/
dhcpdiscover.c
1344 lines (1104 loc) · 41.5 KB
/
dhcpdiscover.c
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/******************************************************************************
*
* Original name: CHECK_DHCP.C
* Current name: DHCPDISCOVER.C
*
* License: GPL
* Copyright (c) 2001-2004 Ethan Galstad (nagios@nagios.org)
* Copyright (c) 2006-2013 OpenWRT.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.
*
*****************************************************************************/
const char* COPYRIGHT = " \
*\n \
* License: GPL\n \
* Copyright (c) 2001-2004 Ethan Galstad (nagios@nagios.org)\n \
* Copyright (c) 2006-2013 OpenWRT.org \n \
* ====================================================== \n \
* Mike Gore 25 Aug 2005 \n \
* Modified for standalone operation \n \
* ====================================================== \n \
* Pau Escrich Jun 2013 \n \
* Added -b option and ported to OpenWRT \n \
* ====================================================== \n \
*\n \
** License Information:\n \
*\n \
* This program is free software; you can redistribute it and/or modify\n \
* it under the terms of the GNU General Public License as published by\n \
* the Free Software Foundation; either version 2 of the License, or\n \
* (at your option) any later version.\n \
*\n \
* This program is distributed in the hope that it will be useful,\n \
* but WITHOUT ANY WARRANTY; without even the implied warranty of\n \
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the\n \
* GNU General Public License for more details.\n \
*\n \
* You should have received a copy of the GNU General Public License\n \
* along with this program; if not, write to the Free Software\n \
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.\n \
*\n \
* $Id: dhcpdiscover.c,v 2$\n \
*";
const char* progname = "dhcpdiscover";
const char* revision = "$Revision: 2$";
const char* copyright = "2006-2013";
const char* email = "p4u@dabax.net";
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <locale.h>
#include <net/if.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <time.h>
#if defined(__linux__)
#include <features.h>
#include <linux/if_ether.h>
#elif defined(__bsd__)
#include <net/if_dl.h>
#include <netinet/if_ether.h>
#include <sys/sysctl.h>
#elif defined(__sun__) || defined(__solaris__) || defined(__hpux__)
#define INSAP 22
#define OUTSAP 24
#include <ctype.h>
#include <signal.h>
#include <sys/dlpi.h>
#include <sys/poll.h>
#include <sys/stropts.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
#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);
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
#define HAVE_GETOPT_H
#define usage printf
/**** 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] = "";
unsigned int my_client_mac[MAX_DHCP_CHADDR_LENGTH];
int mymac = 0;
struct in_addr banned_ip;
int banned = 0;
char baddr[16];
char network_interface_name[16] = "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;
int verbose = 0;
int prometheus = 0;
struct in_addr requested_address;
void print_revision(const char* progname, const char* revision) {
fprintf(stdout, "Program: %s %s\n", progname, revision);
}
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;
setlocale(LC_ALL, "");
// bindtextdomain (PACKAGE, LOCALEDIR);
// textdomain (PACKAGE);
if (process_arguments(argc, argv) != OK) {
printf("Could not parse arguments");
}
// Set banned addr in string format in global var baddr
if (banned) {
inet_ntop(AF_INET, &(banned_ip), baddr, INET_ADDRSTRLEN);
if (verbose)
fprintf(stdout, "Banned addr:%s\n", baddr);
}
/* 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 */
if (!prometheus) {
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)
{
int i;
#if defined(__linux__)
struct ifreq ifr;
strncpy((char*)&ifr.ifr_name, interface_name, sizeof(ifr.ifr_name));
// Added code to try to set local MAC address just to be through
// If this fails the test will still work since
// we do encode the MAC as part of the DHCP frame - tests show it works
if (mymac) {
int i;
for (i = 0; i < MAX_DHCP_CHADDR_LENGTH; ++i)
