xref: /curl/lib/vtls/hostcheck.c (revision c074ba64)
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 #include "curl_setup.h"
26 
27 #if defined(USE_OPENSSL)                        \
28   || defined(USE_SCHANNEL)
29 /* these backends use functions from this file */
30 
31 #ifdef HAVE_NETINET_IN_H
32 #include <netinet/in.h>
33 #endif
34 #ifdef HAVE_NETINET_IN6_H
35 #include <netinet/in6.h>
36 #endif
37 #include "curl_memrchr.h"
38 
39 #include "hostcheck.h"
40 #include "strcase.h"
41 #include "hostip.h"
42 
43 #include "curl_memory.h"
44 /* The last #include file should be: */
45 #include "memdebug.h"
46 
47 /* check the two input strings with given length, but do not
48    assume they end in nul-bytes */
pmatch(const char * hostname,size_t hostlen,const char * pattern,size_t patternlen)49 static bool pmatch(const char *hostname, size_t hostlen,
50                    const char *pattern, size_t patternlen)
51 {
52   if(hostlen != patternlen)
53     return FALSE;
54   return strncasecompare(hostname, pattern, hostlen);
55 }
56 
57 /*
58  * Match a hostname against a wildcard pattern.
59  * E.g.
60  *  "foo.host.com" matches "*.host.com".
61  *
62  * We use the matching rule described in RFC6125, section 6.4.3.
63  * https://datatracker.ietf.org/doc/html/rfc6125#section-6.4.3
64  *
65  * In addition: ignore trailing dots in the hostnames and wildcards, so that
66  * the names are used normalized. This is what the browsers do.
67  *
68  * Do not allow wildcard matching on IP numbers. There are apparently
69  * certificates being used with an IP address in the CN field, thus making no
70  * apparent distinction between a name and an IP. We need to detect the use of
71  * an IP address and not wildcard match on such names.
72  *
73  * Only match on "*" being used for the leftmost label, not "a*", "a*b" nor
74  * "*b".
75  *
76  * Return TRUE on a match. FALSE if not.
77  *
78  * @unittest: 1397
79  */
80 
hostmatch(const char * hostname,size_t hostlen,const char * pattern,size_t patternlen)81 static bool hostmatch(const char *hostname,
82                       size_t hostlen,
83                       const char *pattern,
84                       size_t patternlen)
85 {
86   const char *pattern_label_end;
87 
88   DEBUGASSERT(pattern);
89   DEBUGASSERT(patternlen);
90   DEBUGASSERT(hostname);
91   DEBUGASSERT(hostlen);
92 
93   /* normalize pattern and hostname by stripping off trailing dots */
94   if(hostname[hostlen-1]=='.')
95     hostlen--;
96   if(pattern[patternlen-1]=='.')
97     patternlen--;
98 
99   if(strncmp(pattern, "*.", 2))
100     return pmatch(hostname, hostlen, pattern, patternlen);
101 
102   /* detect IP address as hostname and fail the match if so */
103   else if(Curl_host_is_ipnum(hostname))
104     return FALSE;
105 
106   /* We require at least 2 dots in the pattern to avoid too wide wildcard
107      match. */
108   pattern_label_end = memchr(pattern, '.', patternlen);
109   if(!pattern_label_end ||
110      (memrchr(pattern, '.', patternlen) == pattern_label_end))
111     return pmatch(hostname, hostlen, pattern, patternlen);
112   else {
113     const char *hostname_label_end = memchr(hostname, '.', hostlen);
114     if(hostname_label_end) {
115       size_t skiphost = hostname_label_end - hostname;
116       size_t skiplen = pattern_label_end - pattern;
117       return pmatch(hostname_label_end, hostlen - skiphost,
118                     pattern_label_end, patternlen - skiplen);
119     }
120   }
121   return FALSE;
122 }
123 
124 /*
125  * Curl_cert_hostcheck() returns TRUE if a match and FALSE if not.
126  */
Curl_cert_hostcheck(const char * match,size_t matchlen,const char * hostname,size_t hostlen)127 bool Curl_cert_hostcheck(const char *match, size_t matchlen,
128                          const char *hostname, size_t hostlen)
129 {
130   if(match && *match && hostname && *hostname)
131     return hostmatch(hostname, hostlen, match, matchlen);
132   return FALSE;
133 }
134 
135 #endif /* OPENSSL or SCHANNEL */
136