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      1 // Copyright 2007, Google Inc.
      2 // All rights reserved.
      3 //
      4 // Redistribution and use in source and binary forms, with or without
      5 // modification, are permitted provided that the following conditions are
      6 // met:
      7 //
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      9 // notice, this list of conditions and the following disclaimer.
     10 //     * Redistributions in binary form must reproduce the above
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     28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29 #ifndef GOOGLEURL_SRC_URL_CANON_H__
     30 #define GOOGLEURL_SRC_URL_CANON_H__
     31 
     32 #include <memory.h>
     33 #include <stdlib.h>
     34 
     35 #include "base/string16.h"
     36 #include "googleurl/src/url_common.h"
     37 #include "googleurl/src/url_parse.h"
     38 
     39 namespace url_canon {
     40 
     41 // Canonicalizer output -------------------------------------------------------
     42 
     43 // Base class for the canonicalizer output, this maintains a buffer and
     44 // supports simple resizing and append operations on it.
     45 //
     46 // It is VERY IMPORTANT that no virtual function calls be made on the common
     47 // code path. We only have two virtual function calls, the destructor and a
     48 // resize function that is called when the existing buffer is not big enough.
     49 // The derived class is then in charge of setting up our buffer which we will
     50 // manage.
     51 template<typename T>
     52 class CanonOutputT {
     53  public:
     54   CanonOutputT() : buffer_(NULL), buffer_len_(0), cur_len_(0) {
     55   }
     56   virtual ~CanonOutputT() {
     57   }
     58 
     59   // Implemented to resize the buffer. This function should update the buffer
     60   // pointer to point to the new buffer, and any old data up to |cur_len_| in
     61   // the buffer must be copied over.
     62   //
     63   // The new size |sz| must be larger than buffer_len_.
     64   virtual void Resize(int sz) = 0;
     65 
     66   // Accessor for returning a character at a given position. The input offset
     67   // must be in the valid range.
     68   inline char at(int offset) const {
     69     return buffer_[offset];
     70   }
     71 
     72   // Sets the character at the given position. The given position MUST be less
     73   // than the length().
     74   inline void set(int offset, int ch) {
     75     buffer_[offset] = ch;
     76   }
     77 
     78   // Returns the number of characters currently in the buffer.
     79   inline int length() const {
     80     return cur_len_;
     81   }
     82 
     83   // Returns the current capacity of the buffer. The length() is the number of
     84   // characters that have been declared to be written, but the capacity() is
     85   // the number that can be written without reallocation. If the caller must
     86   // write many characters at once, it can make sure there is enough capacity,
     87   // write the data, then use set_size() to declare the new length().
     88   int capacity() const {
     89     return buffer_len_;
     90   }
     91 
     92   // Called by the user of this class to get the output. The output will NOT
     93   // be NULL-terminated. Call length() to get the
     94   // length.
     95   const T* data() const {
     96     return buffer_;
     97   }
     98   T* data() {
     99     return buffer_;
    100   }
    101 
    102   // Shortens the URL to the new length. Used for "backing up" when processing
    103   // relative paths. This can also be used if an external function writes a lot
    104   // of data to the buffer (when using the "Raw" version below) beyond the end,
    105   // to declare the new length.
    106   //
    107   // This MUST NOT be used to expand the size of the buffer beyond capacity().
    108   void set_length(int new_len) {
    109     cur_len_ = new_len;
    110   }
    111 
    112   // This is the most performance critical function, since it is called for
    113   // every character.
    114   void push_back(T ch) {
    115     // In VC2005, putting this common case first speeds up execution
    116     // dramatically because this branch is predicted as taken.
    117     if (cur_len_ < buffer_len_) {
    118       buffer_[cur_len_] = ch;
    119       cur_len_++;
    120       return;
    121     }
    122 
    123     // Grow the buffer to hold at least one more item. Hopefully we won't have
    124     // to do this very often.
    125     if (!Grow(1))
    126       return;
    127 
    128     // Actually do the insertion.
    129     buffer_[cur_len_] = ch;
    130     cur_len_++;
    131   }
    132 
    133   // Appends the given string to the output.
    134   void Append(const T* str, int str_len) {
    135     if (cur_len_ + str_len > buffer_len_) {
    136       if (!Grow(cur_len_ + str_len - buffer_len_))
    137         return;
    138     }
    139     for (int i = 0; i < str_len; i++)
    140       buffer_[cur_len_ + i] = str[i];
    141     cur_len_ += str_len;
    142   }
    143 
    144  protected:
    145   // Grows the given buffer so that it can fit at least |min_additional|
    146   // characters. Returns true if the buffer could be resized, false on OOM.
