check_snmp: Handle SNMPv3 noAuthNoPriv properly

The SNMPv3 noAuthNoPriv security level, somewhat unintuitively, requires
a security name to be passed along together with the request. Check_snmp
previously did not do this, causing snmpget to throw an error:

"External command error: No log handling enabled - turning on stderr
logging
snmpget: No securityName specified"

This patch fixes the issue by always providing the security name when
noAuthNoPriv is specified.

See also:
https:://bugs.op5.com/view.php?id=8385.

Signed-off-by: Anton Lofgren <alofgren@op5.com>

plugins/check_snmp.c

@@ -986,11 +986,16 @@ validate_arguments ()
 		if (seclevel == NULL)
 			xasprintf(&seclevel, "noAuthNoPriv");
 
+		if (secname == NULL)
+			die(STATE_UNKNOWN, _("Required parameter: %s\n"), "secname");
+
 		if (strcmp(seclevel, "noAuthNoPriv") == 0) {
-			numauthpriv = 2;
+			numauthpriv = 4;
 			authpriv = calloc (numauthpriv, sizeof (char *));
 			authpriv[0] = strdup ("-l");
 			authpriv[1] = strdup ("noAuthNoPriv");
+			authpriv[2] = strdup ("-u");
+			authpriv[3] = strdup (secname);
 		} else {
 			if (! ( (strcmp(seclevel, "authNoPriv")==0) || (strcmp(seclevel, "authPriv")==0) ) ) {
 				usage2 (_("Invalid seclevel"), seclevel);
@@ -999,9 +1004,6 @@ validate_arguments ()
 			if (authproto == NULL )
 				xasprintf(&authproto, DEFAULT_AUTH_PROTOCOL);
 
-			if (secname == NULL)
-				die(STATE_UNKNOWN, _("Required parameter: %s\n"), "secname");
-
 			if (authpasswd == NULL)
 				die(STATE_UNKNOWN, _("Required parameter: %s\n"), "authpasswd");
 

plugins/t/check_snmp.t

@@ -10,7 +10,7 @@ use NPTest;
 
 BEGIN {
     plan skip_all => 'check_snmp is not compiled' unless -x "./check_snmp";
-    plan tests => 60;
+    plan tests => 61;
 }
 
 my $res;
@@ -26,6 +26,7 @@ my $host_nonresponsive = getTestParameter( "host_nonresponsive", "NP_HOST_NONRES
 
 my $hostname_invalid   = getTestParameter( "hostname_invalid",   "NP_HOSTNAME_INVALID",   "nosuchhost",
                                            "An invalid (not known to DNS) hostname" );
+my $user_snmp = getTestParameter( "user_snmp",    "NP_SNMP_USER",    "auth_md5", "An SNMP user");
 
 $res = NPTest->testCmd( "./check_snmp -t 1" );
 is( $res->return_code, 3, "No host name" );
@@ -35,7 +36,7 @@ $res = NPTest->testCmd( "./check_snmp -H fakehostname" );
 is( $res->return_code, 3, "No OIDs specified" );
 is( $res->output, "No OIDs specified" );
 
-$res = NPTest->testCmd( "./check_snmp -H fakehost -o oids -P 3 --seclevel=rubbish" );
+$res = NPTest->testCmd( "./check_snmp -H fakehost -o oids -P 3 -U not_a_user --seclevel=rubbish" );
 is( $res->return_code, 3, "Invalid seclevel" );
 like( $res->output, "/check_snmp: Invalid seclevel - rubbish/" );
 
@@ -154,6 +155,12 @@ SKIP: {
     like($res->output, '/^SNMP OK - Timeticks:\s\(\d+\)\s+(?:\d+ days?,\s+)?\d+:\d+:\d+\.\d+\s.*$/', "Timetick used as a string, result printed rather than parsed");
 }
 
+SKIP: {
+    skip "no SNMP user defined", 1 if ( ! $user_snmp );
+    $res = NPTest->testCmd( "./check_snmp -H $host_snmp -o HOST-RESOURCES-MIB::hrSystemUptime.0 -P 3 -U $user_snmp -L noAuthNoPriv");
+    like( $res->output, '/^SNMP OK - Timeticks:\s\(\d+\)\s+(?:\d+ days?,\s+)?\d+:\d+:\d+\.\d+\s.*$/', "noAuthNoPriv security level works properly" );
+}
+
 # These checks need a complete command line. An invalid community is used so
 # the tests can run on hosts w/o snmp host/community in NPTest.cache. Execution will fail anyway
 SKIP: {