1 files changed, 376 insertions, 362 deletions

diff --git a/plugins-root/check_dhcp.c b/plugins-root/check_dhcp.c
index 2d22619..6b07df5 100644
--- a/plugins-root/check_dhcp.c
+++ b/plugins-root/check_dhcp.c
@@ -1,40 +1,40 @@
 /*****************************************************************************
-* 
-* Monitoring check_dhcp plugin
-* 
-* License: GPL
-* Copyright (c) 2001-2004 Ethan Galstad (nagios@nagios.org)
-* Copyright (c) 2001-2007 Monitoring Plugins Development Team
-* 
-* Description:
-* 
-* This file contains the check_dhcp plugin
-* 
-* This plugin tests the availability of DHCP servers on a network.
-* 
-* Unicast mode was originally implemented by Heiti of Boras Kommun with
-* general improvements as well as usability fixes and "forward"-porting by
-* Andreas Ericsson of OP5 AB.
-* 
-* 
-* This program is free software: you can redistribute it and/or modify
-* it under the terms of the GNU General Public License as published by
-* the Free Software Foundation, either version 3 of the License, or
-* (at your option) any later version.
-* 
-* This program is distributed in the hope that it will be useful,
-* but WITHOUT ANY WARRANTY; without even the implied warranty of
-* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-* GNU General Public License for more details.
-* 
-* You should have received a copy of the GNU General Public License
-* along with this program.  If not, see <http://www.gnu.org/licenses/>.
-* 
-* 
-*****************************************************************************/
+ *
+ * Monitoring check_dhcp plugin
+ *
+ * License: GPL
+ * Copyright (c) 2001-2004 Ethan Galstad (nagios@nagios.org)
+ * Copyright (c) 2001-2007 Monitoring Plugins Development Team
+ *
+ * Description:
+ *
+ * This file contains the check_dhcp plugin
+ *
+ * This plugin tests the availability of DHCP servers on a network.
+ *
+ * Unicast mode was originally implemented by Heiti of Boras Kommun with
+ * general improvements as well as usability fixes and "forward"-porting by
+ * Andreas Ericsson of OP5 AB.
+ *
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ *****************************************************************************/
 
 const char *progname = "check_dhcp";
-const char *copyright = "2001-2007";
+const char *copyright = "2001-2023";
 const char *email = "devel@monitoring-plugins.org";
 
 #include "common.h"
@@ -57,9 +57,10 @@ const char *email = "devel@monitoring-plugins.org";
 #include <netinet/in.h>
 #include <net/if.h>
 #include <arpa/inet.h>
+
 #if HAVE_SYS_SOCKIO_H
 #include <sys/sockio.h>
-#endif
+#endif // HAVE_SYS_SOCKIO_H
 
 #if defined( __linux__ )
 
@@ -98,10 +99,6 @@ static struct strbuf dat = {AREA_SZ, 0, (char *)dat_area};
 #define GOT_INTR 4
 #define GOT_ERR 128
 
-#define u_int8_t         uint8_t
-#define u_int16_t       uint16_t
-#define u_int32_t       uint32_t
-
 static int get_msg(int);
 static int check_ctrl(int);
 static int put_ctrl(int, int, int);
@@ -110,7 +107,7 @@ static int dl_open(const char *, int, int *);
 static int dl_bind(int, int, u_char *);
 long mac_addr_dlpi( const char *, int, u_char *);
 
-#endif
+#endif // __sun__ || __solaris__ || __hpux
 
 
 
@@ -119,9 +116,6 @@ long mac_addr_dlpi( const char *, int, u_char *);
 #define OK                0
 #define ERROR             -1
 
-#define FALSE             0
-#define TRUE              1
-
 
 /**** DHCP definitions ****/
 
@@ -132,39 +126,40 @@ long mac_addr_dlpi( const char *, int, u_char *);
 
 
 typedef struct dhcp_packet_struct{
-        u_int8_t  op;                   /* packet type */
-        u_int8_t  htype;                /* type of hardware address for this machine (Ethernet, etc) */
-        u_int8_t  hlen;                 /* length of hardware address (of this machine) */
-        u_int8_t  hops;                 /* hops */
-        u_int32_t xid;                  /* random transaction id number - chosen by this machine */
-        u_int16_t secs;                 /* seconds used in timing */
-        u_int16_t flags;                /* flags */
-        struct in_addr ciaddr;          /* IP address of this machine (if we already have one) */
-        struct in_addr yiaddr;          /* IP address of this machine (offered by the DHCP server) */
-        struct in_addr siaddr;          /* IP address of next server */
-        struct in_addr giaddr;          /* IP address of DHCP relay */
-        unsigned char chaddr [MAX_DHCP_CHADDR_LENGTH];      /* hardware address of this machine */
-        char sname [MAX_DHCP_SNAME_LENGTH];    /* name of DHCP server */
-        char file [MAX_DHCP_FILE_LENGTH];      /* boot file name (used for diskless booting?) */
+        uint8_t  op;                   /* packet type */
+        uint8_t  htype;                /* type of hardware address for this machine (Ethernet, etc) */
+        uint8_t  hlen;                 /* length of hardware address (of this machine) */
+        uint8_t  hops;                 /* hops */
+        uint32_t xid;                  /* random transaction id number - chosen by this machine */
+        uint16_t secs;                 /* seconds used in timing */
+        uint16_t flags;                /* flags */
+        struct in_addr ciaddr;          /* IP address of this machine (if we already have one) */
+        struct in_addr yiaddr;          /* IP address of this machine (offered by the DHCP server) */
+        struct in_addr siaddr;          /* IP address of next server */
+        struct in_addr giaddr;          /* IP address of DHCP relay */
+        unsigned char chaddr [MAX_DHCP_CHADDR_LENGTH];      /* hardware address of this machine */
+        char sname [MAX_DHCP_SNAME_LENGTH];    /* name of DHCP server */
+        char file [MAX_DHCP_FILE_LENGTH];      /* boot file name (used for diskless booting?) */
         char options[MAX_DHCP_OPTIONS_LENGTH];  /* options */
-        }dhcp_packet;
+}dhcp_packet;
 
