[monitoring-plugins] Add support for SNI in check_smtp.

[Franz Schwartau]

    Module: monitoring-plugins
    Branch: master
    Commit: 252272344ea63a164eabc1631e9b77450d2b1c4b
    Author: Arkadiusz Miśkiewicz <ar...@maven.pl>
 Committer: Franz Schwartau <fr...@electromail.org>
      Date: Fri Aug 30 11:30:10 2019 +0200
       URL: 
https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=2522723

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

---

 plugins/check_smtp.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/plugins/check_smtp.c b/plugins/check_smtp.c
index 70191ad..c0ab838 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");
 }