulates information on modifying a URL. Each component
    628 // may either be left unchanged, replaced, or deleted.
    629 //
    630 // By default, each component is unchanged. For those components that should be
    631 // modified, call either Set* or Clear* to modify it.
    632 //
    633 // The string passed to Set* functions DOES NOT GET COPIED AND MUST BE KEPT
    634 // IN SCOPE BY THE CALLER for as long as this object exists!
    635 //
    636 // Prefer the 8-bit replacement version if possible since it is more efficient.
    637 template<typename CHAR>
    638 class Replacements {
    639  public:
    640   Replacements() {
    641   }
    642 
    643   // Scheme
    644   void SetScheme(const CHAR* s, const Component& comp) {
    645     sources_.scheme = s;
    646     components_.scheme = comp;
    647   }
    648   // Note: we don't have a ClearScheme since this doesn't make any sense.
    649   bool IsSchemeOverridden() const { return sources_.scheme != NULL; }
    650 
    651   // Username
    652   void SetUsername(const CHAR* s, const Component& comp) {
    653     sources_.username = s;
    654     components_.username = comp;
    655   }
    656   void ClearUsername() {
    657     sources_.username = Placeholder();
    658     components_.username = Component();
    659   }
    660   bool IsUsernameOverridden() const { return sources_.username != NULL; }
    661 
    662   // Password
    663   void SetPassword(const CHAR* s, const Component& comp) {
    664     sources_.password = s;
    665     components_.password = comp;
    666   }
    667   void ClearPassword() {
    668     sources_.password = Placeholder();
    669     components_.password = Component();
    670   }
    671   bool IsPasswordOverridden() const { return sources_.password != NULL; }
    672 
    673   // Host
    674   void SetHost(const CHAR* s, const Component& comp) {
    675     sources_.host = s;
    676     components_.host = comp;
    677   }
    678   void ClearHost() {
    679     sources_.host = Placeholder();
    680     components_.host = Component();
    681   }
    682   bool IsHostOverridden() const { return sources_.host != NULL; }
    683 
    684   // Port
    685   void SetPort(const CHAR* s, const Component& comp) {
    686     sources_.port = s;
    687     components_.port = comp;
    688   }
    689   void ClearPort() {
    690     sources_.port = Placeholder();
    691     components_.port = Component();
    692   }
    693   bool IsPortOverridden() const { return sources_.port != NULL; }
    694 
    695   // Path
    696   void SetPath(const CHAR* s, const Component& comp) {
    697     sources_.path = s;
    698     components_.path = comp;
    699   }
    700   void ClearPath() {
    701     sources_.path = Placeholder();
    702     components_.path = Component();
    703   }
    704   bool IsPathOverridden() const { return sources_.path != NULL; }
    705 
    706   // Query
    707   void SetQuery(const CHAR* s, const Component& comp) {
    708     sources_.query = s;
    709     components_.query = comp;
    710   }
    711   void ClearQuery() {
    712     sources_.query = Placeholder();
    713     components_.query = Component();
    714   }
    715   bool IsQueryOverridden() const { return sources_.query != NULL; }
    716 
    717   // Ref
    718   void SetRef(const CHAR* s, const Component& comp) {
    719     sources_.ref = s;
    720     components_.ref = comp;
    721   }
    722   void ClearRef() {
    723     sources_.ref = Placeholder();
    724     components_.ref = Component();
    725   }
    726   bool IsRefOverridden() const { return sources_.ref != NULL; }
    727 
    728   // Getters for the itnernal data. See the variables below for how the
    729   // information is encoded.
    730   const URLComponentSource<CHAR>& sources() const { return sources_; }
    731   const Parsed& components() const { return components_; }
    732 
    733  private:
    734   // Returns a pointer to a static empty string that is used as a placeholder
    735   // to indicate a component should be deleted (see below).
    736   const CHAR* Placeholder() {
    737     static const CHAR empty_string = 0;
    738     return &empty_string;
    739   }
    740 
    741   // We support three states:
    742   //
    743   // Action                 | Source                Component
    744   // -----------------------+--------------------------------------------------
    745   // Don't change component | NULL                  (unused)
    746   // Replace component      | (replacement string)  (replacement component)
    747   // Delete component       | (non-NULL)            (invalid component: (0,-1))
    748   //
    749   // We use a pointer to the empty string for the source when the component
    750   // should be deleted.
    751   URLComponentSource<CHAR> sources_;
    752   Parsed components_;
    753 };
    754 
    755 // The base must be an 8-bit canonical URL.
    756 URL_EXPORT bool ReplaceStandardURL(const char* base,
    757                                    const Parsed& base_parsed,
    758                                    const Replacements<char>& replacements,
    759                                    CharsetConverter* query_converter,
    760                                    CanonOutput* output,
    761                                    Parsed* new_parsed);
    762 URL_EXPORT bool ReplaceStandardURL(
    763     const char* base,
    764     const Parsed& base_parsed,
    765     const Replacements<base::char16>& replacements,
    766     CharsetConverter* query_converter,
    767     CanonOutput* output,
    768     Parsed* new_parsed);
    769 
    770 // Filesystem URLs can only have the path, query, or ref replaced.
    771 // All other components will be ignored.
