From: Stanley Hopcroft <stanleyhopcroft@users.sourceforge.net>
Date: Tue, 7 Dec 2004 02:33:17 +0000 (+0000)
Subject: New plugin: check_dhcp.c. Attempt to port to non Linux platform.
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=d50a9917ef38c44ac2067dba508cf2e690ff1412;p=nagiosplug.git

New plugin: check_dhcp.c. Attempt to port to non Linux platform.


git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1008 f882894a-f735-0410-b71e-b25c423dba1c
---

diff --git a/plugins/Makefile.am b/plugins/Makefile.am
index b87154d..33f7686 100644
--- a/plugins/Makefile.am
+++ b/plugins/Makefile.am
@@ -10,7 +10,7 @@ localedir = $(datadir)/locale
 DEFS = -DLOCALEDIR=\"$(localedir)\" @DEFS@
 LIBS = @LIBINTL@ @LIBS@
 
-libexec_PROGRAMS = check_disk check_dummy check_http check_load \
+libexec_PROGRAMS = check_dhcp check_disk check_dummy check_http check_load \
 	check_mrtg check_mrtgtraf check_nwstat check_overcr check_ping \
 	check_real check_smtp check_ssh check_tcp check_time \
 	check_udp check_ups check_users negate urlize check_icmp \
@@ -44,6 +44,7 @@ AM_INSTALL_PROGRAM_FLAGS = @INSTALL_OPTS@
 ##############################################################################
 # the actual targets
 
+check_dhcp_LDADD = $(BASEOBJS)
 check_dig_LDADD = $(NETLIBS) popen.o 
 check_disk_LDADD = $(BASEOBJS) popen.o
 check_dns_LDADD = $(NETLIBS) popen.o
@@ -80,6 +81,7 @@ check_ide_smart_LDADD = $(BASEOBJS)
 negate_LDADD = $(BASEOBJS) popen.o
 urlize_LDADD = $(BASEOBJS) popen.o
 
+check_dhcp_DEPENDENCIES = check_dhcp.c $(DEPLIBS)
 check_dig_DEPENDENCIES = check_dig.c $(NETOBJS) popen.o $(DEPLIBS)
 check_disk_DEPENDENCIES = check_disk.c $(BASEOBJS) popen.o $(DEPLIBS)
 check_dns_DEPENDENCIES = check_dns.c $(NETOBJS) popen.o $(DEPLIBS)
@@ -88,6 +90,8 @@ check_fping_DEPENDENCIES = check_fping.c $(NETOBJS) popen.o $(DEPLIBS)
 check_game_DEPENDENCIES = check_game.c  $(DEPLIBS)
 check_http_DEPENDENCIES = check_http.c $(NETOBJS) $(DEPLIBS)
 check_hpjd_DEPENDENCIES = check_hpjd.c $(NETOBJS) popen.o $(DEPLIBS)
+check_icmp_DEPENDENCIES = check_icmp.c $(DEPLIBS)
+check_ide_smart_DEPENDENCIES = check_ide_smart.c $(BASEOBJS) $(DEPLIBS)
 check_ldap_DEPENDENCIES = check_ldap.c $(NETOBJS) $(DEPLIBS)
 check_load_DEPENDENCIES = check_load.c $(BASEOBJS) popen.o $(DEPLIBS)
 check_mrtg_DEPENDENCIES = check_mrtg.c $(DEPLIBS)
@@ -112,10 +116,8 @@ check_udp_DEPENDENCIES = check_udp.c $(NETOBJS) $(DEPLIBS)
 check_ups_DEPENDENCIES = check_ups.c $(NETOBJS) $(DEPLIBS)
 check_users_DEPENDENCIES = check_users.c $(BASEOBJS) popen.o $(DEPLIBS)
 check_by_ssh_DEPENDENCIES = check_by_ssh.c $(NETOBJS) popen.o $(DEPLIBS)
-check_ide_smart_DEPENDENCIES = check_ide_smart.c $(BASEOBJS) $(DEPLIBS)
 negate_DEPENDENCIES = negate.c $(BASEOBJS) popen.o $(DEPLIBS)
 urlize_DEPENDENCIES = urlize.c $(BASEOBJS) popen.o $(DEPLIBS)
-check_icmp_DEPENDENCIES = check_icmp.c $(DEPLIBS)
 
 ##############################################################################
 # secondary dependencies
diff --git a/plugins/check_dhcp.c b/plugins/check_dhcp.c
new file mode 100644
index 0000000..ee893cd
--- /dev/null
+++ b/plugins/check_dhcp.c
@@ -0,0 +1,1061 @@
+/******************************************************************************
+*
+* CHECK_DHCP.C
+*
+* Program: DHCP plugin for Nagios
+* License: GPL
+* Copyright (c) 2001-2004 Ethan Galstad (nagios@nagios.org)
+*
+* License Information:
+*
+* 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 2 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, write to the Free Software
+* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*
+*****************************************************************************/
+
+#include "common.h"
+#include "netutils.h"
