aboutsummaryrefslogtreecommitdiff
path: root/src/util/url.c
blob: 73f61dee8e6830c10a9a4ba0e729057d7aac519b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
/*
  This file is part of TALER
  Copyright (C) 2014-2020 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU General Public License as published by the Free Software
  Foundation; either version 3, or (at your option) any later version.

  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

  You should have received a copy of the GNU General Public License along with
  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
*/
/**
 * @file url.c
 * @brief URL handling utility functions
 * @author Florian Dold
 */
#include "platform.h"
#include "taler_util.h"


/**
 * Check if a character is reserved and should
 * be urlencoded.
 *
 * @param c character to look at
 * @return true if @a c needs to be urlencoded,
 *         false otherwise
 */
static bool
is_reserved (char c)
{
  switch (c)
  {
  case '0': case '1': case '2': case '3': case '4':
  case '5': case '6': case '7': case '8': case '9':
  case 'a': case 'b': case 'c': case 'd': case 'e':
  case 'f': case 'g': case 'h': case 'i': case 'j':
  case 'k': case 'l': case 'm': case 'n': case 'o':
  case 'p': case 'q': case 'r': case 's': case 't':
  case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
  case 'A': case 'B': case 'C': case 'D': case 'E':
  case 'F': case 'G': case 'H': case 'I': case 'J':
  case 'K': case 'L': case 'M': case 'N': case 'O':
  case 'P': case 'Q': case 'R': case 'S': case 'T':
  case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
  case '-': case '.': case '_': case '~':
    return false;
  default:
    break;
  }
  return true;
}


/**
 * Get the length of a string after it has been
 * urlencoded.
 *
 * @param s the string
 * @returns the size of the urlencoded @a s
 */
static size_t
urlencode_len (const char *s)
{
  size_t len = 0;
  for (; *s != '\0'; len++, s++)
    if (is_reserved (*s))
      len += 2;
  return len;
}


/**
 * URL-encode a string according to rfc3986.
 *
 * @param buf buffer to write the result to
 * @param s string to encode
 */
static void
buffer_write_urlencode (struct GNUNET_Buffer *buf,
                        const char *s)
{
  size_t ulen;

  ulen = urlencode_len (s);
  GNUNET_assert (ulen < ulen + 1);
  GNUNET_buffer_ensure_remaining (buf,
                                  ulen + 1);
  for (size_t i = 0; i < strlen (s); i++)
  {
    if (GNUNET_YES == is_reserved (s[i]))
      GNUNET_buffer_write_fstr (buf,
                                "%%%02X",
                                s[i]);
    else
      buf->mem[buf->position++] = s[i];
  }
}


char *
TALER_urlencode (const char *s)
{
  struct GNUNET_Buffer buf = { 0 };

  buffer_write_urlencode (&buf,
                          s);
  return GNUNET_buffer_reap_str (&buf);
}


/**
 * Compute the total length of the @a args given. The args are a
 * NULL-terminated list of key-value pairs, where the values
 * must be URL-encoded.  When serializing, the pairs will be separated
 * via '?' or '&' and an '=' between key and value. Hence each
 * pair takes an extra 2 characters to encode.  This function computes
 * how many bytes are needed.  It must match the #serialize_arguments()
 * function.
 *
 * @param args NULL-terminated key-value pairs (char *) for query parameters
 * @return number of bytes needed (excluding 0-terminator) for the string buffer
 */
static size_t
calculate_argument_length (va_list args)
{
  size_t len = 0;
  va_list ap;

  va_copy (ap,
           args);
  while (1)
  {
    char *key;
    char *value;
    size_t vlen;
    size_t klen;

    key = va_arg (ap,
                  char *);
    if (NULL == key)
      break;
    value = va_arg (ap,
                    char *);
    if (NULL == value)
      continue;
    vlen = urlencode_len (value);
    klen = strlen (key);
    GNUNET_assert ( (len <= len + vlen) &&
                    (len <= len + vlen + klen) &&
                    (len < len + vlen + klen + 2) );
    len += vlen + klen + 2;
  }
  va_end (ap);
  return len;
}


