-/*
- * Copyright (c) 2004, Swedish Institute of Computer Science.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the Institute nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * This file is part of the uIP TCP/IP stack
- *
- * Author: Adam Dunkels <adam@sics.se>
- *
- * $Id: uip-fw.c,v 1.2 2006/06/12 08:00:30 adam Exp $
- */
-/**
- * \addtogroup uip
- * @{
- */
-
-/**
- * \defgroup uipfw uIP packet forwarding
- * @{
- *
- */
-
-/**
- * \file
- * uIP packet forwarding.
- * \author Adam Dunkels <adam@sics.se>
- *
- * This file implements a number of simple functions which do packet
- * forwarding over multiple network interfaces with uIP.
- *
- */
-
-#include "uip.h"
-#include "uip_arch.h"
-#include "uip-fw.h"
-
-#include <string.h> /* for memcpy() */
-
-/*
- * The list of registered network interfaces.
- */
-static struct uip_fw_netif *netifs = NULL;
-
-/*
- * A pointer to the default network interface.
- */
-static struct uip_fw_netif *defaultnetif = NULL;
-
-struct tcpip_hdr {
- /* IP header. */
- u8_t vhl,
- tos;
- u16_t len,
- ipid,
- ipoffset;
- u8_t ttl,
- proto;
- u16_t ipchksum;
- u16_t srcipaddr[2],
- destipaddr[2];
-
- /* TCP header. */
- u16_t srcport,
- destport;
- u8_t seqno[4],
- ackno[4],
- tcpoffset,
- flags,
- wnd[2];
- u16_t tcpchksum;
- u8_t urgp[2];
- u8_t optdata[4];
-};
-
-struct icmpip_hdr {
- /* IP header. */
- u8_t vhl,
- tos,
- len[2],
- ipid[2],
- ipoffset[2],
- ttl,
- proto;
- u16_t ipchksum;
- u16_t srcipaddr[2],
- destipaddr[2];
- /* ICMP (echo) header. */
- u8_t type, icode;
- u16_t icmpchksum;
- u16_t id, seqno;
- u8_t payload[1];
-};
-
-/* ICMP ECHO. */
-#define ICMP_ECHO 8
-
-/* ICMP TIME-EXCEEDED. */
-#define ICMP_TE 11
-
-/*
- * Pointer to the TCP/IP headers of the packet in the uip_buf buffer.
- */
-#define BUF ((struct tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
-
-/*
- * Pointer to the ICMP/IP headers of the packet in the uip_buf buffer.
- */
-#define ICMPBUF ((struct icmpip_hdr *)&uip_buf[UIP_LLH_LEN])
-
-/*
- * Certain fields of an IP packet that are used for identifying
- * duplicate packets.
- */
-struct fwcache_entry {
- u16_t timer;
-
- u16_t srcipaddr[2];
- u16_t destipaddr[2];
- u16_t ipid;
- u8_t proto;
- u8_t unused;
-
-#if notdef
- u16_t payload[2];
-#endif
-
-#if UIP_REASSEMBLY > 0
- u16_t len, offset;
-#endif
-};
-
-/*
- * The number of packets to remember when looking for duplicates.
- */
-#ifdef UIP_CONF_FWCACHE_SIZE
-#define FWCACHE_SIZE UIP_CONF_FWCACHE_SIZE
-#else
-#define FWCACHE_SIZE 2
-#endif
-
-
-/*
- * A cache of packet header fields which are used for
- * identifying duplicate packets.
- */
-static struct fwcache_entry fwcache[FWCACHE_SIZE];
-
-/**
- * \internal
- * The time that a packet cache is active.
- */
-#define FW_TIME 20
-
-/*------------------------------------------------------------------------------*/
-/**
- * Initialize the uIP packet forwarding module.
