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