    147   bool Grow(int min_additional) {
    148     static const int kMinBufferLen = 16;
    149     int new_len = (buffer_len_ == 0) ? kMinBufferLen : buffer_len_;
    150     do {
    151       if (new_len >= (1 << 30))  // Prevent overflow below.
    152         return false;
    153       new_len *= 2;
    154     } while (new_len < buffer_len_ + min_additional);
    155     Resize(new_len);
    156     return true;
    157   }
    158 
    159   T* buffer_;
    160   int buffer_len_;
    161 
    162   // Used characters in the buffer.
    163   int cur_len_;
    164 };
    165 
    166 // Simple implementation of the CanonOutput using new[]. This class
    167 // also supports a static buffer so if it is allocated on the stack, most
    168 // URLs can be canonicalized with no heap allocations.
    169 template<typename T, int fixed_capacity = 1024>
    170 class RawCanonOutputT : public CanonOutputT<T> {
    171  public:
    172   RawCanonOutputT() : CanonOutputT<T>() {
    173     this->buffer_ = fixed_buffer_;
    174     this->buffer_len_ = fixed_capacity;
    175   }
    176   virtual ~RawCanonOutputT() {
    177     if (this->buffer_ != fixed_buffer_)
    178       delete[] this->buffer_;
    179   }
    180 
    181   virtual void Resize(int sz) {
    182     T* new_buf = new T[sz];
    183     memcpy(new_buf, this->buffer_,
    184            sizeof(T) * (this->cur_len_ < sz ? this->cur_len_ : sz));
    185     if (this->buffer_ != fixed_buffer_)
    186       delete[] this->buffer_;
    187     this->buffer_ = new_buf;
    188     this->buffer_len_ = sz;
    189   }
    190 
    191  protected:
    192   T fixed_buffer_[fixed_capacity];
    193 };
    194 
    195 // Normally, all canonicalization output is in narrow characters. We support
    196 // the templates so it can also be used internally if a wide buffer is
    197 // required.
    198 typedef CanonOutputT<char> CanonOutput;
    199 typedef CanonOutputT<char16> CanonOutputW;
    200 
    201 template<int fixed_capacity>
    202 class RawCanonOutput : public RawCanonOutputT<char, fixed_capacity> {};
    203 template<int fixed_capacity>
    204 class RawCanonOutputW : public RawCanonOutputT<char16, fixed_capacity> {};
    205 
    206 // Character set converter ----------------------------------------------------
    207 //
    208 // Converts query strings into a custom encoding. The embedder can supply an
    209 // implementation of this class to interface with their own character set
    210 // conversion libraries.
    211 //
    212 // Embedders will want to see the unit test for the ICU version.
    213 
    214 class CharsetConverter {
    215  public:
    216   CharsetConverter() {}
    217   virtual ~CharsetConverter() {}
    218 
    219   // Converts the given input string from UTF-16 to whatever output format the
    220   // converter supports. This is used only for the query encoding conversion,
    221   // which does not fail. Instead, the converter should insert "invalid
    222   // character" characters in the output for invalid sequences, and do the
    223   // best it can.
    224   //
    225   // If the input contains a character not representable in the output
    226   // character set, the converter should append the HTML entity sequence in
    227   // decimal, (such as "&#20320;") with escaping of the ampersand, number
    228   // sign, and semicolon (in the previous example it would be
    229   // "%26%2320320%3B"). This rule is based on what IE does in this situation.
    230   virtual void ConvertFromUTF16(const char16* input,
    231                                 int input_len,
    232                                 CanonOutput* output) = 0;
    233 };
    234 
    235 // Whitespace -----------------------------------------------------------------
    236 
    237 // Searches for whitespace that should be removed from the middle of URLs, and
    238 // removes it. Removed whitespace are tabs and newlines, but NOT spaces. Spaces
    239 // are preserved, which is what most browsers do. A pointer to the output will
    240 // be returned, and the length of that output will be in |output_len|.
    241 //
    242 // This should be called before parsing if whitespace removal is desired (which
    243 // it normally is when you are canonicalizing).
    244 //
    245 // If no whitespace is removed, this function will not use the buffer and will
    246 // return a pointer to the input, to avoid the extra copy. If modification is
    247 // required, the given |buffer| will be used and the returned pointer will
    248 // point to the beginning of the buffer.
    249 //
    250 // Therefore, callers should not use the buffer, since it may actuall be empty,
    251 // use the computed pointer and |*output_len| instead.
