GSSAPI Client Example: main() Function

As with all C programs, the outer shell of the program is contained in the entry-point function, main(). main() performs four functions:

• Parses command-line arguments and assigns the arguments to variables.

• Calls parse_oid() to create a GSS-API OID, object identifier, if a mechanism other than the default is to be used. The object identifier comes from the name of the security mechanism, provided that a mechanism name has been supplied.

• Calls call_server(), which does the actual work of creating a context and sending data.

• Releases the storage space for the OID if necessary, after the data is sent.

The source code for the main() routine is shown in the following example.

Example 5-1 gss-client Example: main()

int main(argc, argv)
     int argc;
     char **argv;
{
     char *msg;
     char service_name[128]; 
     char hostname[128];  
     char *mechanism = 0;
     u_short port = 4444;
     int use_file = 0;
     OM_uint32 deleg_flag = 0, min_stat;
     
     display_file = stdout;

     /* Parse command-line arguments. */

        argc--; argv++;
     while (argc) {
          if (strcmp(*argv, "-port") == 0) {
               argc--; argv++;
               if (!argc) usage();
               port = atoi(*argv);
          } else if (strcmp(*argv, "-mech") == 0) {
               argc--; argv++;
               if (!argc) usage();
               mechanism = *argv;
          } else if (strcmp(*argv, "-d") == 0) {
               deleg_flag = GSS_C_DELEG_FLAG;
          } else if (strcmp(*argv, "-f") == 0) {
               use_file = 1;
          } else
               break;
          argc--; argv++;
     }
     if (argc != 3)
          usage();

     if (argc > 1) {
                strcpy(hostname, argv[0]);
        } else if (gethostname(hostname, sizeof(hostname)) == -1) {
                        perror("gethostname");
                        exit(1);
        }


     if (argc > 2) { 
        strcpy(service_name, argv[1]);
        strcat(service_name, "@");
        strcat(service_name, hostname);
 
     }

      msg = argv[2];

     /* Create GSSAPI object ID. */
     if (mechanism)
         parse_oid(mechanism, &g_mechOid);

     /* Call server to create context and send data. */
     if (call_server(hostname, port, g_mechOid, service_name,
                   deleg_flag, msg, use_file) < 0)
          exit(1);

     /* Release storage space for OID, if still allocated  */
     if (g_mechOid != GSS_C_NULL_OID)
         (void) gss_release_oid(&min_stat, &gmechOid);
         
     return 0;
}