Index: monitoring-plugins-2.3.1/plugins-root/check_dhcp.c
===================================================================
--- monitoring-plugins-2.3.1.orig/plugins-root/check_dhcp.c
+++ monitoring-plugins-2.3.1/plugins-root/check_dhcp.c
@@ -156,6 +156,7 @@ typedef struct dhcp_offer_struct{
 	u_int32_t lease_time;            /* lease time in seconds */
 	u_int32_t renewal_time;          /* renewal time in seconds */
 	u_int32_t rebinding_time;        /* rebinding time in seconds */
+	u_int8_t desired;                 /* is this offer desired (necessary in exclusive mode) */
 	struct dhcp_offer_struct *next;
         }dhcp_offer;
 
@@ -199,6 +200,7 @@ typedef struct requested_server_struct{
 #define ETHERNET_HARDWARE_ADDRESS_LENGTH     6     /* length of Ethernet hardware addresses */
 
 u_int8_t unicast = 0;        /* unicast mode: mimic a DHCP relay */
+u_int8_t exclusive = 0;      /* exclusive mode aka "rogue DHCP server detection" */
 struct in_addr my_ip;        /* our address (required for relay) */
 struct in_addr dhcp_ip;      /* server to query (if in unicast mode) */
 unsigned char client_hardware_address[MAX_DHCP_CHADDR_LENGTH]="";
@@ -229,7 +231,7 @@ struct in_addr requested_address;
 
 int process_arguments(int, char **);
 int call_getopt(int, char **);
-int validate_arguments(int, int);
+int validate_arguments(void);
 void print_usage(void);
 void print_help(void);
 
@@ -323,8 +325,7 @@ int get_hardware_address(int sock,char *
 #elif defined(__bsd__)
 						/* King 2004	see ACKNOWLEDGEMENTS */
 
-        size_t                  len;
-        int                     mib[6];
+        int                     mib[6], len;
         char                    *buf;
         unsigned char           *ptr;
         struct if_msghdr        *ifm;
@@ -464,9 +465,10 @@ int send_dhcp_discover(int sock){
 	discover_packet.hlen=ETHERNET_HARDWARE_ADDRESS_LENGTH;
 
 	/*
-	 * transaction ID is supposed to be random.
+	 * transaction ID is supposed to be random.  We won't use the address so
+	 * we don't care about high entropy here.  time(2) is good enough.
 	 */
-	srand(time(NULL)^getpid());
+	srand(time(NULL));
 	packet_xid=random();
 	discover_packet.xid=htonl(packet_xid);
 
@@ -692,11 +694,17 @@ int receive_dhcp_packet(void *buffer, in
                 }
 
         else{
+
+		/* why do we need to peek first?  i don't know, its a hack.  without it, the source address of the first packet received was
+		   not being interpreted correctly.  sigh... */
 		bzero(&source_address,sizeof(source_address));
 		address_size=sizeof(source_address);
+                recv_result=recvfrom(sock,(char *)buffer,buffer_size,MSG_PEEK,(struct sockaddr *)&source_address,&address_size);
+		if(verbose)
+			printf("recv_result_1: %d\n",recv_result);
                 recv_result=recvfrom(sock,(char *)buffer,buffer_size,0,(struct sockaddr *)&source_address,&address_size);
 		if(verbose)
-			printf("recv_result: %d\n",recv_result);
+			printf("recv_result_2: %d\n",recv_result);
 
                 if(recv_result==-1){
 			if(verbose){
@@ -904,6 +912,7 @@ int add_dhcp_offer(struct in_addr source
 	new_offer->lease_time=dhcp_lease_time;
 	new_offer->renewal_time=dhcp_renewal_time;
 	new_offer->rebinding_time=dhcp_rebinding_time;
+	new_offer->desired=FALSE; /* exclusive mode: we'll check that in get_results */
 