    772 URL_EXPORT bool ReplaceFileSystemURL(const char* base,
    773                                      const Parsed& base_parsed,
    774                                      const Replacements<char>& replacements,
    775                                      CharsetConverter* query_converter,
    776                                      CanonOutput* output,
    777                                      Parsed* new_parsed);
    778 URL_EXPORT bool ReplaceFileSystemURL(
    779     const char* base,
    780     const Parsed& base_parsed,
    781     const Replacements<base::char16>& replacements,
    782     CharsetConverter* query_converter,
    783     CanonOutput* output,
    784     Parsed* new_parsed);
    785 
    786 // Replacing some parts of a file URL is not permitted. Everything except
    787 // the host, path, query, and ref will be ignored.
    788 URL_EXPORT bool ReplaceFileURL(const char* base,
    789                                const Parsed& base_parsed,
    790                                const Replacements<char>& replacements,
    791                                CharsetConverter* query_converter,
    792                                CanonOutput* output,
    793                                Parsed* new_parsed);
    794 URL_EXPORT bool ReplaceFileURL(const char* base,
    795                                const Parsed& base_parsed,
    796                                const Replacements<base::char16>& replacements,
    797                                CharsetConverter* query_converter,
    798                                CanonOutput* output,
    799                                Parsed* new_parsed);
    800 
    801 // Path URLs can only have the scheme and path replaced. All other components
    802 // will be ignored.
    803 URL_EXPORT bool ReplacePathURL(const char* base,
    804                                const Parsed& base_parsed,
    805                                const Replacements<char>& replacements,
    806                                CanonOutput* output,
    807                                Parsed* new_parsed);
    808 URL_EXPORT bool ReplacePathURL(const char* base,
    809                                const Parsed& base_parsed,
    810                                const Replacements<base::char16>& replacements,
    811                                CanonOutput* output,
    812                                Parsed* new_parsed);
    813 
    814 // Mailto URLs can only have the scheme, path, and query replaced.
    815 // All other components will be ignored.
    816 URL_EXPORT bool ReplaceMailtoURL(const char* base,
    817                                  const Parsed& base_parsed,
    818                                  const Replacements<char>& replacements,
    819                                  CanonOutput* output,
    820                                  Parsed* new_parsed);
    821 URL_EXPORT bool ReplaceMailtoURL(const char* base,
    822                                  const Parsed& base_parsed,
    823                                  const Replacements<base::char16>& replacements,
    824                                  CanonOutput* output,
    825                                  Parsed* new_parsed);
    826 
    827 // Relative URL ---------------------------------------------------------------
    828 
    829 // Given an input URL or URL fragment |fragment|, determines if it is a
    830 // relative or absolute URL and places the result into |*is_relative|. If it is
    831 // relative, the relevant portion of the URL will be placed into
    832 // |*relative_component| (there may have been trimmed whitespace, for example).
    833 // This value is passed to ResolveRelativeURL. If the input is not relative,
    834 // this value is UNDEFINED (it may be changed by the function).
    835 //
    836 // Returns true on success (we successfully determined the URL is relative or
    837 // not). Failure means that the combination of URLs doesn't make any sense.
    838 //
    839 // The base URL should always be canonical, therefore is ASCII.
    840 URL_EXPORT bool IsRelativeURL(const char* base,
    841                               const Parsed& base_parsed,
    842                               const char* fragment,
    843                               int fragment_len,
    844                               bool is_base_hierarchical,
    845                               bool* is_relative,
    846                               Component* relative_component);
    847 URL_EXPORT bool IsRelativeURL(const char* base,
    848                               const Parsed& base_parsed,
    849                               const base::char16* fragment,
    850                               int fragment_len,
    851                               bool is_base_hierarchical,
    852                               bool* is_relative,
    853                               Component* relative_component);
    854 
    855 // Given a canonical parsed source URL, a URL fragment known to be relative,
    856 // and the identified relevant portion of the relative URL (computed by
    857 // IsRelativeURL), this produces a new parsed canonical URL in |output| and
    858 // |out_parsed|.
    859 //
    860 // It also requires a flag indicating whether the base URL is a file: URL
    861 // which triggers additional logic.
    862 //
    863 // The base URL should be canonical and have a host (may be empty for file
    864 // URLs) and a path. If it doesn't have these, we can't resolve relative
    865 // URLs off of it and will return the base as the output with an error flag.
    866 // Becausee it is canonical is should also be ASCII.
    867 //
    868 // The query charset converter follows the same rules as CanonicalizeQuery.
    869 //
    870 // Returns true on success. On failure, the output will be "something
    871 // reasonable" that will be consistent and valid, just probably not what
    872 // was intended by the web page author or caller.
    873 URL_EXPORT bool ResolveRelativeURL(const char* base_url,
    874                                    const Parsed& base_parsed,
    875                                    bool base_is_file,
    876                                    const char* relative_url,
    877                                    const Component& relative_component,
    878                                    CharsetConverter* query_converter,
    879                                    CanonOutput* output,
    880                                    Parsed* out_parsed);
    881 URL_EXPORT bool ResolveRelativeURL(const char* base_url,
    882                                    const Parsed& base_parsed,
    883                                    bool base_is_file,
    884                                    const base::char16* relative_url,
    885                                    const Component& relative_component,
    886                                    CharsetConverter* query_converter,
    887                                    CanonOutput* output,
    888                                    Parsed* out_parsed);
    889 
    890 }  // namespace url
    891 
    892 #endif  // URL_URL_CANON_H_
    893