+#include "utils.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 defined( __linux__ )
+#include <linux/if_ether.h>
+#include <features.h>
+#else
+#include <netinet/if_ether.h>
+#include <sys/sysctl.h>
+#include <net/if_dl.h>
+#endif
+
+const char *progname = "check_dhcp";
+
+/*#define DEBUG*/
+#define HAVE_GETOPT_H
+
+
+/**** Common definitions ****/
+
+#define STATE_OK          0
+#define STATE_WARNING     1
+#define STATE_CRITICAL    2
+#define STATE_UNKNOWN     -1
+
+#define OK                0
+#define ERROR             -1
+
+#define FALSE             0
+#define TRUE              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{
+        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 DHCP 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 */
+	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 */
+	struct dhcp_offer_struct *next;
+        }dhcp_offer;
+
+
+typedef struct requested_server_struct{
+	struct in_addr server_address;
+	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_RENEWAL_TIME        58
+#define DHCP_OPTION_REBINDING_TIME      59
+
+#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 */
+
+unsigned char client_hardware_address[MAX_DHCP_CHADDR_LENGTH]="";
+
+char network_interface_name[8]="eth0";
+
+u_int32_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;
+
+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;
+
+int request_specific_address=FALSE;
+int received_requested_address=FALSE;
+struct in_addr requested_address;
+
+
+int process_arguments(int, char **);
+int call_getopt(int, char **);
+int validate_arguments(void);
+void print_usage(void);
+void print_help(void);
+
+int get_hardware_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;
+
+	if(process_arguments(argc,argv)!=OK){
+		/*usage("Invalid command arguments supplied\n");*/
+		printf("Invalid command arguments supplied\n");
+		exit(STATE_UNKNOWN);
+	        }
+
+
+	/* create socket for DHCP communications */
+	dhcp_socket=create_dhcp_socket();
+
+	/* get hardware address of client machine */
+	get_hardware_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));
+	
+	/* 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);
+#else
+	/* Code from getmac.c posted at http://lists.freebsd.org/pipermail/freebsd-hackers/2004-June/007415.html
+         * by Alecs King based on Unix Network programming Ch 17
+         */
+
+        int                     mib[6], len;
+        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) {
+                perror("if_nametoindex error");
+                exit(2);
+        }
+
+        if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0) {
+                perror("sysctl 1 error");
+                exit(3);
+        }
+
+        if ((buf = malloc(len)) == NULL) {
+                perror("malloc error");
+                exit(4);
+        }
+
+        if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
+                perror("sysctl 2 error");
+                exit(5);
+        }
+
+        ifm = (struct if_msghdr *)buf;
+        sdl = (struct sockaddr_dl *)(ifm + 1);
+        ptr = (unsigned char *)LLADDR(sdl);
+        memcpy(&client_hardware_address[0], ptr, 6) ;
+#endif
+
+
+#ifdef DEBUG
+	printf("Hardware address: %02x:%02x:%02x:",client_hardware_address[0],client_hardware_address[1],client_hardware_address[2]);
+	printf("%02x:",client_hardware_address[3]);
+	printf("%02x:%02x\n",client_hardware_address[4],client_hardware_address[5]);
+	printf("\n");
+#endif
+
+	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;
+
+
+	/* 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;
+
+	discover_packet.hops=0;
+
+	/* transaction id is supposed to be random */
+	srand(time(NULL));
+	packet_xid=random();
+	discover_packet.xid=htonl(packet_xid);
