1 files changed, 325 insertions, 0 deletions
diff --git a/release/src/router/busybox/networking/udhcp/dhcprelay.c b/release/src/router/busybox/networking/udhcp/dhcprelay.c
new file mode 100644
index 00000000..53540d1a
--- /dev/null
+++ b/release/src/router/busybox/networking/udhcp/dhcprelay.c
@@ -0,0 +1,325 @@
+/* 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 "options.h"
+
+#define SERVER_PORT      67
+#define SELECT_TIMEOUT    5 /* select timeout in sec. */
+#define MAX_LIFETIME   2*60 /* lifetime of an xid entry in sec. */
+
+/* This list holds information about clients. The xid_* functions manipulate this list. */
+struct xid_item {
+	unsigned timestamp;
+	int client;
+	uint32_t xid;
+	struct sockaddr_in ip;
+	struct xid_item *next;
+};
+
+#define dhcprelay_xid_list (*(struct xid_item*)&bb_common_bufsiz1)
+
+static struct xid_item *xid_add(uint32_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 = monotonic_sec();
+	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;
+	unsigned current_time = monotonic_sec();
+
+	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(uint32_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(uint32_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)
+{
+	uint8_t *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;
+}
+
+/**
+ * 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, **client_dev;
+	int i, cn;
+
+	/* copy list */
+	dev_list = xstrdup(dev_list);
+
+	/* get number of items, replace ',' with NULs */
+	s = dev_list;
+	cn = 1;
+	while (*s) {
+		if (*s == ',') {
+			*s = '\0';
+			cn++;
+		}
+		s++;
+	}
+	*client_number = cn;
+
+	/* create vector of pointers */
+	client_dev = xzalloc(cn * sizeof(*client_dev));
+	client_dev[0] = dev_list;
+	i = 1;
+	while (i != cn) {
+		client_dev[i] = client_dev[i - 1] + strlen(client_dev[i - 1]) + 1;
+		i++;
+	}
+	return client_dev;
+}
+
+
+/* Creates listen sockets (in fds) bound to client and server ifaces,
+ * and returns numerically max fd.
+ */
+static int init_sockets(char **client_ifaces, int num_clients,
+			char *server_iface, int *fds)
+{
+	int i, n;
+
+	/* talk to real server on bootps */
+	fds[0] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, server_iface);
+	n = fds[0];
+
+	for (i = 1; i < num_clients; i++) {
+		/* listen for clients on bootps */
+		fds[i] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, client_ifaces[i-1]);
+		if (fds[i] > n)
+			n = fds[i];
+	}
+	return n;
+}
+
+
+/**
+ * pass_to_server() - forwards dhcp packets from client to server
+ * p - packet to send
+ * client - number of the client
+ */
+static void pass_to_server(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) */
+	errno = 0;
+	res = sendto(fds[0], p, packet_len, 0, (struct sockaddr*)server_addr,
+			sizeof(struct sockaddr_in));
+	if (res != packet_len) {
+		bb_perror_msg("sendto");
+	}
+}
+
+/**
+ * pass_to_client() - forwards dhcp packets from server to client
+ * p - packet to send
+ */
+static void pass_to_client(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);
+	errno = 0;
+	res = sendto(fds[item->client], p, packet_len, 0, (struct sockaddr*) &(item->ip),
+			sizeof(item->ip));
+	if (res != packet_len) {
+		bb_perror_msg("sendto");
+		return;
+	}
+
+	/* remove xid entry */
+	xid_del(p->xid);
+}
+
+int dhcprelay_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int dhcprelay_main(int argc, char **argv)
+{
+	struct dhcpMessage dhcp_msg;
+	struct sockaddr_in server_addr;
+	struct sockaddr_in client_addr;
+	fd_set rfds;
+	char **client_ifaces;
+	int *fds;
+	int num_sockets, max_socket;
+	uint32_t our_ip;
+
+	server_addr.sin_family = AF_INET;
+	server_addr.sin_port = htons(SERVER_PORT);
+
+	/* dhcprelay client_iface1,client_iface2,... server_iface [server_IP] */
+	if (argc == 4) {
+		if (!inet_aton(argv[3], &server_addr.sin_addr))
+			bb_perror_msg_and_die("bad server IP");
+	} else if (argc == 3) {
+		server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
+	} else {
+		bb_show_usage();
+	}
+
+	/* Produce list of client ifaces */
+	client_ifaces = get_client_devices(argv[1], &num_sockets);
+
+	num_sockets++; /* for server socket at fds[0] */
+	fds = xmalloc(num_sockets * sizeof(fds[0]));
+
+	/* Create sockets and bind one to every iface */
+	max_socket = init_sockets(client_ifaces, num_sockets, argv[2], fds);
+
+	/* Get our IP on server_iface */
+	if (udhcp_read_interface(argv[2], NULL, &our_ip, NULL))
+		return 1;
+
+	/* Main loop */
+	while (1) {
+//reinit stuff from time to time? go back to get_client_devices
+//every N minutes?
+		struct timeval tv;
+		size_t packlen;
+		socklen_t addr_size;
+		int i;
+
+		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_recv_kernel_packet(&dhcp_msg, fds[0]);
+				if (packlen > 0) {
+					pass_to_client(&dhcp_msg, packlen, fds);
+				}
+			}
+			/* clients */
+			for (i = 1; i < num_sockets; i++) {
+				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;
+
+				/* Get our IP on corresponding client_iface */
+//why? what if server can't route such IP?
+				if (udhcp_read_interface(client_ifaces[i-1], NULL, &dhcp_msg.giaddr, NULL)) {
+					/* Fall back to our server_iface's IP */
+//this makes more sense!
+					dhcp_msg.giaddr = our_ip;
+				}
+//maybe set dhcp_msg.flags |= BROADCAST_FLAG too?
+				pass_to_server(&dhcp_msg, packlen, i, fds, &client_addr, &server_addr);
+			}
+		}
+		xid_expire();
+	} /* while (1) */
+
+	/* return 0; - not reached */
+}