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
15 #define SERVER_PORT 67
16 #define SELECT_TIMEOUT 5 /* select timeout in sec. */
17 #define MAX_LIFETIME 2*60 /* lifetime of an xid entry in sec. */
19 /* This list holds information about clients. The xid_* functions manipulate this list. */
24 struct sockaddr_in ip;
25 struct xid_item *next;
28 #define dhcprelay_xid_list (*(struct xid_item*)&bb_common_bufsiz1)
30 static struct xid_item *xid_add(uint32_t xid, struct sockaddr_in *ip, int client)
32 struct xid_item *item;
34 /* create new xid entry */
35 item = xmalloc(sizeof(struct xid_item));
40 item->client = client;
41 item->timestamp = monotonic_sec();
42 item->next = dhcprelay_xid_list.next;
43 dhcprelay_xid_list.next = item;
48 static void xid_expire(void)
50 struct xid_item *item = dhcprelay_xid_list.next;
51 struct xid_item *last = &dhcprelay_xid_list;
52 unsigned current_time = monotonic_sec();
54 while (item != NULL) {
55 if ((current_time - item->timestamp) > MAX_LIFETIME) {
56 last->next = item->next;
66 static struct xid_item *xid_find(uint32_t xid)
68 struct xid_item *item = dhcprelay_xid_list.next;
69 while (item != NULL) {
70 if (item->xid == xid) {
78 static void xid_del(uint32_t xid)
80 struct xid_item *item = dhcprelay_xid_list.next;
81 struct xid_item *last = &dhcprelay_xid_list;
82 while (item != NULL) {
83 if (item->xid == xid) {
84 last->next = item->next;
95 * get_dhcp_packet_type - gets the message type of a dhcp packet
96 * p - pointer to the dhcp packet
97 * returns the message type on success, -1 otherwise
99 static int get_dhcp_packet_type(struct dhcp_packet *p)
103 /* it must be either a BOOTREQUEST or a BOOTREPLY */
104 if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
106 /* get message type option */
107 op = udhcp_get_option(p, DHCP_MESSAGE_TYPE);
114 * get_client_devices - parses the devices list
115 * dev_list - comma separated list of devices
118 static char **get_client_devices(char *dev_list, int *client_number)
120 char *s, **client_dev;
124 dev_list = xstrdup(dev_list);
126 /* get number of items, replace ',' with NULs */
138 /* create vector of pointers */
139 client_dev = xzalloc(cn * sizeof(*client_dev));
140 client_dev[0] = dev_list;
143 client_dev[i] = client_dev[i - 1] + strlen(client_dev[i - 1]) + 1;
150 /* Creates listen sockets (in fds) bound to client and server ifaces,
151 * and returns numerically max fd.
153 static int init_sockets(char **client_ifaces, int num_clients,
154 char *server_iface, int *fds)
158 /* talk to real server on bootps */
159 fds[0] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, server_iface);
162 for (i = 1; i < num_clients; i++) {
163 /* listen for clients on bootps */
164 fds[i] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, client_ifaces[i-1]);
173 * pass_to_server() - forwards dhcp packets from client to server
175 * client - number of the client
177 static void pass_to_server(struct dhcp_packet *p, int packet_len, int client, int *fds,
178 struct sockaddr_in *client_addr, struct sockaddr_in *server_addr)
181 struct xid_item *item;
183 /* check packet_type */
184 type = get_dhcp_packet_type(p);
185 if (type != DHCPDISCOVER && type != DHCPREQUEST
186 && type != DHCPDECLINE && type != DHCPRELEASE
187 && type != DHCPINFORM
192 /* create new xid entry */
193 item = xid_add(p->xid, client_addr, client);
195 /* forward request to LAN (server) */
197 res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
198 sizeof(struct sockaddr_in));
199 if (res != packet_len) {
200 bb_perror_msg("sendto");
205 * pass_to_client() - forwards dhcp packets from server to client
208 static void pass_to_client(struct dhcp_packet *p, int packet_len, int *fds)
211 struct xid_item *item;
214 item = xid_find(p->xid);
219 /* check packet type */
220 type = get_dhcp_packet_type(p);
221 if (type != DHCPOFFER && type != DHCPACK && type != DHCPNAK) {
225 if (item->ip.sin_addr.s_addr == htonl(INADDR_ANY))
226 item->ip.sin_addr.s_addr = htonl(INADDR_BROADCAST);
228 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*) &(item->ip),
230 if (res != packet_len) {
231 bb_perror_msg("sendto");
235 /* remove xid entry */
239 int dhcprelay_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
240 int dhcprelay_main(int argc, char **argv)
242 struct dhcp_packet dhcp_msg;
243 struct sockaddr_in server_addr;
244 struct sockaddr_in client_addr;
246 char **client_ifaces;
248 int num_sockets, max_socket;
251 server_addr.sin_family = AF_INET;
252 server_addr.sin_port = htons(SERVER_PORT);
254 /* dhcprelay client_iface1,client_iface2,... server_iface [server_IP] */
256 if (!inet_aton(argv[3], &server_addr.sin_addr))
257 bb_perror_msg_and_die("bad server IP");
258 } else if (argc == 3) {
259 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
264 /* Produce list of client ifaces */
265 client_ifaces = get_client_devices(argv[1], &num_sockets);
267 num_sockets++; /* for server socket at fds[0] */
268 fds = xmalloc(num_sockets * sizeof(fds[0]));
270 /* Create sockets and bind one to every iface */
271 max_socket = init_sockets(client_ifaces, num_sockets, argv[2], fds);
273 /* Get our IP on server_iface */
274 if (udhcp_read_interface(argv[2], NULL, &our_nip, NULL))
279 //reinit stuff from time to time? go back to get_client_devices
287 for (i = 0; i < num_sockets; i++)
288 FD_SET(fds[i], &rfds);
289 tv.tv_sec = SELECT_TIMEOUT;
291 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
293 if (FD_ISSET(fds[0], &rfds)) {
294 packlen = udhcp_recv_kernel_packet(&dhcp_msg, fds[0]);
296 pass_to_client(&dhcp_msg, packlen, fds);
300 for (i = 1; i < num_sockets; i++) {
301 if (!FD_ISSET(fds[i], &rfds))
303 addr_size = sizeof(struct sockaddr_in);
304 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
305 (struct sockaddr *)(&client_addr), &addr_size);
309 /* Get our IP on corresponding client_iface */
310 //why? what if server can't route such IP?
311 if (udhcp_read_interface(client_ifaces[i-1], NULL, &dhcp_msg.gateway_nip, NULL)) {
312 /* Fall back to our server_iface's IP */
313 //this makes more sense!
314 dhcp_msg.gateway_nip = our_nip;
316 //maybe set dhcp_msg.flags |= BROADCAST_FLAG too?
317 pass_to_server(&dhcp_msg, packlen, i, fds, &client_addr, &server_addr);
323 /* return 0; - not reached */