+
+	/**** WHAT THE HECK IS UP WITH THIS?!?  IF I DON'T MAKE THIS CALL, ONLY ONE SERVER RESPONSE IS PROCESSED!!!! ****/
+	/* downright bizzarre... */
+	ntohl(discover_packet.xid);
+
+	/*discover_packet.secs=htons(65535);*/
+	discover_packet.secs=0xFF;
+
+	/* tell server it should broadcast its response */ 
+	discover_packet.flags=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';
+
+	/* DHCP message type is embedded in options field */
+	discover_packet.options[4]=DHCP_OPTION_MESSAGE_TYPE;    /* DHCP message type option identifier */
+	discover_packet.options[5]='\x01';               /* DHCP message option length in bytes */
+	discover_packet.options[6]=DHCPDISCOVER;
+
+	/* the IP address we're requesting */
+	if(request_specific_address==TRUE){
+		discover_packet.options[7]=DHCP_OPTION_REQUESTED_ADDRESS;
+		discover_packet.options[8]='\x04';
+		memcpy(&discover_packet.options[9],&requested_address,sizeof(requested_address));
+	        }
+	
+	/* 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=INADDR_BROADCAST;
+	bzero(&sockaddr_broadcast.sin_zero,sizeof(sockaddr_broadcast.sin_zero));
+
+
+#ifdef DEBUG
+	printf("DHCPDISCOVER to %s port %d\n",inet_ntoa(sockaddr_broadcast.sin_addr),ntohs(sockaddr_broadcast.sin_port));
+	printf("DHCPDISCOVER XID: %lu (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));
+#endif
+
+	/* send the DHCPDISCOVER packet out */
+	send_dhcp_packet(&discover_packet,sizeof(discover_packet),sock,&sockaddr_broadcast);
+
+#ifdef DEBUG
+	printf("\n\n");
+#endif
+
+	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;
+	int result=OK;
+	int timeout=1;
+	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;
+
+#ifdef DEBUG
+		printf("\n\n");
+#endif
+
+		bzero(&source,sizeof(source));
+		bzero(&offer_packet,sizeof(offer_packet));
+
+		result=OK;
+		result=receive_dhcp_packet(&offer_packet,sizeof(offer_packet),sock,dhcpoffer_timeout,&source);
+		
+		if(result!=OK){
+#ifdef DEBUG
+			printf("Result=ERROR\n");
+#endif
+			continue;
+		        }
+		else{
+#ifdef DEBUG
+			printf("Result=OK\n");
+#endif
+			responses++;
+		        }
+
+#ifdef DEBUG
+		printf("DHCPOFFER from IP address %s\n",inet_ntoa(source.sin_addr));
+		printf("DHCPOFFER XID: %lu (0x%X)\n",ntohl(offer_packet.xid),ntohl(offer_packet.xid));
+#endif
+
+		/* 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){
+#ifdef DEBUG
+			printf("DHCPOFFER XID (%lu) did not match DHCPDISCOVER XID (%lu) - ignoring packet\n",ntohl(offer_packet.xid),packet_xid);
+#endif
+			continue;
+		        }
+
+		/* check hardware address */
+		result=OK;
+#ifdef DEBUG
+		printf("DHCPOFFER chaddr: ");
+#endif
+		for(x=0;x<ETHERNET_HARDWARE_ADDRESS_LENGTH;x++){
+#ifdef DEBUG
+			printf("%02X",(unsigned char)offer_packet.chaddr[x]);
+#endif
+			if(offer_packet.chaddr[x]!=client_hardware_address[x]){
+				result=ERROR;
+			        }
+		        }
+#ifdef DEBUG
+		printf("\n");
+#endif
+		if(result==ERROR){
+#ifdef DEBUG
+			printf("DHCPOFFER hardware address did not match our own - ignoring packet\n");
+#endif
+			continue;
+		        }
+
+#ifdef DEBUG
+		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));
+#endif
+
+		add_dhcp_offer(source.sin_addr,&offer_packet);
+
+		valid_responses++;
+	        }
+
+#ifdef DEBUG
+	printf("Total responses seen on the wire: %d\n",responses);
+	printf("Valid responses for this machine: %d\n",valid_responses);
+#endif
+
+	return OK;
+        }
+
+
+
+/* sends a DHCP packet */
+int send_dhcp_packet(void *buffer, int buffer_size, int sock, struct sockaddr_in *dest){
+	struct sockaddr_in myname;
+	int result;
+
+	result=sendto(sock,(char *)buffer,buffer_size,0,(struct sockaddr *)dest,sizeof(*dest));
+
+#ifdef DEBUG
+	printf("send_dhcp_packet result: %d\n",result);
