|X509_CHECK_HOST(3)||Library Functions Manual||X509_CHECK_HOST(3)|
X509_check_ip_asc — X.509
const char *name, size_t
namelen, unsigned int flags,
const char *address, size_t
addresslen, unsigned int flags);
const unsigned char *address, size_t
addresslen, unsigned int flags);
const char *address, unsigned int
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.
X509_check_host() checks if the
certificate Subject Alternative Name (SAN) or Subject CommonName (CN)
matches the specified host name, which must be encoded in the preferred name
syntax described in section 3.5 of RFC 1034. By default, wildcards are
supported and they match only in the left-most label; they may match part of
that label with an explicit prefix or suffix. For example, by default, the
host name "www.example.com" would match a
certificate with a SAN or CN value of "*.example.com",
"w*.example.com" or "*w.example.com".
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
name starts with a dot (e.g.
".example.com"), it will be matched by a certificate valid for any
sub-domain of name; see also
When the certificate is matched and peername
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 free(3) when it is no
X509_check_email() checks if the
certificate matches the specified email address. Only
the mailbox syntax of RFC 822 is supported. Comments are not allowed, and no
attempt is made to normalize quoted characters. The
addresslen argument must be the number of characters
in the address string or zero, in which case the length is calculated with
X509_check_ip() checks if the certificate
matches a specified IPv4 or IPv6 address. The address
array is in binary format, in network byte order. The length is either 4
(IPv4) or 16 (IPv6). Only explicitly marked addresses in the certificates
are considered; IP addresses stored in DNS names and Common Names are
X509_check_ip_asc() is similar, except
that the NUL-terminated string address is first
converted to the internal representation.
The flags argument is usually 0, but it can be the bitwise OR of the following flags.
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.
The remaining flags are only meaningful for
disables wildcard expansion.
flag suppresses support for "*" as a wildcard pattern in labels
that have a prefix or suffix, such as "www*" or
flag allows a "*" that constitutes the complete label of a DNS
name (e.g. "*.example.com") to match more than one label in
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
The functions return 1 for a successful match, 0 for a failed match and -1 for an internal error: typically a memory allocation failure or an ASN.1 decoding error.
All functions can also return -2 if the input is malformed. For
X509_check_host() returns -2 if the
provided name contains embedded NUL bytes.
These functions first appeared in OpenSSL 1.0.2 and have been available since OpenBSD 6.1.
|August 23, 2019||OpenBSD-current|