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
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 dhcpMessage *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) and returns numerically max fd. */
152 static int init_sockets(char **client, int num_clients,
153 char *server, int *fds)
157 /* talk to real server on bootps */
158 fds[0] = listen_socket(/*INADDR_ANY,*/ 67, server);
161 for (i = 1; i < num_clients; i++) {
162 /* listen for clients on bootps */
163 fds[i] = listen_socket(/*INADDR_ANY,*/ 67, client[i-1]);
172 * pass_on() - forwards dhcp packets from client to server
174 * client - number of the client
176 static void pass_on(struct dhcpMessage *p, int packet_len, int client, int *fds,
177 struct sockaddr_in *client_addr, struct sockaddr_in *server_addr)
180 struct xid_item *item;
182 /* check packet_type */
183 type = get_dhcp_packet_type(p);
184 if (type != DHCPDISCOVER && type != DHCPREQUEST
185 && type != DHCPDECLINE && type != DHCPRELEASE
186 && type != DHCPINFORM
191 /* create new xid entry */
192 item = xid_add(p->xid, client_addr, client);
194 /* forward request to LAN (server) */
195 res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
196 sizeof(struct sockaddr_in));
197 if (res != packet_len) {
198 bb_perror_msg("pass_on");
204 * pass_back() - forwards dhcp packets from server to client
207 static void pass_back(struct dhcpMessage *p, int packet_len, int *fds)
210 struct xid_item *item;
213 item = xid_find(p->xid);
218 /* check packet type */
219 type = get_dhcp_packet_type(p);
220 if (type != DHCPOFFER && type != DHCPACK && type != DHCPNAK) {
224 if (item->ip.sin_addr.s_addr == htonl(INADDR_ANY))
225 item->ip.sin_addr.s_addr = htonl(INADDR_BROADCAST);
226 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*)(&item->ip),
228 if (res != packet_len) {
229 bb_perror_msg("pass_back");
233 /* remove xid entry */
237 static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
238 struct sockaddr_in *server_addr, uint32_t gw_ip) ATTRIBUTE_NORETURN;
239 static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
240 struct sockaddr_in *server_addr, uint32_t gw_ip)
242 struct dhcpMessage dhcp_msg;
246 struct sockaddr_in client_addr;
252 for (i = 0; i < num_sockets; i++)
253 FD_SET(fds[i], &rfds);
254 tv.tv_sec = SELECT_TIMEOUT;
256 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
258 if (FD_ISSET(fds[0], &rfds)) {
259 packlen = udhcp_recv_packet(&dhcp_msg, fds[0]);
261 pass_back(&dhcp_msg, packlen, fds);
264 for (i = 1; i < num_sockets; i++) {
266 if (!FD_ISSET(fds[i], &rfds))
268 addr_size = sizeof(struct sockaddr_in);
269 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
270 (struct sockaddr *)(&client_addr), &addr_size);
273 if (read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL))
274 dhcp_msg.giaddr = gw_ip;
275 pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
282 int dhcprelay_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
283 int dhcprelay_main(int argc, char **argv)
285 int num_sockets, max_socket;
289 struct sockaddr_in server_addr;
291 server_addr.sin_family = AF_INET;
292 server_addr.sin_port = htons(67);
294 if (!inet_aton(argv[3], &server_addr.sin_addr))
295 bb_perror_msg_and_die("didn't grok server");
296 } else if (argc == 3) {
297 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
302 clients = get_client_devices(argv[1], &num_sockets);
303 num_sockets++; /* for server socket at fds[0] */
304 fds = xmalloc(num_sockets * sizeof(fds[0]));
305 max_socket = init_sockets(clients, num_sockets, argv[2], fds);
307 if (read_interface(argv[2], NULL, &gw_ip, NULL))
311 dhcprelay_loop(fds, num_sockets, max_socket, clients, &server_addr, gw_ip);
312 /* return 0; - not reached */