+#endif
+
+	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;
+	int recv_result;
+	socklen_t address_size;
+	struct sockaddr_in source_address;
+
+
+        /* wait for data to arrive (up time timeout) */
+        tv.tv_sec=timeout;
+        tv.tv_usec=0;
+        FD_ZERO(&readfds);
+        FD_SET(sock,&readfds);
+        select(sock+1,&readfds,NULL,NULL,&tv);
+
+        /* make sure some data has arrived */
+        if(!FD_ISSET(sock,&readfds)){
+#ifdef DEBUG
+                printf("No (more) data received\n");
+#endif
+                return ERROR;
+                }
+
+        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);
+#ifdef DEBUG
+		printf("recv_result_1: %d\n",recv_result);
+#endif
+                recv_result=recvfrom(sock,(char *)buffer,buffer_size,0,(struct sockaddr *)&source_address,&address_size);
+#ifdef DEBUG
+		printf("recv_result_2: %d\n",recv_result);
+#endif
+
+                if(recv_result==-1){
+#ifdef DEBUG
+			printf("recvfrom() failed, ");
+			printf("errno: (%d) -> %s\n",errno,strerror(errno));
+#endif
+                        return ERROR;
+                        }
+		else{
+#ifdef DEBUG
+			printf("receive_dhcp_packet() result: %d\n",recv_result);
+			printf("receive_dhcp_packet() source: %s\n",inet_ntoa(source_address.sin_addr));
+#endif
+
+			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;
+        myname.sin_port=htons(DHCP_CLIENT_PORT);
+        myname.sin_addr.s_addr=INADDR_ANY;                 /* listen on any address */
+        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);
+	        }
+
+#ifdef DEBUG
+	printf("DHCP socket: %d\n",sock);
+#endif
+
+        /* 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(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);
+	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);
+#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->next=requested_server_list;
+	requested_server_list=new_server;
+
+	requested_servers++;
+
+#ifdef DEBUG
+	printf("Requested server address: %s\n",inet_ntoa(new_server->server_address));
+#endif
+
+	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;
+	int y;
+	unsigned option_type;
+	unsigned option_length;
+
+	if(offer_packet==NULL)
+		return ERROR;
+
+	/* process all DHCP options present in the packet */
+	for(x=4;x<MAX_DHCP_OPTIONS_LENGTH;){
+
+		/* end of options (0 is really just a pad, but bail out anyway) */
+		if((int)offer_packet->options[x]==-1 || (int)offer_packet->options[x]==0)
+			break;
+
+		/* get option type */
+		option_type=offer_packet->options[x++];
+
+		/* get option length */
+		option_length=offer_packet->options[x++];
+
+#ifdef DEBUG
+		printf("Option: %d (0x%02X)\n",option_type,option_length);
+#endif
+
+		/* get option data */
+		if(option_type==DHCP_OPTION_LEASE_TIME)
+			dhcp_lease_time=ntohl(*((u_int32_t *)&offer_packet->options[x]));
+		if(option_type==DHCP_OPTION_RENEWAL_TIME)
+			dhcp_renewal_time=ntohl(*((u_int32_t *)&offer_packet->options[x]));
+		if(option_type==DHCP_OPTION_REBINDING_TIME)
+			dhcp_rebinding_time=ntohl(*((u_int32_t *)&offer_packet->options[x]));
+
+		/* skip option data we're ignoring */
+		else
+			for(y=0;y<option_length;y++,x++);
+	        }
+
+#ifdef DEBUG
+	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);
+#endif
+
+	new_offer=(dhcp_offer *)malloc(sizeof(dhcp_offer));
+
+	if(new_offer==NULL)
+		return ERROR;
+
+
+	new_offer->server_address=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;
+
+
+#ifdef DEBUG
+	printf("Added offer from server @ %s",inet_ntoa(new_offer->server_address));
+	printf(" of IP address %s\n",inet_ntoa(new_offer->offered_address));
+#endif
+
+	/* 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;
