multiple fixes in check_smtp from debian (bts #285554):

- fix for double free via SSL_CTX_free.  looks like the previous author
  knew this was a problem but didn't care enough to fix it ;p.
- use defines instead of const chars for SMTP strings.
- default to send our fqdn (via gethostbyname lookup on gethostname)
  in the HELO string, as this is an RFC/SMTP requirement.  overridable
  via cmdline.
- use EHLO instead of HELO if using STARTTLS, as it is not SMTP but
  ESMTP.
- verify the server supports STARTTLS before initializing it.
- always send QUIT before disconnecting when possible.


git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1246 f882894a-f735-0410-b71e-b25c423dba1c

1 files changed, 65 insertions, 21 deletions

diff --git a/plugins/check_smtp.c b/plugins/check_smtp.c
index f0bc736..3bb6a32 100644
--- a/plugins/check_smtp.c
+++ b/plugins/check_smtp.c
@@ -59,10 +59,17 @@ int check_certificate (X509 **);
 enum {
         SMTP_PORT       = 25
 };
-const char *SMTP_EXPECT = "220";
-const char *SMTP_HELO = "HELO ";
-const char *SMTP_QUIT   = "QUIT\r\n";
-const char *SMTP_STARTTLS = "STARTTLS\r\n";
+#define SMTP_EXPECT "220"
+#define SMTP_HELO "HELO "
+#define SMTP_EHLO "EHLO "
+#define SMTP_QUIT "QUIT\r\n"
+#define SMTP_STARTTLS "STARTTLS\r\n"
+
+#ifndef HOST_MAX_BYTES
+#define HOST_MAX_BYTES 255
+#endif
+
+#define EHLO_SUPPORTS_STARTTLS 1
 
 int process_arguments (int, char **);
 int validate_arguments (void);
@@ -101,6 +108,9 @@ int critical_time = 0;
 int check_critical_time = FALSE;
 int verbose = 0;
 int use_ssl = FALSE;
+short use_ehlo = FALSE;
+short ssl_established = TRUE;
+char *localhostname = NULL;
 int sd;
 char buffer[MAX_INPUT_BUFFER];
 enum {
@@ -112,7 +122,7 @@ enum {
 int
 main (int argc, char **argv)
 {
-
+        short supports_tls=FALSE;
         int n = 0;
         double elapsed_time;
         long microsec;
@@ -120,6 +130,7 @@ main (int argc, char **argv)
         char *cmd_str = NULL;
         char *helocmd = NULL;
         struct timeval tv;
+        struct hostent *hp;
 
         setlocale (LC_ALL, "");
         bindtextdomain (PACKAGE, LOCALEDIR);
@@ -129,12 +140,26 @@ main (int argc, char **argv)
                 usage4 (_("Could not parse arguments"));
 
         /* initialize the HELO command with the localhostname */
-#ifndef HOST_MAX_BYTES
-#define HOST_MAX_BYTES 255
-#endif
-        helocmd = malloc (HOST_MAX_BYTES);
-        gethostname(helocmd, HOST_MAX_BYTES);
-        asprintf (&helocmd, "%s%s%s", SMTP_HELO, helocmd, "\r\n");
+        if(! localhostname){
+                localhostname = malloc (HOST_MAX_BYTES);
+                if(!localhostname){
+                        printf(_("malloc() failed!\n"));
+                        return STATE_CRITICAL;
+                }
+                if(gethostname(localhostname, HOST_MAX_BYTES)){
+                        printf(_("gethostname() failed!\n"));
+                        return STATE_CRITICAL;
+                }
+                hp = gethostbyname(localhostname);
+                if(!hp) helocmd = localhostname;
+                else helocmd = hp->h_name;
+        } else {
+                helocmd = localhostname;
+        }
+        if(use_ehlo)
+                asprintf (&helocmd, "%s%s%s", SMTP_EHLO, helocmd, "\r\n");
+        else
+                asprintf (&helocmd, "%s%s%s", SMTP_HELO, helocmd, "\r\n");
 
         /* initialize the MAIL command with optional FROM command  */
         asprintf (&cmd_str, "%sFROM: %s%s", mail_command, from_arg, "\r\n");
@@ -178,11 +203,26 @@ main (int argc, char **argv)
                         }
                 }
 
