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/*
* 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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