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      1 /* ***** BEGIN LICENSE BLOCK *****
      2  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
      3  *
      4  * The contents of this file are subject to the Mozilla Public License Version
      5  * 1.1 (the "License"); you may not use this file except in compliance with
      6  * the License. You may obtain a copy of the License at
      7  * http://www.mozilla.org/MPL/
      8  *
      9  * Software distributed under the License is distributed on an "AS IS" basis,
     10  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
     11  * for the specific language governing rights and limitations under the
     12  * License.
     13  *
     14  * The Original Code is Mozilla.
     15  *
     16  * The Initial Developer of the Original Code is
     17  * Netscape Communications.
     18  * Portions created by the Initial Developer are Copyright (C) 2001
     19  * the Initial Developer. All Rights Reserved.
     20  *
     21  * Contributor(s):
     22  *   Darin Fisher <darin (at) netscape.com> (original author)
     23  *
     24  * Alternatively, the contents of this file may be used under the terms of
     25  * either the GNU General Public License Version 2 or later (the "GPL"), or
     26  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
     27  * in which case the provisions of the GPL or the LGPL are applicable instead
     28  * of those above. If you wish to allow use of your version of this file only
     29  * under the terms of either the GPL or the LGPL, and not to allow others to
     30  * use your version of this file under the terms of the MPL, indicate your
     31  * decision by deleting the provisions above and replace them with the notice
     32  * and other provisions required by the GPL or the LGPL. If you do not delete
     33  * the provisions above, a recipient may use your version of this file under
     34  * the terms of any one of the MPL, the GPL or the LGPL.
     35  *
     36  * ***** END LICENSE BLOCK ***** */
     37 
     38 // Derived from:
     39 // mozilla/netwerk/protocol/http/src/nsHttpChunkedDecoder.h
     40 
     41 #ifndef NET_HTTP_HTTP_CHUNKED_DECODER_H_
     42 #define NET_HTTP_HTTP_CHUNKED_DECODER_H_
     43 
     44 #include <string>
     45 
     46 namespace net {
     47 
     48 // From RFC2617 section 3.6.1, the chunked transfer coding is defined as:
     49 //
     50 //   Chunked-Body    = *chunk
     51 //                     last-chunk
     52 //                     trailer
     53 //                     CRLF
     54 //   chunk           = chunk-size [ chunk-extension ] CRLF
     55 //                     chunk-data CRLF
     56 //   chunk-size      = 1*HEX
     57 //   last-chunk      = 1*("0") [ chunk-extension ] CRLF
     58 //
     59 //   chunk-extension = *( ";" chunk-ext-name [ "=" chunk-ext-val ] )
     60 //   chunk-ext-name  = token
     61 //   chunk-ext-val   = token | quoted-string
     62 //   chunk-data      = chunk-size(OCTET)
     63 //   trailer         = *(entity-header CRLF)
     64 //
     65 // The chunk-size field is a string of hex digits indicating the size of the
     66 // chunk.  The chunked encoding is ended by any chunk whose size is zero,
     67 // followed by the trailer, which is terminated by an empty line.
     68 //
     69 // NOTE: This implementation does not bother to parse trailers since they are
     70 // not used on the web.
     71 //
     72 class HttpChunkedDecoder {
     73  public:
     74   HttpChunkedDecoder();
     75 
     76   // Indicates that a previous call to FilterBuf encountered the final CRLF.
     77   bool reached_eof() const { return reached_eof_; }
     78 
     79   // Returns the number of bytes after the final CRLF.
     80   int bytes_after_eof() const { return bytes_after_eof_; }
     81 
     82   // Called to filter out the chunk markers from buf and to check for end-of-
     83   // file.  This method modifies |buf| inline if necessary to remove chunk
     84   // markers.  The return value indicates the final size of decoded data stored
     85   // in |buf|.  Call reached_eof() after this method to check if end-of-file
     86   // was encountered.
     87   int FilterBuf(char* buf, int buf_len);
     88 
     89  private:
     90   // Scans |buf| for the next chunk delimiter.  This method returns the number
     91   // of bytes consumed from |buf|.  If found, |chunk_remaining_| holds the
     92   // value for the next chunk size.
     93   int ScanForChunkRemaining(const char* buf, int buf_len);
     94 
     95   // Converts string |start| of length |len| to a numeric value.
     96   // |start| is a string of type "chunk-size" (hex string).
     97   // If the conversion succeeds, returns true and places the result in |out|.
     98   static bool ParseChunkSize(const char* start, int len, int* out);
     99 
    100   // Indicates the number of bytes remaining for the current chunk.
    101   int chunk_remaining_;
    102 
    103   // A small buffer used to store a partial chunk marker.
    104   std::string line_buf_;
    105 
    106   // True if waiting for the terminal CRLF of a chunk's data.
    107   bool chunk_terminator_remaining_;
    108 
    109   // Set to true when FilterBuf encounters the last-chunk.
    110   bool reached_last_chunk_;
    111 
    112   // Set to true when FilterBuf encounters the final CRLF.
    113   bool reached_eof_;
    114 
    115   // The number of unfiltered bytes after the final CRLF, either extraneous
    116   // data or the first part of the next response in a pipelined stream.
    117   int bytes_after_eof_;
    118 };
    119 
    120 }  // namespace net
    121 
    122 #endif  // NET_HTTP_HTTP_CHUNKED_DECODER_H_
    123