-                /* send the HELO command */
+                /* send the HELO/EHLO command */
                 send(sd, helocmd, strlen(helocmd), 0);
 
                 /* allow for response to helo command to reach us */
-                read (sd, buffer, MAXBUF - 1);
+                if(read (sd, buffer, MAXBUF - 1) < 0){
+                        printf (_("recv() failed\n"));
+                        return STATE_WARNING;
+                } else if(use_ehlo){
+                        buffer[MAXBUF-1]='\0';
+                        if(strstr(buffer, "250 STARTTLS") != NULL ||
+                           strstr(buffer, "250-STARTTLS") != NULL){
+                                supports_tls=TRUE;
+                        }
+                }
+
+                if(use_ssl && ! supports_tls){
+                        printf(_("WARNING - TLS not supported by server\n"));
+                        send (sd, SMTP_QUIT, strlen (SMTP_QUIT), 0);
+                        return STATE_WARNING;
+                }
 
 #ifdef HAVE_SSL
                 if(use_ssl) {
@@ -192,11 +232,14 @@ main (int argc, char **argv)
                   recv(sd,buffer, MAX_INPUT_BUFFER-1, 0); /* wait for it */
                   if (!strstr (buffer, server_expect)) {
                     printf (_("Server does not support STARTTLS\n"));
+                    send (sd, SMTP_QUIT, strlen (SMTP_QUIT), 0);
                     return STATE_UNKNOWN;
                   }
                   if(connect_STARTTLS() != OK) {
                     printf (_("CRITICAL - Cannot create SSL context.\n"));
                     return STATE_CRITICAL;
+                  } else {
+                        ssl_established = TRUE;
                   }
                   if ( check_cert ) {
                     if ((server_cert = SSL_get_peer_certificate (ssl)) != NULL) {
@@ -333,6 +376,7 @@ process_arguments (int argc, char **argv)
                 {"timeout", required_argument, 0, 't'},
                 {"port", required_argument, 0, 'p'},
                 {"from", required_argument, 0, 'f'},
+                {"fqdn", required_argument, 0, 'F'},
                 {"command", required_argument, 0, 'C'},
                 {"response", required_argument, 0, 'R'},
                 {"nocommand", required_argument, 0, 'n'},
@@ -359,7 +403,7 @@ process_arguments (int argc, char **argv)
         }
 
         while (1) {
-                c = getopt_long (argc, argv, "+hVv46t:p:f:e:c:w:H:C:R:SD:",
+                c = getopt_long (argc, argv, "+hVv46t:p:f:e:c:w:H:C:R:SD:F:",
                                  longopts, &option);
 
                 if (c == -1 || c == EOF)
@@ -380,6 +424,10 @@ process_arguments (int argc, char **argv)
                         else
                                 usage4 (_("Port must be a positive integer"));
                         break;
+                case 'F':
+                /* localhostname */
+                        localhostname = strdup(optarg);
+                        break;
                 case 'f':                                                                       /* from argument */
                         from_arg = optarg;
                         smtp_use_dummycmd = 1;
@@ -439,6 +487,7 @@ process_arguments (int argc, char **argv)
                 case 'S':
                 /* starttls */
                         use_ssl = TRUE;
+                        use_ehlo = TRUE;
                         break;
                 case 'D':
                 /* Check SSL cert validity */
@@ -581,7 +630,7 @@ connect_STARTTLS (void)
 
   /* Initialize SSL context */
   SSLeay_add_ssl_algorithms ();
-  meth = SSLv2_client_method ();
+  meth = SSLv23_client_method ();
   SSL_load_error_strings ();
   if ((ctx = SSL_CTX_new (meth)) == NULL)
     {
@@ -602,11 +651,6 @@ connect_STARTTLS (void)
     {
       printf (_("CRITICAL - Cannot initiate SSL handshake.\n"));
     }
-  /* this causes a seg faul
-     not sure why, being sloppy
-     and commenting it out */
-  /*  SSL_free (ssl); */
-  SSL_CTX_free(ctx);
   my_close();
   
   return STATE_CRITICAL;
@@ -708,7 +752,7 @@ int
 my_close (void)
 {
 #ifdef HAVE_SSL
-  if (use_ssl == TRUE) {
+  if (use_ssl == TRUE && ssl_established == TRUE) {
     SSL_shutdown (ssl);
     SSL_free (ssl);
     SSL_CTX_free (ctx);