source: MondoRescue/branches/2.2.5/mindi-busybox/networking/udhcp/dhcprelay.c@ 1765

Last change on this file since 1765 was 1765, checked in by Bruno Cornec, 16 years ago

Update to busybox 1.7.2
  • Property svn:eol-style set to native
File size: 7.7 KB
Line 
1/* vi: set sw=4 ts=4: */
2/* Port to Busybox Copyright (C) 2006 Jesse Dutton <jessedutton@gmail.com>
3 *
4 * Licensed under GPL v2, see file LICENSE in this tarball for details.
5 *
6 * DHCP Relay for 'DHCPv4 Configuration of IPSec Tunnel Mode' support
7 * Copyright (C) 2002 Mario Strasser <mast@gmx.net>,
8 * Zuercher Hochschule Winterthur,
9 * Netbeat AG
10 * Upstream has GPL v2 or later
11 */
12
13#include "common.h"
14#include "dhcpd.h"
15#include "options.h"
16
17/* constants */
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
21
22
23/* This list holds information about clients. The xid_* functions manipulate this list. */
24static struct xid_item {
25 uint32_t xid;
26 struct sockaddr_in ip;
27 int client;
28 time_t timestamp;
29 struct xid_item *next;
30} dhcprelay_xid_list = {0, {0}, 0, 0, NULL};
31
32
33static struct xid_item *xid_add(uint32_t xid, struct sockaddr_in *ip, int client)
34{
35 struct xid_item *item;
36
37 /* create new xid entry */
38 item = xmalloc(sizeof(struct xid_item));
39
40 /* add xid entry */
41 item->ip = *ip;
42 item->xid = xid;
43 item->client = client;
44 item->timestamp = time(NULL);
45 item->next = dhcprelay_xid_list.next;
46 dhcprelay_xid_list.next = item;
47
48 return item;
49}
50
51static void xid_expire(void)
52{
53 struct xid_item *item = dhcprelay_xid_list.next;
54 struct xid_item *last = &dhcprelay_xid_list;
55 time_t current_time = time(NULL);
56
57 while (item != NULL) {
58 if ((current_time - item->timestamp) > MAX_LIFETIME) {
59 last->next = item->next;
60 free(item);
61 item = last->next;
62 } else {
63 last = item;
64 item = item->next;
65 }
66 }
67}
68
69static struct xid_item *xid_find(uint32_t xid)
70{
71 struct xid_item *item = dhcprelay_xid_list.next;
72 while (item != NULL) {
73 if (item->xid == xid) {
74 return item;
75 }
76 item = item->next;
77 }
78 return NULL;
79}
80
81static void xid_del(uint32_t xid)
82{
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;
88 free(item);
89 item = last->next;
90 } else {
91 last = item;
92 item = item->next;
93 }
94 }
95}
96
97/**
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
101 */
102static int get_dhcp_packet_type(struct dhcpMessage *p)
103{
104 uint8_t *op;
105
106 /* it must be either a BOOTREQUEST or a BOOTREPLY */
107 if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
108 return -1;
109 /* get message type option */
110 op = get_option(p, DHCP_MESSAGE_TYPE);
111 if (op != NULL)
112 return op[0];
113 return -1;
114}
115
116/**
117 * signal_handler - handles signals ;-)
118 * sig - sent signal
119 */
120static smallint dhcprelay_stopflag;
121
122static void dhcprelay_signal_handler(int sig)
123{
124 dhcprelay_stopflag = 1;
125}
126
127/**
128 * get_client_devices - parses the devices list
129 * dev_list - comma separated list of devices
130 * returns array
131 */
132static char **get_client_devices(char *dev_list, int *client_number)
133{
134 char *s, *list, **client_dev;
135 int i, cn;
136
137 /* copy list */
138 list = xstrdup(dev_list);
139 if (list == NULL) return NULL;
140
141 /* get number of items */
142 for (s = dev_list, cn = 1; *s; s++)
143 if (*s == ',')
144 cn++;
145
146 client_dev = xzalloc(cn * sizeof(*client_dev));
147
148 /* parse list */
149 s = strtok(list, ",");
150 i = 0;
151 while (s != NULL) {
152 client_dev[i++] = xstrdup(s);
153 s = strtok(NULL, ",");
154 }
155
156 /* free copy and exit */
157 free(list);
158 *client_number = cn;
159 return client_dev;
160}
161
162
163/* Creates listen sockets (in fds) and returns the number allocated. */
164static int init_sockets(char **client, int num_clients,
165 char *server, int *fds, int *max_socket)
166{
167 int i;
168
169 /* talk to real server on bootps */
170 fds[0] = listen_socket(/*INADDR_ANY,*/ 67, server);
171 *max_socket = fds[0];
172
173 /* array starts at 1 since server is 0 */
174 num_clients++;
175
176 for (i = 1; i < num_clients; i++) {
177 /* listen for clients on bootps */
178 fds[i] = listen_socket(/*NADDR_ANY,*/ 67, client[i-1]);
