/*****************************************************************************
 *
 * 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 = "2001-2023";
const char *email = "devel@monitoring-plugins.org";

#include "common.h"
#include "netutils.h"
#include "utils.h"

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <getopt.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <netinet/in.h>
#include <net/if.h>
#include <arpa/inet.h>

#if HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif // HAVE_SYS_SOCKIO_H

#if defined( __linux__ )

#include <linux/if_ether.h>
#include <features.h>

#elif defined (__bsd__)

#include <netinet/if_ether.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include <net/if_dl.h>

#elif defined(__sun__) || defined(__solaris__) || defined(__hpux__)

#define INSAP 22
#define OUTSAP 24

#include <signal.h>
#include <ctype.h>
#include <sys/stropts.h>
#include <sys/poll.h>
#include <sys/dlpi.h>

#define bcopy(source, destination, length) memcpy(destination, source, length)

#define AREA_SZ 5000		/* buffer length in bytes */
static u_long ctl_area[AREA_SZ];
static u_long dat_area[AREA_SZ];
static struct strbuf ctl = {AREA_SZ, 0, (char *)ctl_area};
static struct strbuf dat = {AREA_SZ, 0, (char *)dat_area};

#define GOT_CTRL 1
#define GOT_DATA 2
#define GOT_BOTH 3
#define GOT_INTR 4
#define GOT_ERR 128

static int get_msg(int);
static int check_ctrl(int);
static int put_ctrl(int, int, int);
static int put_both(int, int, int, int);
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 // __sun__ || __solaris__ || __hpux



/**** Common definitions ****/

#define OK                0
#define ERROR             -1


/**** DHCP definitions ****/

#define MAX_DHCP_CHADDR_LENGTH           16
#define MAX_DHCP_SNAME_LENGTH            64
#define MAX_DHCP_FILE_LENGTH             128
#define MAX_DHCP_OPTIONS_LENGTH          312


typedef struct dhcp_packet_struct{
	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;


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 */
	uint32_t lease_time;            /* lease time in seconds */
	uint32_t renewal_time;          /* renewal time in seconds */
	uint32_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;


typedef struct requested_server_struct{
	struct in_addr server_address;
	bool answered;
	struct requested_server_struct *next;
}requested_server;


#define BOOTREQUEST     1
#define BOOTREPLY       2

#define DHCPDISCOVER    1
#define DHCPOFFER       2
#define DHCPREQUEST     3
#define DHCPDECLINE     4
#define DHCPACK         5
#define DHCPNACK        6
#define DHCPRELEASE     7

#define DHCP_OPTION_MESSAGE_TYPE        53
#define DHCP_OPTION_HOST_NAME           12
#define DHCP_OPTION_BROADCAST_ADDRESS   28
#define DHCP_OPTION_REQUESTED_ADDRESS   50
#define DHCP_OPTION_LEASE_TIME          51
#define DHCP_OPTION_SERVER_IDENTIFIER   54
#define DHCP_OPTION_RENEWAL_TIME        58
#define DHCP_OPTION_REBINDING_TIME      59
#define DHCP_OPTION_END                 255

#define DHCP_INFINITE_TIME              0xFFFFFFFF

#define DHCP_BROADCAST_FLAG 32768

#define DHCP_SERVER_PORT   67
#define DHCP_CLIENT_PORT   68

#define ETHERNET_HARDWARE_ADDRESS            1     /* used in htype field of dhcp packet */
#define ETHERNET_HARDWARE_ADDRESS_LENGTH     6     /* length of Ethernet hardware addresses */

uint8_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]="";
unsigned char *user_specified_mac=NULL;

char network_interface_name[IFNAMSIZ]="eth0";

uint32_t packet_xid=0;

uint32_t dhcp_lease_time=0;
uint32_t dhcp_renewal_time=0;
uint32_t dhcp_rebinding_time=0;

int dhcpoffer_timeout=2;

