1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, 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 /* for ABI-compatibility with previous versions */
curl_escape(const char * string,int inlength)42 char *curl_escape(const char *string, int inlength)
43 {
44 return curl_easy_escape(NULL, string, inlength);
45 }
46
47 /* for ABI-compatibility with previous versions */
curl_unescape(const char * string,int length)48 char *curl_unescape(const char *string, int length)
49 {
50 return curl_easy_unescape(NULL, string, length, NULL);
51 }
52
53 /* Escapes for URL the given unescaped string of given length.
54 * 'data' is ignored since 7.82.0.
55 */
curl_easy_escape(struct Curl_easy * data,const char * string,int inlength)56 char *curl_easy_escape(struct Curl_easy *data, const char *string,
57 int inlength)
58 {
59 size_t length;
60 struct dynbuf d;
61 (void)data;
62
63 if(inlength < 0)
64 return NULL;
65
66 Curl_dyn_init(&d, CURL_MAX_INPUT_LENGTH * 3);
67
68 length = (inlength?(size_t)inlength:strlen(string));
69 if(!length)
70 return strdup("");
71
72 while(length--) {
73 unsigned char in = *string++; /* treat the characters unsigned */
74
75 if(ISUNRESERVED(in)) {
76 /* append this */
77 if(Curl_dyn_addn(&d, &in, 1))
78 return NULL;
79 }
80 else {
81 /* encode it */
82 const char hex[] = "0123456789ABCDEF";
83 char out[3]={'%'};
84 out[1] = hex[in>>4];
85 out[2] = hex[in & 0xf];
86 if(Curl_dyn_addn(&d, out, 3))
87 return NULL;
88 }
89 }
90
91 return Curl_dyn_ptr(&d);
92 }
93
94 static const unsigned char hextable[] = {
95 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, /* 0x30 - 0x3f */
96 0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x40 - 0x4f */
97 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x50 - 0x5f */
98 0, 10, 11, 12, 13, 14, 15 /* 0x60 - 0x66 */
99 };
100
101 /* the input is a single hex digit */
102 #define onehex2dec(x) hextable[x - '0']
103
104 /*
105 * Curl_urldecode() URL decodes the given string.
106 *
107 * Returns a pointer to a malloced string in *ostring with length given in
108 * *olen. If length == 0, the length is assumed to be strlen(string).
109 *
110 * ctrl options:
111 * - REJECT_NADA: accept everything
112 * - REJECT_CTRL: rejects control characters (byte codes lower than 32) in
113 * the data
114 * - REJECT_ZERO: rejects decoded zero bytes
115 *
116 * The values for the enum starts at 2, to make the assert detect legacy
117 * invokes that used TRUE/FALSE (0 and 1).
118 */
119
Curl_urldecode(const char * string,size_t length,char ** ostring,size_t * olen,enum urlreject ctrl)120 CURLcode Curl_urldecode(const char *string, size_t length,
121 char **ostring, size_t *olen,
122 enum urlreject ctrl)
123 {
124 size_t alloc;
125 char *ns;
126
127 DEBUGASSERT(string);
128 DEBUGASSERT(ctrl >= REJECT_NADA); /* crash on TRUE/FALSE */
129
130 alloc = (length?length:strlen(string));
131 ns = malloc(alloc + 1);
132
133 if(!ns)
134 return CURLE_OUT_OF_MEMORY;
135
136 /* store output string */
137 *ostring = ns;
138
139 while(alloc) {
140 unsigned char in = *string;
141 if(('%' == in) && (alloc > 2) &&
142 ISXDIGIT(string[1]) && ISXDIGIT(string[2])) {
143 /* this is two hexadecimal digits following a '%' */
144 in = (unsigned char)(onehex2dec(string[1]) << 4) | onehex2dec(string[2]);
145
146 string += 3;
147 alloc -= 3;
148 }
149 else {
150 string++;
151 alloc--;
152 }
153
154 if(((ctrl == REJECT_CTRL) && (in < 0x20)) ||
155 ((ctrl == REJECT_ZERO) && (in == 0))) {
156 Curl_safefree(*ostring);
157 return CURLE_URL_MALFORMAT;
158 }
159
160 *ns++ = in;
161 }
162 *ns = 0; /* terminate it */
163
164 if(olen)
165 /* store output size */
166 *olen = ns - *ostring;
167
168 return CURLE_OK;
169 }
170
171 /*
172 * Unescapes the given URL escaped string of given length. Returns a
173 * pointer to a malloced string with length given in *olen.
174 * If length == 0, the length is assumed to be strlen(string).
175 * If olen == NULL, no output length is stored.
176 * 'data' is ignored since 7.82.0.
177 */
curl_easy_unescape(struct Curl_easy * data,const char * string,int length,int * olen)178 char *curl_easy_unescape(struct Curl_easy *data, const char *string,
179 int length, int *olen)
180 {
181 char *str = NULL;
182 (void)data;
183 if(length >= 0) {
184 size_t inputlen = (size_t)length;
185 size_t outputlen;
186 CURLcode res = Curl_urldecode(string, inputlen, &str, &outputlen,
187 REJECT_NADA);
188 if(res)
189 return NULL;
190
191 if(olen) {
192 if(outputlen <= (size_t) INT_MAX)
193 *olen = curlx_uztosi(outputlen);
194 else
195 /* too large to return in an int, fail! */
196 Curl_safefree(str);
197 }
198 }
199 return str;
200 }
201
202 /* For operating systems/environments that use different malloc/free
203 systems for the app and for this library, we provide a free that uses
204 the library's memory system */
curl_free(void * p)205 void curl_free(void *p)
206 {
207 free(p);
208 }
209
210 /*
211 * Curl_hexencode()
212 *
213 * Converts binary input to lowercase hex-encoded ASCII output.
214 * Null-terminated.
215 */
Curl_hexencode(const unsigned char * src,size_t len,unsigned char * out,size_t olen)216 void Curl_hexencode(const unsigned char *src, size_t len, /* input length */
217 unsigned char *out, size_t olen) /* output buffer size */
218 {
219 const char *hex = "0123456789abcdef";
220 DEBUGASSERT(src && len && (olen >= 3));
221 if(src && len && (olen >= 3)) {
222 while(len-- && (olen >= 3)) {
223 /* clang-tidy warns on this line without this comment: */
224 /* NOLINTNEXTLINE(clang-analyzer-core.UndefinedBinaryOperatorResult) */
225 *out++ = hex[(*src & 0xF0)>>4];
226 *out++ = hex[*src & 0x0F];
227 ++src;
228 olen -= 2;
229 }
230 *out = 0;
231 }
232 else if(olen)
233 *out = 0;
234 }
235