/* 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.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
*
* DHCP Relay for 'DHCPv4 Configuration of IPSec Tunnel Mode' support
* Copyright (C) 2002 Mario Strasser <mast@gmx.net>,
* Upstream has GPL v2 or later
*/
+//usage:#define dhcprelay_trivial_usage
+//usage: "CLIENT_IFACE[,CLIENT_IFACE2]... SERVER_IFACE [SERVER_IP]"
+//usage:#define dhcprelay_full_usage "\n\n"
+//usage: "Relay DHCP requests between clients and server"
+
#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
+#define SERVER_PORT 67
+/* lifetime of an xid entry in sec. */
+#define MAX_LIFETIME 2*60
+/* select timeout in sec. */
+#define SELECT_TIMEOUT (MAX_LIFETIME / 8)
/* This list holds information about clients. The xid_* functions manipulate this list. */
-static struct xid_item {
+struct xid_item {
+ unsigned timestamp;
+ int client;
uint32_t xid;
struct sockaddr_in ip;
- int client;
- time_t timestamp;
struct xid_item *next;
-} dhcprelay_xid_list = {0, {0}, 0, 0, NULL};
+} FIX_ALIASING;
+#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)
{
item->ip = *ip;
item->xid = xid;
item->client = client;
- item->timestamp = time(NULL);
+ item->timestamp = monotonic_sec();
item->next = dhcprelay_xid_list.next;
dhcprelay_xid_list.next = item;
{
struct xid_item *item = dhcprelay_xid_list.next;
struct xid_item *last = &dhcprelay_xid_list;
- time_t current_time = time(NULL);
+ unsigned current_time = monotonic_sec();
while (item != NULL) {
if ((current_time - item->timestamp) > MAX_LIFETIME) {
struct xid_item *item = dhcprelay_xid_list.next;
while (item != NULL) {
if (item->xid == xid) {
- return item;
+ break;
}
item = item->next;
}
- return NULL;
+ return item;
}
static void xid_del(uint32_t xid)
* p - pointer to the dhcp packet
* returns the message type on success, -1 otherwise
*/
-static int get_dhcp_packet_type(struct dhcpMessage *p)
+static int get_dhcp_packet_type(struct dhcp_packet *p)
{
uint8_t *op;
if (p->op != BOOTREQUEST && p->op != BOOTREPLY)
return -1;
/* get message type option */
- op = get_option(p, DHCP_MESSAGE_TYPE);
+ op = udhcp_get_option(p, DHCP_MESSAGE_TYPE);
if (op != NULL)
return op[0];
return -1;
}
/**
- * signal_handler - handles signals ;-)
- * sig - sent signal
- */
-static smallint 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
+ * make_iface_list - parses client/server interface names
* returns array
*/
-static char **get_client_devices(char *dev_list, int *client_number)
+static char **make_iface_list(char **client_and_server_ifaces, int *client_number)
{
- char *s, *list, **client_dev;
+ char *s, **iface_list;
int i, cn;
- /* copy list */
- list = xstrdup(dev_list);
- if (list == NULL) return NULL;
-
/* get number of items */
- for (s = dev_list, cn = 1; *s; s++)
+ cn = 2; /* 1 server iface + at least 1 client one */
+ s = client_and_server_ifaces[0]; /* list of client ifaces */
+ while (*s) {
if (*s == ',')
cn++;
+ s++;
+ }
+ *client_number = cn;
+
+ /* create vector of pointers */
+ iface_list = xzalloc(cn * sizeof(iface_list[0]));
+
+ iface_list[0] = client_and_server_ifaces[1]; /* server iface */
- client_dev = xzalloc(cn * sizeof(*client_dev));
+ i = 1;
+ s = xstrdup(client_and_server_ifaces[0]); /* list of client ifaces */
+ goto store_client_iface_name;
- /* parse list */
- s = strtok(list, ",");
- i = 0;
- while (s != NULL) {
- client_dev[i++] = xstrdup(s);
- s = strtok(NULL, ",");
+ while (i < cn) {
+ if (*s++ == ',') {
+ s[-1] = '\0';
+ store_client_iface_name:
+ iface_list[i++] = s;
+ }
}
- /* free copy and exit */
- free(list);
- *client_number = cn;
- return client_dev;
+ return iface_list;
}
-
-/* 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)
+/* Creates listen sockets (in fds) bound to client and server ifaces,
+ * and returns numerically max fd.