dhcp_offer *dhcp_offer_list=NULL;
requested_server *requested_server_list=NULL;

int valid_responses=0;     /* number of valid DHCPOFFERs we received */
int requested_servers=0;
int requested_responses=0;

bool request_specific_address=false;
bool received_requested_address=false;
int verbose=0;
struct in_addr requested_address;


int process_arguments(int, char **);
int call_getopt(int, char **);
int validate_arguments(int);
void print_usage(void);
void print_help(void);

void resolve_host(const char *in,struct in_addr *out);
unsigned char *mac_aton(const char *);
void print_hardware_address(const unsigned char *);
int get_hardware_address(int,char *);
int get_ip_address(int,char *);

int send_dhcp_discover(int);
int get_dhcp_offer(int);

int get_results(void);

int add_dhcp_offer(struct in_addr,dhcp_packet *);
int free_dhcp_offer_list(void);
int free_requested_server_list(void);

int create_dhcp_socket(void);
int close_dhcp_socket(int);
int send_dhcp_packet(void *,int,int,struct sockaddr_in *);
int receive_dhcp_packet(void *,int,int,int,struct sockaddr_in *);



int main(int argc, char **argv){
	int dhcp_socket;
	int result = STATE_UNKNOWN;

	setlocale (LC_ALL, "");
	bindtextdomain (PACKAGE, LOCALEDIR);
	textdomain (PACKAGE);

	/* Parse extra opts if any */
	argv=np_extra_opts(&argc, argv, progname);

	if(process_arguments(argc,argv)!=OK){
		usage4 (_("Could not parse arguments"));
	}

	/* create socket for DHCP communications */
	dhcp_socket=create_dhcp_socket();

	/* get hardware address of client machine */
	if(user_specified_mac!=NULL)
		memcpy(client_hardware_address,user_specified_mac,6);
	else
		get_hardware_address(dhcp_socket,network_interface_name);

	if(unicast) /* get IP address of client machine */
		get_ip_address(dhcp_socket,network_interface_name);

	/* send DHCPDISCOVER packet */
	send_dhcp_discover(dhcp_socket);

	/* wait for a DHCPOFFER packet */
	get_dhcp_offer(dhcp_socket);

	/* close socket we created */
	close_dhcp_socket(dhcp_socket);

	/* determine state/plugin output to return */
	result=get_results();

	/* free allocated memory */
	free_dhcp_offer_list();
	free_requested_server_list();

	return result;
}



/* determines hardware address on client machine */
int get_hardware_address(int sock,char *interface_name){

#if defined(__linux__)
	struct ifreq ifr;

	strncpy((char *)&ifr.ifr_name,interface_name,sizeof(ifr.ifr_name)-1);
	ifr.ifr_name[sizeof(ifr.ifr_name)-1]='\0';

	/* 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);
		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);
	}

	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(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 */

#elif defined(__sun__) || defined(__solaris__)

	/* 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;
	for(i = strlen(interface_name) -1; i > 0; p--) {
		if(isalpha(*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__)

	long stat;
	char dev[20] = "/dev/dlpi" ;
	int unit = 0;

	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);
	}
	/* Kompf 2000-2003 */

#else
	printf(_("Error: can't get MAC address for this architecture.  Use the --mac option.\n"));
	exit(STATE_UNKNOWN);
#endif

	if(verbose)
		print_hardware_address(client_hardware_address);

	return OK;
}

/* determines IP address of the client interface */
int get_ip_address(int sock,char *interface_name){
#if defined(SIOCGIFADDR)
	struct ifreq ifr;

	strncpy((char *)&ifr.ifr_name,interface_name,sizeof(ifr.ifr_name)-1);
	ifr.ifr_name[sizeof(ifr.ifr_name)-1]='\0';

	if(ioctl(sock,SIOCGIFADDR,&ifr)<0){
		printf(_("Error: Cannot determine IP address of interface %s\n"),
				interface_name);
		exit(STATE_UNKNOWN);
	}

	my_ip=((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr;

