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
16 #define SERVER_PORT 67
17 #define SELECT_TIMEOUT 5 /* select timeout in sec. */
18 #define MAX_LIFETIME 2*60 /* lifetime of an xid entry in sec. */
20 /* This list holds information about clients. The xid_* functions manipulate this list. */
25 struct sockaddr_in ip;
26 struct xid_item *next;
29 #define dhcprelay_xid_list (*(struct xid_item*)&bb_common_bufsiz1)
31 static struct xid_item *xid_add(uint32_t xid, struct sockaddr_in *ip, int client)
33 struct xid_item *item;
35 /* create new xid entry */
36 item = xmalloc(sizeof(struct xid_item));
41 item->client = client;
42 item->timestamp = monotonic_sec();
43 item->next = dhcprelay_xid_list.next;
44 dhcprelay_xid_list.next = item;
49 static void xid_expire(void)
51 struct xid_item *item = dhcprelay_xid_list.next;
52 struct xid_item *last = &dhcprelay_xid_list;
53 unsigned current_time = monotonic_sec();
55 while (item != NULL) {
56 if ((current_time - item->timestamp) > MAX_LIFETIME) {
57 last->next = item->next;
67 static struct xid_item *xid_find(uint32_t xid)
69 struct xid_item *item = dhcprelay_xid_list.next;
70 while (item != NULL) {
71 if (item->xid == xid) {
79 static void xid_del(uint32_t xid)
81 struct xid_item *item = dhcprelay_xid_list.next;
82 struct xid_item *last = &dhcprelay_xid_list;
83 while (item != NULL) {
84 if (item->xid == xid) {
85 last->next = item->next;
96 * get_dhcp_packet_type - gets the message type of a dhcp packet
97 * p - pointer to the dhcp packet
98 * returns the message type on success, -1 otherwise
100 static int get_dhcp_packet_type(struct dhcp_packet *p)
104 /* it must be either a BOOTREQUEST or a BOOTREPLY */
105 if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
107 /* get message type option */
108 op = get_option(p, DHCP_MESSAGE_TYPE);
115 * get_client_devices - parses the devices list
116 * dev_list - comma separated list of devices
119 static char **get_client_devices(char *dev_list, int *client_number)
121 char *s, **client_dev;
125 dev_list = xstrdup(dev_list);
127 /* get number of items, replace ',' with NULs */
139 /* create vector of pointers */
140 client_dev = xzalloc(cn * sizeof(*client_dev));
141 client_dev[0] = dev_list;
144 client_dev[i] = client_dev[i - 1] + strlen(client_dev[i - 1]) + 1;
151 /* Creates listen sockets (in fds) bound to client and server ifaces,
152 * and returns numerically max fd.
154 static int init_sockets(char **client_ifaces, int num_clients,
155 char *server_iface, int *fds)
159 /* talk to real server on bootps */
160 fds[0] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, server_iface);
163 for (i = 1; i < num_clients; i++) {
164 /* listen for clients on bootps */
165 fds[i] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, client_ifaces[i-1]);
174 * pass_to_server() - forwards dhcp packets from client to server
176 * client - number of the client
178 static void pass_to_server(struct dhcp_packet *p, int packet_len, int client, int *fds,
179 struct sockaddr_in *client_addr, struct sockaddr_in *server_addr)
182 struct xid_item *item;
184 /* check packet_type */
185 type = get_dhcp_packet_type(p);
186 if (type != DHCPDISCOVER && type != DHCPREQUEST
187 && type != DHCPDECLINE && type != DHCPRELEASE
188 && type != DHCPINFORM
193 /* create new xid entry */
194 item = xid_add(p->xid, client_addr, client);
196 /* forward request to LAN (server) */
198 res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
199 sizeof(struct sockaddr_in));
200 if (res != packet_len) {
201 bb_perror_msg("sendto");
206 * pass_to_client() - forwards dhcp packets from server to client
209 static void pass_to_client(struct dhcp_packet *p, int packet_len, int *fds)
212 struct xid_item *item;
215 item = xid_find(p->xid);
220 /* check packet type */
221 type = get_dhcp_packet_type(p);
222 if (type != DHCPOFFER && type != DHCPACK && type != DHCPNAK) {
226 if (item->ip.sin_addr.s_addr == htonl(INADDR_ANY))
227 item->ip.sin_addr.s_addr = htonl(INADDR_BROADCAST);
229 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*) &(item->ip),
231 if (res != packet_len) {
232 bb_perror_msg("sendto");
236 /* remove xid entry */
240 int dhcprelay_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
241 int dhcprelay_main(int argc, char **argv)
243 struct dhcp_packet dhcp_msg;
244 struct sockaddr_in server_addr;
245 struct sockaddr_in client_addr;
247 char **client_ifaces;
249 int num_sockets, max_socket;
252 server_addr.sin_family = AF_INET;
253 server_addr.sin_port = htons(SERVER_PORT);
255 /* dhcprelay client_iface1,client_iface2,... server_iface [server_IP] */
257 if (!inet_aton(argv[3], &server_addr.sin_addr))
258 bb_perror_msg_and_die("bad server IP");
259 } else if (argc == 3) {
260 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
265 /* Produce list of client ifaces */
266 client_ifaces = get_client_devices(argv[1], &num_sockets);
268 num_sockets++; /* for server socket at fds[0] */
269 fds = xmalloc(num_sockets * sizeof(fds[0]));
271 /* Create sockets and bind one to every iface */
272 max_socket = init_sockets(client_ifaces, num_sockets, argv[2], fds);
274 /* Get our IP on server_iface */
275 if (udhcp_read_interface(argv[2], NULL, &our_nip, NULL))
280 //reinit stuff from time to time? go back to get_client_devices
288 for (i = 0; i < num_sockets; i++)
289 FD_SET(fds[i], &rfds);
290 tv.tv_sec = SELECT_TIMEOUT;
292 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
294 if (FD_ISSET(fds[0], &rfds)) {
295 packlen = udhcp_recv_kernel_packet(&dhcp_msg, fds[0]);
297 pass_to_client(&dhcp_msg, packlen, fds);
301 for (i = 1; i < num_sockets; i++) {
302 if (!FD_ISSET(fds[i], &rfds))
304 addr_size = sizeof(struct sockaddr_in);
305 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
306 (struct sockaddr *)(&client_addr), &addr_size);
310 /* Get our IP on corresponding client_iface */
311 //why? what if server can't route such IP?
312 if (udhcp_read_interface(client_ifaces[i-1], NULL, &dhcp_msg.gateway_nip, NULL)) {
313 /* Fall back to our server_iface's IP */
314 //this makes more sense!
315 dhcp_msg.gateway_nip = our_nip;
317 //maybe set dhcp_msg.flags |= BROADCAST_FLAG too?
318 pass_to_server(&dhcp_msg, packlen, i, fds, &client_addr, &server_addr);
324 /* return 0; - not reached */