    252 GURL_API const char* RemoveURLWhitespace(const char* input, int input_len,
    253                                          CanonOutputT<char>* buffer,
    254                                          int* output_len);
    255 GURL_API const char16* RemoveURLWhitespace(const char16* input, int input_len,
    256                                            CanonOutputT<char16>* buffer,
    257                                            int* output_len);
    258 
    259 // IDN ------------------------------------------------------------------------
    260 
    261 // Converts the Unicode input representing a hostname to ASCII using IDN rules.
    262 // The output must fall in the ASCII range, but will be encoded in UTF-16.
    263 //
    264 // On success, the output will be filled with the ASCII host name and it will
    265 // return true. Unlike most other canonicalization functions, this assumes that
    266 // the output is empty. The beginning of the host will be at offset 0, and
    267 // the length of the output will be set to the length of the new host name.
    268 //
    269 // On error, returns false. The output in this case is undefined.
    270 GURL_API bool IDNToASCII(const char16* src, int src_len, CanonOutputW* output);
    271 
    272 // Piece-by-piece canonicalizers ----------------------------------------------
    273 //
    274 // These individual canonicalizers append the canonicalized versions of the
    275 // corresponding URL component to the given std::string. The spec and the
    276 // previously-identified range of that component are the input. The range of
    277 // the canonicalized component will be written to the output component.
    278 //
    279 // These functions all append to the output so they can be chained. Make sure
    280 // the output is empty when you start.
    281 //
    282 // These functions returns boolean values indicating success. On failure, they
    283 // will attempt to write something reasonable to the output so that, if
    284 // displayed to the user, they will recognise it as something that's messed up.
    285 // Nothing more should ever be done with these invalid URLs, however.
    286 
    287 // Scheme: Appends the scheme and colon to the URL. The output component will
    288 // indicate the range of characters up to but not including the colon.
    289 //
    290 // Canonical URLs always have a scheme. If the scheme is not present in the
    291 // input, this will just write the colon to indicate an empty scheme. Does not
    292 // append slashes which will be needed before any authority components for most
    293 // URLs.
    294 //
    295 // The 8-bit version requires UTF-8 encoding.
    296 GURL_API bool CanonicalizeScheme(const char* spec,
    297                                  const url_parse::Component& scheme,
    298                                  CanonOutput* output,
    299                                  url_parse::Component* out_scheme);
    300 GURL_API bool CanonicalizeScheme(const char16* spec,
    301                                  const url_parse::Component& scheme,
    302                                  CanonOutput* output,
    303                                  url_parse::Component* out_scheme);
    304 
    305 // User info: username/password. If present, this will add the delimiters so
    306 // the output will be "<username>:<password>@" or "<username>@". Empty
    307 // username/password pairs, or empty passwords, will get converted to
    308 // nonexistant in the canonical version.
    309 //
    310 // The components for the username and password refer to ranges in the
    311 // respective source strings. Usually, these will be the same string, which
    312 // is legal as long as the two components don't overlap.
    313 //
    314 // The 8-bit version requires UTF-8 encoding.
    315 GURL_API bool CanonicalizeUserInfo(const char* username_source,
    316                                    const url_parse::Component& username,
    317                                    const char* password_source,
    318                                    const url_parse::Component& password,
    319                                    CanonOutput* output,
    320                                    url_parse::Component* out_username,
    321                                    url_parse::Component* out_password);
    322 GURL_API bool CanonicalizeUserInfo(const char16* username_source,
    323                                    const url_parse::Component& username,
    324                                    const char16* password_source,
    325                                    const url_parse::Component& password,
    326                                    CanonOutput* output,
    327                                    url_parse::Component* out_username,
    328                                    url_parse::Component* out_password);
    329 
    330 
    331 // This structure holds detailed state exported from the IP/Host canonicalizers.
    332 // Additional fields may be added as callers require them.
    333 struct CanonHostInfo {
    334   CanonHostInfo() : family(NEUTRAL), num_ipv4_components(0), out_host() {}
    335 
    336   // Convenience function to test if family is an IP address.
    337   bool IsIPAddress() const { return family == IPV4 || family == IPV6; }
    338 
    339   // This field summarizes how the input was classified by the canonicalizer.
    340   enum Family {
    341     NEUTRAL,   // - Doesn't resemble an IP address.  As far as the IP
    342                //   canonicalizer is concerned, it should be treated as a
    343                //   hostname.
    344     BROKEN,    // - Almost an IP, but was not canonicalized.  This could be an
    345                //   IPv4 address where truncation occurred, or something
    346                //   containing the special characters :[] which did not parse
    347                //   as an IPv6 address.  Never attempt to connect to this
    348                //   address, because it might actually succeed!
