Experimental uIP packet forwarding module
diff --git a/contiki/uip/uip-fw.c b/contiki/uip/uip-fw.c
new file mode 100644
index 0000000..adf6635
--- /dev/null
+++ b/contiki/uip/uip-fw.c
@@ -0,0 +1,288 @@
+/**
+ * \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-fw.h"
+
+/**
+ * \internal
+ * The list of registered network interfaces.
+ */
+static struct uip_fw_netif *netifs = NULL;
+
+/**
+ * \internal
+ * 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];
+};
+
+/**
+ * \internal
+ * Pointer to the TCP/IP headers of the packet in the uip_buf buffer.
+ */
+#define BUF ((struct tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
+
+/**
+ * \internal
+ * Certain fields of an IP packet that are used for identifying
+ * duplicate packets.
+ */
+struct fwcache_entry {
+ u16_t timestamp;
+
+ u16_t len, offset, ipid;
+ u16_t srcipaddr[2];
+ u16_t destipaddr[2];
+ u16_t payload[2];
+};
+
+/**
+ * \internal
+ * The number of packets to remember when looking for duplicates.
+ */
+#define FWCACHE_SIZE 2
+
+/**
+ * \internal
+ * A cache of packet header fields which are used for
+ * identifying duplicate packets.
+ */
+static struct fwcache_entry fwcache[FWCACHE_SIZE];
+
+/*------------------------------------------------------------------------------*/
+/**
+ * Initialize the uIP packet forwarding module.
+ */
+/*------------------------------------------------------------------------------*/
+void
+uip_fw_init(void)
+{
+ defaultnetif = netifs = 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
+ * Register a packet in the forwarding cache so that it won't be
+ * forwarded again.
+ */
+/*------------------------------------------------------------------------------*/
+static void
+fwcache_register(void)
+{
+ struct fwcache_entry *fw;
+
+ /* Register packet in forwarding cache. */
+ fw = &fwcache[0];
+ fw->len = BUF->len;
+ fw->offset = BUF->ipoffset;
+ 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->payload[0] = BUF->srcport;
+ fw->payload[1] = BUF->destport;
+}
+/*------------------------------------------------------------------------------*/
+/**
+ * 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.
+ */
+/*------------------------------------------------------------------------------*/
+void
+uip_fw_output(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. */
+ break;
+ }
+ }
+
+ /* If no matching netif was found, we use default netif. */
+ if(netif == NULL) {
+ netif = defaultnetif;
+ }
+
+ /* If we now have found a suitable network interface, we call its
+ output function to send out the packet. */
+ if(netif != NULL && uip_len > 0) {
+ fwcache_register();
+ netif->output();
+ }
+}
+/*------------------------------------------------------------------------------*/
+/**
+ * Forward an IP packet in the uip_buf buffer.
+ *
+ *
+ *
+ * \return Non-zero if the packet was forwarded, zero if the packet
+ * should be processed locally.
+ */
+/*------------------------------------------------------------------------------*/
+unsigned char
+uip_fw_forward(void)
+{
+ struct uip_fw_netif *netif;
+ 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 0;
+ }
+
+ /* Check if the packet is in the forwarding cache already, and if so
+ we drop it. */
+ /* for(fw = fwcache; fw <= &fwcache[FWCACHE_SIZE]; ++fw) {*/
+ fw = &fwcache[0];
+ {
+ if(fw->len == BUF->len &&
+ fw->offset == BUF->ipoffset &&
+ 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->payload[0] == BUF->srcport &&
+ fw->payload[1] == BUF->destport) {
+ /* Drop packet. */
+ return 1;
+ }
+ }
+
+
+ /* 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. */
+ break;
+ }
+ }
+
+ /* If no matching netif was found, we use default netif. */
+ if(netif == NULL) {
+ netif = defaultnetif;
+ }
+
+ /* Decrement the TTL (time-to-live) value in the IP header */
+ BUF->ttl = htons(htons(BUF->ttl) - 1);
+
+ /* We should really send an ICMP message if TTL == 0, but we skip it
+ for now... Instead, we just drop the packet (and pretend that it
+ was forwarded by returning 1). */
+ if(BUF->ttl == 0) {
+ return 1;
+ }
+
+ /* Incrementally 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 we now have found a suitable network interface, we call its
+ output function to send out the packet. */
+ if(netif != NULL && uip_len > 0) {
+ uip_appdata = &uip_buf[UIP_LLH_LEN + 40];
+ fwcache_register();
+ netif->output();
+ }
+
+ /* Return non-zero to indicate that the packet was forwarded and that no
+ other processing should be made. */
+ return 1;
+}
+/*------------------------------------------------------------------------------*/
+/**
+ * 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;
+}
+/*------------------------------------------------------------------------------*/