--- /dev/null
+/* vi: set sw=4 ts=4: */
+/* Port to Busybox Copyright (C) 2006 Jesse Dutton <jessedutton@gmail.com>
+ *
+ * Licensed under GPL v2, see file LICENSE in this tarball for details.
+ *
+ * DHCP Relay for 'DHCPv4 Configuration of IPSec Tunnel Mode' support
+ * Copyright (C) 2002 Mario Strasser <mast@gmx.net>,
+ * Zuercher Hochschule Winterthur,
+ * Netbeat AG
+ * Upstream has GPL v2 or later
+ */
+
+#include "common.h"
+#include "dhcpd.h"
+#include "options.h"
+
+/* constants */
+#define SELECT_TIMEOUT 5 /* select timeout in sec. */
+#define MAX_LIFETIME 2*60 /* lifetime of an xid entry in sec. */
+#define MAX_INTERFACES 9
+
+
+/* This list holds information about clients. The xid_* functions manipulate this list. */
+struct xid_item {
+ u_int32_t xid;
+ struct sockaddr_in ip;
+ int client;
+ time_t timestamp;
+ struct xid_item *next;
+} dhcprelay_xid_list = {0, {0}, 0, 0, NULL};
+
+
+static struct xid_item * xid_add(u_int32_t xid, struct sockaddr_in *ip, int client)
+{
+ struct xid_item *item;
+
+ /* create new xid entry */
+ item = xmalloc(sizeof(struct xid_item));
+
+ /* add xid entry */
+ item->ip = *ip;
+ item->xid = xid;
+ item->client = client;
+ item->timestamp = time(NULL);
+ item->next = dhcprelay_xid_list.next;
+ dhcprelay_xid_list.next = item;
+
+ return item;
+}
+
+
+static void xid_expire(void)
+{
+ struct xid_item *item = dhcprelay_xid_list.next;
+ struct xid_item *last = &dhcprelay_xid_list;
+ time_t current_time = time(NULL);
+
+ while (item != NULL) {
+ if ((current_time-item->timestamp) > MAX_LIFETIME) {
+ last->next = item->next;
+ free(item);
+ item = last->next;
+ } else {
+ last = item;
+ item = item->next;
+ }
+ }
+}
+
+static struct xid_item * xid_find(u_int32_t xid)
+{
+ struct xid_item *item = dhcprelay_xid_list.next;
+ while (item != NULL) {
+ if (item->xid == xid) {
+ return item;
+ }
+ item = item->next;
+ }
+ return NULL;
+}
+
+static void xid_del(u_int32_t xid)
+{
+ struct xid_item *item = dhcprelay_xid_list.next;
+ struct xid_item *last = &dhcprelay_xid_list;
+ while (item != NULL) {
+ if (item->xid == xid) {
+ last->next = item->next;
+ free(item);
+ item = last->next;
+ } else {
+ last = item;
+ item = item->next;
+ }
+ }
+}
+
+
+/**
+ * get_dhcp_packet_type - gets the message type of a dhcp packet
+ * p - pointer to the dhcp packet
+ * returns the message type on success, -1 otherwise
+ */
+static int get_dhcp_packet_type(struct dhcpMessage *p)
+{
+ u_char *op;
+
+ /* it must be either a BOOTREQUEST or a BOOTREPLY */
+ if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
+ return -1;
+ /* get message type option */
+ op = get_option(p, DHCP_MESSAGE_TYPE);
+ if (op != NULL)
+ return op[0];
+ return -1;
+}
+
+/**
+ * signal_handler - handles signals ;-)
+ * sig - sent signal
+ */
+static int dhcprelay_stopflag;
+static void dhcprelay_signal_handler(int sig)
+{
+ dhcprelay_stopflag = 1;
+}
+
+/**
+ * get_client_devices - parses the devices list
+ * dev_list - comma separated list of devices
+ * returns array
+ */
+static char ** get_client_devices(char *dev_list, int *client_number)
+{
+ char *s, *list, **client_dev;
+ int i, cn=1;
+
+ /* copy list */
+ list = xstrdup(dev_list);
+ if (list == NULL) return NULL;
+
+ /* get number of items */
+ for (s = dev_list; *s; s++) if (*s == ',')
+ cn++;
+
+ client_dev = xzalloc(cn * sizeof(*client_dev));
+
+ /* parse list */
+ s = strtok(list, ",");
+ i = 0;
+ while (s != NULL) {
+ client_dev[i++] = xstrdup(s);
+ s = strtok(NULL, ",");
+ }
+
+ /* free copy and exit */
+ free(list);
+ *client_number = cn;
+ return client_dev;
+}
+
+
+/* Creates listen sockets (in fds) and returns the number allocated. */
+static int init_sockets(char **client, int num_clients,
+ char *server, int *fds, int *max_socket)
+{
+ int i;
+
+ // talk to real server on bootps
+ fds[0] = listen_socket(htonl(INADDR_ANY), 67, server);
+ if (fds[0] < 0) return -1;
+ *max_socket = fds[0];
+
+ // array starts at 1 since server is 0
+ num_clients++;
+
+ for (i=1; i < num_clients; i++) {
+ // listen for clients on bootps
