1 /* vi: set sw=4 ts=4: */
2 /* Port to Busybox Copyright (C) 2006 Jesse Dutton <jessedutton@gmail.com>
4 * Licensed under GPLv2, see file LICENSE in this source tree.
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
14 #define SERVER_PORT 67
15 #define SELECT_TIMEOUT 5 /* select timeout in sec. */
16 #define MAX_LIFETIME 2*60 /* lifetime of an xid entry in sec. */
18 /* This list holds information about clients. The xid_* functions manipulate this list. */
23 struct sockaddr_in ip;
24 struct xid_item *next;
27 #define dhcprelay_xid_list (*(struct xid_item*)&bb_common_bufsiz1)
29 static struct xid_item *xid_add(uint32_t xid, struct sockaddr_in *ip, int client)
31 struct xid_item *item;
33 /* create new xid entry */
34 item = xmalloc(sizeof(struct xid_item));
39 item->client = client;
40 item->timestamp = monotonic_sec();
41 item->next = dhcprelay_xid_list.next;
42 dhcprelay_xid_list.next = item;
47 static void xid_expire(void)
49 struct xid_item *item = dhcprelay_xid_list.next;
50 struct xid_item *last = &dhcprelay_xid_list;
51 unsigned current_time = monotonic_sec();
53 while (item != NULL) {
54 if ((current_time - item->timestamp) > MAX_LIFETIME) {
55 last->next = item->next;
65 static struct xid_item *xid_find(uint32_t xid)
67 struct xid_item *item = dhcprelay_xid_list.next;
68 while (item != NULL) {
69 if (item->xid == xid) {
77 static void xid_del(uint32_t xid)
79 struct xid_item *item = dhcprelay_xid_list.next;
80 struct xid_item *last = &dhcprelay_xid_list;
81 while (item != NULL) {
82 if (item->xid == xid) {
83 last->next = item->next;
94 * get_dhcp_packet_type - gets the message type of a dhcp packet
95 * p - pointer to the dhcp packet
96 * returns the message type on success, -1 otherwise
98 static int get_dhcp_packet_type(struct dhcp_packet *p)
102 /* it must be either a BOOTREQUEST or a BOOTREPLY */
103 if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
105 /* get message type option */
106 op = udhcp_get_option(p, DHCP_MESSAGE_TYPE);
113 * get_client_devices - parses the devices list
114 * dev_list - comma separated list of devices
117 static char **get_client_devices(char *dev_list, int *client_number)
119 char *s, **client_dev;
123 dev_list = xstrdup(dev_list);
125 /* get number of items, replace ',' with NULs */
137 /* create vector of pointers */
138 client_dev = xzalloc(cn * sizeof(*client_dev));
139 client_dev[0] = dev_list;
142 client_dev[i] = client_dev[i - 1] + strlen(client_dev[i - 1]) + 1;
148 /* Creates listen sockets (in fds) bound to client and server ifaces,
149 * and returns numerically max fd.
151 static int init_sockets(char **client_ifaces, int num_clients,
152 char *server_iface, int *fds)
156 /* talk to real server on bootps */
157 fds[0] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, server_iface);
160 for (i = 1; i < num_clients; i++) {
161 /* listen for clients on bootps */
162 fds[i] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, client_ifaces[i-1]);
170 * pass_to_server() - forwards dhcp packets from client to server
172 * client - number of the client
174 static void pass_to_server(struct dhcp_packet *p, int packet_len, int client, int *fds,
175 struct sockaddr_in *client_addr, struct sockaddr_in *server_addr)
179 /* check packet_type */
180 type = get_dhcp_packet_type(p);
181 if (type != DHCPDISCOVER && type != DHCPREQUEST
182 && type != DHCPDECLINE && type != DHCPRELEASE
183 && type != DHCPINFORM
188 /* create new xid entry */
189 xid_add(p->xid, client_addr, client);
191 /* forward request to LAN (server) */
193 res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
194 sizeof(struct sockaddr_in));
195 if (res != packet_len) {
196 bb_perror_msg("sendto");
201 * pass_to_client() - forwards dhcp packets from server to client
204 static void pass_to_client(struct dhcp_packet *p, int packet_len, int *fds)
207 struct xid_item *item;
210 item = xid_find(p->xid);
215 /* check packet type */
216 type = get_dhcp_packet_type(p);
217 if (type != DHCPOFFER && type != DHCPACK && type != DHCPNAK) {
221 if (item->ip.sin_addr.s_addr == htonl(INADDR_ANY))
222 item->ip.sin_addr.s_addr = htonl(INADDR_BROADCAST);
224 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*) &(item->ip),
226 if (res != packet_len) {
227 bb_perror_msg("sendto");
231 /* remove xid entry */
235 int dhcprelay_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
236 int dhcprelay_main(int argc, char **argv)
238 struct dhcp_packet dhcp_msg;
239 struct sockaddr_in server_addr;
240 struct sockaddr_in client_addr;
242 char **client_ifaces;
244 int num_sockets, max_socket;
247 server_addr.sin_family = AF_INET;
248 server_addr.sin_port = htons(SERVER_PORT);
250 /* dhcprelay client_iface1,client_iface2,... server_iface [server_IP] */
252 if (!inet_aton(argv[3], &server_addr.sin_addr))
253 bb_perror_msg_and_die("bad server IP");
254 } else if (argc == 3) {
255 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
260 /* Produce list of client ifaces */
261 client_ifaces = get_client_devices(argv[1], &num_sockets);
263 num_sockets++; /* for server socket at fds[0] */
264 fds = xmalloc(num_sockets * sizeof(fds[0]));
266 /* Create sockets and bind one to every iface */
267 max_socket = init_sockets(client_ifaces, num_sockets, argv[2], fds);
269 /* Get our IP on server_iface */
270 if (udhcp_read_interface(argv[2], NULL, &our_nip, NULL))
275 //reinit stuff from time to time? go back to get_client_devices
283 for (i = 0; i < num_sockets; i++)
284 FD_SET(fds[i], &rfds);
285 tv.tv_sec = SELECT_TIMEOUT;
287 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
289 if (FD_ISSET(fds[0], &rfds)) {
290 packlen = udhcp_recv_kernel_packet(&dhcp_msg, fds[0]);
292 pass_to_client(&dhcp_msg, packlen, fds);
296 for (i = 1; i < num_sockets; i++) {
297 if (!FD_ISSET(fds[i], &rfds))
299 addr_size = sizeof(struct sockaddr_in);
300 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
301 (struct sockaddr *)(&client_addr), &addr_size);
305 /* Get our IP on corresponding client_iface */
306 //why? what if server can't route such IP?
307 if (udhcp_read_interface(client_ifaces[i-1], NULL, &dhcp_msg.gateway_nip, NULL)) {
308 /* Fall back to our server_iface's IP */
309 //this makes more sense!
310 dhcp_msg.gateway_nip = our_nip;
312 //maybe set dhcp_msg.flags |= BROADCAST_FLAG too?
313 pass_to_server(&dhcp_msg, packlen, i, fds, &client_addr, &server_addr);
319 /* return 0; - not reached */