.functions: Add getcertnames

This function shows all the names (CNs and SANs) listed in the SSL certificate for a given domain.

As always, improvements and other feedback is welcome!

.functions

@@ -118,6 +118,40 @@ function codepoint() {
 	echo # newline
 }
 
+# Show all the names (CNs and SANs) listed in the SSL certificate
+# for a given domain
+function getcertnames() {
+	if [ -z "${1}" ]; then
+		echo "ERROR: No domain specified."
+		return 1
+	fi
+
+	domain="${1}"
+	echo "Testing ${domain}…"
+	echo # newline
+
+	tmp=$(echo -e "GET / HTTP/1.0\nEOT" \
+		| openssl s_client -connect "${domain}:443" 2>&1);
+
+	if [[ "${tmp}" = *"-----BEGIN CERTIFICATE-----"* ]]; then
+		certText=$(echo "${tmp}" \
+			| openssl x509 -text -certopt "no_header, no_serial, no_version, \
+			no_signame, no_validity, no_issuer, no_pubkey, no_sigdump, no_aux");
+			echo "Common Name:"
+			echo # newline
+			echo "${certText}" | grep "Subject:" | sed -e "s/^.*CN=//";
+			echo # newline
+			echo "Subject Alternative Name(s):"
+			echo # newline
+			echo "${certText}" | grep -A 1 "Subject Alternative Name:" \
+				| head -2 | tail -1 | sed "s/DNS://g" | sed "s/ //g" | tr "," "\n"
+			return 0
+	else
+		echo "ERROR: Certificate not found.";
+		return 1
+	fi
+}
+
 # Add note to Notes.app (OS X 10.8)
 # Usage: `note 'foo'` or `echo 'foo' | note`
 function note() {