 
 typedef struct dhcp_offer_struct{
         struct in_addr server_address;   /* address of DHCP server that sent this offer */
         struct in_addr offered_address;  /* the IP address that was offered to us */
-        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 */
+        uint32_t lease_time;            /* lease time in seconds */
+        uint32_t renewal_time;          /* renewal time in seconds */
+        uint32_t rebinding_time;        /* rebinding time in seconds */
+        bool desired;                 /* is this offer desired (necessary in exclusive mode) */
         struct dhcp_offer_struct *next;
-        }dhcp_offer;
+}dhcp_offer;
 
 
 typedef struct requested_server_struct{
         struct in_addr server_address;
-        int answered;
+        bool answered;
         struct requested_server_struct *next;
-        }requested_server;
+}requested_server;
 
 
 #define BOOTREQUEST     1
@@ -198,7 +193,8 @@ typedef struct requested_server_struct{
 #define ETHERNET_HARDWARE_ADDRESS            1     /* used in htype field of dhcp packet */
 #define ETHERNET_HARDWARE_ADDRESS_LENGTH     6     /* length of Ethernet hardware addresses */
 
-u_int8_t unicast = 0;        /* unicast mode: mimic a DHCP relay */
+bool unicast = false;        /* unicast mode: mimic a DHCP relay */
+bool exclusive = false;      /* 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]="";
@@ -206,11 +202,11 @@ unsigned char *user_specified_mac=NULL;
 
 char network_interface_name[IFNAMSIZ]="eth0";
 
-u_int32_t packet_xid=0;
+uint32_t packet_xid=0;
 
-u_int32_t dhcp_lease_time=0;
-u_int32_t dhcp_renewal_time=0;
-u_int32_t dhcp_rebinding_time=0;
+uint32_t dhcp_lease_time=0;
+uint32_t dhcp_renewal_time=0;
+uint32_t dhcp_rebinding_time=0;
 
 int dhcpoffer_timeout=2;
 
@@ -221,8 +217,8 @@ int valid_responses=0;     /* number of valid DHCPOFFERs we received */
 int requested_servers=0;
 int requested_responses=0;
 
-int request_specific_address=FALSE;
-int received_requested_address=FALSE;
+bool request_specific_address=false;
+bool received_requested_address=false;
 int verbose=0;
 struct in_addr requested_address;
 
@@ -268,7 +264,7 @@ int main(int argc, char **argv){
 
         if(process_arguments(argc,argv)!=OK){
                 usage4 (_("Could not parse arguments"));
-                }
+        }
 
         /* create socket for DHCP communications */
         dhcp_socket=create_dhcp_socket();
@@ -299,7 +295,7 @@ int main(int argc, char **argv){
         free_requested_server_list();
 
         return result;
-        }
+}
 
 
 
@@ -314,83 +310,83 @@ int get_hardware_address(int sock,char *interface_name){
 
         /* try and grab hardware address of requested interface */
         if(ioctl(sock,SIOCGIFHWADDR,&ifr)<0){
-                printf(_("Error: Could not get hardware address of interface '%s'\n"),interface_name);
+                printf(_("Error: Could not get hardware address of interface '%s'\n"),interface_name);
                 exit(STATE_UNKNOWN);
-                }
+        }
 
         memcpy(&client_hardware_address[0],&ifr.ifr_hwaddr.sa_data,6);
 
 #elif defined(__bsd__)
-                                                /* King 2004    see ACKNOWLEDGEMENTS */
-
-        size_t                  len;
-        int                     mib[6];
-        char                    *buf;
-        unsigned char           *ptr;
-        struct if_msghdr        *ifm;
-        struct sockaddr_dl      *sdl;
-
-        mib[0] = CTL_NET;
-        mib[1] = AF_ROUTE;
-        mib[2] = 0;
-        mib[3] = AF_LINK;
-        mib[4] = NET_RT_IFLIST;
-
-        if((mib[5] = if_nametoindex(interface_name)) == 0){
-                printf(_("Error: if_nametoindex error - %s.\n"), strerror(errno));
-                exit(STATE_UNKNOWN);
-                }
+        /* King 2004    see ACKNOWLEDGEMENTS */
+
+        size_t                  len;
+        int                     mib[6];
+        char                    *buf;
+        unsigned char           *ptr;
+        struct if_msghdr        *ifm;
+        struct sockaddr_dl      *sdl;
+
+        mib[0] = CTL_NET;
+        mib[1] = AF_ROUTE;
+        mib[2] = 0;
+        mib[3] = AF_LINK;
+        mib[4] = NET_RT_IFLIST;
+
+        if((mib[5] = if_nametoindex(interface_name)) == 0){
+                printf(_("Error: if_nametoindex error - %s.\n"), strerror(errno));
+                exit(STATE_UNKNOWN);
+        }
 
-        if(sysctl(mib, 6, NULL, &len, NULL, 0) < 0){
-                printf(_("Error: Couldn't get hardware address from %s. sysctl 1 error - %s.\n"), interface_name, strerror(errno));
-                exit(STATE_UNKNOWN);
-                }
+        if(sysctl(mib, 6, NULL, &len, NULL, 0) < 0){
+                printf(_("Error: Couldn't get hardware address from %s. sysctl 1 error - %s.\n"), interface_name, strerror(errno));
+                exit(STATE_UNKNOWN);
+        }
 
