[1765] | 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. */
|
---|
| 24 | static 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 |
|
---|
| 33 | static 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 |
|
---|
| 51 | static 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 |
|
---|
| 69 | static 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 |
|
---|
| 81 | static 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 | */
|
---|
| 102 | static 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 | */
|
---|
| 120 | static smallint dhcprelay_stopflag;
|
---|
| 121 |
|
---|
| 122 | static 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 | */
|
---|
| 132 | static 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. */
|
---|
| 164 | static 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 | */
|
---|
| 192 | static 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 | */
|
---|
| 223 | static 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 |
|
---|
| 255 | static 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 |
|
---|
| 298 | int dhcprelay_main(int argc, char **argv);
|
---|
| 299 | int 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 | }
|
---|