#else
	printf(_("Error: Cannot get interface IP address on this platform.\n"));
	exit(STATE_UNKNOWN);
#endif

	if(verbose)
		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;


	/* clear the packet data structure */
	bzero(&discover_packet,sizeof(discover_packet));


	/* boot request flag (backward compatible with BOOTP servers) */
	discover_packet.op=BOOTREQUEST;

	/* hardware address type */
	discover_packet.htype=ETHERNET_HARDWARE_ADDRESS;

	/* length of our hardware address */
	discover_packet.hlen=ETHERNET_HARDWARE_ADDRESS_LENGTH;

	/*
	 * transaction ID is supposed to be random.
	 */
	srand(time(NULL)^getpid());
	packet_xid=random();
	discover_packet.xid=htonl(packet_xid);

	/*discover_packet.secs=htons(65535);*/
	discover_packet.secs=0xFF;

	/*
	 * server needs to know if it should broadcast or unicast its response:
	 * 0x8000L == 32768 == 1 << 15 == broadcast, 0 == unicast
	 */
	discover_packet.flags = unicast ? 0 : htons(DHCP_BROADCAST_FLAG);

	/* our hardware address */
	memcpy(discover_packet.chaddr,client_hardware_address,ETHERNET_HARDWARE_ADDRESS_LENGTH);

	/* first four bytes of options field is magic cookie (as per RFC 2132) */
	discover_packet.options[0]='\x63';
	discover_packet.options[1]='\x82';
	discover_packet.options[2]='\x53';
	discover_packet.options[3]='\x63';

	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){
		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 */
	if(unicast)
		discover_packet.giaddr.s_addr = my_ip.s_addr;

	/* see RFC 1542, 4.1.1 */
	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_addr.s_addr = unicast ? dhcp_ip.s_addr : INADDR_BROADCAST;
	bzero(&sockaddr_broadcast.sin_zero,sizeof(sockaddr_broadcast.sin_zero));


	if(verbose){
		printf(_("DHCPDISCOVER to %s port %d\n"),inet_ntoa(sockaddr_broadcast.sin_addr),ntohs(sockaddr_broadcast.sin_port));
		printf("DHCPDISCOVER XID: %u (0x%X)\n",ntohl(discover_packet.xid),ntohl(discover_packet.xid));
		printf("DHCDISCOVER ciaddr:  %s\n",inet_ntoa(discover_packet.ciaddr));
		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);

	if(verbose)
		printf("\n\n");

	return OK;
}




/* waits for a DHCPOFFER message from one or more DHCP servers */
int get_dhcp_offer(int sock){
	dhcp_packet offer_packet;
	struct sockaddr_in source;
	struct sockaddr_in via;
	int result=OK;
	int responses=0;
	int x;
	time_t start_time;
	time_t current_time;

	time(&start_time);

	/* receive as many responses as we can */
	for(responses=0,valid_responses=0;;){

		time(&current_time);
		if((current_time-start_time)>=dhcpoffer_timeout)
			break;

		if(verbose)
			printf("\n\n");

		bzero(&source,sizeof(source));
		bzero(&via,sizeof(via));
		bzero(&offer_packet,sizeof(offer_packet));

		result=OK;
		result=receive_dhcp_packet(&offer_packet,sizeof(offer_packet),sock,dhcpoffer_timeout,&source);

		if(result!=OK){
			if(verbose)
				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 */
		memcpy(&via,&source,sizeof(source)) ;

		if(verbose){
			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){
			if(verbose)
				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;
		if(verbose)
			printf("DHCPOFFER chaddr: ");

		for(x=0;x<ETHERNET_HARDWARE_ADDRESS_LENGTH;x++){
			if(verbose)
				printf("%02X",(unsigned char)offer_packet.chaddr[x]);

			if(offer_packet.chaddr[x]!=client_hardware_address[x])
				result=ERROR;
		}
		if(verbose)
			printf("\n");

		if(result==ERROR){
			if(verbose)
				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;
}



