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Move dhcp packet reply code to packet.c.

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This commit is contained in:
Nicholas J. Kain 2010-12-24 08:55:59 -05:00
parent 9390e131b6
commit adcc4bdd3d
4 changed files with 144 additions and 128 deletions
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3
ndhc/config.h
View File

@ -1,6 +1,9 @@
#ifndef DHCPC_H_
#define DHCPC_H_
#define NUMPACKETS 3 /* number of packets to send before delay */
#define RETRY_DELAY 30 /* time in seconds to delay after sending NUMPACKETS */
enum {
DS_NULL = 0,
DS_INIT_SELECTING,

140
ndhc/ndhc.c
View File

@ -59,8 +59,6 @@
#include "io.h"
#define VERSION "1.0"
#define NUMPACKETS 3 /* number of packets to send before delay */
#define RETRY_DELAY 30 /* time in seconds to delay after sending NUMPACKETS */
struct client_state_t cs = {
.dhcpState = DS_INIT_SELECTING,
@ -150,7 +148,7 @@ static void show_usage(void)
}
/* Switch listen socket between raw (if-bound), kernel (ip-bound), and none */
static void change_listen_mode(int new_mode)
void change_listen_mode(int new_mode)
{
log_line("entering %s listen mode",
new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
@ -260,6 +258,19 @@ static struct arpMsg arpreply;
static int arpreply_offset;
static struct dhcpMessage arp_dhcp_packet;
void arp_check(struct dhcpMessage *packet)
{
cs.arpPrevState = cs.dhcpState;
cs.dhcpState = DS_ARP_CHECK;
memcpy(&arp_dhcp_packet, packet, sizeof (struct dhcpMessage));
cs.arpFd = arpping(arp_dhcp_packet.yiaddr, NULL, 0,
client_config.arp, client_config.interface);
epoll_add(cs.arpFd);
cs.timeout = 2000;
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
}
static void arp_failed(void)
{
log_line("Offered address is in use: declining.");
@ -426,127 +437,6 @@ static void handle_timeout(void)
}
}
static void init_selecting_packet(struct dhcpMessage *packet,
unsigned char *message)
{
unsigned char *temp = NULL;
/* Must be a DHCPOFFER to one of our xid's */
if (*message == DHCPOFFER) {
if ((temp = get_option(packet, DHCP_SERVER_ID))) {
/* Memcpy to a temp buffer to force alignment */
memcpy(&cs.serverAddr, temp, 4);
cs.xid = packet->xid;
cs.requestedIP = packet->yiaddr;
/* enter requesting state */
cs.dhcpState = DS_REQUESTING;
cs.timeout = 0;
cs.packetNum = 0;
} else {
log_line("No server ID in message");
}
}
}
static void dhcp_ack_or_nak_packet(struct dhcpMessage *packet,
unsigned char *message)
{
unsigned char *temp = NULL;
if (*message == DHCPACK) {
if (!(temp = get_option(packet, DHCP_LEASE_TIME))) {
log_line("No lease time received, assuming 1h.");
cs.lease = 60 * 60;
} else {
/* Memcpy to a temp buffer to force alignment */
memcpy(&cs.lease, temp, 4);
cs.lease = ntohl(cs.lease);
/* Enforce upper and lower bounds on lease. */
cs.lease &= 0x0fffffff;
if (cs.lease < RETRY_DELAY)
cs.lease = RETRY_DELAY;
}
cs.arpPrevState = cs.dhcpState;
cs.dhcpState = DS_ARP_CHECK;
memcpy(&arp_dhcp_packet, packet, sizeof (struct dhcpMessage));
cs.arpFd = arpping(arp_dhcp_packet.yiaddr, NULL, 0,
client_config.arp, client_config.interface);
epoll_add(cs.arpFd);
cs.timeout = 2000;
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
// Can transition to DS_BOUND or DS_INIT_SELECTING.
} else if (*message == DHCPNAK) {
/* return to init state */
log_line("Received DHCP NAK.");
run_script(packet, SCRIPT_NAK);
if (cs.dhcpState != DS_REQUESTING)
run_script(NULL, SCRIPT_DECONFIG);
cs.dhcpState = DS_INIT_SELECTING;
cs.timeout = 0;
cs.requestedIP = 0;
cs.packetNum = 0;
change_listen_mode(LM_RAW);
// XXX: this isn't rfc compliant: should be exp backoff
sleep(3); /* avoid excessive network traffic */
}
}
static void handle_packet(void)
{
unsigned char *message = NULL;
int len;
struct dhcpMessage packet;
if (cs.listenMode == LM_KERNEL)
len = get_packet(&packet, cs.listenFd);
else if (cs.listenMode == LM_RAW)
len = get_raw_packet(&packet, cs.listenFd);
else /* LM_NONE */
return;
if (len == -1 && errno != EINTR) {
log_error("reopening socket.");
change_listen_mode(cs.listenMode); /* just close and reopen */
}
if (len < 0)
return;
if (packet.xid != cs.xid) {
log_line("Ignoring XID %lx (our xid is %lx).",
(uint32_t) packet.xid, cs.xid);
return;
}
if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
log_line("couldnt get option from packet -- ignoring");
return;
}
switch (cs.dhcpState) {
case DS_INIT_SELECTING:
init_selecting_packet(&packet, message);
break;
case DS_ARP_CHECK:
/* We ignore dhcp packets for now. This state will
* be changed by the callback for arp ping.
*/
break;
case DS_RENEW_REQUESTED:
case DS_REQUESTING:
case DS_RENEWING:
case DS_REBINDING:
dhcp_ack_or_nak_packet(&packet, message);
break;
case DS_BOUND:
case DS_RELEASED:
default:
break;
}
}
typedef uint32_t aliased_uint32_t __attribute__((__may_alias__));
static void handle_arp_response(void)
{
@ -655,7 +545,7 @@ static void do_work(void)
if (fd == cs.signalFd)
signal_dispatch();
else if (fd == cs.listenFd)
handle_packet();
handle_packet(&cs);
else if (fd == cs.arpFd)
handle_arp_response();
else

