mdw@git.distorted.org.uk Git - mLib/blob - url.c

   1 /* -*-c-*-
   2  *
   3  * $Id: url.c,v 1.5 2004/04/08 01:36:13 mdw Exp $
   4  *
   5  * Parsing and construction of url-encoded name/value pairs
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the mLib utilities library.
  13  *
  14  * mLib is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * mLib is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with mLib; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Header files ------------------------------------------------------*/
  31
  32 #include <ctype.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36
  37 #include "dstr.h"
  38 #include "url.h"
  39
  40 /*----- Main code ---------------------------------------------------------*/
  41
  42 /* --- @url_initenc@ --- *
  43  *
  44  * Arguments:   @url_ectx *ctx@ = pointer to context block
  45  *
  46  * Returns:     ---
  47  *
  48  * Use:         Initializes a URL encoding context.
  49  */
  50
  51 void url_initenc(url_ectx *ctx) { ctx->f = 0; }
  52
  53 /* --- @encode@ --- *
  54  *
  55  * Arguments:   @dstr *d@ = pointer to output string
  56  *              @const char *p@ = pointer to thing to encode
  57  *
  58  * Returns:     ---
  59  *
  60  * Use:         Encodes the input string into the output string.
  61  */
  62
  63 static void encode(dstr *d, const char *p)
  64 {
  65   while (*p) {
  66     switch (*p) {
  67       case ' ':
  68         DPUTC(d, '+');
  69         break;
  70       default:
  71         if (isalnum((unsigned char)*p))
  72           DPUTC(d, *p);
  73         else
  74           dstr_putf(d, "%%%02x", *p);
  75         break;
  76     }
  77     p++;
  78   }
  79 }
  80
  81 /* --- @url_enc@ --- *
  82  *
  83  * Arguments:   @url_ectx *ctx@ = pointer to encoding context
  84  *              @dstr *d@ = pointer to output string
  85  *              @const char *name@ = pointer to name
  86  *              @const char *value@ = pointer to value
  87  *
  88  * Returns:     ---
  89  *
  90  * Use:         Writes an assignment between @name@ and @value@ to the
  91  *              output string, encoding the values properly.
  92  */
  93
  94 void url_enc(url_ectx *ctx, dstr *d, const char *name, const char *value)
  95 {
  96   if (ctx->f & URLF_SEP)
  97     DPUTC(d, '&');
  98   encode(d, name);
  99   DPUTC(d, '=');
 100   encode(d, value);
 101   DPUTZ(d);
 102   ctx->f |= URLF_SEP;
 103 }
 104
 105 /* --- @url_initdec@ --- *
 106  *
 107  * Arguments:   @url_dctx *ctx@ = pointer to context block
 108  *              @const char *p@ = string to read data from
 109  *
 110  * Returns:     ---
 111  *
 112  * Use:         Initializes a URL decoding context.
 113  */
 114
 115 void url_initdec(url_dctx *ctx, const char *p) { ctx->p = p; }
 116
 117 /* --- @decode@ --- *
 118  *
 119  * Arguments:   @dstr *d@ = pointer to output string
 120  *              @const char *p@ = pointer to input data
 121  *              @int eq@ = whether to stop at `=' characters
 122  *
 123  * Returns:     Pointer to next available character.
 124  *
 125  * Use:         Does a URL decode.
 126  */
 127
 128 static const char *decode(dstr *d, const char *p, int eq)
 129 {
 130   if (!*p)
 131     return (0);
 132   for (;;) {
 133     switch (*p) {
 134       case '=':
 135         if (eq)
 136           return (p);
 137         DPUTC(d, *p);
 138         break;
 139       case 0:
 140       case '&':
 141         return (p);
 142       case '+':
 143         DPUTC(d, ' ');
 144         break;
 145       case '%': {
 146         unsigned int ch;
 147         int n;
 148         int x = sscanf(p + 1, "%2x%n", &ch, &n);
 149         if (x == 1) {
 150           DPUTC(d, ch);
 151           p += n;
 152           break;
 153         }
 154       }
 155       default:
 156         DPUTC(d, *p);
 157         break;
 158     }
 159     p++;
 160   }
 161 }
 162
 163 /* --- @url_dec@ --- *
 164  *
 165  * Arguments:   @url_dctx *ctx@ = pointer to decode context
 166  *              @dstr *n@ = pointer to output string for name
 167  *              @dstr *v@ = pointer to output string for value
 168  *
 169  * Returns:     Nonzero if it read something, zero if there's nothing left
 170  *
 171  * Use:         Decodes the next name/value pair from a urlencoded string.
 172  */
 173
 174 int url_dec(url_dctx *ctx, dstr *n, dstr *v)
 175 {
 176   const char *p = ctx->p;
 177   size_t l = n->len;
 178
 179 again:
 180   if ((p = decode(n, p, 1)) == 0 || *p == 0)
 181     return (0);
 182   if (*p != '=') {
 183     p++;
 184     n->len = l;
 185     goto again;
 186   }
 187   p++;
 188   if ((p = decode(v, p, 0)) == 0)
 189     return (0);
 190   DPUTZ(n);
 191   DPUTZ(v);
 192   ctx->p = p;
 193   return (1);
 194 }
 195
 196 /*----- That's all, folks -------------------------------------------------*/