- */
-/*------------------------------------------------------------------------------*/
-void
-uip_fw_init(void)
-{
- struct uip_fw_netif *t;
- defaultnetif = NULL;
- while(netifs != NULL) {
- t = netifs;
- netifs = netifs->next;
- t->next = NULL;
- }
-}
-/*------------------------------------------------------------------------------*/
-/**
- * \internal
- * Check if an IP address is within the network defined by an IP
- * address and a netmask.
- *
- * \param ipaddr The IP address to be checked.
- * \param netipaddr The IP address of the network.
- * \param netmask The netmask of the network.
- *
- * \return Non-zero if IP address is in network, zero otherwise.
- */
-/*------------------------------------------------------------------------------*/
-static unsigned char
-ipaddr_maskcmp(u16_t *ipaddr, u16_t *netipaddr, u16_t *netmask)
-{
- return (ipaddr[0] & netmask [0]) == (netipaddr[0] & netmask[0]) &&
- (ipaddr[1] & netmask[1]) == (netipaddr[1] & netmask[1]);
-}
-/*------------------------------------------------------------------------------*/
-/**
- * \internal
- * Send out an ICMP TIME-EXCEEDED message.
- *
- * This function replaces the packet in the uip_buf buffer with the
- * ICMP packet.
- */
-/*------------------------------------------------------------------------------*/
-static void
-time_exceeded(void)
-{
- u16_t tmp16;
-
- /* We don't send out ICMP errors for ICMP messages. */
- if(ICMPBUF->proto == UIP_PROTO_ICMP) {
- uip_len = 0;
- return;
- }
- /* Copy fields from packet header into payload of this ICMP packet. */
- memcpy(&(ICMPBUF->payload[0]), ICMPBUF, 28);
-
- /* Set the ICMP type and code. */
- ICMPBUF->type = ICMP_TE;
- ICMPBUF->icode = 0;
-
- /* Calculate the ICMP checksum. */
- ICMPBUF->icmpchksum = 0;
- ICMPBUF->icmpchksum = ~uip_chksum((u16_t *)&(ICMPBUF->type), 36);
-
- /* Set the IP destination address to be the source address of the
- original packet. */
- tmp16= BUF->destipaddr[0];
- BUF->destipaddr[0] = BUF->srcipaddr[0];
- BUF->srcipaddr[0] = tmp16;
- tmp16 = BUF->destipaddr[1];
- BUF->destipaddr[1] = BUF->srcipaddr[1];
- BUF->srcipaddr[1] = tmp16;
-
- /* Set our IP address as the source address. */
- BUF->srcipaddr[0] = uip_hostaddr[0];
- BUF->srcipaddr[1] = uip_hostaddr[1];
-
- /* The size of the ICMP time exceeded packet is 36 + the size of the
- IP header (20) = 56. */
- uip_len = 56;
- ICMPBUF->len[0] = 0;
- ICMPBUF->len[1] = uip_len;
-
- /* Fill in the other fields in the IP header. */
- ICMPBUF->vhl = 0x45;
- ICMPBUF->tos = 0;
- ICMPBUF->ipoffset[0] = ICMPBUF->ipoffset[1] = 0;
- ICMPBUF->ttl = UIP_TTL;
- ICMPBUF->proto = UIP_PROTO_ICMP;
-
- /* Calculate IP checksum. */
- ICMPBUF->ipchksum = 0;
- ICMPBUF->ipchksum = ~(uip_ipchksum());
-
-
-}
-/*------------------------------------------------------------------------------*/
-/**
- * \internal
- * Register a packet in the forwarding cache so that it won't be
- * forwarded again.