121
ndhc/packet.c
View File

@ -10,6 +10,8 @@
#include <errno.h>
#include "packet.h"
#include "clientpacket.h"
#include "script.h"
#include "log.h"
#include "io.h"
#include "dhcpd.h"
@ -169,3 +171,122 @@ int kernel_packet(struct dhcpMessage *payload, uint32_t source_ip,
out:
return result;
}
static void init_selecting_packet(struct client_state_t *cs,
struct dhcpMessage *packet,
unsigned char *message)
{
unsigned char *temp = NULL;
/* Must be a DHCPOFFER to one of our xid's */
if (*message == DHCPOFFER) {
if ((temp = get_option(packet, DHCP_SERVER_ID))) {
/* Memcpy to a temp buffer to force alignment */
memcpy(&cs->serverAddr, temp, 4);
cs->xid = packet->xid;
cs->requestedIP = packet->yiaddr;
/* enter requesting state */
cs->dhcpState = DS_REQUESTING;
cs->timeout = 0;
cs->packetNum = 0;
} else {
log_line("No server ID in message");
}
}
}
// from ndhc.c
void change_listen_mode(int new_mode);
void arp_check(struct dhcpMessage *packet);
static void dhcp_ack_or_nak_packet(struct client_state_t *cs,
struct dhcpMessage *packet,
unsigned char *message)
{
unsigned char *temp = NULL;
if (*message == DHCPACK) {
if (!(temp = get_option(packet, DHCP_LEASE_TIME))) {
log_line("No lease time received, assuming 1h.");
cs->lease = 60 * 60;
} else {
/* Memcpy to a temp buffer to force alignment */
memcpy(&cs->lease, temp, 4);
cs->lease = ntohl(cs->lease);
/* Enforce upper and lower bounds on lease. */
cs->lease &= 0x0fffffff;
if (cs->lease < RETRY_DELAY)
cs->lease = RETRY_DELAY;
}
arp_check(packet);
// Can transition from DS_ARP_CHECK to DS_BOUND or DS_INIT_SELECTING.
} else if (*message == DHCPNAK) {
/* return to init state */
log_line("Received DHCP NAK.");
run_script(packet, SCRIPT_NAK);
if (cs->dhcpState != DS_REQUESTING)
run_script(NULL, SCRIPT_DECONFIG);
cs->dhcpState = DS_INIT_SELECTING;
cs->timeout = 0;
cs->requestedIP = 0;
cs->packetNum = 0;
change_listen_mode(LM_RAW);
// XXX: this isn't rfc compliant: should be exp backoff
sleep(3); /* avoid excessive network traffic */
}
}
void handle_packet(struct client_state_t *cs)
{
unsigned char *message = NULL;
int len;
struct dhcpMessage packet;
if (cs->listenMode == LM_KERNEL)
len = get_packet(&packet, cs->listenFd);
else if (cs->listenMode == LM_RAW)
len = get_raw_packet(&packet, cs->listenFd);
else /* LM_NONE */
return;
if (len == -1 && errno != EINTR) {
log_error("reopening socket.");
change_listen_mode(cs->listenMode); /* just close and reopen */
}
if (len < 0)
return;
if (packet.xid != cs->xid) {
log_line("Ignoring XID %lx (our xid is %lx).",
(uint32_t) packet.xid, cs->xid);
return;
}
if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
log_line("couldnt get option from packet -- ignoring");
return;
}
switch (cs->dhcpState) {
case DS_INIT_SELECTING:
init_selecting_packet(cs, &packet, message);
break;
case DS_ARP_CHECK:
/* We ignore dhcp packets for now. This state will
* be changed by the callback for arp ping.
*/
break;
case DS_RENEW_REQUESTED:
case DS_REQUESTING:
case DS_RENEWING:
case DS_REBINDING:
dhcp_ack_or_nak_packet(cs, &packet, message);
break;
case DS_BOUND:
case DS_RELEASED:
default:
break;
}
}

4
ndhc/packet.h
View File

@ -4,6 +4,8 @@
#include <netinet/udp.h>
#include <netinet/ip.h>
#include "config.h"
struct dhcpMessage {
uint8_t op;
uint8_t htype;
@ -52,5 +54,5 @@ int raw_packet(struct dhcpMessage *payload, uint32_t source_ip,
unsigned char *dest_arp, int ifindex);
int kernel_packet(struct dhcpMessage *payload, uint32_t source_ip,
int source_port, uint32_t dest_ip, int dest_port);
void handle_packet(struct client_state_t *cs);
#endif