-        if((buf = malloc(len)) == NULL){
-                printf(_("Error: Couldn't get hardware address from interface %s. malloc error - %s.\n"), interface_name, strerror(errno));
-                exit(4);
-                }
+        if((buf = malloc(len)) == NULL){
+                printf(_("Error: Couldn't get hardware address from interface %s. malloc error - %s.\n"), interface_name, strerror(errno));
+                exit(4);
+        }
 
-        if(sysctl(mib, 6, buf, &len, NULL, 0) < 0){
-                printf(_("Error: Couldn't get hardware address from %s. sysctl 2 error - %s.\n"), interface_name, strerror(errno));
-                exit(STATE_UNKNOWN);
-                }
+        if(sysctl(mib, 6, buf, &len, NULL, 0) < 0){
+                printf(_("Error: Couldn't get hardware address from %s. sysctl 2 error - %s.\n"), interface_name, strerror(errno));
+                exit(STATE_UNKNOWN);
+        }
 
-        ifm = (struct if_msghdr *)buf;
-        sdl = (struct sockaddr_dl *)(ifm + 1);
-        ptr = (unsigned char *)LLADDR(sdl);
-        memcpy(&client_hardware_address[0], ptr, 6) ;
-                                                /* King 2004 */
+        ifm = (struct if_msghdr *)buf;
+        sdl = (struct sockaddr_dl *)(ifm + 1);
+        ptr = (unsigned char *)LLADDR(sdl);
+        memcpy(&client_hardware_address[0], ptr, 6) ;
+        /* King 2004 */
 
 #elif defined(__sun__) || defined(__solaris__)
 
-                                                /* Kompf 2000-2003      see ACKNOWLEDGEMENTS */
+        /* Kompf 2000-2003      see ACKNOWLEDGEMENTS */
         long stat;
         char dev[20] = "/dev/";
         char *p;
         int unit;
 
-    /* get last number from interfacename, eg lnc0, e1000g0*/
-    int i;
-    p = interface_name + strlen(interface_name) -1;
+        /* get last number from interfacename, eg lnc0, e1000g0*/
+        int i;
+        p = interface_name + strlen(interface_name) -1;
         for(i = strlen(interface_name) -1; i > 0; p--) {
                 if(isalpha(*p))
-            break;
-    }
-    p++;
+                        break;
+        }
+        p++;
         if( p != interface_name ){
                 unit = atoi(p) ;
                 strncat(dev, interface_name, 6) ;
-                }
+        }
         else{
                 printf(_("Error: can't find unit number in interface_name (%s) - expecting TypeNumber eg lnc0.\n"), interface_name);
                 exit(STATE_UNKNOWN);
-                }
+        }
         stat = mac_addr_dlpi(dev, unit, client_hardware_address);
         if(stat != 0){
                 printf(_("Error: can't read MAC address from DLPI streams interface for device %s unit %d.\n"), dev, unit);
                 exit(STATE_UNKNOWN);
-                }
+        }
 
 #elif defined(__hpux__)
 
@@ -402,8 +398,8 @@ int get_hardware_address(int sock,char *interface_name){
         if(stat != 0){
                 printf(_("Error: can't read MAC address from DLPI streams interface for device %s unit %d.\n"), dev, unit);
                 exit(STATE_UNKNOWN);
-                }
-                                                /* Kompf 2000-2003 */
+        }
+        /* Kompf 2000-2003 */
 
 #else
         printf(_("Error: can't get MAC address for this architecture.  Use the --mac option.\n"));
@@ -414,7 +410,7 @@ int get_hardware_address(int sock,char *interface_name){
                 print_hardware_address(client_hardware_address);
 
         return OK;
-        }
+}
 
 /* determines IP address of the client interface */
 int get_ip_address(int sock,char *interface_name){
@@ -426,9 +422,9 @@ int get_ip_address(int sock,char *interface_name){
 
         if(ioctl(sock,SIOCGIFADDR,&ifr)<0){
                 printf(_("Error: Cannot determine IP address of interface %s\n"),
-                        interface_name);
+                                interface_name);
                 exit(STATE_UNKNOWN);
-                }
+        }
 
         my_ip=((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr;
 
@@ -441,13 +437,13 @@ int get_ip_address(int sock,char *interface_name){
                 printf(_("Pretending to be relay client %s\n"),inet_ntoa(my_ip));
 
         return OK;
-        }
+}
 
 /* sends a DHCPDISCOVER broadcast message in an attempt to find DHCP servers */
 int send_dhcp_discover(int sock){
         dhcp_packet discover_packet;
         struct sockaddr_in sockaddr_broadcast;
-    unsigned short opts;
+        unsigned short opts;
 
 
         /* clear the packet data structure */
@@ -488,19 +484,19 @@ int send_dhcp_discover(int sock){
         discover_packet.options[2]='\x53';
         discover_packet.options[3]='\x63';
 
-    opts = 4;
+        opts = 4;
         /* DHCP message type is embedded in options field */
         discover_packet.options[opts++]=DHCP_OPTION_MESSAGE_TYPE;    /* DHCP message type option identifier */
         discover_packet.options[opts++]='\x01';               /* DHCP message option length in bytes */
         discover_packet.options[opts++]=DHCPDISCOVER;
 
         /* the IP address we're requesting */
-        if(request_specific_address==TRUE){
+        if(request_specific_address){
                 discover_packet.options[opts++]=DHCP_OPTION_REQUESTED_ADDRESS;
                 discover_packet.options[opts++]='\x04';
                 memcpy(&discover_packet.options[opts],&requested_address,sizeof(requested_address));
                 opts += sizeof(requested_address);
-                }
+        }
         discover_packet.options[opts++]=DHCP_OPTION_END;
 