- */
-/*------------------------------------------------------------------------------*/
-static void
-fwcache_register(void)
-{
- struct fwcache_entry *fw;
- int i, oldest;
-
- oldest = FW_TIME;
- fw = NULL;
-
- /* Find the oldest entry in the cache. */
- for(i = 0; i < FWCACHE_SIZE; ++i) {
- if(fwcache[i].timer == 0) {
- fw = &fwcache[i];
- break;
- } else if(fwcache[i].timer <= oldest) {
- fw = &fwcache[i];
- oldest = fwcache[i].timer;
- }
- }
-
- fw->timer = FW_TIME;
- fw->ipid = BUF->ipid;
- fw->srcipaddr[0] = BUF->srcipaddr[0];
- fw->srcipaddr[1] = BUF->srcipaddr[1];
- fw->destipaddr[0] = BUF->destipaddr[0];
- fw->destipaddr[1] = BUF->destipaddr[1];
- fw->proto = BUF->proto;
-#if notdef
- fw->payload[0] = BUF->srcport;
- fw->payload[1] = BUF->destport;
-#endif
-#if UIP_REASSEMBLY > 0
- fw->len = BUF->len;
- fw->offset = BUF->ipoffset;
-#endif
-}
-/*------------------------------------------------------------------------------*/
-/**
- * \internal
- * Find a network interface for the IP packet in uip_buf.
- */
-/*------------------------------------------------------------------------------*/
-static struct uip_fw_netif *
-find_netif(void)
-{
- struct uip_fw_netif *netif;
-
- /* Walk through every network interface to check for a match. */
- for(netif = netifs; netif != NULL; netif = netif->next) {
- if(ipaddr_maskcmp(BUF->destipaddr, netif->ipaddr,
- netif->netmask)) {
- /* If there was a match, we break the loop. */
- return netif;
- }
- }
-
- /* If no matching netif was found, we use default netif. */
- return defaultnetif;
-}
-/*------------------------------------------------------------------------------*/
-/**
- * Output an IP packet on the correct network interface.
- *
- * The IP packet should be present in the uip_buf buffer and its
- * length in the global uip_len variable.
- *
- * \retval UIP_FW_ZEROLEN Indicates that a zero-length packet
- * transmission was attempted and that no packet was sent.
- *
- * \retval UIP_FW_NOROUTE No suitable network interface could be found
- * for the outbound packet, and the packet was not sent.
- *
- * \return The return value from the actual network interface output
- * function is passed unmodified as a return value.
- */
-/*------------------------------------------------------------------------------*/
-u8_t
-uip_fw_output(void)
-{
- struct uip_fw_netif *netif;
-
- if(uip_len == 0) {
- return UIP_FW_ZEROLEN;
- }
-
- fwcache_register();
-
-#if UIP_BROADCAST
- /* Link local broadcasts go out on all interfaces. */
- if(/*BUF->proto == UIP_PROTO_UDP &&*/
- BUF->destipaddr[0] == 0xffff &&
- BUF->destipaddr[1] == 0xffff) {
- if(defaultnetif != NULL) {
- defaultnetif->output();
- }
- for(netif = netifs; netif != NULL; netif = netif->next) {
- netif->output();
- }
- return UIP_FW_OK;
- }
-#endif /* UIP_BROADCAST */
-
- netif = find_netif();
- /* printf("uip_fw_output: netif %p ->output %p len %d\n", netif,
- netif->output,
- uip_len);*/
-
- if(netif == NULL) {
- return UIP_FW_NOROUTE;
- }
- /* If we now have found a suitable network interface, we call its
- output function to send out the packet. */
- return netif->output();
-}
-/*------------------------------------------------------------------------------*/
-/**
- * Forward an IP packet in the uip_buf buffer.
- *
- *
- *
- * \return UIP_FW_FORWARDED if the packet was forwarded, UIP_FW_LOCAL if
- * the packet should be processed locally.
