1/***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2022, Daniel Stenberg, <[email protected]>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24
25/* Escape and unescape URL encoding in strings. The functions return a new
26 * allocated string or NULL if an error occurred. */
27
28#include "curl_setup.h"
29
30#include <curl/curl.h>
31
32#include "urldata.h"
33#include "warnless.h"
34#include "escape.h"
35#include "strdup.h"
36/* The last 3 #include files should be in this order */
37#include "curl_printf.h"
38#include "curl_memory.h"
39#include "memdebug.h"
40
41/* Portable character check (remember EBCDIC). Do not use isalnum() because
42 its behavior is altered by the current locale.
43 See https://datatracker.ietf.org/doc/html/rfc3986#section-2.3
44*/
45bool Curl_isunreserved(unsigned char in)
46{
47 switch(in) {
48 case '0': case '1': case '2': case '3': case '4':
49 case '5': case '6': case '7': case '8': case '9':
50 case 'a': case 'b': case 'c': case 'd': case 'e':
51 case 'f': case 'g': case 'h': case 'i': case 'j':
52 case 'k': case 'l': case 'm': case 'n': case 'o':
53 case 'p': case 'q': case 'r': case 's': case 't':
54 case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
55 case 'A': case 'B': case 'C': case 'D': case 'E':
56 case 'F': case 'G': case 'H': case 'I': case 'J':
57 case 'K': case 'L': case 'M': case 'N': case 'O':
58 case 'P': case 'Q': case 'R': case 'S': case 'T':
59 case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
60 case '-': case '.': case '_': case '~':
61 return TRUE;
62 default:
63 break;
64 }
65 return FALSE;
66}
67
68/* for ABI-compatibility with previous versions */
69char *curl_escape(const char *string, int inlength)
70{
71 return curl_easy_escape(NULL, string, inlength);
72}
73
74/* for ABI-compatibility with previous versions */
75char *curl_unescape(const char *string, int length)
76{
77 return curl_easy_unescape(NULL, string, length, NULL);
78}
79
80/* Escapes for URL the given unescaped string of given length.
81 * 'data' is ignored since 7.82.0.
82 */
83char *curl_easy_escape(struct Curl_easy *data, const char *string,
84 int inlength)
85{
86 size_t length;
87 struct dynbuf d;
88 (void)data;
89
90 if(inlength < 0)
91 return NULL;
92
93 Curl_dyn_init(&d, CURL_MAX_INPUT_LENGTH * 3);
94
95 length = (inlength?(size_t)inlength:strlen(string));
96 if(!length)
97 return strdup("");
98
99 while(length--) {
100 unsigned char in = *string; /* we need to treat the characters unsigned */
101
102 if(Curl_isunreserved(in)) {
103 /* append this */
104 if(Curl_dyn_addn(&d, &in, 1))
105 return NULL;
106 }
107 else {
108 /* encode it */
109 if(Curl_dyn_addf(&d, "%%%02X", in))
110 return NULL;
111 }
112 string++;
113 }
114
115 return Curl_dyn_ptr(&d);
116}
117
118/*
119 * Curl_urldecode() URL decodes the given string.
120 *
121 * Returns a pointer to a malloced string in *ostring with length given in
122 * *olen. If length == 0, the length is assumed to be strlen(string).
123 *
124 * ctrl options:
125 * - REJECT_NADA: accept everything
126 * - REJECT_CTRL: rejects control characters (byte codes lower than 32) in
127 * the data
128 * - REJECT_ZERO: rejects decoded zero bytes
129 *
130 * The values for the enum starts at 2, to make the assert detect legacy
131 * invokes that used TRUE/FALSE (0 and 1).
132 */
133
134CURLcode Curl_urldecode(const char *string, size_t length,
135 char **ostring, size_t *olen,
136 enum urlreject ctrl)
137{
138 size_t alloc;
139 char *ns;
140 size_t strindex = 0;
141 unsigned long hex;
142
143 DEBUGASSERT(string);
144 DEBUGASSERT(ctrl >= REJECT_NADA); /* crash on TRUE/FALSE */
145
146 alloc = (length?length:strlen(string)) + 1;
147 ns = malloc(alloc);
148
149 if(!ns)
150 return CURLE_OUT_OF_MEMORY;
151
152 while(--alloc > 0) {
153 unsigned char in = *string;
154 if(('%' == in) && (alloc > 2) &&
155 ISXDIGIT(string[1]) && ISXDIGIT(string[2])) {
156 /* this is two hexadecimal digits following a '%' */
157 char hexstr[3];
158 char *ptr;
159 hexstr[0] = string[1];
160 hexstr[1] = string[2];
161 hexstr[2] = 0;
162
163 hex = strtoul(hexstr, &ptr, 16);
164
165 in = curlx_ultouc(hex); /* this long is never bigger than 255 anyway */
166
167 string += 2;
168 alloc -= 2;
169 }
170
171 if(((ctrl == REJECT_CTRL) && (in < 0x20)) ||
172 ((ctrl == REJECT_ZERO) && (in == 0))) {
173 free(ns);
174 return CURLE_URL_MALFORMAT;
175 }
176
177 ns[strindex++] = in;
178 string++;
179 }
180 ns[strindex] = 0; /* terminate it */
181
182 if(olen)
183 /* store output size */
184 *olen = strindex;
185
186 /* store output string */
187 *ostring = ns;
188
189 return CURLE_OK;
190}
191
192/*
193 * Unescapes the given URL escaped string of given length. Returns a
194 * pointer to a malloced string with length given in *olen.
195 * If length == 0, the length is assumed to be strlen(string).
196 * If olen == NULL, no output length is stored.
197 * 'data' is ignored since 7.82.0.
198 */
199char *curl_easy_unescape(struct Curl_easy *data, const char *string,
200 int length, int *olen)
201{
202 char *str = NULL;
203 (void)data;
204 if(length >= 0) {
205 size_t inputlen = length;
206 size_t outputlen;
207 CURLcode res = Curl_urldecode(string, inputlen, &str, &outputlen,
208 REJECT_NADA);
209 if(res)
210 return NULL;
211
212 if(olen) {
213 if(outputlen <= (size_t) INT_MAX)
214 *olen = curlx_uztosi(outputlen);
215 else
216 /* too large to return in an int, fail! */
217 Curl_safefree(str);
218 }
219 }
220 return str;
221}
222
223/* For operating systems/environments that use different malloc/free
224 systems for the app and for this library, we provide a free that uses
225 the library's memory system */
226void curl_free(void *p)
227{
228 free(p);
229}
230