/* sends a DHCP packet */
int send_dhcp_packet(void *buffer, int buffer_size, int sock, struct sockaddr_in *dest){
	int result;

	result=sendto(sock,(char *)buffer,buffer_size,0,(struct sockaddr *)dest,sizeof(*dest));

	if(verbose)
		printf(_("send_dhcp_packet result: %d\n"),result);

	if(result<0)
		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;
	fd_set oobfds;
	int recv_result;
	socklen_t address_size;
	struct sockaddr_in source_address;
	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);

	/* make sure some data has arrived */
	if(!FD_ISSET(sock,&readfds)){
		if(verbose)
			printf(_("No (more) data received (nfound: %d)\n"), nfound);
		return ERROR;
	}

	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);
		if(verbose)
			printf("recv_result: %d\n",recv_result);

		if(recv_result==-1){
			if(verbose){
				printf(_("recvfrom() failed, "));
				printf("errno: (%d) -> %s\n",errno,strerror(errno));
			}
			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 ifreq interface;
	int sock;
	int flag=1;

	/* 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));

	/* create a socket for DHCP communications */
	sock=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);
	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){
		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){
		printf(_("Error: Could not set broadcast option on DHCP socket!\n"));
		exit(STATE_UNKNOWN);
	}

	/* bind socket to interface */
#if defined(__linux__)
	strncpy(interface.ifr_ifrn.ifrn_name,network_interface_name,IFNAMSIZ-1);
	interface.ifr_ifrn.ifrn_name[IFNAMSIZ-1]='\0';
	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){
		printf(_("Error: Could not bind to DHCP socket (port %d)!  Check your privileges...\n"),DHCP_CLIENT_PORT);
		exit(STATE_UNKNOWN);
	}

	return sock;
}


/* closes DHCP socket */
int close_dhcp_socket(int sock){

	close(sock);

	return OK;
}


/* adds a requested server address to list in memory */
int add_requested_server(struct in_addr server_address){
	requested_server *new_server;

	new_server=(requested_server *)malloc(sizeof(requested_server));
	if(new_server==NULL)
		return ERROR;

	new_server->server_address=server_address;
	new_server->answered=false;

	new_server->next=requested_server_list;
	requested_server_list=new_server;

	requested_servers++;

	if(verbose)
		printf(_("Requested server address: %s\n"),inet_ntoa(new_server->server_address));

	return OK;
}




/* adds a DHCP OFFER to list in memory */
int add_dhcp_offer(struct in_addr source,dhcp_packet *offer_packet){
	dhcp_offer *new_offer;
	int x;
	unsigned option_type;
	unsigned option_length;
	struct in_addr serv_ident = {0};

	if(offer_packet==NULL)
		return ERROR;

	/* process all DHCP options present in the packet */
	for(x=4;x<MAX_DHCP_OPTIONS_LENGTH-1;){

		if((int)offer_packet->options[x]==-1)
			break;

		/* get option type */
		option_type=offer_packet->options[x++];

		/* get option length */
		option_length=offer_packet->options[x++];

		if(verbose)
			printf("Option: %d (0x%02X)\n",option_type,option_length);

		/* 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;
		}

		/* 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)
			printf(_("Lease Time: Infinite\n"));
		else
			printf(_("Lease Time: %lu seconds\n"),(unsigned long)dhcp_lease_time);
		if(dhcp_renewal_time==DHCP_INFINITE_TIME)
			printf(_("Renewal Time: Infinite\n"));
		else
			printf(_("Renewal Time: %lu seconds\n"),(unsigned long)dhcp_renewal_time);
		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));

	if(new_offer==NULL)
		return ERROR;