client_hardware_address[i] = my_client_mac[i];
memcpy(&ifr.ifr_hwaddr.sa_data, &client_hardware_address[0], 6);
if (ioctl(sock, SIOCSIFHWADDR, &ifr) < 0) {
fprintf(stderr, "Could not set hardware address of interface '%s'\n", interface_name);
// perror("Error");
// exit(STATE_UNKNOWN);
}
} else {
/* try and grab hardware address of requested interface */
if (ioctl(sock, SIOCGIFHWADDR, &ifr) < 0) {
fprintf(stderr, "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 */
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) {
fprintf(stderr, "if_nametoindex error - %s.\n", strerror(errno);
exit(STATE_UNKNOWN);
}
if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0) {
fprintf(stderr, "Couldn't get hardware address from %s. sysctl 1 error - %s.\n", interface_name, strerror(errno);
exit(STATE_UNKNOWN);
}
if ((buf = malloc(len)) == NULL) {
fprintf(stderr, "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) {
fprintf(stderr, "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;
for (p = interface_name; *p && isalpha(*p); p++)
/* no-op */;
if (p != '\0') {
unit = atoi(p);
*p = '\0';
strncat(dev, interface_name, 6);
} else {
fprintf(stderr, "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) {
fprintf(stderr, "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) {
fprintf(stderr, "can't read MAC address from DLPI streams interface for "
"device %s unit %d.\n", dev, unit);
exit(STATE_UNKNOWN);
}
/* Kompf 2000-2003 */
#else
fprintf(stderr, "can't get MAC address for this architecture.\n");
exit(STATE_UNKNOWN);
#endif
if (verbose) {
fprintf(stdout, "Hardware address: ");
for (i = 0; i < 6; ++i)
fprintf(stdout, "%2.2x", client_hardware_address[i]);
fprintf(stdout, "\n");
}
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));
if (verbose) {
fprintf(stdout, "DHCPDISCOVER to %s port %d\n",
inet_ntoa(sockaddr_broadcast.sin_addr),
ntohs(sockaddr_broadcast.sin_port));
fprintf(stdout, "DHCPDISCOVER XID: %lu (0x%X)\n",
(unsigned long)ntohl(discover_packet.xid),
ntohl(discover_packet.xid));
fprintf(stdout, "DHCDISCOVER ciaddr: %s\n", inet_ntoa(discover_packet.ciaddr));
fprintf(stdout, "DHCDISCOVER yiaddr: %s\n", inet_ntoa(discover_packet.yiaddr));
fprintf(stdout, "DHCDISCOVER siaddr: %s\n", inet_ntoa(discover_packet.siaddr));
fprintf(stdout, "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)
fprintf(stdout, "\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;
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(¤t_time);
if ((current_time - start_time) >= dhcpoffer_timeout)
break;
if (verbose)
fprintf(stdout, "\n\n");
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);
// checks if the source address is the banned one
char saddr[16];
inet_ntop(AF_INET, &(source.sin_addr), saddr, INET_ADDRSTRLEN);
if (banned && strcmp(saddr, baddr) == 0) {
fprintf(stdout, "DHCP offer comming from the banned addr %s, ignoring it\n",
baddr);
result = 1;
}
if (result != OK) {
if (verbose)
fprintf(stdout, "Result=ERROR\n");
continue;
} else {
if (verbose)
fprintf(stdout, "Result=OK\n");
responses++;
}
if (verbose) {
fprintf(stdout, "DHCPOFFER from IP address %s\n", inet_ntoa(source.sin_addr));
fprintf(stdout, "DHCPOFFER XID: %lu (0x%X)\n",
(unsigned long)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)
fprintf(stdout, "DHCPOFFER XID (%lu) did not match DHCPDISCOVER XID (%lu) - "
"ignoring packet\n",
(unsigned long)ntohl(offer_packet.xid),
(unsigned long)packet_xid);
continue;
}
/* check hardware address */
result = OK;
if (verbose)
fprintf(stdout, "DHCPOFFER chaddr: ");
for (x = 0; x < ETHERNET_HARDWARE_ADDRESS_LENGTH; x++) {
if (verbose)
fprintf(stdout, "%02X", (unsigned char)offer_packet.chaddr[x]);
if (offer_packet.chaddr[x] != client_hardware_address[x])
result = ERROR;
}
if (verbose)
fprintf(stdout, "\n");
if (result == ERROR) {
if (verbose)
fprintf(stdout, "DHCPOFFER hardware address did not match our own - ignoring "
"packet\n");
continue;
}
if (verbose) {
fprintf(stdout, "DHCPOFFER ciaddr: %s\n", inet_ntoa(offer_packet.ciaddr));
fprintf(stdout, "DHCPOFFER yiaddr: %s\n", inet_ntoa(offer_packet.yiaddr));