    349     IPV4,      // - Successfully canonicalized as an IPv4 address.
    350     IPV6,      // - Successfully canonicalized as an IPv6 address.
    351   };
    352   Family family;
    353 
    354   // If |family| is IPV4, then this is the number of nonempty dot-separated
    355   // components in the input text, from 1 to 4.  If |family| is not IPV4,
    356   // this value is undefined.
    357   int num_ipv4_components;
    358 
    359   // Location of host within the canonicalized output.
    360   // CanonicalizeIPAddress() only sets this field if |family| is IPV4 or IPV6.
    361   // CanonicalizeHostVerbose() always sets it.
    362   url_parse::Component out_host;
    363 };
    364 
    365 
    366 // Host.
    367 //
    368 // The 8-bit version requires UTF-8 encoding.  Use this version when you only
    369 // need to know whether canonicalization succeeded.
    370 GURL_API bool CanonicalizeHost(const char* spec,
    371                                const url_parse::Component& host,
    372                                CanonOutput* output,
    373                                url_parse::Component* out_host);
    374 GURL_API bool CanonicalizeHost(const char16* spec,
    375                                const url_parse::Component& host,
    376                                CanonOutput* output,
    377                                url_parse::Component* out_host);
    378 
    379 // Extended version of CanonicalizeHost, which returns additional information.
    380 // Use this when you need to know whether the hostname was an IP address.
    381 // A successful return is indicated by host_info->family != BROKEN.  See the
    382 // definition of CanonHostInfo above for details.
    383 GURL_API void CanonicalizeHostVerbose(const char* spec,
    384                                       const url_parse::Component& host,
    385                                       CanonOutput* output,
    386                                       CanonHostInfo* host_info);
    387 GURL_API void CanonicalizeHostVerbose(const char16* spec,
    388                                       const url_parse::Component& host,
    389                                       CanonOutput* output,
    390                                       CanonHostInfo* host_info);
    391 
    392 
    393 // IP addresses.
    394 //
    395 // Tries to interpret the given host name as an IPv4 or IPv6 address. If it is
    396 // an IP address, it will canonicalize it as such, appending it to |output|.
    397 // Additional status information is returned via the |*host_info| parameter.
    398 // See the definition of CanonHostInfo above for details.
    399 //
    400 // This is called AUTOMATICALLY from the host canonicalizer, which ensures that
    401 // the input is unescaped and name-prepped, etc. It should not normally be
    402 // necessary or wise to call this directly.
    403 GURL_API void CanonicalizeIPAddress(const char* spec,
    404                                     const url_parse::Component& host,
    405                                     CanonOutput* output,
    406                                     CanonHostInfo* host_info);
    407 GURL_API void CanonicalizeIPAddress(const char16* spec,
    408                                     const url_parse::Component& host,
    409                                     CanonOutput* output,
    410                                     CanonHostInfo* host_info);
    411 
    412 // Port: this function will add the colon for the port if a port is present.
    413 // The caller can pass url_parse::PORT_UNSPECIFIED as the
    414 // default_port_for_scheme argument if there is no default port.
    415 //
    416 // The 8-bit version requires UTF-8 encoding.
    417 GURL_API bool CanonicalizePort(const char* spec,
    418                                const url_parse::Component& port,
    419                                int default_port_for_scheme,
    420                                CanonOutput* output,
    421                                url_parse::Component* out_port);
    422 GURL_API bool CanonicalizePort(const char16* spec,
    423                                const url_parse::Component& port,
    424                                int default_port_for_scheme,
    425                                CanonOutput* output,
    426                                url_parse::Component* out_port);
    427 
    428 // Returns the default port for the given canonical scheme, or PORT_UNSPECIFIED
    429 // if the scheme is unknown.
    430 GURL_API int DefaultPortForScheme(const char* scheme, int scheme_len);
    431 
    432 // Path. If the input does not begin in a slash (including if the input is
    433 // empty), we'll prepend a slash to the path to make it canonical.
    434 //
    435 // The 8-bit version assumes UTF-8 encoding, but does not verify the validity
    436 // of the UTF-8 (i.e., you can have invalid UTF-8 sequences, invalid
    437 // characters, etc.). Normally, URLs will come in as UTF-16, so this isn't
    438 // an issue. Somebody giving us an 8-bit path is responsible for generating
    439 // the path that the server expects (we'll escape high-bit characters), so
    440 // if something is invalid, it's their problem.
