+# ifdef EXPERIMENTAL_CERTNAMES
+/* Compare a domain name with a possibly-wildcarded name. Wildcards
+are restricted to a single one, as the first element of patterns
+having at least three dot-separated elements. Case-independent.
+Return TRUE for a match
+*/
+static BOOL
+is_name_match(const uschar * name, const uschar * pat)
+{
+uschar * cp;
+return *pat == '*' /* possible wildcard match */
+ ? *++pat == '.' /* starts star, dot */
+ && !Ustrchr(++pat, '*') /* has no more stars */
+ && Ustrchr(pat, '.') /* and has another dot. */
+ && (cp = Ustrchr(name, '.'))/* The name has at least one dot */
+ && strcmpic(++cp, pat) == 0 /* and we only compare after it. */
+ : !Ustrchr(pat+1, '*')
+ && strcmpic(name, pat) == 0;
+}
+
+/* Compare a list of names with the dnsname elements
+of the Subject Alternate Name, if any, and the
+Subject otherwise.
+
+Arguments:
+ namelist names to compare
+ cert certificate
+
+Returns:
+ TRUE/FALSE
+*/
+
+BOOL
+tls_is_name_for_cert(uschar * namelist, void * cert)
+{
+uschar * altnames = tls_cert_subject_altname(cert, US"dns");
+uschar * subjdn;
+uschar * certname;
+int cmp_sep = 0;
+uschar * cmpname;
+
+if ((altnames = tls_cert_subject_altname(cert, US"dns")))
+ {
+ int alt_sep = '\n';
+ while ((cmpname = string_nextinlist(&namelist, &cmp_sep, NULL, 0)))
+ {
+ uschar * an = altnames;
+ while ((certname = string_nextinlist(&an, &alt_sep, NULL, 0)))
+ if (is_name_match(cmpname, certname))
+ return TRUE;
+ }
+ }
+
+else if ((subjdn = tls_cert_subject(cert, NULL)))
+ {
+ int sn_sep = ',';
+
+ dn_to_list(subjdn);
+ while ((cmpname = string_nextinlist(&namelist, &cmp_sep, NULL, 0)))
+ {
+ uschar * sn = subjdn;
+ while ((certname = string_nextinlist(&sn, &sn_sep, NULL, 0)))
+ if ( *certname++ == 'C'
+ && *certname++ == 'N'
+ && *certname++ == '='
+ && is_name_match(cmpname, certname)
+ )
+ return TRUE;
+ }
+ }
+return FALSE;
+}
+# endif /*EXPERIMENTAL_CERTNAMES*/
+#endif /*SUPPORT_TLS*/