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
22 /* This list holds information about clients. The xid_* functions manipulate this list. */
27 struct sockaddr_in ip;
28 struct xid_item *next;
31 #define dhcprelay_xid_list (*(struct xid_item*)&bb_common_bufsiz1)
33 static struct xid_item *xid_add(uint32_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;
51 static void xid_expire(void)
53 struct xid_item *item = dhcprelay_xid_list.next;
54 struct xid_item *last = &dhcprelay_xid_list;
55 time_t current_time = time(NULL);
57 while (item != NULL) {
58 if ((current_time - item->timestamp) > MAX_LIFETIME) {
59 last->next = item->next;
69 static struct xid_item *xid_find(uint32_t xid)
71 struct xid_item *item = dhcprelay_xid_list.next;
72 while (item != NULL) {
73 if (item->xid == xid) {
81 static void xid_del(uint32_t xid)
83 struct xid_item *item = dhcprelay_xid_list.next;
84 struct xid_item *last = &dhcprelay_xid_list;
85 while (item != NULL) {
86 if (item->xid == xid) {
87 last->next = item->next;
98 * get_dhcp_packet_type - gets the message type of a dhcp packet
99 * p - pointer to the dhcp packet
100 * returns the message type on success, -1 otherwise
102 static int get_dhcp_packet_type(struct dhcpMessage *p)
106 /* it must be either a BOOTREQUEST or a BOOTREPLY */
107 if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
109 /* get message type option */
110 op = get_option(p, DHCP_MESSAGE_TYPE);
117 * get_client_devices - parses the devices list
118 * dev_list - comma separated list of devices
121 static char **get_client_devices(char *dev_list, int *client_number)
123 char *s, *list, **client_dev;
127 list = xstrdup(dev_list);
128 if (list == NULL) return NULL;
130 /* get number of items */
131 for (s = dev_list, cn = 1; *s; s++)
135 client_dev = xzalloc(cn * sizeof(*client_dev));
138 s = strtok(list, ",");
141 client_dev[i++] = xstrdup(s);
142 s = strtok(NULL, ",");
145 /* free copy and exit */
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] = listen_socket(/*INADDR_ANY,*/ 67, server);
162 for (i = 1; i < num_clients; i++) {
163 /* listen for clients on bootps */
164 fds[i] = listen_socket(/*NADDR_ANY,*/ 67, 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 if (item->client > MAX_INTERFACES)
229 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*)(&item->ip),
231 if (res != packet_len) {
232 bb_perror_msg("pass_back");
236 /* remove xid entry */
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) ATTRIBUTE_NORETURN;
242 static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
243 struct sockaddr_in *server_addr, uint32_t gw_ip)
245 struct dhcpMessage dhcp_msg;
249 struct sockaddr_in client_addr;
255 for (i = 0; i < num_sockets; i++)
256 FD_SET(fds[i], &rfds);
257 tv.tv_sec = SELECT_TIMEOUT;
259 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
261 if (FD_ISSET(fds[0], &rfds)) {
262 packlen = udhcp_get_packet(&dhcp_msg, fds[0]);
264 pass_back(&dhcp_msg, packlen, fds);
267 for (i = 1; i < num_sockets; i++) {
269 if (!FD_ISSET(fds[i], &rfds))
271 addr_size = sizeof(struct sockaddr_in);
272 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
273 (struct sockaddr *)(&client_addr), &addr_size);
276 if (read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL))
277 dhcp_msg.giaddr = gw_ip;
278 pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
285 int dhcprelay_main(int argc, char **argv);
286 int dhcprelay_main(int argc, char **argv)
288 int num_sockets, max_socket, fds[MAX_INTERFACES];
291 struct sockaddr_in server_addr;
293 server_addr.sin_family = AF_INET;
294 server_addr.sin_port = htons(67);
296 if (!inet_aton(argv[3], &server_addr.sin_addr))
297 bb_perror_msg_and_die("didn't grok server");
298 } else if (argc == 3) {
299 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
303 clients = get_client_devices(argv[1], &num_sockets);
304 if (!clients) return 0;
306 num_sockets++; /* for server socket at fds[0] */
307 max_socket = init_sockets(clients, num_sockets, argv[2], fds);
309 if (read_interface(argv[2], NULL, &gw_ip, NULL))
313 dhcprelay_loop(fds, num_sockets, max_socket, clients, &server_addr, gw_ip);
314 /* return 0; - not reached */