summaryrefslogtreecommitdiffstats
path: root/common/percent.c
blob: e0c359289ec4c69d5c0244a3f4835eff84778623 (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
/* percent.c - Percent escaping
 * Copyright (C) 2008, 2009 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG 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 of the License, or
 * (at your option) any later version.
 *
 * GnuPG 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 this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include <assert.h>

#include "util.h"


/* Create a newly alloced string from STRING with all spaces and
   control characters converted to plus signs or %xx sequences.  The
   function returns the new string or NULL in case of a malloc
   failure.

   Note that we also escape the quote character to work around a bug
   in the mingw32 runtime which does not correcty handle command line
   quoting.  We correctly double the quote mark when calling a program
   (i.e. gpg-protect-tool), but the pre-main code does not notice the
   double quote as an escaped quote.  We do this also on POSIX systems
   for consistency.  */
char *
percent_plus_escape (const char *string)
{
  char *buffer, *p;
  const char *s;
  size_t length;

  for (length=1, s=string; *s; s++)
    {
      if (*s == '+' || *s == '\"' || *s == '%' 
          || *(const unsigned char *)s < 0x20)
        length += 3;
      else
        length++;
    }
  
  buffer = p = xtrymalloc (length);
  if (!buffer)
    return NULL;

  for (s=string; *s; s++)
    {
      if (*s == '+' || *s == '\"' || *s == '%'
          || *(const unsigned char *)s < 0x20)
        {
          snprintf (p, 4, "%%%02X", *(unsigned char *)s);
          p += 3;
        }
      else if (*s == ' ')
        *p++ = '+';
      else
        *p++ = *s;
    }
  *p = 0;

  return buffer;

}


/* Do the percent and plus/space unescaping from STRING to BUFFER and
   return the length of the valid buffer.  Plus unescaping is only
   done if WITHPLUS is true.  An escaped Nul character will be
   replaced by NULREPL.  */
static size_t
do_unescape (unsigned char *buffer, const unsigned char *string, 
             int withplus, int nulrepl)
{
  unsigned char *p = buffer;

  while (*string)
    {
      if (*string == '%' && string[1] && string[2])
        { 
          string++;
          *p = xtoi_2 (string);
          if (!*p)
            *p = nulrepl;
          string++;
        }
      else if (*string == '+' && withplus)
        *p = ' ';
      else
        *p = *string;
      p++;
      string++;
    }

  return (p - buffer);
}


/* Count space required after unescaping STRING.  Note that this will
   never be larger than strlen (STRING).  */
static size_t
count_unescape (const unsigned char *string)
{
  size_t n = 0;

  while (*string)
    {
      if (*string == '%' && string[1] && string[2])
        { 
          string++;
          string++;
        }
      string++;
      n++;
    }

  return n;
}


/* Helper.  */
static char *
do_plus_or_plain_unescape (const char *string, int withplus, int nulrepl)
{
  size_t nbytes, n;
  char *newstring;

  nbytes = count_unescape (string);
  newstring = xtrymalloc (nbytes+1);
  if (newstring)
    {
      n = do_unescape (newstring, string, withplus, nulrepl);
      assert (n == nbytes);
      newstring[n] = 0;
    }
  return newstring;
}


/* Create a new allocated string from STRING with all "%xx" sequences
   decoded and all plus signs replaced by a space.  Embedded Nul
   characters are replaced by the value of NULREPL.  The function
   returns the new string or NULL in case of a malloc failure.  */
char *
percent_plus_unescape (const char *string, int nulrepl)
{
  return do_plus_or_plain_unescape (string, 1, nulrepl);
}


/* Create a new allocated string from STRING with all "%xx" sequences
   decoded.  Embedded Nul characters are replaced by the value of
   NULREPL.  The function returns the new string or NULL in case of a
   malloc failure.  */
char *
percent_unescape (const char *string, int nulrepl)
{
  return do_plus_or_plain_unescape (string, 0, nulrepl);
}


static size_t
do_unescape_inplace (char *string, int withplus, int nulrepl)
{
  unsigned char *p, *p0;

  p = p0 = string;
  while (*string)
    {
      if (*string == '%' && string[1] && string[2])
        { 
          string++;
          *p = xtoi_2 (string);
          if (!*p)
            *p = nulrepl;
          string++;
        }
      else if (*string == '+' && withplus)
        *p = ' ';
      else
        *p = *string;
      p++;
      string++;
    }

  return (p - p0);
}


/* Perform percent and plus unescaping in STRING and return the new
   valid length of the string.  Embedded Nul characters are replaced
   by the value of NULREPL.  A terminating Nul character is not
   inserted; the caller might want to call this function this way:

      foo[percent_plus_unescape_inplace (foo, 0)] = 0;
 */
size_t
percent_plus_unescape_inplace (char *string, int nulrepl)
{
  return do_unescape_inplace (string, 1, nulrepl);
}


/* Perform percent unescaping in STRING and return the new valid
   length of the string.  Embedded Nul characters are replaced by the
   value of NULREPL.  A terminating Nul character is not inserted; the
   caller might want to call this function this way:

      foo[percent_unescape_inplace (foo, 0)] = 0;
 */
size_t
percent_unescape_inplace (char *string, int nulrepl)
{
  return do_unescape_inplace (string, 0, nulrepl);
}