/* | |
* 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]; | |
} PACK_STRUCT_END; | |
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]; | |
} PACK_STRUCT_END; | |
/* 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; | |
} | |
} | |
} | |
/*------------------------------------------------------------------------------*/ |