         /* unicast fields */
@@ -511,8 +507,8 @@ int send_dhcp_discover(int sock){
         discover_packet.hops = unicast ? 1 : 0;
 
         /* send the DHCPDISCOVER packet to broadcast address */
-        sockaddr_broadcast.sin_family=AF_INET;
-        sockaddr_broadcast.sin_port=htons(DHCP_SERVER_PORT);
+        sockaddr_broadcast.sin_family=AF_INET;
+        sockaddr_broadcast.sin_port=htons(DHCP_SERVER_PORT);
         sockaddr_broadcast.sin_addr.s_addr = unicast ? dhcp_ip.s_addr : INADDR_BROADCAST;
         bzero(&sockaddr_broadcast.sin_zero,sizeof(sockaddr_broadcast.sin_zero));
 
@@ -524,7 +520,7 @@ int send_dhcp_discover(int sock){
                 printf("DHCDISCOVER yiaddr:  %s\n",inet_ntoa(discover_packet.yiaddr));
                 printf("DHCDISCOVER siaddr:  %s\n",inet_ntoa(discover_packet.siaddr));
                 printf("DHCDISCOVER giaddr:  %s\n",inet_ntoa(discover_packet.giaddr));
-                }
+        }
 
         /* send the DHCPDISCOVER packet out */
         send_dhcp_packet(&discover_packet,sizeof(discover_packet),sock,&sockaddr_broadcast);
@@ -533,7 +529,7 @@ int send_dhcp_discover(int sock){
                 printf("\n\n");
 
         return OK;
-        }
+}
 
 
 
@@ -573,13 +569,13 @@ int get_dhcp_offer(int sock){
                                 printf(_("Result=ERROR\n"));
 
                         continue;
-                        }
+                }
                 else{
                         if(verbose)
                                 printf(_("Result=OK\n"));
 
                         responses++;
-                        }
+                }
 
                 /* The "source" is either a server or a relay. */
                 /* Save a copy of "source" into "via" even if it's via itself */
@@ -589,7 +585,7 @@ int get_dhcp_offer(int sock){
                         printf(_("DHCPOFFER from IP address %s"),inet_ntoa(source.sin_addr));
                         printf(_(" via %s\n"),inet_ntoa(via.sin_addr));
                         printf("DHCPOFFER XID: %u (0x%X)\n",ntohl(offer_packet.xid),ntohl(offer_packet.xid));
-                        }
+                }
 
                 /* check packet xid to see if its the same as the one we used in the discover packet */
                 if(ntohl(offer_packet.xid)!=packet_xid){
@@ -597,7 +593,7 @@ int get_dhcp_offer(int sock){
                                 printf(_("DHCPOFFER XID (%u) did not match DHCPDISCOVER XID (%u) - ignoring packet\n"),ntohl(offer_packet.xid),packet_xid);
 
                         continue;
-                        }
+                }
 
                 /* check hardware address */
                 result=OK;
@@ -610,7 +606,7 @@ int get_dhcp_offer(int sock){
 
                         if(offer_packet.chaddr[x]!=client_hardware_address[x])
                                 result=ERROR;
-                        }
+                }
                 if(verbose)
                         printf("\n");
 
@@ -619,27 +615,27 @@ int get_dhcp_offer(int sock){
                                 printf(_("DHCPOFFER hardware address did not match our own - ignoring packet\n"));
 
                         continue;
-                        }
+                }
 
                 if(verbose){
                         printf("DHCPOFFER ciaddr: %s\n",inet_ntoa(offer_packet.ciaddr));
                         printf("DHCPOFFER yiaddr: %s\n",inet_ntoa(offer_packet.yiaddr));
                         printf("DHCPOFFER siaddr: %s\n",inet_ntoa(offer_packet.siaddr));
                         printf("DHCPOFFER giaddr: %s\n",inet_ntoa(offer_packet.giaddr));
-                        }
+                }
 
                 add_dhcp_offer(source.sin_addr,&offer_packet);
 
                 valid_responses++;
-                }
+        }
 
         if(verbose){
                 printf(_("Total responses seen on the wire: %d\n"),responses);
                 printf(_("Valid responses for this machine: %d\n"),valid_responses);
-                }
+        }
 
         return OK;
-        }
+}
 
 
 
@@ -656,14 +652,14 @@ int send_dhcp_packet(void *buffer, int buffer_size, int sock, struct sockaddr_in
                 return ERROR;
 
         return OK;
-        }
+}
 
 
 
 /* receives a DHCP packet */
 int receive_dhcp_packet(void *buffer, int buffer_size, int sock, int timeout, struct sockaddr_in *address){
-        struct timeval tv;
-        fd_set readfds;
+        struct timeval tv;
+        fd_set readfds;
         fd_set oobfds;
         int recv_result;
         socklen_t address_size;
@@ -671,88 +667,88 @@ int receive_dhcp_packet(void *buffer, int buffer_size, int sock, int timeout, st
         int nfound;
 
 
-        /* wait for data to arrive (up time timeout) */
-        tv.tv_sec=timeout;
-        tv.tv_usec=0;
-        FD_ZERO(&readfds);
-        FD_ZERO(&oobfds);
-        FD_SET(sock,&readfds);
-        FD_SET(sock,&oobfds);
-        nfound = select(sock+1,&readfds,NULL,&oobfds,&tv);
+        /* wait for data to arrive (up time timeout) */
+        tv.tv_sec=timeout;
+        tv.tv_usec=0;
+        FD_ZERO(&readfds);
+        FD_ZERO(&oobfds);
+        FD_SET(sock,&readfds);
+        FD_SET(sock,&oobfds);
+        nfound = select(sock+1,&readfds,NULL,&oobfds,&tv);
 