- */
-/*------------------------------------------------------------------------------*/
-u8_t
-uip_fw_forward(void)
-{
- struct fwcache_entry *fw;
-
- /* First check if the packet is destined for ourselves and return 0
- to indicate that the packet should be processed locally. */
- if(BUF->destipaddr[0] == uip_hostaddr[0] &&
- BUF->destipaddr[1] == uip_hostaddr[1]) {
- return UIP_FW_LOCAL;
- }
-
- /* If we use ping IP address configuration, and our IP address is
- not yet configured, we should intercept all ICMP echo packets. */
-#if UIP_PINGADDRCONF
- if((uip_hostaddr[0] | uip_hostaddr[1]) == 0 &&
- BUF->proto == UIP_PROTO_ICMP &&
- ICMPBUF->type == ICMP_ECHO) {
- return UIP_FW_LOCAL;
- }
-#endif /* UIP_PINGADDRCONF */
-
- /* Check if the packet is in the forwarding cache already, and if so
- we drop it. */
-
- for(fw = fwcache; fw < &fwcache[FWCACHE_SIZE]; ++fw) {
- if(fw->timer != 0 &&
-#if UIP_REASSEMBLY > 0
- fw->len == BUF->len &&
- fw->offset == BUF->ipoffset &&
-#endif
- fw->ipid == BUF->ipid &&
- fw->srcipaddr[0] == BUF->srcipaddr[0] &&
- fw->srcipaddr[1] == BUF->srcipaddr[1] &&
- fw->destipaddr[0] == BUF->destipaddr[0] &&
- fw->destipaddr[1] == BUF->destipaddr[1] &&
-#if notdef
- fw->payload[0] == BUF->srcport &&
- fw->payload[1] == BUF->destport &&
-#endif
- fw->proto == BUF->proto) {
- /* Drop packet. */
- return UIP_FW_FORWARDED;
- }
- }
-
- /* If the TTL reaches zero we produce an ICMP time exceeded message
- in the uip_buf buffer and forward that packet back to the sender
- of the packet. */
- if(BUF->ttl <= 1) {
- /* No time exceeded for broadcasts and multicasts! */
- if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
- return UIP_FW_LOCAL;
- }
- time_exceeded();
- }
-
- /* Decrement the TTL (time-to-live) value in the IP header */
- BUF->ttl = BUF->ttl - 1;
-
- /* Update the IP checksum. */
- if(BUF->ipchksum >= HTONS(0xffff - 0x0100)) {
- BUF->ipchksum = BUF->ipchksum + HTONS(0x0100) + 1;
- } else {
- BUF->ipchksum = BUF->ipchksum + HTONS(0x0100);
- }
-
- if(uip_len > 0) {
- uip_appdata = &uip_buf[UIP_LLH_LEN + UIP_TCPIP_HLEN];
- uip_fw_output();
- }
-
-#if UIP_BROADCAST
- if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
- return UIP_FW_LOCAL;
- }
-#endif /* UIP_BROADCAST */
-
- /* Return non-zero to indicate that the packet was forwarded and that no
- other processing should be made. */
- return UIP_FW_FORWARDED;
-}
-/*------------------------------------------------------------------------------*/
-/**
- * Register a network interface with the forwarding module.
- *
- * \param netif A pointer to the network interface that is to be
- * registered.
- */
-/*------------------------------------------------------------------------------*/
-void
-uip_fw_register(struct uip_fw_netif *netif)
-{
- netif->next = netifs;
- netifs = netif;
-}
-/*------------------------------------------------------------------------------*/
-/**
- * Register a default network interface.
- *
- * All packets that don't go out on any of the other interfaces will
- * be routed to the default interface.
- *
- * \param netif A pointer to the network interface that is to be
- * registered.
- */
-/*------------------------------------------------------------------------------*/
-void
-uip_fw_default(struct uip_fw_netif *netif)
-{
- defaultnetif = netif;
-}
-/*------------------------------------------------------------------------------*/
-/**
- * Perform periodic processing.
- */
-/*------------------------------------------------------------------------------*/
-void
-uip_fw_periodic(void)
-{
- struct fwcache_entry *fw;
- for(fw = fwcache; fw < &fwcache[FWCACHE_SIZE]; ++fw) {
- if(fw->timer > 0) {
- --fw->timer;
- }
- }
-}
-/*------------------------------------------------------------------------------*/
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