+ fds[i] = listen_socket(htonl(INADDR_ANY), 67, client[i-1]);
+ if (fds[i] < 0) return -1;
+ if (fds[i] > *max_socket) *max_socket = fds[i];
+ }
+
+ return i;
+}
+
+
+/**
+ * pass_on() - forwards dhcp packets from client to server
+ * p - packet to send
+ * client - number of the client
+ */
+static void pass_on(struct dhcpMessage *p, int packet_len, int client, int *fds,
+ struct sockaddr_in *client_addr, struct sockaddr_in *server_addr)
+{
+ int res, type;
+ struct xid_item *item;
+
+ /* check packet_type */
+ type = get_dhcp_packet_type(p);
+ if (type != DHCPDISCOVER && type != DHCPREQUEST
+ && type != DHCPDECLINE && type != DHCPRELEASE
+ && type != DHCPINFORM
+ ) {
+ return;
+ }
+
+ /* create new xid entry */
+ item = xid_add(p->xid, client_addr, client);
+
+ /* forward request to LAN (server) */
+ res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
+ sizeof(struct sockaddr_in));
+ if (res != packet_len) {
+ bb_perror_msg("pass_on");
+ return;
+ }
+}
+
+/**
+ * pass_back() - forwards dhcp packets from server to client
+ * p - packet to send
+ */
+static void pass_back(struct dhcpMessage *p, int packet_len, int *fds)
+{
+ int res, type;
+ struct xid_item *item;
+
+ /* check xid */
+ item = xid_find(p->xid);
+ if (!item) {
+ return;
+ }
+
+ /* check packet type */
+ type = get_dhcp_packet_type(p);
+ if (type != DHCPOFFER && type != DHCPACK && type != DHCPNAK) {
+ return;
+ }
+
+ if (item->ip.sin_addr.s_addr == htonl(INADDR_ANY))
+ item->ip.sin_addr.s_addr = htonl(INADDR_BROADCAST);
+ if (item->client > MAX_INTERFACES)
+ return;
+ res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*)(&item->ip),
+ sizeof(item->ip));
+ if (res != packet_len) {
+ bb_perror_msg("pass_back");
+ return;
+ }
+
+ /* remove xid entry */
+ xid_del(p->xid);
+}
+
+static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
+ struct sockaddr_in *server_addr, uint32_t gw_ip)
+{
+ struct dhcpMessage dhcp_msg;
+ fd_set rfds;
+ size_t packlen, addr_size;
+ struct sockaddr_in client_addr;
+ struct timeval tv;
+ int i;
+
+ while (!dhcprelay_stopflag) {
+ FD_ZERO(&rfds);
+ for (i = 0; i < num_sockets; i++)
+ FD_SET(fds[i], &rfds);
+ tv.tv_sec = SELECT_TIMEOUT;
+ tv.tv_usec = 0;
+ if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
+ /* server */
+ if (FD_ISSET(fds[0], &rfds)) {
+ packlen = udhcp_get_packet(&dhcp_msg, fds[0]);
+ if (packlen > 0) {
+ pass_back(&dhcp_msg, packlen, fds);
+ }
+ }
+ for (i = 1; i < num_sockets; i++) {
+ /* clients */
+ if (!FD_ISSET(fds[i], &rfds))
+ continue;
+ addr_size = sizeof(struct sockaddr_in);
+ packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
+ (struct sockaddr *)(&client_addr), &addr_size);
+ if (packlen <= 0)
+ continue;
+ if (read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL) < 0)
+ dhcp_msg.giaddr = gw_ip;
+ pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
+ }
+ }
+ xid_expire();
+ }
+}
+
+int dhcprelay_main(int argc, char **argv)
+{
+ int i, num_sockets, max_socket, fds[MAX_INTERFACES];
+ uint32_t gw_ip;
+ char **clients;
+ struct sockaddr_in server_addr;
+
+ server_addr.sin_family = AF_INET;
+ server_addr.sin_port = htons(67);
+ if (argc == 4) {
+ if (!inet_aton(argv[3], &server_addr.sin_addr))
+ bb_perror_msg_and_die("didn't grok server");
+ } else if (argc == 3) {
+ server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
+ } else {
+ bb_show_usage();
+ }
+ clients = get_client_devices(argv[1], &num_sockets);
+ if (!clients) return 0;
+
+ signal(SIGTERM, dhcprelay_signal_handler);
+ signal(SIGQUIT, dhcprelay_signal_handler);
+ signal(SIGINT, dhcprelay_signal_handler);
+
+ num_sockets = init_sockets(clients, num_sockets, argv[2], fds, &max_socket);
+ if (num_sockets == -1)
+ bb_perror_msg_and_die("init_sockets() failed");
+
+ if (read_interface(argv[2], NULL, &gw_ip, NULL) == -1)
+ return 1;
+
+ dhcprelay_loop(fds, num_sockets, max_socket, clients, &server_addr, gw_ip);
+
+ if (ENABLE_FEATURE_CLEAN_UP) {
+ for (i = 0; i < num_sockets; i++) {
+ close(fds[i]);
+ free(clients[i]);
+ }
+ }
+
+ return 0;
+}
projects / oweals / busybox.git / commitdiff