-        /* make sure some data has arrived */
-        if(!FD_ISSET(sock,&readfds)){
+        /* make sure some data has arrived */
+        if(!FD_ISSET(sock,&readfds)){
                 if(verbose)
-                        printf(_("No (more) data received (nfound: %d)\n"), nfound);
-                return ERROR;
-                }
+                        printf(_("No (more) data received (nfound: %d)\n"), nfound);
+                return ERROR;
+        }
 
-        else{
+        else{
                 bzero(&source_address,sizeof(source_address));
                 address_size=sizeof(source_address);
-                recv_result=recvfrom(sock,(char *)buffer,buffer_size,0,(struct sockaddr *)&source_address,&address_size);
+                recv_result=recvfrom(sock,(char *)buffer,buffer_size,0,(struct sockaddr *)&source_address,&address_size);
                 if(verbose)
                         printf("recv_result: %d\n",recv_result);
 
-                if(recv_result==-1){
+                if(recv_result==-1){
                         if(verbose){
                                 printf(_("recvfrom() failed, "));
                                 printf("errno: (%d) -> %s\n",errno,strerror(errno));
-                                }
-                        return ERROR;
-                        }
+                        }
+                        return ERROR;
+                }
                 else{
                         if(verbose){
                                 printf(_("receive_dhcp_packet() result: %d\n"),recv_result);
                                 printf(_("receive_dhcp_packet() source: %s\n"),inet_ntoa(source_address.sin_addr));
-                                }
+                        }
 
                         memcpy(address,&source_address,sizeof(source_address));
                         return OK;
-                        }
-                }
+                }
+        }
 
         return OK;
-        }
+}
 
 
 /* creates a socket for DHCP communication */
 int create_dhcp_socket(void){
-        struct sockaddr_in myname;
+        struct sockaddr_in myname;
         struct ifreq interface;
-        int sock;
-        int flag=1;
+        int sock;
+        int flag=1;
 
-        /* Set up the address we're going to bind to. */
+        /* Set up the address we're going to bind to. */
         bzero(&myname,sizeof(myname));
-        myname.sin_family=AF_INET;
-        /* listen to DHCP server port if we're in unicast mode */
-        myname.sin_port = htons(unicast ? DHCP_SERVER_PORT : DHCP_CLIENT_PORT);
-        myname.sin_addr.s_addr = unicast ? my_ip.s_addr : INADDR_ANY;
-        bzero(&myname.sin_zero,sizeof(myname.sin_zero));
+        myname.sin_family=AF_INET;
+        /* listen to DHCP server port if we're in unicast mode */
+        myname.sin_port = htons(unicast ? DHCP_SERVER_PORT : DHCP_CLIENT_PORT);
+        myname.sin_addr.s_addr = unicast ? my_ip.s_addr : INADDR_ANY;
+        bzero(&myname.sin_zero,sizeof(myname.sin_zero));
 
-        /* create a socket for DHCP communications */
+        /* create a socket for DHCP communications */
         sock=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);
-        if(sock<0){
+        if(sock<0){
                 printf(_("Error: Could not create socket!\n"));
                 exit(STATE_UNKNOWN);
-                }
+        }
 
         if(verbose)
                 printf("DHCP socket: %d\n",sock);
 
-        /* set the reuse address flag so we don't get errors when restarting */
-        flag=1;
-        if(setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,(char *)&flag,sizeof(flag))<0){
+        /* set the reuse address flag so we don't get errors when restarting */
+        flag=1;
+        if(setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,(char *)&flag,sizeof(flag))<0){
                 printf(_("Error: Could not set reuse address option on DHCP socket!\n"));
                 exit(STATE_UNKNOWN);
-                }
+        }
 
-        /* set the broadcast option - we need this to listen to DHCP broadcast messages */
-        if(!unicast && setsockopt(sock,SOL_SOCKET,SO_BROADCAST,(char *)&flag,sizeof flag)<0){
+        /* set the broadcast option - we need this to listen to DHCP broadcast messages */
+        if(!unicast && setsockopt(sock,SOL_SOCKET,SO_BROADCAST,(char *)&flag,sizeof flag)<0){
                 printf(_("Error: Could not set broadcast option on DHCP socket!\n"));
                 exit(STATE_UNKNOWN);
-                }
+        }
 
         /* bind socket to interface */
 #if defined(__linux__)
@@ -761,21 +757,21 @@ int create_dhcp_socket(void){
         if(setsockopt(sock,SOL_SOCKET,SO_BINDTODEVICE,(char *)&interface,sizeof(interface))<0){
                 printf(_("Error: Could not bind socket to interface %s.  Check your privileges...\n"),network_interface_name);
                 exit(STATE_UNKNOWN);
-                }
+        }
 
 #else
         strncpy(interface.ifr_name,network_interface_name,IFNAMSIZ-1);
         interface.ifr_name[IFNAMSIZ-1]='\0';
 #endif
 
-        /* bind the socket */
-        if(bind(sock,(struct sockaddr *)&myname,sizeof(myname))<0){
+        /* bind the socket */
+        if(bind(sock,(struct sockaddr *)&myname,sizeof(myname))<0){
                 printf(_("Error: Could not bind to DHCP socket (port %d)!  Check your privileges...\n"),DHCP_CLIENT_PORT);
                 exit(STATE_UNKNOWN);
-                }
+        }
 
