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Diffstat (limited to 'uip/uip/uip-fw.c')
| -rw-r--r-- | uip/uip/uip-fw.c | 532 |
1 files changed, 532 insertions, 0 deletions
diff --git a/uip/uip/uip-fw.c b/uip/uip/uip-fw.c new file mode 100644 index 0000000..01858ea --- /dev/null +++ b/uip/uip/uip-fw.c @@ -0,0 +1,532 @@ +/* + * 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; + } + } +} +/*------------------------------------------------------------------------------*/ |