+	requested_server *temp_server;
+	int result;
+	u_int32_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))){
+#ifdef DEBUG
+					printf("DHCP Server Match: Offerer=%s",inet_ntoa(temp_offer->server_address));
+					printf(" Requested=%s\n",inet_ntoa(temp_server->server_address));
+#endif				       
+					requested_responses++;
+				        }
+		                }
+		        }
+
+	        }
+
+	/* 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==TRUE && received_requested_address==FALSE)
+		result=STATE_WARNING;
+
+
+	printf("DHCP %s: ",(result==STATE_OK)?"ok":"problem");
+
+	/* 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(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 ");
+
+	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;
+        }
+
+
+
+
+
+
+/* print usage help */
+void print_help(void){
+
+	/*print_revision(progname,"$Revision$");*/
+
+	printf("Copyright (c) 2001-2004 Ethan Galstad (nagios@nagios.org)\n\n");
+	printf("This plugin tests the availability of DHCP servers on a network.\n\n");
+
+	print_usage();
+
+	printf
+		("\nOptions:\n"
+		 " -s, --serverip=IPADDRESS\n"
+		 "   IP address of DHCP server that we must hear from\n"
+		 " -r, --requestedip=IPADDRESS\n"
+		 "   IP address that should be offered by at least one DHCP server\n"
+		 " -t, --timeout=INTEGER\n"
+		 "   Seconds to wait for DHCPOFFER before timeout occurs\n"
+		 " -i, --interface=STRING\n"
+		 "   Interface to to use for listening (i.e. eth0)\n"
+		 " -v, --verbose\n"
+		 "   Print extra information (command-line use only)\n"
+		 " -h, --help\n"
+		 "   Print detailed help screen\n"
+		 " -V, --version\n"
+		 "   Print version information\n\n"
+		 );
+
+	/*support();*/
+
+	return;
+        }
+
+
+/* prints usage information */
+void print_usage(void){
+
+	printf("Usage: %s [-s serverip] [-r requestedip] [-t timeout] [-i interface]\n",progname);
+	printf("       %s --help\n",progname);
+	printf("       %s --version\n",progname);
+
+	return;
+        }
+
+
+
+
+/* process command-line arguments */
+int process_arguments(int argc, char **argv){
+	int c;
+
+	if(argc<1)
+		return ERROR;
+
+	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){
+	int c=0;
+	int i=0;
+	struct in_addr ipaddress;
+
+#ifdef HAVE_GETOPT_H
+	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'},
+		{"verbose",        no_argument,      0,'v'},
+		{"version",        no_argument,      0,'V'},
+		{"help",           no_argument,      0,'h'},
+		{0,0,0,0}
+	};
+#endif
+
+	while(1){
+#ifdef HAVE_GETOPT_H
+		c=getopt_long(argc,argv,"+hVvt:s:r:t:i:",long_options,&option_index);
+#else
+		c=getopt(argc,argv,"+?hVvt:s:r:t:i:");
+#endif
+
+		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 */
+			if(inet_aton(optarg,&ipaddress))
+				add_requested_server(ipaddress);
+			/*
+			else
+				usage("Invalid server IP address\n");
+			*/
+			break;
+
+		case 'r': /* address we are requested from DHCP servers */
+			if(inet_aton(optarg,&ipaddress)){
+				requested_address=ipaddress;
+				request_specific_address=TRUE;
+			        }
+			/*
+			else
+				usage("Invalid requested IP address\n");
+			*/
+			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 'i': /* interface name */
+
+			strncpy(network_interface_name,optarg,sizeof(network_interface_name)-1);
+			network_interface_name[sizeof(network_interface_name)-1]='\x0';
+
+			break;
+
+		case 'V': /* version */
+
+			/*print_revision(progname,"$Revision$");*/
+			exit(STATE_OK);
+
+		case 'h': /* help */
+
+			print_help();
+			exit(STATE_OK);
+
+		case '?': /* help */
+
+			/*usage("Invalid argument\n");*/
+			break;
+
+		default:
+			break;
+		        }
+	        }
+
+	return i;
+        }
+
+
+
+int validate_arguments(void){
+
+	return OK;
+        }
+