 
 	if(verbose){
@@ -949,7 +958,7 @@ int free_requested_server_list(void){
 
 /* gets state and plugin output to return */
 int get_results(void){
-	dhcp_offer *temp_offer;
+	dhcp_offer *temp_offer, *undesired_offer=NULL;
 	requested_server *temp_server;
 	int result;
 	u_int32_t max_lease_time=0;
@@ -980,16 +989,24 @@ int get_results(void){
 						if(temp_server->answered)
 							printf(_(" (duplicate)"));
 						printf(_("\n"));
-						}
+					}
 					if(temp_server->answered == FALSE){
 						requested_responses++;
 						temp_server->answered=TRUE;
-						}
-				        }
-		                }
-		        }
-
-	        }
+						temp_offer->desired=TRUE;
+					}
+		        	}
+                	}
+        	}
+
+		/* exclusive mode: check for undesired offers */
+		for(temp_offer=dhcp_offer_list;temp_offer!=NULL;temp_offer=temp_offer->next) {
+			if (temp_offer->desired == FALSE) {
+				undesired_offer=temp_offer; /* Checks only for the first undesired offer */
+				break; /* no further checks needed */
+			}
+		}
+	}
 
 	/* else check and see if we got our requested address from any server */
 	else{
@@ -1003,8 +1020,8 @@ int get_results(void){
 			/* see if we got the address we requested */
 			if(!memcmp(&requested_address,&temp_offer->offered_address,sizeof(requested_address)))
 				received_requested_address=TRUE;
-	                }
-	        }
+		}
+	}
 
 	result=STATE_OK;
 	if(valid_responses==0)
@@ -1016,6 +1033,9 @@ int get_results(void){
 	else if(request_specific_address==TRUE && received_requested_address==FALSE)
 		result=STATE_WARNING;
 
+	if(exclusive && undesired_offer)
+		result=STATE_CRITICAL;
+
 	if(result==0)               /* garrett honeycutt 2005 */
 		printf("OK: ");
 	else if(result==1)
@@ -1033,6 +1053,13 @@ int get_results(void){
 
 	printf(_("Received %d DHCPOFFER(s)"),valid_responses);
 
+
+	if(exclusive && undesired_offer){
+		printf(_(", Rogue DHCP Server detected! Server %s"),inet_ntoa(undesired_offer->server_address));
+		printf(_(" offered %s \n"),inet_ntoa(undesired_offer->offered_address));
+		return result;
+	}
+
 	if(requested_servers>0)
 		printf(_(", %s%d of %d requested servers responded"),((requested_responses<requested_servers) && requested_responses>0)?"only ":"",requested_responses,requested_servers);
 
@@ -1053,19 +1080,29 @@ int get_results(void){
 
 /* process command-line arguments */
 int process_arguments(int argc, char **argv){
-	int arg_index;
+	int c;
 
 	if(argc<1)
 		return ERROR;
 
-	arg_index = call_getopt(argc,argv);
-	return validate_arguments(argc,arg_index);
+	c=0;
+	while((c+=(call_getopt(argc-c,&argv[c])))<argc){
+
+		/*
+		if(is_option(argv[c]))
+			continue;
+		*/
+		}
+
+	return validate_arguments();
         }
 
 
 
 int call_getopt(int argc, char **argv){
-	extern int optind;
+	int c=0;
+	int i=0;
+
 	int option_index = 0;
 	static struct option long_options[] =
 	{
@@ -1075,6 +1112,7 @@ int call_getopt(int argc, char **argv){
 		{"interface",      required_argument,0,'i'},
 		{"mac",            required_argument,0,'m'},
 		{"unicast",        no_argument,      0,'u'},
+		{"exclusive",      no_argument,      0,'x'},
 		{"verbose",        no_argument,      0,'v'},
 		{"version",        no_argument,      0,'V'},
 		{"help",           no_argument,      0,'h'},
@@ -1082,14 +1120,25 @@ int call_getopt(int argc, char **argv){
 	};
 
 	while(1){
-		int c=0;
+		c=getopt_long(argc,argv,"+hVvxt:s:r:t:i:m:u",long_options,&option_index);
 
