Add support for SNI in check_smtp.

Add support for SSL/TLS hostname extension support (SNI) for check_smtp
plugin.

Backported from nagios-plugins:
https://github.com/nagios-plugins/nagios-plugins/commit/9f1628f4b5525335ce1d6e48e8ac8b07d0757f82

1 files changed, 17 insertions, 2 deletions

diff --git a/plugins/check_smtp.c b/plugins/check_smtp.c
index 70191ad9..c0ab838a 100644
--- a/plugins/check_smtp.c
+++ b/plugins/check_smtp.c
@@ -103,6 +103,7 @@ double critical_time = 0;
 int check_critical_time = FALSE;
 int verbose = 0;
 int use_ssl = FALSE;
+int use_sni = FALSE;
 short use_proxy_prefix = FALSE;
 short use_ehlo = FALSE;
 short use_lhlo = FALSE;
@@ -234,7 +235,7 @@ main (int argc, char **argv)
                     smtp_quit();
                     return STATE_UNKNOWN;
                   }
-                  result = np_net_ssl_init(sd);
+                  result = np_net_ssl_init_with_hostname(sd, (use_sni ? server_address : NULL));
                   if(result != STATE_OK) {
                     printf (_("CRITICAL - Cannot create SSL context.\n"));
                     close(sd);
@@ -463,6 +464,10 @@ process_arguments (int argc, char **argv)
         int c;
         char* temp;
 
+        enum {
+          SNI_OPTION
+        };
+
         int option = 0;
         static struct option longopts[] = {
                 {"hostname", required_argument, 0, 'H'},
@@ -485,6 +490,7 @@ process_arguments (int argc, char **argv)
                 {"help", no_argument, 0, 'h'},
                 {"lmtp", no_argument, 0, 'L'},
                 {"starttls",no_argument,0,'S'},
+                {"sni", no_argument, 0, SNI_OPTION},
                 {"certificate",required_argument,0,'D'},
                 {"ignore-quit-failure",no_argument,0,'q'},
                 {"proxy",no_argument,0,'r'},
@@ -631,6 +637,13 @@ process_arguments (int argc, char **argv)
                         use_ssl = TRUE;
                         use_ehlo = TRUE;
                         break;
+                case SNI_OPTION:
+#ifdef HAVE_SSL
+                        use_sni = TRUE;
+#else
+                        usage (_("SSL support not available - install OpenSSL and recompile"));
+#endif
+                        break;
                 case 'r':
                         use_proxy_prefix = TRUE;
                         break;
@@ -839,6 +852,8 @@ print_help (void)
   printf ("    %s\n", _("Minimum number of days a certificate has to be valid."));
   printf (" %s\n", "-S, --starttls");
   printf ("    %s\n", _("Use STARTTLS for the connection."));
+  printf (" %s\n", "--sni");
+  printf ("    %s\n", _("Enable SSL/TLS hostname extension support (SNI)"));
 #endif
 
         printf (" %s\n", "-A, --authtype=STRING");
@@ -875,6 +890,6 @@ print_usage (void)
   printf ("%s\n", _("Usage:"));
   printf ("%s -H host [-p port] [-4|-6] [-e expect] [-C command] [-R response] [-f from addr]\n", progname);
   printf ("[-A authtype -U authuser -P authpass] [-w warn] [-c crit] [-t timeout] [-q]\n");
-  printf ("[-F fqdn] [-S] [-L] [-D warn days cert expire[,crit days cert expire]] [-r] [-v] \n");
+  printf ("[-F fqdn] [-S] [-L] [-D warn days cert expire[,crit days cert expire]] [-r] [--sni] [-v] \n");
 }