fprintf(stdout, "DHCPOFFER siaddr: %s\n", inet_ntoa(offer_packet.siaddr));
fprintf(stdout, "DHCPOFFER giaddr: %s\n", inet_ntoa(offer_packet.giaddr));
}
add_dhcp_offer(source.sin_addr, &offer_packet);
valid_responses++;
}
if (verbose) {
fprintf(stdout, "Total responses seen on the wire: %d\n", responses);
fprintf(stdout, "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)
fprintf(stdout, "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;
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)) {
if (verbose)
fprintf(stdout, "No (more) data received\n");
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);
if (verbose)
fprintf(stdout, "recv_result_1: %d\n", recv_result);
recv_result = recvfrom(sock, (char *)buffer, buffer_size, 0,
(struct sockaddr *)&source_address, &address_size);
if (verbose)
fprintf(stdout, "recv_result_2: %d\n", recv_result);
if (recv_result == -1) {
if (verbose) {
fprintf(stdout, "recvfrom() failed, ");
fprintf(stdout, "errno: (%d) -> %s\n", errno, strerror(errno));
}
return ERROR;
} else {
if (verbose) {
fprintf(stdout, "receive_dhcp_packet() result: %d\n", recv_result);
fprintf(stdout, "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;
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) {
fprintf(stderr, "Could not create socket!\n");
exit(STATE_UNKNOWN);
}
if (verbose)
fprintf(stdout, "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) {
fprintf(stderr, "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) {
fprintf(stderr, "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) {
fprintf(stderr, "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) {
fprintf(stderr, "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++;
if (verbose)
fprintf(stdout, "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;
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++];
if (verbose)
fprintf(stdout, "Option: %d (0x%02X)\n", option_type, option_length);
/* get option data */
if (option_type == DHCP_OPTION_LEASE_TIME) {
memcpy(&dhcp_lease_time, &offer_packet->options[x], sizeof(dhcp_lease_time));
dhcp_lease_time = ntohl(dhcp_lease_time);
}
if (option_type == DHCP_OPTION_RENEWAL_TIME) {
memcpy(&dhcp_renewal_time, &offer_packet->options[x], sizeof(dhcp_renewal_time));
dhcp_renewal_time = ntohl(dhcp_renewal_time);
}
if (option_type == DHCP_OPTION_REBINDING_TIME) {
memcpy(&dhcp_rebinding_time, &offer_packet->options[x], sizeof(dhcp_rebinding_time));
dhcp_rebinding_time = ntohl(dhcp_rebinding_time);
}
/* skip option data we're ignoring */
else
for (y = 0; y < option_length; y++, x++);
}
if (verbose) {
if (dhcp_lease_time == DHCP_INFINITE_TIME)
fprintf(stdout, "Lease Time: Infinite\n");
else
fprintf(stdout, "Lease Time: %lu seconds\n", (unsigned long)dhcp_lease_time);
if (dhcp_renewal_time == DHCP_INFINITE_TIME)
fprintf(stdout, "Renewal Time: Infinite\n");
else
fprintf(stdout, "Renewal Time: %lu seconds\n", (unsigned long)dhcp_renewal_time);
if (dhcp_rebinding_time == DHCP_INFINITE_TIME)
fprintf(stdout, "Rebinding Time: Infinite\n");
fprintf(stdout, "Rebinding Time: %lu seconds\n", (unsigned long)dhcp_rebinding_time);
}
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;
if (verbose) {
fprintf(stdout, "Added offer from server @ %s",
inet_ntoa(new_offer->server_address));
fprintf(stdout, " of IP address %s\n", inet_ntoa(new_offer->offered_address));
}
if (prometheus) {
fprintf(stdout, "dhcpdiscover_offer{ ");
fprintf(stdout, "server=\"%s\",", inet_ntoa(new_offer->server_address));
fprintf(stdout, "address=\"%s\",", inet_ntoa(new_offer->offered_address));
fprintf(stdout, "dev=\"%s\" } 1\n", network_interface_name);
}
/* 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))) {
if (verbose) {
fprintf(stdout, "DHCP Server Match: Offerer=%s",
inet_ntoa(temp_offer->server_address));
fprintf(stdout, " Requested=%s\n", inet_ntoa(temp_server->server_address));
}
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;
fprintf(stdout, "DHCP %s: ", (result == STATE_OK) ? "ok" : "problem");
/* we didn't receive any DHCPOFFERs */
if (dhcp_offer_list == NULL) {
fprintf(stdout, "No DHCPOFFERs were received.\n");