-		c=getopt_long(argc,argv,"+hVvt:s:r:t:i:m:u",long_options,&option_index);
+		i++;
 
 		if(c==-1||c==EOF||c==1)
 			break;
 
 		switch(c){
+		case 'w':
+		case 'r':
+		case 't':
+		case 'i':
+			i++;
+			break;
+		default:
+			break;
+		        }
+
+		switch(c){
 
 		case 's': /* DHCP server address */
 			resolve_host(optarg,&dhcp_ip);
@@ -1133,6 +1182,9 @@ int call_getopt(int argc, char **argv){
 		case 'u': /* unicast testing */
 			unicast=1;
 			break;
+		case 'x': /* exclusive testing aka "rogue DHCP server detection" */
+			exclusive=1;
+			break;
 
 		case 'V': /* version */
 			print_revision(progname, NP_VERSION);
@@ -1146,22 +1198,16 @@ int call_getopt(int argc, char **argv){
 			verbose=1;
 			break;
 
-		case '?': /* help */
-			usage5 ();
-			break;
-
 		default:
 			break;
 		        }
 	        }
-	return optind;
-        }
 
+	return i;
+        }
 
-int validate_arguments(int argc, int arg_index){
 
-	if(argc-optind > 0)
-		usage(_("Got unexpected non-option argument"));
+int validate_arguments(void){
 
 	return OK;
         }
@@ -1361,7 +1407,7 @@ void print_help(void){
 
 	printf("%s\n", _("This plugin tests the availability of DHCP servers on a network."));
 
-  printf ("\n\n");
+	printf ("\n\n");
 
 	print_usage();
 
@@ -1371,19 +1417,21 @@ void print_help(void){
 	printf (UT_VERBOSE);
 
 	printf (" %s\n", "-s, --serverip=IPADDRESS");
-  printf ("    %s\n", _("IP address of DHCP server that we must hear from"));
-  printf (" %s\n", "-r, --requestedip=IPADDRESS");
-  printf ("    %s\n", _("IP address that should be offered by at least one DHCP server"));
-  printf (" %s\n", "-t, --timeout=INTEGER");
-  printf ("    %s\n", _("Seconds to wait for DHCPOFFER before timeout occurs"));
-  printf (" %s\n", "-i, --interface=STRING");
-  printf ("    %s\n", _("Interface to to use for listening (i.e. eth0)"));
-  printf (" %s\n", "-m, --mac=STRING");
-  printf ("    %s\n", _("MAC address to use in the DHCP request"));
-  printf (" %s\n", "-u, --unicast");
-  printf ("    %s\n", _("Unicast testing: mimic a DHCP relay, requires -s"));
+	printf ("    %s\n", _("IP address of DHCP server that we must hear from"));
+	printf (" %s\n", "-r, --requestedip=IPADDRESS");
+	printf ("    %s\n", _("IP address that should be offered by at least one DHCP server"));
+	printf (" %s\n", "-t, --timeout=INTEGER");
+	printf ("    %s\n", _("Seconds to wait for DHCPOFFER before timeout occurs"));
+	printf (" %s\n", "-i, --interface=STRING");
+	printf ("    %s\n", _("Interface to to use for listening (i.e. eth0)"));
+	printf (" %s\n", "-m, --mac=STRING");
+	printf ("    %s\n", _("MAC address to use in the DHCP request"));
+	printf (" %s\n", "-u, --unicast");
+	printf ("    %s\n", _("Unicast testing: mimic a DHCP relay, requires -s"));
+	printf (" %s\n", "-x, --exclusive");
+	printf ("    %s\n", _("Only requested DHCP server may response (rogue DHCP server detection), requires -s"));
 
-  printf (UT_SUPPORT);
+	printf (UT_SUPPORT);
 	return;
 	}
 
@@ -1391,12 +1439,10 @@ void print_help(void){
 void
 print_usage(void){
 
-  printf ("%s\n", _("Usage:"));
-  printf (" %s [-v] [-u] [-s serverip] [-r requestedip] [-t timeout]\n",progname);
-  printf ("                  [-i interface] [-m mac]\n");
+	printf ("%s\n", _("Usage:"));
+	printf (" %s [-v] [-u] [-x] [-s serverip] [-r requestedip] [-t timeout]\n",progname);
+	printf ("                  [-i interface] [-m mac]\n");
 
 	return;
 	}
 
-
-