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| + | /* vi: set sw=4 ts=4: */ |
| + | /* Port to Busybox Copyright (C) 2006 Jesse Dutton <[email protected]> |
| + | * |
| + | * 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 <[email protected]>, |
| + | * 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; |
| + | } |