    441 GURL_API bool CanonicalizePath(const char* spec,
    442                                const url_parse::Component& path,
    443                                CanonOutput* output,
    444                                url_parse::Component* out_path);
    445 GURL_API bool CanonicalizePath(const char16* spec,
    446                                const url_parse::Component& path,
    447                                CanonOutput* output,
    448                                url_parse::Component* out_path);
    449 
    450 // Canonicalizes the input as a file path. This is like CanonicalizePath except
    451 // that it also handles Windows drive specs. For example, the path can begin
    452 // with "c|\" and it will get properly canonicalized to "C:/".
    453 // The string will be appended to |*output| and |*out_path| will be updated.
    454 //
    455 // The 8-bit version requires UTF-8 encoding.
    456 GURL_API bool FileCanonicalizePath(const char* spec,
    457                                    const url_parse::Component& path,
    458                                    CanonOutput* output,
    459                                    url_parse::Component* out_path);
    460 GURL_API bool FileCanonicalizePath(const char16* spec,
    461                                    const url_parse::Component& path,
    462                                    CanonOutput* output,
    463                                    url_parse::Component* out_path);
    464 
    465 // Query: Prepends the ? if needed.
    466 //
    467 // The 8-bit version requires the input to be UTF-8 encoding. Incorrectly
    468 // encoded characters (in UTF-8 or UTF-16) will be replaced with the Unicode
    469 // "invalid character." This function can not fail, we always just try to do
    470 // our best for crazy input here since web pages can set it themselves.
    471 //
    472 // This will convert the given input into the output encoding that the given
    473 // character set converter object provides. The converter will only be called
    474 // if necessary, for ASCII input, no conversions are necessary.
    475 //
    476 // The converter can be NULL. In this case, the output encoding will be UTF-8.
    477 GURL_API void CanonicalizeQuery(const char* spec,
    478                                 const url_parse::Component& query,
    479                                 CharsetConverter* converter,
    480                                 CanonOutput* output,
    481                                 url_parse::Component* out_query);
    482 GURL_API void CanonicalizeQuery(const char16* spec,
    483                                 const url_parse::Component& query,
    484                                 CharsetConverter* converter,
    485                                 CanonOutput* output,
    486                                 url_parse::Component* out_query);
    487 
    488 // Ref: Prepends the # if needed. The output will be UTF-8 (this is the only
    489 // canonicalizer that does not produce ASCII output). The output is
    490 // guaranteed to be valid UTF-8.
    491 //
    492 // This function will not fail. If the input is invalid UTF-8/UTF-16, we'll use
    493 // the "Unicode replacement character" for the confusing bits and copy the rest.
    494 GURL_API void CanonicalizeRef(const char* spec,
    495                               const url_parse::Component& path,
    496                               CanonOutput* output,
    497                               url_parse::Component* out_path);
    498 GURL_API void CanonicalizeRef(const char16* spec,
    499                               const url_parse::Component& path,
    500                               CanonOutput* output,
    501                               url_parse::Component* out_path);
    502 
    503 // Full canonicalizer ---------------------------------------------------------
    504 //
    505 // These functions replace any string contents, rather than append as above.
    506 // See the above piece-by-piece functions for information specific to
    507 // canonicalizing individual components.
    508 //
    509 // The output will be ASCII except the reference fragment, which may be UTF-8.
    510 //
    511 // The 8-bit versions require UTF-8 encoding.
    512 
    513 // Use for standard URLs with authorities and paths.
    514 GURL_API bool CanonicalizeStandardURL(const char* spec,
    515                                       int spec_len,
    516                                       const url_parse::Parsed& parsed,
    517                                       CharsetConverter* query_converter,
    518                                       CanonOutput* output,
    519                                       url_parse::Parsed* new_parsed);
    520 GURL_API bool CanonicalizeStandardURL(const char16* spec,
    521                                       int spec_len,
    522                                       const url_parse::Parsed& parsed,
    523                                       CharsetConverter* query_converter,
    524                                       CanonOutput* output,
    525                                       url_parse::Parsed* new_parsed);
    526 
    527 // Use for file URLs.
    528 GURL_API bool CanonicalizeFileURL(const char* spec,
    529                                   int spec_len,
    530                                   const url_parse::Parsed& parsed,
    531                                   CharsetConverter* query_converter,
    532                                   CanonOutput* output,
    533                                   url_parse::Parsed* new_parsed);
    534 GURL_API bool CanonicalizeFileURL(const char16* spec,
    535                                   int spec_len,
    536                                   const url_parse::Parsed& parsed,
    537                                   CharsetConverter* query_converter,
    538                                   CanonOutput* output,
    539                                   url_parse::Parsed* new_parsed);
    540 
    541 // Use for path URLs such as javascript. This does not modify the path in any
    542 // way, for example, by escaping it.
