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Diffstat (limited to 'plugins-root/check_dhcp.c')
-rw-r--r--plugins-root/check_dhcp.c84
1 files changed, 74 insertions, 10 deletions
diff --git a/plugins-root/check_dhcp.c b/plugins-root/check_dhcp.c
index 7cb2d300..a1d04c18 100644
--- a/plugins-root/check_dhcp.c
+++ b/plugins-root/check_dhcp.c
@@ -33,6 +33,12 @@
*
* $Id$
*
+* ------------------------------------------------------------------------
+* 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.
+* ------------------------------------------------------------------------
+*
*****************************************************************************/
const char *progname = "check_dhcp";
@@ -59,6 +65,9 @@ const char *email = "nagiosplug-devel@lists.sourceforge.net";
#include <netinet/in.h>
#include <net/if.h>
#include <arpa/inet.h>
+#if HAVE_SYS_SOCKIO_H
+#include <sys/sockio.h>
+#endif
#if defined( __linux__ )
@@ -190,6 +199,7 @@ typedef struct requested_server_struct{
#define DHCP_INFINITE_TIME 0xFFFFFFFF
#define DHCP_BROADCAST_FLAG 32768
+#define DHCP_UNICAST_FLAG 0
#define DHCP_SERVER_PORT 67
#define DHCP_CLIENT_PORT 68
@@ -197,6 +207,9 @@ typedef struct requested_server_struct{
#define ETHERNET_HARDWARE_ADDRESS 1 /* used in htype field of dhcp packet */
#define ETHERNET_HARDWARE_ADDRESS_LENGTH 6 /* length of Ethernet hardware addresses */
+u_int8_t unicast = 0; /* unicast mode: mimic a DHCP relay */
+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]="";
char network_interface_name[IFNAMSIZ]="eth0";
@@ -229,6 +242,7 @@ void print_usage(void);
void print_help(void);
int get_hardware_address(int,char *);
+int get_ip_address(int,char *);
int send_dhcp_discover(int);
int get_dhcp_offer(int);
@@ -267,6 +281,9 @@ int main(int argc, char **argv){
/* get hardware address of client machine */
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);
@@ -400,6 +417,32 @@ int get_hardware_address(int sock,char *interface_name){
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){
@@ -421,8 +464,6 @@ int send_dhcp_discover(int sock){
/* 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();
@@ -435,8 +476,11 @@ int send_dhcp_discover(int sock){
/*discover_packet.secs=htons(65535);*/
discover_packet.secs=0xFF;
- /* tell server it should broadcast its response */
- discover_packet.flags=htons(DHCP_BROADCAST_FLAG);
+ /*
+ * 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);
@@ -462,10 +506,17 @@ int send_dhcp_discover(int sock){
}
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=INADDR_BROADCAST;
+ sockaddr_broadcast.sin_addr.s_addr = unicast ? dhcp_ip.s_addr : INADDR_BROADCAST;
bzero(&sockaddr_broadcast.sin_zero,sizeof(sockaddr_broadcast.sin_zero));
@@ -685,8 +736,9 @@ int create_dhcp_socket(void){
/* 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 */
+ /* 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 */
@@ -1035,6 +1087,7 @@ int call_getopt(int argc, char **argv){
{"requestedip", required_argument,0,'r'},
{"timeout", required_argument,0,'t'},
{"interface", required_argument,0,'i'},
+ {"unicast", no_argument, 0,'u'},
{"verbose", no_argument, 0,'v'},
{"version", no_argument, 0,'V'},
{"help", no_argument, 0,'h'},
@@ -1042,7 +1095,7 @@ int call_getopt(int argc, char **argv){
};
while(1){
- c=getopt_long(argc,argv,"+hVvt:s:r:t:i:",long_options,&option_index);
+ c=getopt_long(argc,argv,"+hVvt:s:r:t:i:u",long_options,&option_index);
i++;
@@ -1063,8 +1116,12 @@ int call_getopt(int argc, char **argv){
switch(c){
case 's': /* DHCP server address */
- if(inet_aton(optarg,&ipaddress))
+ if(inet_aton(optarg,&ipaddress)){
add_requested_server(ipaddress);
+ inet_aton(optarg, &dhcp_ip);
+ if (verbose)
+ printf("querying %s\n",inet_ntoa(dhcp_ip));
+ }
/*
else
usage("Invalid server IP address\n");
@@ -1102,6 +1159,10 @@ int call_getopt(int argc, char **argv){
break;
+ case 'u': /* unicast testing */
+ unicast=1;
+ break;
+
case 'V': /* version */
print_revision(progname,revision);
exit(STATE_OK);
@@ -1296,6 +1357,8 @@ void print_help(void){
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", "-u, --unicast");
+ printf (" %s\n", _("Unicast testing: mimic a DHCP relay, requires -s"));
return;
}
@@ -1305,7 +1368,8 @@ void
print_usage(void){
printf (_("Usage:"));
- printf ("%s [-s serverip] [-r requestedip] [-t timeout] [-i interface] [-v]\n",progname);
+ printf (" %s [-v] [-u] [-s serverip] [-r requestedip] [-t timeout]\n",progname);
+ printf (" [-i interface]\n");
return;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-25 16:17:31 +0000