-        return sock;
-        }
+        return sock;
+}
 
 
 /* closes DHCP socket */
@@ -784,7 +780,7 @@ int close_dhcp_socket(int sock){
         close(sock);
 
         return OK;
-        }
+}
 
 
 /* adds a requested server address to list in memory */
@@ -796,7 +792,7 @@ int add_requested_server(struct in_addr server_address){
                 return ERROR;
 
         new_server->server_address=server_address;
-        new_server->answered=FALSE;
+        new_server->answered=false;
 
         new_server->next=requested_server_list;
         requested_server_list=new_server;
@@ -807,7 +803,7 @@ int add_requested_server(struct in_addr server_address){
                 printf(_("Requested server address: %s\n"),inet_ntoa(new_server->server_address));
 
         return OK;
-        }
+}
 
 
 
@@ -840,29 +836,29 @@ int add_dhcp_offer(struct in_addr source,dhcp_packet *offer_packet){
 
                 /* get option data */
                 switch(option_type){
-                case DHCP_OPTION_LEASE_TIME:
-                        memcpy(&dhcp_lease_time, &offer_packet->options[x],sizeof(dhcp_lease_time));
-                        dhcp_lease_time = ntohl(dhcp_lease_time);
-                        break;
-                case DHCP_OPTION_RENEWAL_TIME:
-                        memcpy(&dhcp_renewal_time, &offer_packet->options[x],sizeof(dhcp_renewal_time));
-                        dhcp_renewal_time = ntohl(dhcp_renewal_time);
-                        break;
-                case DHCP_OPTION_REBINDING_TIME:
-                        memcpy(&dhcp_rebinding_time, &offer_packet->options[x],sizeof(dhcp_rebinding_time));
-                        dhcp_rebinding_time = ntohl(dhcp_rebinding_time);
-                        break;
-                case DHCP_OPTION_SERVER_IDENTIFIER:
-                        memcpy(&serv_ident.s_addr, &offer_packet->options[x],sizeof(serv_ident.s_addr));
-                        break;
-                        }
+                        case DHCP_OPTION_LEASE_TIME:
+                                memcpy(&dhcp_lease_time, &offer_packet->options[x],sizeof(dhcp_lease_time));
+                                dhcp_lease_time = ntohl(dhcp_lease_time);
+                                break;
+                        case DHCP_OPTION_RENEWAL_TIME:
+                                memcpy(&dhcp_renewal_time, &offer_packet->options[x],sizeof(dhcp_renewal_time));
+                                dhcp_renewal_time = ntohl(dhcp_renewal_time);
+                                break;
+                        case DHCP_OPTION_REBINDING_TIME:
+                                memcpy(&dhcp_rebinding_time, &offer_packet->options[x],sizeof(dhcp_rebinding_time));
+                                dhcp_rebinding_time = ntohl(dhcp_rebinding_time);
+                                break;
+                        case DHCP_OPTION_SERVER_IDENTIFIER:
+                                memcpy(&serv_ident.s_addr, &offer_packet->options[x],sizeof(serv_ident.s_addr));
+                                break;
+                }
 
                 /* skip option data we're ignoring */
                 if(option_type==0) /* "pad" option, see RFC 2132 (3.1) */
                         x+=1;
                 else
                         x+=option_length;
-                }
+        }
 
         if(verbose){
                 if(dhcp_lease_time==DHCP_INFINITE_TIME)
@@ -876,7 +872,7 @@ int add_dhcp_offer(struct in_addr source,dhcp_packet *offer_packet){
                 if(dhcp_rebinding_time==DHCP_INFINITE_TIME)
                         printf(_("Rebinding Time: Infinite\n"));
                 printf(_("Rebinding Time: %lu seconds\n"),(unsigned long)dhcp_rebinding_time);
-                }
+        }
 
         new_offer=(dhcp_offer *)malloc(sizeof(dhcp_offer));
 
@@ -900,19 +896,20 @@ int add_dhcp_offer(struct in_addr source,dhcp_packet *offer_packet){
         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){
                 printf(_("Added offer from server @ %s"),inet_ntoa(new_offer->server_address));
                 printf(_(" of IP address %s\n"),inet_ntoa(new_offer->offered_address));
-                }
+        }
 
         /* add new offer to head of list */
         new_offer->next=dhcp_offer_list;
         dhcp_offer_list=new_offer;
 
         return OK;
-        }
+}
 
 
 /* frees memory allocated to DHCP OFFER list */
@@ -923,10 +920,10 @@ int free_dhcp_offer_list(void){
         for(this_offer=dhcp_offer_list;this_offer!=NULL;this_offer=next_offer){
                 next_offer=this_offer->next;
                 free(this_offer);
-                }
+        }
 
         return OK;
-        }
+}
 
 
 /* frees memory allocated to requested server list */
@@ -937,20 +934,20 @@ int free_requested_server_list(void){
         for(this_server=requested_server_list;this_server!=NULL;this_server=next_server){
                 next_server=this_server->next;
                 free(this_server);
-                }
+        }
 
         return OK;
-        }
+}
 
 
 /* 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;
+        uint32_t max_lease_time=0;
 
-        received_requested_address=FALSE;
+        received_requested_address=false;
 
         /* checks responses from requested servers */
         requested_responses=0;
@@ -966,7 +963,7 @@ 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;
+                                        received_requested_address=true;
 
