zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/app/busybox/src/networking/udhcp/dhcprelay.c b/ap/app/busybox/src/networking/udhcp/dhcprelay.c
new file mode 100644
index 0000000..f82ac05
--- /dev/null
+++ b/ap/app/busybox/src/networking/udhcp/dhcprelay.c
@@ -0,0 +1,373 @@
+/* vi: set sw=4 ts=4: */
+/* Port to Busybox Copyright (C) 2006 Jesse Dutton <jessedutton@gmail.com>
+ *
+ * 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>,
+ * Zuercher Hochschule Winterthur,
+ * Netbeat AG
+ * 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"
+
+#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. */
+struct xid_item {
+ unsigned timestamp;
+ int client;
+ uint32_t xid;
+ struct sockaddr_in ip;
+ struct xid_item *next;
+} 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)
+{
+ 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) {
+ break;
+ }
+ item = item->next;
+ }
+ return item;
+}
+
+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 dhcp_packet *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 = udhcp_get_option(p, DHCP_MESSAGE_TYPE);
+ if (op != NULL)
+ return op[0];
+ return -1;
+}
+
+/**
+ * make_iface_list - parses client/server interface names
+ * returns array
+ */
+static char **make_iface_list(char **client_and_server_ifaces, int *client_number)
+{
+ char *s, **iface_list;
+ int i, cn;
+
+ /* get number of items */
+ 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 */
+
+ i = 1;
+ s = xstrdup(client_and_server_ifaces[0]); /* list of client ifaces */
+ goto store_client_iface_name;
+
+ while (i < cn) {
+ if (*s++ == ',') {
+ s[-1] = '\0';
+ store_client_iface_name:
+ iface_list[i++] = s;
+ }
+ }
+
+ return iface_list;
+}
+
+/* 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, n;
+
+ 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 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_to_server() - forwards dhcp packets from client to server
+ * p - packet to send
+ * client - number of the client
+ */
+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 type;
+
+ /* 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 */
+ 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_to_client() - forwards dhcp packets from server to client
+ * p - packet to send
+ */
+static void pass_to_client(struct dhcp_packet *p, int packet_len, int *fds)
+{
+ int 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;
+ }
+
+//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 (sendto_ip4(fds[item->client], p, packet_len, &item->ip) != 0) {
+ return; /* send error occurred */
+ }
+
+ /* 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 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_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++) {
+ struct sockaddr_in client_addr;
+ socklen_t addr_size;
+
+ if (!FD_ISSET(fds[i], &rfds))
+ continue;
+
+ addr_size = sizeof(client_addr);
+ 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 */
+// 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();
+ } /* while (1) */
+
+ /* return 0; - not reached */
+}