    543 GURL_API bool CanonicalizePathURL(const char* spec,
    544                                   int spec_len,
    545                                   const url_parse::Parsed& parsed,
    546                                   CanonOutput* output,
    547                                   url_parse::Parsed* new_parsed);
    548 GURL_API bool CanonicalizePathURL(const char16* spec,
    549                                   int spec_len,
    550                                   const url_parse::Parsed& parsed,
    551                                   CanonOutput* output,
    552                                   url_parse::Parsed* new_parsed);
    553 
    554 // Use for mailto URLs. This "canonicalizes" the url into a path and query
    555 // component. It does not attempt to merge "to" fields. It uses UTF-8 for
    556 // the query encoding if there is a query. This is because a mailto URL is
    557 // really intended for an external mail program, and the encoding of a page,
    558 // etc. which would influence a query encoding normally are irrelevant.
    559 GURL_API bool CanonicalizeMailtoURL(const char* spec,
    560                                     int spec_len,
    561                                     const url_parse::Parsed& parsed,
    562                                     CanonOutput* output,
    563                                     url_parse::Parsed* new_parsed);
    564 GURL_API bool CanonicalizeMailtoURL(const char16* spec,
    565                                     int spec_len,
    566                                     const url_parse::Parsed& parsed,
    567                                     CanonOutput* output,
    568                                     url_parse::Parsed* new_parsed);
    569 
    570 // Part replacer --------------------------------------------------------------
    571 
    572 // Internal structure used for storing separate strings for each component.
    573 // The basic canonicalization functions use this structure internally so that
    574 // component remplacement (different strings for different components) can be
    575 // treated on the same code path as regular canonicalization (the same string
    576 // for each component).
    577 //
    578 // A url_parse::Parsed structure usually goes along with this. Those
    579 // components identify offsets within these strings, so that they can all be
    580 // in the same string, or spread arbitrarily across different ones.
    581 //
    582 // This structures does not own any data. It is the caller's responsibility to
    583 // ensure that the data the pointers point to stays in scope and is not
    584 // modified.
    585 template<typename CHAR>
    586 struct URLComponentSource {
    587   // Constructor normally used by callers wishing to replace components. This
    588   // will make them all NULL, which is no replacement. The caller would then
    589   // override the components they want to replace.
    590   URLComponentSource()
    591       : scheme(NULL),
    592         username(NULL),
    593         password(NULL),
    594         host(NULL),
    595         port(NULL),
    596         path(NULL),
    597         query(NULL),
    598         ref(NULL) {
    599   }
    600 
    601   // Constructor normally used internally to initialize all the components to
    602   // point to the same spec.
    603   explicit URLComponentSource(const CHAR* default_value)
    604       : scheme(default_value),
    605         username(default_value),
    606         password(default_value),
    607         host(default_value),
    608         port(default_value),
    609         path(default_value),
    610         query(default_value),
    611         ref(default_value) {
    612   }
    613 
    614   const CHAR* scheme;
    615   const CHAR* username;
    616   const CHAR* password;
    617   const CHAR* host;
    618   const CHAR* port;
    619   const CHAR* path;
    620   const CHAR* query;
    621   const CHAR* ref;
    622 };
    623 
    624 // This structure encapsulates information on modifying a URL. Each component
    625 // may either be left unchanged, replaced, or deleted.
    626 //
    627 // By default, each component is unchanged. For those components that should be
    628 // modified, call either Set* or Clear* to modify it.
    629 //
    630 // The string passed to Set* functions DOES NOT GET COPIED AND MUST BE KEPT
    631 // IN SCOPE BY THE CALLER for as long as this object exists!
    632 //
    633 // Prefer the 8-bit replacement version if possible since it is more efficient.
    634 template<typename CHAR>
    635 class Replacements {
    636  public:
    637   Replacements() {
    638   }
    639 
    640   // Scheme
    641   void SetScheme(const CHAR* s, const url_parse::Component& comp) {
    642     sources_.scheme = s;
    643     components_.scheme = comp;
    644   }
    645   // Note: we don't have a ClearScheme since this doesn't make any sense.
