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1 /***************************************************************************
2  *                                  _   _ ____  _
3  *  Project                     ___| | | |  _ \| |
4  *                             / __| | | | |_) | |
5  *                            | (__| |_| |  _ <| |___
6  *                             \___|\___/|_| \_\_____|
7  *
8  * Copyright (C) 1998 - 2016, 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.haxx.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  ***************************************************************************/
22 
23 /* Escape and unescape URL encoding in strings. The functions return a new
24  * allocated string or NULL if an error occurred.  */
25 
26 #include "curl_setup.h"
27 
28 #include <curl/curl.h>
29 
30 #include "urldata.h"
31 #include "warnless.h"
32 #include "non-ascii.h"
33 #include "escape.h"
34 #include "strdup.h"
35 /* The last 3 #include files should be in this order */
36 #include "curl_printf.h"
37 #include "curl_memory.h"
38 #include "memdebug.h"
39 
40 /* Portable character check (remember EBCDIC). Do not use isalnum() because
41    its behavior is altered by the current locale.
42    See https://tools.ietf.org/html/rfc3986#section-2.3
43 */
Curl_isunreserved(unsigned char in)44 static bool Curl_isunreserved(unsigned char in)
45 {
46   switch (in) {
47     case '0': case '1': case '2': case '3': case '4':
48     case '5': case '6': case '7': case '8': case '9':
49     case 'a': case 'b': case 'c': case 'd': case 'e':
50     case 'f': case 'g': case 'h': case 'i': case 'j':
51     case 'k': case 'l': case 'm': case 'n': case 'o':
52     case 'p': case 'q': case 'r': case 's': case 't':
53     case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
54     case 'A': case 'B': case 'C': case 'D': case 'E':
55     case 'F': case 'G': case 'H': case 'I': case 'J':
56     case 'K': case 'L': case 'M': case 'N': case 'O':
57     case 'P': case 'Q': case 'R': case 'S': case 'T':
58     case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
59     case '-': case '.': case '_': case '~':
60       return TRUE;
61     default:
62       break;
63   }
64   return FALSE;
65 }
66 
67 /* for ABI-compatibility with previous versions */
curl_escape(const char * string,int inlength)68 char *curl_escape(const char *string, int inlength)
69 {
70   return curl_easy_escape(NULL, string, inlength);
71 }
72 
73 /* for ABI-compatibility with previous versions */
curl_unescape(const char * string,int length)74 char *curl_unescape(const char *string, int length)
75 {
76   return curl_easy_unescape(NULL, string, length, NULL);
77 }
78 
curl_easy_escape(struct Curl_easy * data,const char * string,int inlength)79 char *curl_easy_escape(struct Curl_easy *data, const char *string,
80                        int inlength)
81 {
82   size_t alloc;
83   char *ns;
84   char *testing_ptr = NULL;
85   unsigned char in; /* we need to treat the characters unsigned */
86   size_t newlen;
87   size_t strindex=0;
88   size_t length;
89   CURLcode result;
90 
91   if(inlength < 0)
92     return NULL;
93 
94   alloc = (inlength?(size_t)inlength:strlen(string))+1;
95   newlen = alloc;
96 
97   ns = malloc(alloc);
98   if(!ns)
99     return NULL;
100 
101   length = alloc-1;
102   while(length--) {
103     in = *string;
104 
105     if(Curl_isunreserved(in))
106       /* just copy this */
107       ns[strindex++]=in;
108     else {
109       /* encode it */
110       newlen += 2; /* the size grows with two, since this'll become a %XX */
111       if(newlen > alloc) {
112         alloc *= 2;
113         testing_ptr = Curl_saferealloc(ns, alloc);
114         if(!testing_ptr)
115           return NULL;
116         else {
117           ns = testing_ptr;
118         }
119       }
120 
121       result = Curl_convert_to_network(data, &in, 1);
122       if(result) {
123         /* Curl_convert_to_network calls failf if unsuccessful */
124         free(ns);
125         return NULL;
126       }
127 
128       snprintf(&ns[strindex], 4, "%%%02X", in);
129 
130       strindex+=3;
131     }
132     string++;
133   }
134   ns[strindex]=0; /* terminate it */
135   return ns;
136 }
137 
138 /*
139  * Curl_urldecode() URL decodes the given string.
140  *
141  * Optionally detects control characters (byte codes lower than 32) in the
142  * data and rejects such data.
143  *
144  * Returns a pointer to a malloced string in *ostring with length given in
145  * *olen. If length == 0, the length is assumed to be strlen(string).
146  *
147  */
Curl_urldecode(struct Curl_easy * data,const char * string,size_t length,char ** ostring,size_t * olen,bool reject_ctrl)148 CURLcode Curl_urldecode(struct Curl_easy *data,
149                         const char *string, size_t length,
150                         char **ostring, size_t *olen,
151                         bool reject_ctrl)
152 {
153   size_t alloc = (length?length:strlen(string))+1;
154   char *ns = malloc(alloc);
155   unsigned char in;
156   size_t strindex=0;
157   unsigned long hex;
158   CURLcode result;
159 
160   if(!ns)
161     return CURLE_OUT_OF_MEMORY;
162 
163   while(--alloc > 0) {
164     in = *string;
165     if(('%' == in) && (alloc > 2) &&
166        ISXDIGIT(string[1]) && ISXDIGIT(string[2])) {
167       /* this is two hexadecimal digits following a '%' */
168       char hexstr[3];
169       char *ptr;
170       hexstr[0] = string[1];
171       hexstr[1] = string[2];
172       hexstr[2] = 0;
173 
174       hex = strtoul(hexstr, &ptr, 16);
175 
176       in = curlx_ultouc(hex); /* this long is never bigger than 255 anyway */
177 
178       result = Curl_convert_from_network(data, &in, 1);
179       if(result) {
180         /* Curl_convert_from_network calls failf if unsuccessful */
181         free(ns);
182         return result;
183       }
184 
185       string+=2;
186       alloc-=2;
187     }
188 
189     if(reject_ctrl && (in < 0x20)) {
190       free(ns);
191       return CURLE_URL_MALFORMAT;
192     }
193 
194     ns[strindex++] = in;
195     string++;
196   }
197   ns[strindex]=0; /* terminate it */
198 
199   if(olen)
200     /* store output size */
201     *olen = strindex;
202 
203   /* store output string */
204   *ostring = ns;
205 
206   return CURLE_OK;
207 }
208 
209 /*
210  * Unescapes the given URL escaped string of given length. Returns a
211  * pointer to a malloced string with length given in *olen.
212  * If length == 0, the length is assumed to be strlen(string).
213  * If olen == NULL, no output length is stored.
214  */
curl_easy_unescape(struct Curl_easy * data,const char * string,int length,int * olen)215 char *curl_easy_unescape(struct Curl_easy *data, const char *string,
216                          int length, int *olen)
217 {
218   char *str = NULL;
219   if(length >= 0) {
220     size_t inputlen = length;
221     size_t outputlen;
222     CURLcode res = Curl_urldecode(data, string, inputlen, &str, &outputlen,
223                                   FALSE);
224     if(res)
225       return NULL;
226 
227     if(olen) {
228       if(outputlen <= (size_t) INT_MAX)
229         *olen = curlx_uztosi(outputlen);
230       else
231         /* too large to return in an int, fail! */
232         Curl_safefree(str);
233     }
234   }
235   return str;
236 }
237 
238 /* For operating systems/environments that use different malloc/free
239    systems for the app and for this library, we provide a free that uses
240    the library's memory system */
curl_free(void * p)241 void curl_free(void *p)
242 {
243   free(p);
244 }
245