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 SERVER_PORT 67
18 #define SELECT_TIMEOUT 5 /* select timeout in sec. */
19 #define MAX_LIFETIME 2*60 /* lifetime of an xid entry in sec. */
21 /* This list holds information about clients. The xid_* functions manipulate this list. */
26 struct sockaddr_in ip;
27 struct xid_item *next;
30 #define dhcprelay_xid_list (*(struct xid_item*)&bb_common_bufsiz1)
32 static struct xid_item *xid_add(uint32_t xid, struct sockaddr_in *ip, int client)
34 struct xid_item *item;
36 /* create new xid entry */
37 item = xmalloc(sizeof(struct xid_item));
42 item->client = client;
43 item->timestamp = monotonic_sec();
44 item->next = dhcprelay_xid_list.next;
45 dhcprelay_xid_list.next = item;
50 static void xid_expire(void)
52 struct xid_item *item = dhcprelay_xid_list.next;
53 struct xid_item *last = &dhcprelay_xid_list;
54 unsigned current_time = monotonic_sec();
56 while (item != NULL) {
57 if ((current_time - item->timestamp) > MAX_LIFETIME) {
58 last->next = item->next;
68 static struct xid_item *xid_find(uint32_t xid)
70 struct xid_item *item = dhcprelay_xid_list.next;
71 while (item != NULL) {
72 if (item->xid == xid) {
80 static void xid_del(uint32_t xid)
82 struct xid_item *item = dhcprelay_xid_list.next;
83 struct xid_item *last = &dhcprelay_xid_list;
84 while (item != NULL) {
85 if (item->xid == xid) {
86 last->next = item->next;
97 * get_dhcp_packet_type - gets the message type of a dhcp packet
98 * p - pointer to the dhcp packet
99 * returns the message type on success, -1 otherwise
101 static int get_dhcp_packet_type(struct dhcpMessage *p)
105 /* it must be either a BOOTREQUEST or a BOOTREPLY */
106 if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
108 /* get message type option */
109 op = get_option(p, DHCP_MESSAGE_TYPE);
116 * get_client_devices - parses the devices list
117 * dev_list - comma separated list of devices
120 static char **get_client_devices(char *dev_list, int *client_number)
122 char *s, **client_dev;
126 dev_list = xstrdup(dev_list);
128 /* get number of items, replace ',' with NULs */
140 /* create vector of pointers */
141 client_dev = xzalloc(cn * sizeof(*client_dev));
142 client_dev[0] = dev_list;
145 client_dev[i] = client_dev[i - 1] + strlen(client_dev[i - 1]) + 1;
152 /* Creates listen sockets (in fds) and returns numerically max fd. */
153 static int init_sockets(char **client, int num_clients,
154 char *server, int *fds)
158 /* talk to real server on bootps */
159 fds[0] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, server);
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[i-1]);
173 * pass_on() - forwards dhcp packets from client to server
175 * client - number of the client
177 static void pass_on(struct dhcpMessage *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) */
196 res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
197 sizeof(struct sockaddr_in));
198 if (res != packet_len) {
199 bb_perror_msg("pass_on");
205 * pass_back() - forwards dhcp packets from server to client
208 static void pass_back(struct dhcpMessage *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);
227 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*)(&item->ip),
229 if (res != packet_len) {
230 bb_perror_msg("pass_back");
234 /* remove xid entry */
238 static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
239 struct sockaddr_in *server_addr, uint32_t gw_ip) NORETURN;
240 static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
241 struct sockaddr_in *server_addr, uint32_t gw_ip)
243 struct dhcpMessage dhcp_msg;
247 struct sockaddr_in client_addr;
253 for (i = 0; i < num_sockets; i++)
254 FD_SET(fds[i], &rfds);
255 tv.tv_sec = SELECT_TIMEOUT;
257 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
259 if (FD_ISSET(fds[0], &rfds)) {
260 packlen = udhcp_recv_kernel_packet(&dhcp_msg, fds[0]);
262 pass_back(&dhcp_msg, packlen, fds);
265 for (i = 1; i < num_sockets; i++) {
267 if (!FD_ISSET(fds[i], &rfds))
269 addr_size = sizeof(struct sockaddr_in);
270 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
271 (struct sockaddr *)(&client_addr), &addr_size);
274 if (udhcp_read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL))
275 dhcp_msg.giaddr = gw_ip;
276 pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
283 int dhcprelay_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
284 int dhcprelay_main(int argc, char **argv)
286 int num_sockets, max_socket;
290 struct sockaddr_in server_addr;
292 server_addr.sin_family = AF_INET;
293 server_addr.sin_port = htons(SERVER_PORT);
295 if (!inet_aton(argv[3], &server_addr.sin_addr))
296 bb_perror_msg_and_die("didn't grok server");
297 } else if (argc == 3) {
298 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
303 clients = get_client_devices(argv[1], &num_sockets);
304 num_sockets++; /* for server socket at fds[0] */
305 fds = xmalloc(num_sockets * sizeof(fds[0]));
306 max_socket = init_sockets(clients, num_sockets, argv[2], fds);
308 if (udhcp_read_interface(argv[2], NULL, &gw_ip, NULL))
312 dhcprelay_loop(fds, num_sockets, max_socket, clients, &server_addr, gw_ip);
313 /* return 0; - not reached */