/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2004, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id: http_chunks.c,v 1.25 2004/05/12 07:54:44 bagder Exp $
 ***************************************************************************/
#include "setup.h"

#ifndef CURL_DISABLE_HTTP
/* -- WIN32 approved -- */
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <ctype.h>

#include "urldata.h" /* it includes http_chunks.h */
#include "sendf.h"   /* for the client write stuff */

#include "content_encoding.h"
#include "http.h"
#include "memory.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

/* The last #include file should be: */
#include "memdebug.h"

/*
 * Chunk format (simplified):
 *
 * <HEX SIZE>[ chunk extension ] CRLF
 * <DATA> CRLF
 *
 * Highlights from RFC2616 section 3.6 say:

   The chunked encoding modifies the body of a message in order to
   transfer it as a series of chunks, each with its own size indicator,
   followed by an OPTIONAL trailer containing entity-header fields. This
   allows dynamically produced content to be transferred along with the
   information necessary for the recipient to verify that it has
   received the full message.

	   Chunked-Body   = *chunk
						last-chunk
						trailer
						CRLF

	   chunk          = chunk-size [ chunk-extension ] CRLF
						chunk-data CRLF
	   chunk-size     = 1*HEX
	   last-chunk     = 1*("0") [ chunk-extension ] CRLF

	   chunk-extension= *( ";" chunk-ext-name [ "=" chunk-ext-val ] )
	   chunk-ext-name = token
	   chunk-ext-val  = token | quoted-string
	   chunk-data     = chunk-size(OCTET)
	   trailer        = *(entity-header CRLF)

   The chunk-size field is a string of hex digits indicating the size of
   the chunk. The chunked encoding is ended by any chunk whose size is
   zero, followed by the trailer, which is terminated by an empty line.

 */


void Curl_httpchunk_init( struct connectdata *conn ) {
	struct Curl_chunker *chunk = &conn->proto.http->chunk;
	chunk->hexindex = 0; /* start at 0 */
	chunk->dataleft = 0; /* no data left yet! */
	chunk->state = CHUNK_HEX; /* we get hex first! */
}

/*
 * chunk_read() returns a OK for normal operations, or a positive return code
 * for errors. STOP means this sequence of chunks is complete.  The 'wrote'
 * argument is set to tell the caller how many bytes we actually passed to the
 * client (for byte-counting and whatever).
 *
 * The states and the state-machine is further explained in the header file.
 */
CHUNKcode Curl_httpchunk_read( struct connectdata *conn,
							   char *datap,
							   ssize_t datalen,
							   ssize_t *wrotep ) {
	CURLcode result = CURLE_OK;
	struct Curl_chunker *ch = &conn->proto.http->chunk;
	struct Curl_transfer_keeper *k = &conn->keep;
	size_t piece;
	size_t length = (size_t)datalen;
	size_t *wrote = (size_t *)wrotep;

	*wrote = 0; /* nothing's written yet */

	while ( length ) {
		switch ( ch->state ) {
		case CHUNK_HEX:
			if ( isxdigit( (int)*datap ) ) {
				if ( ch->hexindex < MAXNUM_SIZE ) {
					ch->hexbuffer[ch->hexindex] = *datap;
					datap++;
					length--;
					ch->hexindex++;
				} else {
					return CHUNKE_TOO_LONG_HEX; /* longer hex than we support */
				}
			} else {
				if ( 0 == ch->hexindex ) {
					/* This is illegal data, we received junk where we expected
					   a hexadecimal digit. */
					return CHUNKE_ILLEGAL_HEX;
				}
				/* length and datap are unmodified */
				ch->hexbuffer[ch->hexindex] = 0;
				ch->datasize = strtoul( ch->hexbuffer, NULL, 16 );
				ch->state = CHUNK_POSTHEX;
			}
			break;

		case CHUNK_POSTHEX:
			/* In this state, we're waiting for CRLF to arrive. We support
			   this to allow so called chunk-extensions to show up here
			   before the CRLF comes. */
			if ( *datap == '\r' ) {
				ch->state = CHUNK_CR;
			}
			length--;
			datap++;
			break;

		case CHUNK_CR:
			/* waiting for the LF */
			if ( *datap == '\n' ) {
				/* we're now expecting data to come, unless size was zero! */
				if ( 0 == ch->datasize ) {
					ch->state = CHUNK_STOP; /* stop reading! */
					if ( 1 == length ) {
						/* This was the final byte, return right now */
						return CHUNKE_STOP;
					}
				} else {
					ch->state = CHUNK_DATA;
				}
			} else {
				/* previously we got a fake CR, go back to CR waiting! */
				ch->state = CHUNK_CR;
			}
			datap++;
			length--;
			break;

		case CHUNK_DATA:
			/* we get pure and fine data

			   We expect another 'datasize' of data. We have 'length' right now,
			   it can be more or less than 'datasize'. Get the smallest piece.
			*/
			piece = ( ch->datasize >= length ) ? length : ch->datasize;

			/* Write the data portion available */
#ifdef HAVE_LIBZ
			switch ( conn->keep.content_encoding ) {
			case IDENTITY:
#endif
			if ( !k->ignorebody ) {
				result = Curl_client_write( conn->data, CLIENTWRITE_BODY, datap,
											piece );
			}
#ifdef HAVE_LIBZ
			break;

		case DEFLATE:
			/* update conn->keep.str to point to the chunk data. */
			conn->keep.str = datap;
			result = Curl_unencode_deflate_write( conn->data, &conn->keep,
												  (ssize_t)piece );
			break;

		case GZIP:
			/* update conn->keep.str to point to the chunk data. */
			conn->keep.str = datap;
			result = Curl_unencode_gzip_write( conn->data, &conn->keep,
											   (ssize_t)piece );
			break;

		case COMPRESS:
		default:
			failf( conn->data,
				   "Unrecognized content encoding type. "
				   "libcurl understands `identity', `deflate' and `gzip' "
				   "content encodings." );
			return CHUNKE_BAD_ENCODING;
		}
#endif

			if ( result ) {
				return CHUNKE_WRITE_ERROR;
			}

			*wrote += piece;

			ch->datasize -= piece; /* decrease amount left to expect */
			datap += piece; /* move read pointer forward */
			length -= piece; /* decrease space left in this round */

			if ( 0 == ch->datasize ) {
				/* end of data this round, we now expect a trailing CRLF */
				ch->state = CHUNK_POSTCR;
			}
			break;

		case CHUNK_POSTCR:
			if ( *datap == '\r' ) {
				ch->state = CHUNK_POSTLF;
				datap++;
				length--;
			} else {
				return CHUNKE_BAD_CHUNK;
			}
			break;

		case CHUNK_POSTLF:
			if ( *datap == '\n' ) {
				/*
				 * The last one before we go back to hex state and start all
				 * over.
				 */
				Curl_httpchunk_init( conn );
				datap++;
				length--;
			} else {
				return CHUNKE_BAD_CHUNK;
			}
			break;

		case CHUNK_STOP:
			/* If we arrive here, there is data left in the end of the buffer
			   even if there's no more chunks to read */
			ch->dataleft = length;
			return CHUNKE_STOP; /* return stop */
		default:
			return CHUNKE_STATE_ERROR;
		}
	}
	return CHUNKE_OK;
}
#endif /* CURL_DISABLE_HTTP */