/**
 * Take the key-value pairs in @a args and serialize them into
 * @a buf, using URL encoding for the values.  If a 'value' is
 * given as NULL, both the key and the value are skipped. Note
 * that a NULL value does not terminate the list, only a NULL
 * key signals the end of the list of arguments.
 *
 * @param buf where to write the values
 * @param args NULL-terminated key-value pairs (char *) for query parameters,
 *        the value will be url-encoded
 */
static void
serialize_arguments (struct GNUNET_Buffer *buf,
                     va_list args)
{
  /* used to indicate if we are processing the initial
     parameter which starts with '?' or subsequent
     parameters which are separated with '&' */
  unsigned int iparam = 0;

  while (1)
  {
    char *key;
    char *value;

    key = va_arg (args,
                  char *);
    if (NULL == key)
      break;
    value = va_arg (args,
                    char *);
    if (NULL == value)
      continue;
    GNUNET_buffer_write_str (buf,
                             (0 == iparam) ? "?" : "&");
    iparam = 1;
    GNUNET_buffer_write_str (buf,
                             key);
    GNUNET_buffer_write_str (buf,
                             "=");
    buffer_write_urlencode (buf,
                            value);
  }
}


char *
TALER_url_join (const char *base_url,
                const char *path,
                ...)
{
  struct GNUNET_Buffer buf = { 0 };
  va_list args;
  size_t len;

  GNUNET_assert (NULL != base_url);
  GNUNET_assert (NULL != path);
  if (0 == strlen (base_url))
  {
    /* base URL can't be empty */
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Empty base URL specified\n");
    return NULL;
  }
  if ('/' != base_url[strlen (base_url) - 1])
  {
    /* Must be an actual base URL! */
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Base URL `%s' does not end with '/', cannot join with `%s'\n",
                base_url,
                path);
    return NULL;
  }
  if ('/' == path[0])
  {
    /* The path must be relative. */
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Path `%s' is not relative\n",
                path);
    return NULL;
  }

  va_start (args,
            path);

  len = strlen (base_url) + strlen (path) + 1;
  len += calculate_argument_length (args);

  GNUNET_buffer_prealloc (&buf,
                          len);
  GNUNET_buffer_write_str (&buf,
                           base_url);
  GNUNET_buffer_write_str (&buf,
                           path);
  serialize_arguments (&buf,
                       args);
  va_end (args);

  return GNUNET_buffer_reap_str (&buf);
}


char *
TALER_url_absolute_raw_va (const char *proto,
                           const char *host,
                           const char *prefix,
                           const char *path,
                           va_list args)
{
  struct GNUNET_Buffer buf = { 0 };
  size_t len = 0;

  len += strlen (proto) + strlen ("://") + strlen (host);
  len += strlen (prefix) + strlen (path);
  len += calculate_argument_length (args) + 1; /* 0-terminator */

  GNUNET_buffer_prealloc (&buf,
                          len);
  GNUNET_buffer_write_str (&buf,
                           proto);
  GNUNET_buffer_write_str (&buf,
                           "://");
  GNUNET_buffer_write_str (&buf,
                           host);
  GNUNET_buffer_write_path (&buf,
                            prefix);
  GNUNET_buffer_write_path (&buf,
                            path);
  serialize_arguments (&buf,
                       args);
  return GNUNET_buffer_reap_str (&buf);
}


char *
TALER_url_absolute_raw (const char *proto,
                        const char *host,
                        const char *prefix,
                        const char *path,
                        ...)
{
  char *result;
  va_list args;

  va_start (args,
            path);
  result = TALER_url_absolute_raw_va (proto,
                                      host,
                                      prefix,
                                      path,
                                      args);
  va_end (args);
  return result;
}


bool
TALER_url_valid_charset (const char *url)
{
  for (unsigned int i = 0; '\0' != url[i]; i++)
  {
#define ALLOWED_CHARACTERS \
  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789/:;&?-.,=_~%+#"
    if (NULL == strchr (ALLOWED_CHARACTERS,
                        (int) url[i]))
      return false;
#undef ALLOWED_CHARACTERS
  }
  return true;
}


bool
TALER_is_web_url (const char *url)
{
  if ( (0 != strncasecmp (url,
                          "https://",
                          strlen ("https://"))) &&
       (0 != strncasecmp (url,
                          "http://",
                          strlen ("http://"))) )
    return false;
  if (! TALER_url_valid_charset (url) )
    return false;
  return true;
}


/* end of url.c */