validate.c

   1 /*
   2 COPYRIGHT AND PERMISSION NOTICE
   3
   4 Copyright (c) 1996 - 2010, Daniel Stenberg, <daniel@haxx.se>.
   5
   6 All rights reserved.
   7
   8 Permission to use, copy, modify, and distribute this software for any purpose
   9 with or without fee is hereby granted, provided that the above copyright
  10 notice and this permission notice appear in all copies.
  11
  12 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  13 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  14 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN
  15 NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  16 DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  17 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
  18 OR OTHER DEALINGS IN THE SOFTWARE.
  19
  20 Except as contained in this notice, the name of a copyright holder shall not
  21 be used in advertising or otherwise to promote the sale, use or other dealings
  22 in this Software without prior written authorization of the copyright holder.
  23 */
  24 /* simplified to a basic host name check */
  25 #include <string.h>
  26 #include <openssl/x509_vfy.h>
  27 #include <openssl/x509v3.h>
  28
  29 #define bool int
  30 #define false 0
  31 #define true 1
  32 /** @fn static bool cert_hostcheck(const char *hostname, char *pattern)
  33   * Verifies that the hostname matches against the pattern specified.
  34   * Handles wildcard patterns and ignores the distinction between upper and lower case letters.
  35   * Note: Ported over from ssluse.c in curl (7.1.16) lib
  36   * Note: Explicit pattern match disabled as we do not use that for processing node certificate.
  37   * Note: No longer ignores the distinction between upper and lower case letters.  Our certificate is generated with lowercase letters.
  38   * @return true if matches, false otherwise
  39   * @param hostname The hostname we want to check. e.g: vault.trustcommerce.com
  40   * @param pattern The pattern we wish to match against. e.g: *.trustcommerce.com
  41   */
  42 bool cert_hostcheck(const char *pattern, const char *hostname)
  43 {
  44         if (!hostname || !pattern || !*hostname || !*pattern) return false;
  45         if (!strcmp(hostname,pattern)) return true;
  46         return false;
  47 }
  48 /** @fn static bool checkCertificate(X509 *cert, char *host)
  49   * Provides validation of the hostname associated with a certificate.
  50   * See RFC2818 - Server Identity for an overview of the concept.
  51   * This implementation is based off the one found in curl-7.16.1: ssluse.c
  52   * but we treat the subjectAltName as a recommendation... so if it fails,
  53   * we will proceed to the CN check.
  54   * The rationale for this is that we are not always using HTTP (over SSL)
  55   * and its more of a certification generation / CA issue and we want
  56   * maximum interoperability (as opposed to strict compliance).
  57   * @param cert The X509 certificate in question.
  58   * @param host The hostname or ip we wish to check.
  59   * @return true if matches, false otherwise
  60   */
  61 static bool checkCertificate(X509 * cert, const char *host)
  62 {
  63         int i,j;
  64         bool matched = false;
  65         STACK_OF(GENERAL_NAME) * altnames;
  66         unsigned char *nulstr = { '\0' };
  67         unsigned char *peer_CN = nulstr;
  68         X509_NAME *name;
  69         ASN1_STRING * tmp;
  70         bool status = false;
  71
  72         if (!cert || !host) return false;
  73
  74         altnames = (STACK_OF(GENERAL_NAME) *)(X509_get_ext_d2i(cert, NID_subject_alt_name, NULL, NULL));
  75
  76         if (altnames != NULL)
  77         {
  78                 int numalts = sk_GENERAL_NAME_num(altnames);
  79                 for (i=0; (i<numalts) && (matched == false); i++)
  80                 {
  81                         const GENERAL_NAME *check = sk_GENERAL_NAME_value(altnames, i);
  82                         const char *altptr = (char *)(ASN1_STRING_data(check->d.ia5));
  83                         size_t altlen;
  84                         switch (check->type)
  85                         {
  86                                 case GEN_DNS:
  87                                         altlen = ASN1_STRING_length(check->d.ia5);
  88                                         if (altlen == strlen(host) && cert_hostcheck(altptr, host))
  89                                                 matched = true;
  90                                         break;
  91                                 case GEN_IPADD:
  92                                         altlen = ASN1_STRING_length(check->d.ia5);
  93                                         if (altlen == strlen(host) && !memcmp(altptr, host, altlen))
  94                                                 matched = true;
  95                                         break;
  96                         }
  97                 }
  98                 GENERAL_NAMES_free(altnames);
  99                 if (matched != false) return true;
 100         }
 101
 102         i = j = -1;
 103
 104
 105         name = X509_get_subject_name(cert);
 106         if (!name) return false;
 107
 108
 109         // get the last CN found in the subject (supposedly its the most distinguished one)
 110         while ((j=X509_NAME_get_index_by_NID(name,NID_commonName,i))>=0)
 111                 i=j;
 112
 113         if (i<0) return false;
 114
 115         tmp = X509_NAME_ENTRY_get_data(X509_NAME_get_entry(name, i));
 116         /* workaround for version of openssl < 0.9.7d */
 117         if (tmp && ASN1_STRING_type(tmp) == V_ASN1_UTF8STRING)
 118         {
 119                 j = ASN1_STRING_length(tmp);
 120                 if (j >= 0) {
 121                         peer_CN = (unsigned char *)(OPENSSL_malloc(j+1));
 122                         if (peer_CN)
 123                         {
 124                                 memcpy(peer_CN, ASN1_STRING_data(tmp), j);
 125                                 peer_CN[j] = '\0';
 126                         }
 127                 }
 128         }
 129         else
 130         {
 131                 j = ASN1_STRING_to_UTF8(&peer_CN, tmp);
 132         }
 133
 134         if (peer_CN == nulstr)
 135                 peer_CN = NULL;
 136
 137         if (peer_CN == NULL)
 138                 return false; // the cn isnt missing in virtually all cases
 139         else if(!cert_hostcheck((char *)(peer_CN), host))
 140                 status = false;
 141         else
 142                 status = true;
 143
 144         if (peer_CN)
 145                 OPENSSL_free(peer_CN);
 146         return status;
 147 }
 148
 149 int TCLinkDefaultValidate(int x, void * cert)
 150 {
 151         if (x != 0 || cert == NULL) return 0;
 152         return !checkCertificate((X509 *)cert, "pgw1.trustcommerce.com");
 153
 154 }