check_http: check for and print the certificate cn

This patch adds a check for the certificate cn (hostname) to normal
certificate checks. It returns CRITICAL if th cn is missing, otherwise it
prints it in the normal output.

Patch by Stéphane Urbanovski

5 files changed, 34 insertions, 14 deletions

diff --git a/NEWS b/NEWS
index 540e0cfa..d7fea273 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,7 @@ This file documents the major additions and syntax changes between releases.
 	check_nt UPTIME accepts warning/critical thresholds (Ryan Kelly)
 	check_disk_smb now allows spaces in share names (#990948, #1370031, Debian #601699)
 	check_http now uses standard threshold functions (enables floating point and ranges)
+	check_http now checks for and prints the certificate cn (hostname) in SSL certificate checks (Stéphane Urbanovski)
 
 	FIXES
 	Fix check_disk free space calculation if blocksizes differ within a disk group (Bekar - #2973603)
diff --git a/THANKS.in b/THANKS.in
index ac2b1c24..387a3794 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -266,3 +266,4 @@ Stephane Chazelas
 Craig Leres
 Brian Landers
 Ryan Kelly
+Stéphane Urbanovski
diff --git a/plugins/sslutils.c b/plugins/sslutils.c
index 64f4d61c..0bc61ed3 100644
--- a/plugins/sslutils.c
+++ b/plugins/sslutils.c
@@ -3,7 +3,7 @@
 * Nagios plugins SSL utilities
 * 
 * License: GPL
-* Copyright (c) 2005-2007 Nagios Plugins Development Team
+* Copyright (c) 2005-2010 Nagios Plugins Development Team
 * 
 * Description:
 * 
@@ -26,6 +26,7 @@
 * 
 *****************************************************************************/
 
+#define MAX_CN_LENGTH 256
 #define LOCAL_TIMEOUT_ALARM_HANDLER
 #include "common.h"
 #include "netutils.h"
@@ -97,6 +98,11 @@ int np_net_ssl_read(void *buf, int num){
 int np_net_ssl_check_cert(int days_till_exp){
 #  ifdef USE_OPENSSL
 	X509 *certificate=NULL;
+	X509_NAME *subj=NULL;
+	char cn[MAX_CN_LENGTH]= "";
+	int cnlen =-1;
+	int status=STATE_UNKNOWN;
+
 	ASN1_STRING *tm;
 	int offset;
 	struct tm stamp;
@@ -110,6 +116,17 @@ int np_net_ssl_check_cert(int days_till_exp){
 		return STATE_CRITICAL;
 	}
 
+	/* Extract CN from certificate subject */
+	subj=X509_get_subject_name(certificate);
+
+	if(! subj){
+		printf ("%s\n",_("CRITICAL - Cannot retrieve certificate subject."));
+		return STATE_CRITICAL;
+	}
+	cnlen = X509_NAME_get_text_by_NID (subj, NID_commonName, cn, sizeof(cn));
+	if ( cnlen == -1 )
+		strcpy(cn , _("Unknown CN"));
+
 	/* Retrieve timestamp of certificate */
 	tm = X509_get_notAfter (certificate);
 
@@ -155,19 +172,20 @@ int np_net_ssl_check_cert(int days_till_exp){
 		 stamp.tm_mday, stamp.tm_year + 1900, stamp.tm_hour, stamp.tm_min);
 
 	if (days_left > 0 && days_left <= days_till_exp) {
-		printf (_("WARNING - Certificate expires in %d day(s) (%s).\n"), days_left, timestamp);
-		return STATE_WARNING;
+		printf (_("WARNING - Certificate '%s' expires in %d day(s) (%s).\n"), cn, days_left, timestamp);
+		status=STATE_WARNING;
 	} else if (time_left < 0) {
-		printf (_("CRITICAL - Certificate expired on %s.\n"), timestamp);
-		return STATE_CRITICAL;
+		printf (_("CRITICAL - Certificate '%s' expired on %s.\n"), cn, timestamp);
+		status=STATE_CRITICAL;
 	} else if (days_left == 0) {
-		printf (_("WARNING - Certificate expires today (%s).\n"), timestamp);
-		return STATE_WARNING;
+		printf (_("WARNING - Certificate '%s' expires today (%s).\n"), cn, timestamp);
+		status=STATE_WARNING;
+	} else {
+		printf (_("OK - Certificate '%s' will expire on %s.\n"), cn, timestamp);
+		status=STATE_OK;
 	}
-
-	printf (_("OK - Certificate will expire on %s.\n"), timestamp);
 	X509_free (certificate);
-	return STATE_OK;
+	return status;
 #  else /* ifndef USE_OPENSSL */
 	printf ("%s\n", _("WARNING - Plugin does not support checking certificates."));
 	return STATE_WARNING;
diff --git a/plugins/t/check_http.t b/plugins/t/check_http.t
index c43a64a9..55a5a530 100644
--- a/plugins/t/check_http.t
+++ b/plugins/t/check_http.t
@@ -102,7 +102,7 @@ SKIP: {
 
         $res = NPTest->testCmd( "./check_http -C 1 --ssl www.verisign.com" );
         cmp_ok( $res->return_code, '==', 0, "Checking certificate for www.verisign.com");
-        like  ( $res->output, '/Certificate will expire on/', "Output OK" );
+        like  ( $res->output, "/Certificate 'www.verisign.com' will expire on/", "Output OK" );
         my $saved_cert_output = $res->output;
 
         $res = NPTest->testCmd( "./check_http www.verisign.com -C 1" );
diff --git a/plugins/tests/check_http.t b/plugins/tests/check_http.t
index 74eff175..9ae6bbdc 100755
--- a/plugins/tests/check_http.t
+++ b/plugins/tests/check_http.t
@@ -182,17 +182,17 @@ SKIP: {
 	
 	$result = NPTest->testCmd( "$command -p $port_https -S -C 14" );
 	is( $result->return_code, 0, "$command -p $port_https -S -C 14" );
-	is( $result->output, 'OK - Certificate will expire on 03/03/2019 21:41.', "output ok" );
+	is( $result->output, 'OK - Certificate \'Ton Voon\' will expire on 03/03/2019 21:41.', "output ok" );
 
 	$result = NPTest->testCmd( "$command -p $port_https -S -C 14000" );
 	is( $result->return_code, 1, "$command -p $port_https -S -C 14000" );
-	like( $result->output, '/WARNING - Certificate expires in \d+ day\(s\) \(03/03/2019 21:41\)./', "output ok" );
+	like( $result->output, '/WARNING - Certificate \'Ton Voon\' expires in \d+ day\(s\) \(03/03/2019 21:41\)./', "output ok" );
 
 	# Expired cert tests
 	$result = NPTest->testCmd( "$command -p $port_https_expired -S -C 7" );
 	is( $result->return_code, 2, "$command -p $port_https_expired -S -C 7" );
 	is( $result->output, 
-		'CRITICAL - Certificate expired on 03/05/2009 00:13.',
+		'CRITICAL - Certificate \'Ton Voon\' expired on 03/05/2009 00:13.',
 		"output ok" );
 
 }