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

3 files changed, 32 insertions, 14 deletions

diff --git a/plugins/sslutils.c b/plugins/sslutils.c
index 64f4d61..0bc61ed 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 c43a64a..55a5a53 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 74eff17..9ae6bbd 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" );
 
 }