	/*
	 * RFC 2131 (2.) says: "DHCP clarifies the interpretation of the
	 * 'siaddr' field as the address of the server to use in the next step
	 * of the client's bootstrap process.  A DHCP server may return its own
	 * address in the 'siaddr' field, if the server is prepared to supply
	 * the next bootstrap service (e.g., delivery of an operating system
	 * executable image).  A DHCP server always returns its own address in
	 * the 'server identifier' option."  'serv_ident' is the 'server
	 * identifier' option, 'source' is the IP address we received the
	 * DHCPOFFER from.  If 'serv_ident' isn't available for some reason, we
	 * use 'source'.
	 */
	new_offer->server_address=serv_ident.s_addr?serv_ident:source;
	new_offer->offered_address=offer_packet->yiaddr;
	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 */
int free_dhcp_offer_list(void){
	dhcp_offer *this_offer;
	dhcp_offer *next_offer;

	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 */
int free_requested_server_list(void){
	requested_server *this_server;
	requested_server *next_server;

	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, *undesired_offer=NULL;
	requested_server *temp_server;
	int result;
	uint32_t max_lease_time=0;

	received_requested_address=false;

	/* checks responses from requested servers */
	requested_responses=0;
	if(requested_servers>0){

		for(temp_server=requested_server_list;temp_server!=NULL;temp_server=temp_server->next){

			for(temp_offer=dhcp_offer_list;temp_offer!=NULL;temp_offer=temp_offer->next){

				/* get max lease time we were offered */
				if(temp_offer->lease_time>max_lease_time || temp_offer->lease_time==DHCP_INFINITE_TIME)
					max_lease_time=temp_offer->lease_time;

				/* see if we got the address we requested */
				if(!memcmp(&requested_address,&temp_offer->offered_address,sizeof(requested_address)))
					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))){
					if(verbose){
						printf(_("DHCP Server Match: Offerer=%s"),inet_ntoa(temp_offer->server_address));
						printf(_(" Requested=%s"),inet_ntoa(temp_server->server_address));
						if(temp_server->answered)
							printf(_(" (duplicate)"));
						printf(_("\n"));
					}
					if(!temp_server->answered){
						requested_responses++;
						temp_server->answered=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{

		for(temp_offer=dhcp_offer_list;temp_offer!=NULL;temp_offer=temp_offer->next){

			/* get max lease time we were offered */
			if(temp_offer->lease_time>max_lease_time || temp_offer->lease_time==DHCP_INFINITE_TIME)
				max_lease_time=temp_offer->lease_time;

			/* 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)
		result=STATE_CRITICAL;
	else if(requested_servers>0 && requested_responses==0)
		result=STATE_CRITICAL;
	else if(requested_responses<requested_servers)
		result=STATE_WARNING;
	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)
		printf("WARNING: ");
	else if(result==2)
		printf("CRITICAL: ");
	else if(result==3)
		printf("UNKNOWN: ");

	/* we didn't receive any DHCPOFFERs */
	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)
		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)
		printf(_("Infinity"));
	else
		printf("%lu sec",(unsigned long)max_lease_time);

	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);
	return validate_arguments(argc);
}



int call_getopt(int argc, char **argv){
	extern int optind;
	int option_index = 0;
	static struct option long_options[] =
	{
		{"serverip",       required_argument,0,'s'},
		{"requestedip",    required_argument,0,'r'},
		{"timeout",        required_argument,0,'t'},
		{"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}
	};

	int c=0;
	while(1){
		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 'x': /* exclusive testing aka "rogue DHCP server detection" */
			exclusive=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;
		}
	}
	return optind;
}


int validate_arguments(int argc){

	if(argc - optind > 0)
		usage(_("Got unexpected non-option argument"));

	return OK;
}


#if defined(__sun__) || defined(__solaris__) || defined(__hpux__)
/* Kompf 2000-2003	see ACKNOWLEDGEMENTS */