+ */
+static int init_sockets(char **iface_list, int num_clients, int *fds)
{
- int i;
+ int i, n;
- /* talk to real server on bootps */
- fds[0] = listen_socket(htonl(INADDR_ANY), 67, server);
- *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] > *max_socket) *max_socket = fds[i];
+ n = 0;
+ for (i = 0; i < num_clients; i++) {
+ fds[i] = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, iface_list[i]);
+ if (n < fds[i])
+ n = fds[i];
}
-
- return i;
+ return n;
}
+static int sendto_ip4(int sock, const void *msg, int msg_len, struct sockaddr_in *to)
+{
+ int err;
+
+ errno = 0;
+ err = sendto(sock, msg, msg_len, 0, (struct sockaddr*) to, sizeof(*to));
+ err -= msg_len;
+ if (err)
+ bb_perror_msg("sendto");
+ return err;
+}
/**
- * pass_on() - forwards dhcp packets from client to server
+ * pass_to_server() - 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,
+static void pass_to_server(struct dhcp_packet *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;
+ int type;
/* check packet_type */
type = get_dhcp_packet_type(p);
}
/* 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;
- }
+ xid_add(p->xid, client_addr, client);
+
+ /* forward request to server */
+ /* note that we send from fds[0] which is bound to SERVER_PORT (67).
+ * IOW: we send _from_ SERVER_PORT! Although this may look strange,
+ * RFC 1542 not only allows, but prescribes this for BOOTP relays.
+ */
+ sendto_ip4(fds[0], p, packet_len, server_addr);
}
/**
- * pass_back() - forwards dhcp packets from server to client
+ * pass_to_client() - forwards dhcp packets from server to client
* p - packet to send
*/
-static void pass_back(struct dhcpMessage *p, int packet_len, int *fds)
+static void pass_to_client(struct dhcp_packet *p, int packet_len, int *fds)
{
- int res, type;
+ int type;
struct xid_item *item;
/* check xid */
return;
}
+//TODO: also do it if (p->flags & htons(BROADCAST_FLAG)) is set!
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;
+
+ if (sendto_ip4(fds[item->client], p, packet_len, &item->ip) != 0) {
+ return; /* send error occurred */
}
/* 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)
+int dhcprelay_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int dhcprelay_main(int argc, char **argv)
{
- struct dhcpMessage dhcp_msg;
- fd_set rfds;
- size_t packlen;
- socklen_t addr_size;
- struct sockaddr_in client_addr;
- struct timeval tv;
- int i;
-
- while (!dhcprelay_stopflag) {
+ struct sockaddr_in server_addr;
+ char **iface_list;
+ int *fds;
+ int num_sockets, max_socket;
+ uint32_t our_nip;
+
+ server_addr.sin_family = AF_INET;
+ server_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
+ 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) {
+ bb_show_usage();
+ }
+
+ iface_list = make_iface_list(argv + 1, &num_sockets);
+
+ fds = xmalloc(num_sockets * sizeof(fds[0]));
+
+ /* Create sockets and bind one to every iface */
+ max_socket = init_sockets(iface_list, num_sockets, fds);
+
+ /* Get our IP on server_iface */
+ if (udhcp_read_interface(argv[2], NULL, &our_nip, NULL))
+ return 1;
+
+ /* Main loop */
+ while (1) {
+// reinit stuff from time to time? go back to make_iface_list
+// every N minutes?
