1 /* vi: set sw=4 ts=4: */
2 /* Port to Busybox Copyright (C) 2006 Jesse Dutton <jessedutton@gmail.com>
4 * Licensed under GPL v2, see file LICENSE in this tarball for details.
6 * DHCP Relay for 'DHCPv4 Configuration of IPSec Tunnel Mode' support
7 * Copyright (C) 2002 Mario Strasser <mast@gmx.net>,
8 * Zuercher Hochschule Winterthur,
10 * Upstream has GPL v2 or later
18 #define SELECT_TIMEOUT 5 /* select timeout in sec. */
19 #define MAX_LIFETIME 2*60 /* lifetime of an xid entry in sec. */
20 #define MAX_INTERFACES 9
23 /* This list holds information about clients. The xid_* functions manipulate this list. */
24 static struct xid_item {
26 struct sockaddr_in ip;
29 struct xid_item *next;
30 } dhcprelay_xid_list = {0, {0}, 0, 0, NULL};
33 static struct xid_item * xid_add(u_int32_t xid, struct sockaddr_in *ip, int client)
35 struct xid_item *item;
37 /* create new xid entry */
38 item = xmalloc(sizeof(struct xid_item));
43 item->client = client;
44 item->timestamp = time(NULL);
45 item->next = dhcprelay_xid_list.next;
46 dhcprelay_xid_list.next = item;
52 static void xid_expire(void)
54 struct xid_item *item = dhcprelay_xid_list.next;
55 struct xid_item *last = &dhcprelay_xid_list;
56 time_t current_time = time(NULL);
58 while (item != NULL) {
59 if ((current_time-item->timestamp) > MAX_LIFETIME) {
60 last->next = item->next;
70 static struct xid_item * xid_find(u_int32_t xid)
72 struct xid_item *item = dhcprelay_xid_list.next;
73 while (item != NULL) {
74 if (item->xid == xid) {
82 static void xid_del(u_int32_t xid)
84 struct xid_item *item = dhcprelay_xid_list.next;
85 struct xid_item *last = &dhcprelay_xid_list;
86 while (item != NULL) {
87 if (item->xid == xid) {
88 last->next = item->next;
100 * get_dhcp_packet_type - gets the message type of a dhcp packet
101 * p - pointer to the dhcp packet
102 * returns the message type on success, -1 otherwise
104 static int get_dhcp_packet_type(struct dhcpMessage *p)
108 /* it must be either a BOOTREQUEST or a BOOTREPLY */
109 if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
111 /* get message type option */
112 op = get_option(p, DHCP_MESSAGE_TYPE);
119 * signal_handler - handles signals ;-)
122 static int dhcprelay_stopflag;
123 static void dhcprelay_signal_handler(int sig)
125 dhcprelay_stopflag = 1;
129 * get_client_devices - parses the devices list
130 * dev_list - comma separated list of devices
133 static char ** get_client_devices(char *dev_list, int *client_number)
135 char *s, *list, **client_dev;
139 list = xstrdup(dev_list);
140 if (list == NULL) return NULL;
142 /* get number of items */
143 for (s = dev_list, cn = 1; *s; s++)
147 client_dev = xzalloc(cn * sizeof(*client_dev));
150 s = strtok(list, ",");
153 client_dev[i++] = xstrdup(s);
154 s = strtok(NULL, ",");
157 /* free copy and exit */
164 /* Creates listen sockets (in fds) and returns the number allocated. */
165 static int init_sockets(char **client, int num_clients,
166 char *server, int *fds, int *max_socket)
170 /* talk to real server on bootps */
171 fds[0] = listen_socket(htonl(INADDR_ANY), 67, server);
172 *max_socket = fds[0];
174 /* array starts at 1 since server is 0 */
177 for (i=1; i < num_clients; i++) {
178 /* listen for clients on bootps */
179 fds[i] = listen_socket(htonl(INADDR_ANY), 67, client[i-1]);
180 if (fds[i] > *max_socket) *max_socket = fds[i];
188 * pass_on() - forwards dhcp packets from client to server
190 * client - number of the client
192 static void pass_on(struct dhcpMessage *p, int packet_len, int client, int *fds,
193 struct sockaddr_in *client_addr, struct sockaddr_in *server_addr)
196 struct xid_item *item;
198 /* check packet_type */
199 type = get_dhcp_packet_type(p);
200 if (type != DHCPDISCOVER && type != DHCPREQUEST
201 && type != DHCPDECLINE && type != DHCPRELEASE
202 && type != DHCPINFORM
207 /* create new xid entry */
208 item = xid_add(p->xid, client_addr, client);
210 /* forward request to LAN (server) */
211 res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
212 sizeof(struct sockaddr_in));
213 if (res != packet_len) {
214 bb_perror_msg("pass_on");
220 * pass_back() - forwards dhcp packets from server to client
223 static void pass_back(struct dhcpMessage *p, int packet_len, int *fds)
226 struct xid_item *item;
229 item = xid_find(p->xid);
234 /* check packet type */
235 type = get_dhcp_packet_type(p);
236 if (type != DHCPOFFER && type != DHCPACK && type != DHCPNAK) {
240 if (item->ip.sin_addr.s_addr == htonl(INADDR_ANY))
241 item->ip.sin_addr.s_addr = htonl(INADDR_BROADCAST);
242 if (item->client > MAX_INTERFACES)
244 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*)(&item->ip),
246 if (res != packet_len) {
247 bb_perror_msg("pass_back");
251 /* remove xid entry */
255 static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
256 struct sockaddr_in *server_addr, uint32_t gw_ip)
258 struct dhcpMessage dhcp_msg;
262 struct sockaddr_in client_addr;
266 while (!dhcprelay_stopflag) {
268 for (i = 0; i < num_sockets; i++)
269 FD_SET(fds[i], &rfds);
270 tv.tv_sec = SELECT_TIMEOUT;
272 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
274 if (FD_ISSET(fds[0], &rfds)) {
275 packlen = udhcp_get_packet(&dhcp_msg, fds[0]);
277 pass_back(&dhcp_msg, packlen, fds);
280 for (i = 1; i < num_sockets; i++) {
282 if (!FD_ISSET(fds[i], &rfds))
284 addr_size = sizeof(struct sockaddr_in);
285 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
286 (struct sockaddr *)(&client_addr), &addr_size);
289 if (read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL) < 0)
290 dhcp_msg.giaddr = gw_ip;
291 pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
298 int dhcprelay_main(int argc, char **argv)
300 int i, num_sockets, max_socket, fds[MAX_INTERFACES];
303 struct sockaddr_in server_addr;
305 server_addr.sin_family = AF_INET;
306 server_addr.sin_port = htons(67);
308 if (!inet_aton(argv[3], &server_addr.sin_addr))
309 bb_perror_msg_and_die("didn't grok server");
310 } else if (argc == 3) {
311 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
315 clients = get_client_devices(argv[1], &num_sockets);
316 if (!clients) return 0;
318 signal(SIGTERM, dhcprelay_signal_handler);
319 signal(SIGQUIT, dhcprelay_signal_handler);
320 signal(SIGINT, dhcprelay_signal_handler);
322 num_sockets = init_sockets(clients, num_sockets, argv[2], fds, &max_socket);
324 if (read_interface(argv[2], NULL, &gw_ip, NULL) == -1)
327 dhcprelay_loop(fds, num_sockets, max_socket, clients, &server_addr, gw_ip);
329 if (ENABLE_FEATURE_CLEAN_UP) {
330 for (i = 0; i < num_sockets; i++) {