    646   bool IsSchemeOverridden() const { return sources_.scheme != NULL; }
    647 
    648   // Username
    649   void SetUsername(const CHAR* s, const url_parse::Component& comp) {
    650     sources_.username = s;
    651     components_.username = comp;
    652   }
    653   void ClearUsername() {
    654     sources_.username = Placeholder();
    655     components_.username = url_parse::Component();
    656   }
    657   bool IsUsernameOverridden() const { return sources_.username != NULL; }
    658 
    659   // Password
    660   void SetPassword(const CHAR* s, const url_parse::Component& comp) {
    661     sources_.password = s;
    662     components_.password = comp;
    663   }
    664   void ClearPassword() {
    665     sources_.password = Placeholder();
    666     components_.password = url_parse::Component();
    667   }
    668   bool IsPasswordOverridden() const { return sources_.password != NULL; }
    669 
    670   // Host
    671   void SetHost(const CHAR* s, const url_parse::Component& comp) {
    672     sources_.host = s;
    673     components_.host = comp;
    674   }
    675   void ClearHost() {
    676     sources_.host = Placeholder();
    677     components_.host = url_parse::Component();
    678   }
    679   bool IsHostOverridden() const { return sources_.host != NULL; }
    680 
    681   // Port
    682   void SetPort(const CHAR* s, const url_parse::Component& comp) {
    683     sources_.port = s;
    684     components_.port = comp;
    685   }
    686   void ClearPort() {
    687     sources_.port = Placeholder();
    688     components_.port = url_parse::Component();
    689   }
    690   bool IsPortOverridden() const { return sources_.port != NULL; }
    691 
    692   // Path
    693   void SetPath(const CHAR* s, const url_parse::Component& comp) {
    694     sources_.path = s;
    695     components_.path = comp;
    696   }
    697   void ClearPath() {
    698     sources_.path = Placeholder();
    699     components_.path = url_parse::Component();
    700   }
    701   bool IsPathOverridden() const { return sources_.path != NULL; }
    702 
    703   // Query
    704   void SetQuery(const CHAR* s, const url_parse::Component& comp) {
    705     sources_.query = s;
    706     components_.query = comp;
    707   }
    708   void ClearQuery() {
    709     sources_.query = Placeholder();
    710     components_.query = url_parse::Component();
    711   }
    712   bool IsQueryOverridden() const { return sources_.query != NULL; }
    713 
    714   // Ref
    715   void SetRef(const CHAR* s, const url_parse::Component& comp) {
    716     sources_.ref = s;
    717     components_.ref = comp;
    718   }
    719   void ClearRef() {
    720     sources_.ref = Placeholder();
    721     components_.ref = url_parse::Component();
    722   }
    723   bool IsRefOverridden() const { return sources_.ref != NULL; }
    724 
    725   // Getters for the itnernal data. See the variables below for how the
    726   // information is encoded.
    727   const URLComponentSource<CHAR>& sources() const { return sources_; }
    728   const url_parse::Parsed& components() const { return components_; }
    729 
    730  private:
    731   // Returns a pointer to a static empty string that is used as a placeholder
    732   // to indicate a component should be deleted (see below).
    733   const CHAR* Placeholder() {
    734     static const CHAR empty_string = 0;
    735     return &empty_string;
    736   }
    737 
    738   // We support three states:
    739   //
    740   // Action                 | Source                Component
    741   // -----------------------+--------------------------------------------------
    742   // Don't change component | NULL                  (unused)
    743   // Replace component      | (replacement string)  (replacement component)
    744   // Delete component       | (non-NULL)            (invalid component: (0,-1))
    745   //
    746   // We use a pointer to the empty string for the source when the component
    747   // should be deleted.
    748   URLComponentSource<CHAR> sources_;
    749   url_parse::Parsed components_;
    750 };
    751 
    752 // The base must be an 8-bit canonical URL.
    753 GURL_API bool ReplaceStandardURL(const char* base,
    754                                  const url_parse::Parsed& base_parsed,
    755                                  const Replacements<char>& replacements,
    756                                  CharsetConverter* query_converter,
    757                                  CanonOutput* output,
    758                                  url_parse::Parsed* new_parsed);
    759 GURL_API bool ReplaceStandardURL(const char* base,
    760                                  const url_parse::Parsed& base_parsed,
    761                                  const Replacements<char16>& replacements,
    762                                  CharsetConverter* query_converter,
    763                                  CanonOutput* output,
    764                                  url_parse::Parsed* new_parsed);
    765 
    766 // Replacing some parts of a file URL is not permitted. Everything except
    767 // the host, path, query, and ref will be ignored.
    768 GURL_API bool ReplaceFileURL(const char* base,
    769                              const url_parse::Parsed& base_parsed,
    770                              const Replacements<char>& replacements,
    771                              CharsetConverter* query_converter,
    772                              CanonOutput* output,
    773                              url_parse::Parsed* new_parsed);
    774 GURL_API bool ReplaceFileURL(const char* base,
    775                              const url_parse::Parsed& base_parsed,
    776                              const Replacements<char16>& replacements,
    777                              CharsetConverter* query_converter,
    778                              CanonOutput* output,
    779                              url_parse::Parsed* new_parsed);
    780 
    781 // Path URLs can only have the scheme and path replaced. All other components
    782 // will be ignored.