+ fd_set rfds;
+ struct timeval tv;
+ 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) {
+ int packlen;
+ struct dhcp_packet dhcp_msg;
+
/* server */
if (FD_ISSET(fds[0], &rfds)) {
- packlen = udhcp_get_packet(&dhcp_msg, fds[0]);
+ packlen = udhcp_recv_kernel_packet(&dhcp_msg, fds[0]);
if (packlen > 0) {
- pass_back(&dhcp_msg, packlen, fds);
+ pass_to_client(&dhcp_msg, packlen, fds);
}
}
+
+ /* clients */
for (i = 1; i < num_sockets; i++) {
- /* clients */
+ struct sockaddr_in client_addr;
+ socklen_t addr_size;
+
if (!FD_ISSET(fds[i], &rfds))
continue;
- addr_size = sizeof(struct sockaddr_in);
+
+ addr_size = sizeof(client_addr);
packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
- (struct sockaddr *)(&client_addr), &addr_size);
+ (struct sockaddr *)(&client_addr), &addr_size);
if (packlen <= 0)
continue;
- if (read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL))
- dhcp_msg.giaddr = gw_ip;
- pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
+
+ /* Get our IP on corresponding client_iface */
+// RFC 1542
+// 4.1 General BOOTP Processing for Relay Agents
+// 4.1.1 BOOTREQUEST Messages
+// If the relay agent does decide to relay the request, it MUST examine
+// the 'giaddr' ("gateway" IP address) field. If this field is zero,
+// the relay agent MUST fill this field with the IP address of the
+// interface on which the request was received. If the interface has
+// more than one IP address logically associated with it, the relay
+// agent SHOULD choose one IP address associated with that interface and
+// use it consistently for all BOOTP messages it relays. If the
+// 'giaddr' field contains some non-zero value, the 'giaddr' field MUST
+// NOT be modified. The relay agent MUST NOT, under any circumstances,
+// fill the 'giaddr' field with a broadcast address as is suggested in
+// [1] (Section 8, sixth paragraph).
+
+// but why? what if server can't route such IP? Client ifaces may be, say, NATed!
+
+// 4.1.2 BOOTREPLY Messages
+// BOOTP relay agents relay BOOTREPLY messages only to BOOTP clients.
+// It is the responsibility of BOOTP servers to send BOOTREPLY messages
+// directly to the relay agent identified in the 'giaddr' field.
+// (yeah right, unless it is impossible... see comment above)
+// Therefore, a relay agent may assume that all BOOTREPLY messages it
+// receives are intended for BOOTP clients on its directly-connected
+// networks.
+//
+// When a relay agent receives a BOOTREPLY message, it should examine
+// the BOOTP 'giaddr', 'yiaddr', 'chaddr', 'htype', and 'hlen' fields.
+// These fields should provide adequate information for the relay agent
+// to deliver the BOOTREPLY message to the client.
+//
+// The 'giaddr' field can be used to identify the logical interface from
+// which the reply must be sent (i.e., the host or router interface
+// connected to the same network as the BOOTP client). If the content
+// of the 'giaddr' field does not match one of the relay agent's
+// directly-connected logical interfaces, the BOOTREPLY messsage MUST be
+// silently discarded.
+ if (udhcp_read_interface(iface_list[i], NULL, &dhcp_msg.gateway_nip, NULL)) {
+ /* Fall back to our IP on server iface */
+// this makes more sense!
+ dhcp_msg.gateway_nip = our_nip;
+ }
+// maybe dhcp_msg.hops++? drop packets with too many hops (RFC 1542 says 4 or 16)?
+ pass_to_server(&dhcp_msg, packlen, i, fds, &client_addr, &server_addr);
}
}
xid_expire();
- }
-}
-
-int dhcprelay_main(int argc, char **argv);
-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 (read_interface(argv[2], NULL, &gw_ip, NULL))
- 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]);
- }
- }
+ } /* while (1) */
- return 0;
+ /* return 0; - not reached */
}
projects / oweals / busybox.git / blobdiff