--- /dev/null
+/*
+ * 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 1.1 2008/08/06 23:21:19 andrewlxia 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/uip.h>
+#include <uip/uip_arch.h>
+#include <uip/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;
+ }
+ }
+}
+/*------------------------------------------------------------------------------*/