    783 GURL_API bool ReplacePathURL(const char* base,
    784                              const url_parse::Parsed& base_parsed,
    785                              const Replacements<char>& replacements,
    786                              CanonOutput* output,
    787                              url_parse::Parsed* new_parsed);
    788 GURL_API bool ReplacePathURL(const char* base,
    789                              const url_parse::Parsed& base_parsed,
    790                              const Replacements<char16>& replacements,
    791                              CanonOutput* output,
    792                              url_parse::Parsed* new_parsed);
    793 
    794 // Mailto URLs can only have the scheme, path, and query replaced.
    795 // All other components will be ignored.
    796 GURL_API bool ReplaceMailtoURL(const char* base,
    797                                const url_parse::Parsed& base_parsed,
    798                                const Replacements<char>& replacements,
    799                                CanonOutput* output,
    800                                url_parse::Parsed* new_parsed);
    801 GURL_API bool ReplaceMailtoURL(const char* base,
    802                                const url_parse::Parsed& base_parsed,
    803                                const Replacements<char16>& replacements,
    804                                CanonOutput* output,
    805                                url_parse::Parsed* new_parsed);
    806 
    807 // Relative URL ---------------------------------------------------------------
    808 
    809 // Given an input URL or URL fragment |fragment|, determines if it is a
    810 // relative or absolute URL and places the result into |*is_relative|. If it is
    811 // relative, the relevant portion of the URL will be placed into
    812 // |*relative_component| (there may have been trimmed whitespace, for example).
    813 // This value is passed to ResolveRelativeURL. If the input is not relative,
    814 // this value is UNDEFINED (it may be changed by the functin).
    815 //
    816 // Returns true on success (we successfully determined the URL is relative or
    817 // not). Failure means that the combination of URLs doesn't make any sense.
    818 //
    819 // The base URL should always be canonical, therefore is ASCII.
    820 GURL_API bool IsRelativeURL(const char* base,
    821                             const url_parse::Parsed& base_parsed,
    822                             const char* fragment,
    823                             int fragment_len,
    824                             bool is_base_hierarchical,
    825                             bool* is_relative,
    826                             url_parse::Component* relative_component);
    827 GURL_API bool IsRelativeURL(const char* base,
    828                             const url_parse::Parsed& base_parsed,
    829                             const char16* fragment,
    830                             int fragment_len,
    831                             bool is_base_hierarchical,
    832                             bool* is_relative,
    833                             url_parse::Component* relative_component);
    834 
    835 // Given a canonical parsed source URL, a URL fragment known to be relative,
    836 // and the identified relevant portion of the relative URL (computed by
    837 // IsRelativeURL), this produces a new parsed canonical URL in |output| and
    838 // |out_parsed|.
    839 //
    840 // It also requires a flag indicating whether the base URL is a file: URL
    841 // which triggers additional logic.
    842 //
    843 // The base URL should be canonical and have a host (may be empty for file
    844 // URLs) and a path. If it doesn't have these, we can't resolve relative
    845 // URLs off of it and will return the base as the output with an error flag.
    846 // Becausee it is canonical is should also be ASCII.
    847 //
    848 // The query charset converter follows the same rules as CanonicalizeQuery.
    849 //
    850 // Returns true on success. On failure, the output will be "something
    851 // reasonable" that will be consistent and valid, just probably not what
    852 // was intended by the web page author or caller.
    853 GURL_API bool ResolveRelativeURL(const char* base_url,
    854                                  const url_parse::Parsed& base_parsed,
    855                                  bool base_is_file,
    856                                  const char* relative_url,
    857                                  const url_parse::Component& relative_component,
    858                                  CharsetConverter* query_converter,
    859                                  CanonOutput* output,
    860                                  url_parse::Parsed* out_parsed);
    861 GURL_API bool ResolveRelativeURL(const char* base_url,
    862                                  const url_parse::Parsed& base_parsed,
    863                                  bool base_is_file,
    864                                  const char16* relative_url,
    865                                  const url_parse::Component& relative_component,
    866                                  CharsetConverter* query_converter,
    867                                  CanonOutput* output,
    868                                  url_parse::Parsed* out_parsed);
    869 
    870 }  // namespace url_canon
    871 
    872 #endif  // GOOGLEURL_SRC_URL_CANON_H__
    873