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)
  52 {
  53   ctx->f = 0;
  54 }
  55
  56 /* --- @encode@ --- *
  57  *
  58  * Arguments:   @dstr *d@ = pointer to output string
  59  *              @const char *p@ = pointer to thing to encode
  60  *
  61  * Returns:     ---
  62  *
  63  * Use:         Encodes the input string into the output string.
  64  */
  65
  66 static void encode(dstr *d, const char *p)
  67 {
  68   while (*p) {
  69     switch (*p) {
  70       case ' ':
  71         DPUTC(d, '+');
  72         break;
  73       default:
  74         if (isalnum((unsigned char)*p))
  75           DPUTC(d, *p);
  76         else
  77           dstr_putf(d, "%%%02x", *p);
  78         break;
  79     }
  80     p++;
  81   }
  82 }
  83
  84 /* --- @url_enc@ --- *
  85  *
  86  * Arguments:   @url_ectx *ctx@ = pointer to encoding context
  87  *              @dstr *d@ = pointer to output string
  88  *              @const char *name@ = pointer to name
  89  *              @const char *value@ = pointer to value
  90  *
  91  * Returns:     ---
  92  *
  93  * Use:         Writes an assignment between @name@ and @value@ to the
  94  *              output string, encoding the values properly.
  95  */
  96
  97 void url_enc(url_ectx *ctx, dstr *d, const char *name, const char *value)
  98 {
  99   if (ctx->f & URLF_SEP)
 100     DPUTC(d, '&');
 101   encode(d, name);
 102   DPUTC(d, '=');
 103   encode(d, value);
 104   DPUTZ(d);
 105   ctx->f |= URLF_SEP;
 106 }
 107
 108 /* --- @url_initdec@ --- *
 109  *
 110  * Arguments:   @url_dctx *ctx@ = pointer to context block
 111  *              @const char *p@ = string to read data from
 112  *
 113  * Returns:     ---
 114  *
 115  * Use:         Initializes a URL decoding context.
 116  */
 117
 118 void url_initdec(url_dctx *ctx, const char *p)
 119 {
 120   ctx->p = p;
 121 }
 122
 123 /* --- @decode@ --- *
 124  *
 125  * Arguments:   @dstr *d@ = pointer to output string
 126  *              @const char *p@ = pointer to input data
 127  *              @int eq@ = whether to stop at `=' characters
 128  *
 129  * Returns:     Pointer to next available character.
 130  *
 131  * Use:         Does a URL decode.
 132  */
 133
 134 static const char *decode(dstr *d, const char *p, int eq)
 135 {
 136   if (!*p)
 137     return (0);
 138   for (;;) {
 139     switch (*p) {
 140       case '=':
 141         if (eq)
 142           return (p);
 143         DPUTC(d, *p);
 144         break;
 145       case 0:
 146       case '&':
 147         return (p);
 148       case '+':
 149         DPUTC(d, ' ');
 150         break;
 151       case '%': {
 152         unsigned int ch;
 153         int n;
 154         int x = sscanf(p + 1, "%2x%n", &ch, &n);
 155         if (x == 1) {
 156           DPUTC(d, ch);
 157           p += n;
 158           break;
 159         }
 160       }
 161       default:
 162         DPUTC(d, *p);
 163         break;
 164     }
 165     p++;
 166   }
 167 }
 168
 169 /* --- @url_dec@ --- *
 170  *
 171  * Arguments:   @url_dctx *ctx@ = pointer to decode context
 172  *              @dstr *n@ = pointer to output string for name
 173  *              @dstr *v@ = pointer to output string for value
 174  *
 175  * Returns:     Nonzero if it read something, zero if there's nothing left
 176  *
 177  * Use:         Decodes the next name/value pair from a urlencoded string.
 178  */
 179
 180 int url_dec(url_dctx *ctx, dstr *n, dstr *v)
 181 {
 182   const char *p = ctx->p;
 183   size_t l = n->len;
 184
 185 again:
 186   if ((p = decode(n, p, 1)) == 0 || *p == 0)
 187     return (0);
 188   if (*p != '=') {
 189     p++;
 190     n->len = l;
 191     goto again;
 192   }
 193   p++;
 194   if ((p = decode(v, p, 0)) == 0)
 195     return (0);
 196   DPUTZ(n);
 197   DPUTZ(v);
 198   ctx->p = p;
 199   return (1);
 200 }
 201
 202 /*----- That's all, folks -------------------------------------------------*/