                                 /* see if the servers we wanted a response from talked to us or not */
                                 if(!memcmp(&temp_offer->server_address,&temp_server->server_address,sizeof(temp_server->server_address))){
@@ -976,16 +973,24 @@ int get_results(void){
                                                 if(temp_server->answered)
                                                         printf(_(" (duplicate)"));
                                                 printf(_("\n"));
-                                                }
-                                        if(temp_server->answered == FALSE){
+                                        }
+                                        if(!temp_server->answered){
                                                 requested_responses++;
-                                                temp_server->answered=TRUE;
-                                                }
-                                        }
-                                }
-                        }
+                                                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) {
+                                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{
@@ -998,9 +1003,9 @@ 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;
-                        }
-                }
+                                received_requested_address=true;
+                }
+        }
 
         result=STATE_OK;
         if(valid_responses==0)
@@ -1009,9 +1014,12 @@ int get_results(void){
                 result=STATE_CRITICAL;
         else if(requested_responses<requested_servers)
                 result=STATE_WARNING;
-        else if(request_specific_address==TRUE && received_requested_address==FALSE)
+        else if(request_specific_address && !received_requested_address)
                 result=STATE_WARNING;
 
+        if(exclusive && undesired_offer)
+                result=STATE_CRITICAL;
+
         if(result==0)               /* garrett honeycutt 2005 */
                 printf("OK: ");
         else if(result==1)
@@ -1025,15 +1033,22 @@ int get_results(void){
         if(dhcp_offer_list==NULL){
                 printf(_("No DHCPOFFERs were received.\n"));
                 return result;
-                }
+        }
 
         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);
 
-        if(request_specific_address==TRUE)
-                printf(_(", requested address (%s) was %soffered"),inet_ntoa(requested_address),(received_requested_address==TRUE)?"":_("not "));
+        if(request_specific_address)
+                printf(_(", requested address (%s) was %soffered"),inet_ntoa(requested_address),(received_requested_address)?"":_("not "));
 
         printf(_(", max lease time = "));
         if(max_lease_time==DHCP_INFINITE_TIME)
@@ -1044,17 +1059,15 @@ int get_results(void){
         printf(".\n");
 
         return result;
-        }
+}
 
 
 /* process command-line arguments */
 int process_arguments(int argc, char **argv){
-        int arg_index;
-
         if(argc<1)
                 return ERROR;
 
-        arg_index = call_getopt(argc,argv);
+        call_getopt(argc,argv);
         return validate_arguments(argc);
 }
 
@@ -1071,87 +1084,89 @@ 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'},
                 {0,0,0,0}
         };
 
-        while(1){
-                int c=0;
-
-                c=getopt_long(argc,argv,"+hVvt:s:r:t:i:m:u",long_options,&option_index);
+        int c=0;
+        while(true){
+                c=getopt_long(argc,argv,"+hVvxt:s:r:t:i:m:u",long_options,&option_index);
 
                 if(c==-1||c==EOF||c==1)
                         break;
 
                 switch(c){
 
-                case 's': /* DHCP server address */
-                        resolve_host(optarg,&dhcp_ip);
-                        add_requested_server(dhcp_ip);
-                        break;
-
-                case 'r': /* address we are requested from DHCP servers */
-                        resolve_host(optarg,&requested_address);
-                        request_specific_address=TRUE;
-                        break;
-
-                case 't': /* timeout */
-
-                        /*
-                        if(is_intnonneg(optarg))
-                        */
-                        if(atoi(optarg)>0)
-                                dhcpoffer_timeout=atoi(optarg);
-                        /*
-                        else
-                                usage("Time interval must be a nonnegative integer\n");
-                        */
-                        break;
-
-                case 'm': /* MAC address */
-
-                        if((user_specified_mac=mac_aton(optarg)) == NULL)
-                                usage("Cannot parse MAC address.\n");
-                        if(verbose)
-                                print_hardware_address(user_specified_mac);
-
-                        break;
-
-                case 'i': /* interface name */
-
-                        strncpy(network_interface_name,optarg,sizeof(network_interface_name)-1);
-                        network_interface_name[sizeof(network_interface_name)-1]='\x0';
-
-                        break;
-
-                case 'u': /* unicast testing */
-                        unicast=1;
-                        break;
-
-                case 'V': /* version */
-                        print_revision(progname, NP_VERSION);
-                        exit(STATE_UNKNOWN);
-
-                case 'h': /* help */
-                        print_help();
-                        exit(STATE_UNKNOWN);
-
-                case 'v': /* verbose */
-                        verbose=1;
-                        break;
-
-                case '?': /* help */
-                        usage5 ();
-                        break;
-
-                default:
-                        break;
-                        }
-                }
+                        case 's': /* DHCP server address */
+                                resolve_host(optarg,&dhcp_ip);
+                                add_requested_server(dhcp_ip);
+                                break;
+
+                        case 'r': /* address we are requested from DHCP servers */
+                                resolve_host(optarg,&requested_address);
+                                request_specific_address=true;
+                                break;
+
+                        case 't': /* timeout */
+
+                                /*
+                                         if(is_intnonneg(optarg))
+                                         */
+                                if(atoi(optarg)>0)
+                                        dhcpoffer_timeout=atoi(optarg);
+                                /*
+                                         else
+                                         usage("Time interval must be a nonnegative integer\n");
+                                         */
+                                break;
+
+                        case 'm': /* MAC address */
+
+                                if((user_specified_mac=mac_aton(optarg)) == NULL)
+                                        usage("Cannot parse MAC address.\n");
+                                if(verbose)
+                                        print_hardware_address(user_specified_mac);
+
+                                break;
+
+                        case 'i': /* interface name */
+
+                                strncpy(network_interface_name,optarg,sizeof(network_interface_name)-1);
+                                network_interface_name[sizeof(network_interface_name)-1]='\x0';
+
+                                break;
+
+                        case 'u': /* unicast testing */
+                                unicast=true;
+                                break;
+                        case 'x': /* exclusive testing aka "rogue DHCP server detection" */
+                                exclusive=true;
+                                break;
+
+                        case 'V': /* version */
+                                print_revision(progname, NP_VERSION);
+                                exit(STATE_UNKNOWN);
+
+                        case 'h': /* help */
+                                print_help();
+                                exit(STATE_UNKNOWN);
+
+                        case 'v': /* verbose */
+                                verbose=1;
+                                break;
+                        case '?': /* help */
+                                usage5 ();
+                                break;
+
+                        default:
+                                break;
+                }
+        }
         return optind;
-        }
+}
 
