X509_check_host, X509_check_email, X509_check_ip, X509_check_ip_asc - X.509 certificate matching
int X509_check_host(X509 *, const char *name, size_t namelen, unsigned int flags, char **peername); int X509_check_email(X509 *, const char *address, size_t addresslen, unsigned int flags); int X509_check_ip(X509 *, const unsigned char *address, size_t addresslen, unsigned int flags); int X509_check_ip_asc(X509 *, const char *address, unsigned int flags);
The certificate matching functions are used to check whether a certificate matches a given host name, email address, or IP address. The validity of the certificate and its trust level has to be checked by other means.
Per section 6.4.2 of RFC 6125, name values representing international domain names must be given in A-label
form. The namelen argument must be the number of characters in the name string or zero in
which case the length is calculated with
When the certificate is matched, and peername is not NULL, a pointer to a copy of the matching SAN or CN from the peer
certificate is stored at the address passed in peername. The application is responsible for freeing the peername via
The flags argument is usually 0. It can be the bitwise OR of the flags:
The X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT flag causes the function to consider the subject DN even if the certificate contains at least one subject alternative name of the right type (DNS name or email address as appropriate); the default is to ignore the subject DN when at least one corresponding subject alternative names is present.
If set, X509_CHECK_FLAG_NO_WILDCARDS disables wildcard expansion; this only applies to X509_check_host.
If set, X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS suppresses support for ``*'' as wildcard pattern in labels that have a prefix or suffix, such as: ``www*'' or ``*www''; this only aplies to X509_check_host.
If set, X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS allows a ``*'' that constitutes the complete label of a DNS name (e.g. ``*.example.com'') to match more than one label in name; this flag only applies to X509_check_host.
If set, X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS restricts name values which start with ``.'', that would otherwise match any sub-domain in the peer certificate, to only match direct child sub-domains. Thus, for instance, with this flag set a name of ``.example.com'' would match a peer certificate with a DNS name of ``www.example.com'', but would not match a peer certificate with a DNS name of ``www.sub.example.com''; this flag only applies to X509_check_host.
The functions return 1 for a successful match, 0 for a failed match and -1 for an internal error: typically a memory allocation failure.
Applications are encouraged to use
These functions were added in OpenSSL 1.1.0.