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diff --git a/openssl/doc/crypto/X509_check_host.pod b/openssl/doc/crypto/X509_check_host.pod
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+++ b/openssl/doc/crypto/X509_check_host.pod
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+=pod
+
+=head1 NAME
+
+X509_check_host, X509_check_email, X509_check_ip, X509_check_ip_asc - X.509 certificate matching
+
+=head1 SYNOPSIS
+
+ #include <openssl/x509.h>
+
+ 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);
+
+=head1 DESCRIPTION
+
+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; but they may match
+part of that label with an explicit prefix or suffix.  For example,
+by default, the host B<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, B<name> values representing international
+domain names must be given in A-label form.  The B<namelen> argument
+must be the number of characters in the name string or zero in which
+case the length is calculated with strlen(B<name>).  When B<name> starts
+with a dot (e.g ".example.com"), it will be matched by a certificate
+valid for any sub-domain of B<name>, (see also
+B<X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS> below).
+
+When the certificate is matched, and B<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 B<peername>.  The application
+is responsible for freeing the peername via OPENSSL_free() when it
+is no longer needed.
+
+X509_check_email() checks if the certificate matches the specified
+email B<address>.  Only the mailbox syntax of RFC 822 is supported,
+comments are not allowed, and no attempt is made to normalize quoted
+characters.  The B<addresslen> argument must be the number of
+characters in the address string or zero in which case the length
+is calculated with strlen(B<address>).
+
+X509_check_ip() checks if the certificate matches a specified IPv4 or
+IPv6 address.  The B<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 ignored.
+
+X509_check_ip_asc() is similar, except that the NUL-terminated
+string B<address> is first converted to the internal representation.
+
+The B<flags> argument is usually 0.  It can be the bitwise OR of the
+flags:
+
+=over 4
+
+=item B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT>,
+
+=item B<X509_CHECK_FLAG_NO_WILDCARDS>,
+
+=item B<X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS>,
+
+=item B<X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS>.
+
+=item B<X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS>.
+
+=back
+
+The B<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, B<X509_CHECK_FLAG_NO_WILDCARDS> disables wildcard
+expansion; this only applies to B<X509_check_host>.
+
+If set, B<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 B<X509_check_host>.
+
+If set, B<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 B<name>; this flag only applies
+to B<X509_check_host>.
+
+If set, B<X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS> restricts B<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 B<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 B<X509_check_host>.
+
+=head1 RETURN VALUES
+
+The functions return 1 for a successful match, 0 for a failed match
+and -1 for an internal error: typically a memory allocation failure.
+
+X509_check_ip_asc() can also return -2 if the IP address string is malformed.
+
+=head1 NOTES
+
+Applications are encouraged to use X509_VERIFY_PARAM_set1_host()
+rather than explicitly calling L<X509_check_host(3)>. Host name
+checks are out of scope with the DANE-EE(3) certificate usage,
+and the internal checks will be suppressed as appropriate when
+DANE support is added to OpenSSL.
+
+=head1 SEE ALSO
+
+L<SSL_get_verify_result(3)|SSL_get_verify_result(3)>,
+L<X509_VERIFY_PARAM_set1_host(3)|X509_VERIFY_PARAM_set1_host(3)>,
+L<X509_VERIFY_PARAM_add1_host(3)|X509_VERIFY_PARAM_add1_host(3)>,
+L<X509_VERIFY_PARAM_set1_email(3)|X509_VERIFY_PARAM_set1_email(3)>,
+L<X509_VERIFY_PARAM_set1_ip(3)|X509_VERIFY_PARAM_set1_ip(3)>,
+L<X509_VERIFY_PARAM_set1_ipasc(3)|X509_VERIFY_PARAM_set1_ipasc(3)>
+
+=head1 HISTORY
+
+These functions were added in OpenSSL 1.1.0.
+
+=cut