/* get a message from a stream; return type of message */
static int get_msg(int fd){
	int flags = 0;
	int res, ret;
	ctl_area[0] = 0;
	dat_area[0] = 0;
	ret = 0;
	res = getmsg(fd, &ctl, &dat, &flags);

	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){
	dl_error_ack_t *err_ack = (dl_error_ack_t *)ctl_area;

	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){

	ctl.len = len;
	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){

	ctl.len = clen;
	dat.len = dlen;
	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){
	dl_attach_req_t *attach_req = (dl_attach_req_t *)ctl_area;

	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){
	dl_bind_req_t *bind_req = (dl_bind_req_t *)ctl_area;
	dl_bind_ack_t *bind_ack = (dl_bind_ack_t *)ctl_area;

	bind_req->dl_primitive = DL_BIND_REQ;
	bind_req->dl_sap = sap;
	bind_req->dl_max_conind = 1;
	bind_req->dl_service_mode = DL_CLDLS;
	bind_req->dl_conn_mgmt = 0;
	bind_req->dl_xidtest_flg = 0;
	put_ctrl(fd, sizeof(dl_bind_req_t), 0);
	get_msg(fd);
	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);

	return 0;
}

/***********************************************************************
 * interface:
 * function mac_addr_dlpi - get the mac address of the interface with
 *                          type dev (eg lnc, hme) and unit (0, 1 ..)
 *
 * parameter: addr: an array of six bytes, has to be allocated by the caller
 *
 * return: 0 if OK, -1 if the address could not be determined
 *
 *
 ***********************************************************************/

long mac_addr_dlpi( const char *dev, int unit, u_char  *addr){
	int fd;
	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;
		}
	}
	close(fd);

	return -1;
}

/* Kompf 2000-2003 */
#endif


/* resolve host name or die (TODO: move this to netutils.c!) */
void resolve_host(const char *in,struct in_addr *out){
	struct addrinfo hints, *ai;

	memset(&hints,0,sizeof(hints));
	hints.ai_family=PF_INET;
	if (getaddrinfo(in,NULL,&hints,&ai) != 0)
		usage_va(_("Invalid hostname/address - %s"),optarg);

	memcpy(out,&((struct sockaddr_in *)ai->ai_addr)->sin_addr,sizeof(*out));
	freeaddrinfo(ai);
}


/* parse MAC address string, return 6 bytes (unterminated) or NULL */
unsigned char *mac_aton(const char *string){
	static unsigned char result[6];
	char tmp[3];
	unsigned i, j;

	for(i=0, j=0; string[i] != '\0' && j < sizeof(result); i++){
		/* ignore ':' and any other non-hex character */
		if(!isxdigit(string[i]) || !isxdigit(string[i+1]))
			continue;
		tmp[0]=string[i];
		tmp[1]=string[i+1];
		tmp[2]='\0';
		result[j]=strtol(tmp,(char **)NULL,16);
		i++;
		j++;
	}

	return (j==6) ? result : NULL;
}


void print_hardware_address(const unsigned char *address){
	int i;

	printf(_("Hardware address: "));
	for (i=0; i<5; i++)
		printf("%2.2x:", address[i]);
	printf("%2.2x", address[i]);
	putchar('\n');
}


/* print usage help */
void print_help(void){

	print_revision(progname, NP_VERSION);

	printf("Copyright (c) 2001-2004 Ethan Galstad (nagios@nagios.org)\n");
	printf (COPYRIGHT, copyright, email);

	printf("%s\n", _("This plugin tests the availability of DHCP servers on a network."));

	printf ("\n\n");

	print_usage();

	printf (UT_HELP_VRSN);
	printf (UT_EXTRA_OPTS);

	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", "-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] [-x] [-s serverip] [-r requestedip] [-t timeout]\n",progname);
	printf ("                  [-i interface] [-m mac]\n");

	return;
	}