 
 int validate_arguments(int argc){
@@ -1178,21 +1193,21 @@ static int get_msg(int fd){
         if(res < 0){
                 if(errno == EINTR){
                         return(GOT_INTR);
-                        }
+                }
                 else{
                         printf("%s\n", "get_msg FAILED.");
                         return(GOT_ERR);
-                        }
                 }
+        }
         if(ctl.len > 0){
                 ret |= GOT_CTRL;
-                }
+        }
         if(dat.len > 0){
                 ret |= GOT_DATA;
-                }
+        }
 
         return(ret);
-        }
+}
 
 /* verify that dl_primitive in ctl_area = prim */
 static int check_ctrl(int prim){
@@ -1201,10 +1216,10 @@ static int check_ctrl(int prim){
         if(err_ack->dl_primitive != prim){
                 printf(_("Error: DLPI stream API failed to get MAC in check_ctrl: %s.\n"), strerror(errno));
                 exit(STATE_UNKNOWN);
-                }
+        }
 
         return 0;
-        }
+}
 
 /* put a control message on a stream */
 static int put_ctrl(int fd, int len, int pri){
@@ -1213,10 +1228,10 @@ static int put_ctrl(int fd, int len, int pri){
         if(putmsg(fd, &ctl, 0, pri) < 0){
                 printf(_("Error: DLPI stream API failed to get MAC in put_ctrl/putmsg(): %s.\n"), strerror(errno));
                 exit(STATE_UNKNOWN);
-                }
+        }
 
         return  0;
-        }
+}
 
 /* put a control + data message on a stream */
 static int put_both(int fd, int clen, int dlen, int pri){
@@ -1226,10 +1241,10 @@ static int put_both(int fd, int clen, int dlen, int pri){
         if(putmsg(fd, &ctl, &dat, pri) < 0){
                 printf(_("Error: DLPI stream API failed to get MAC in put_both/putmsg().\n"), strerror(errno));
                 exit(STATE_UNKNOWN);
-                }
+        }
 
         return  0;
-        }
+}
 
 /* open file descriptor and attach */
 static int dl_open(const char *dev, int unit, int *fd){
@@ -1238,13 +1253,13 @@ static int dl_open(const char *dev, int unit, int *fd){
         if((*fd = open(dev, O_RDWR)) == -1){
                 printf(_("Error: DLPI stream API failed to get MAC in dl_attach_req/open(%s..): %s.\n"), dev, strerror(errno));
                 exit(STATE_UNKNOWN);
-                }
+        }
         attach_req->dl_primitive = DL_ATTACH_REQ;
         attach_req->dl_ppa = unit;
         put_ctrl(*fd, sizeof(dl_attach_req_t), 0);
         get_msg(*fd);
         return check_ctrl(DL_OK_ACK);
-        }
+}
 
 /* send DL_BIND_REQ */
 static int dl_bind(int fd, int sap, u_char *addr){
@@ -1262,12 +1277,12 @@ static int dl_bind(int fd, int sap, u_char *addr){
         if (GOT_ERR == check_ctrl(DL_BIND_ACK)){
                 printf(_("Error: DLPI stream API failed to get MAC in dl_bind/check_ctrl(): %s.\n"), strerror(errno));
                 exit(STATE_UNKNOWN);
-                }
+        }
         bcopy((u_char *)bind_ack + bind_ack->dl_addr_offset, addr,
-              bind_ack->dl_addr_length);
+                        bind_ack->dl_addr_length);
 
         return 0;
-        }
+}
 
 /***********************************************************************
  * interface:
@@ -1286,15 +1301,15 @@ long mac_addr_dlpi( const char *dev, int unit, u_char  *addr){
         u_char mac_addr[25];
 
         if(GOT_ERR != dl_open(dev, unit, &fd)){
-                if(GOT_ERR != dl_bind(fd, INSAP, mac_addr)){
-                        bcopy( mac_addr, addr, 6);
-                        return 0;
-                        }
+                if(GOT_ERR != dl_bind(fd, INSAP, mac_addr)){
+                        bcopy( mac_addr, addr, 6);
+                        return 0;
                 }
-        close(fd);
+        }
+        close(fd);
 
         return -1;
-        }
+}
 
 /* Kompf 2000-2003 */
 #endif
@@ -1311,7 +1326,7 @@ void resolve_host(const char *in,struct in_addr *out){
 
         memcpy(out,&((struct sockaddr_in *)ai->ai_addr)->sin_addr,sizeof(*out));
         freeaddrinfo(ai);
-        }
+}
 
 
 /* parse MAC address string, return 6 bytes (unterminated) or NULL */
@@ -1330,10 +1345,10 @@ unsigned char *mac_aton(const char *string){
                 result[j]=strtol(tmp,(char **)NULL,16);
                 i++;
                 j++;
-                }
+        }
 
         return (j==6) ? result : NULL;
-        }
+}
 
 
 void print_hardware_address(const unsigned char *address){
@@ -1344,7 +1359,7 @@ void print_hardware_address(const unsigned char *address){
                 printf("%2.2x:", address[i]);
         printf("%2.2x", address[i]);
         putchar('\n');
-        }
+}
 
 
 /* print usage help */
@@ -1357,7 +1372,7 @@ 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();
 
@@ -1367,32 +1382,31 @@ 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 (UT_SUPPORT);
+        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);
         return;
-        }
+}
 
 
 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;
-        }
-
-
-
+}