179 if (fds[i] > *max_socket)
180 *max_socket = fds[i];
181 }
182
183 return i;
184}
185
186
187/**
188 * pass_on() - forwards dhcp packets from client to server
189 * p - packet to send
190 * client - number of the client
191 */
192static void pass_on(struct dhcpMessage *p, int packet_len, int client, int *fds,
193 struct sockaddr_in *client_addr, struct sockaddr_in *server_addr)
194{
195 int res, type;
196 struct xid_item *item;
197
198 /* check packet_type */
199 type = get_dhcp_packet_type(p);
200 if (type != DHCPDISCOVER && type != DHCPREQUEST
201 && type != DHCPDECLINE && type != DHCPRELEASE
202 && type != DHCPINFORM
203 ) {
204 return;
205 }
206
207 /* create new xid entry */
208 item = xid_add(p->xid, client_addr, client);
209
210 /* forward request to LAN (server) */
211 res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
212 sizeof(struct sockaddr_in));
213 if (res != packet_len) {
214 bb_perror_msg("pass_on");
215 return;
216 }
217}
218
219/**
220 * pass_back() - forwards dhcp packets from server to client
221 * p - packet to send
222 */
223static void pass_back(struct dhcpMessage *p, int packet_len, int *fds)
224{
225 int res, type;
226 struct xid_item *item;
227
228 /* check xid */
229 item = xid_find(p->xid);
230 if (!item) {
231 return;
232 }
233
234 /* check packet type */
235 type = get_dhcp_packet_type(p);
236 if (type != DHCPOFFER && type != DHCPACK && type != DHCPNAK) {
237 return;
238 }
239
240 if (item->ip.sin_addr.s_addr == htonl(INADDR_ANY))
241 item->ip.sin_addr.s_addr = htonl(INADDR_BROADCAST);
242 if (item->client > MAX_INTERFACES)
243 return;
244 res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*)(&item->ip),
245 sizeof(item->ip));
246 if (res != packet_len) {
247 bb_perror_msg("pass_back");
248 return;
249 }
250
251 /* remove xid entry */
252 xid_del(p->xid);
253}
254
255static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
256 struct sockaddr_in *server_addr, uint32_t gw_ip)
257{
258 struct dhcpMessage dhcp_msg;
259 fd_set rfds;
260 size_t packlen;
261 socklen_t addr_size;
262 struct sockaddr_in client_addr;
263 struct timeval tv;
264 int i;
265
266 while (!dhcprelay_stopflag) {
267 FD_ZERO(&rfds);
268 for (i = 0; i < num_sockets; i++)
269 FD_SET(fds[i], &rfds);
270 tv.tv_sec = SELECT_TIMEOUT;
271 tv.tv_usec = 0;
272 if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
273 /* server */
274 if (FD_ISSET(fds[0], &rfds)) {
275 packlen = udhcp_get_packet(&dhcp_msg, fds[0]);
276 if (packlen > 0) {
277 pass_back(&dhcp_msg, packlen, fds);
278 }
279 }
280 for (i = 1; i < num_sockets; i++) {
281 /* clients */
282 if (!FD_ISSET(fds[i], &rfds))
283 continue;
284 addr_size = sizeof(struct sockaddr_in);
285 packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
286 (struct sockaddr *)(&client_addr), &addr_size);
287 if (packlen <= 0)
288 continue;
289 if (read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL))
290 dhcp_msg.giaddr = gw_ip;
291 pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
292 }
293 }
294 xid_expire();
295 }
296}
297
298int dhcprelay_main(int argc, char **argv);
299int dhcprelay_main(int argc, char **argv)
300{
301 int i, num_sockets, max_socket, fds[MAX_INTERFACES];
302 uint32_t gw_ip;
303 char **clients;
304 struct sockaddr_in server_addr;
305
306 server_addr.sin_family = AF_INET;
307 server_addr.sin_port = htons(67);
308 if (argc == 4) {
309 if (!inet_aton(argv[3], &server_addr.sin_addr))
310 bb_perror_msg_and_die("didn't grok server");
311 } else if (argc == 3) {
312 server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
313 } else {
314 bb_show_usage();
315 }
316 clients = get_client_devices(argv[1], &num_sockets);
317 if (!clients) return 0;
318
319 signal(SIGTERM, dhcprelay_signal_handler);
320 signal(SIGQUIT, dhcprelay_signal_handler);
321 signal(SIGINT, dhcprelay_signal_handler);
322
323 num_sockets = init_sockets(clients, num_sockets, argv[2], fds, &max_socket);
324
325 if (read_interface(argv[2], NULL, &gw_ip, NULL))
326 return 1;
327
328 dhcprelay_loop(fds, num_sockets, max_socket, clients, &server_addr, gw_ip);
329
330 if (ENABLE_FEATURE_CLEAN_UP) {
331 for (i = 0; i < num_sockets; i++) {
332 close(fds[i]);
333 free(clients[i]);
334 }
335 }
336
337 return 0;
338}
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