Diff: stack/pico_arp.c

Revision:

133:5b075f5e141a

Parent:

132:40ba3014da35

Child:

134:cc4e6d2654d9

--- a/stack/pico_arp.c	Tue Jan 07 13:55:29 2014 +0100
+++ b/stack/pico_arp.c	Thu Jan 16 10:13:37 2014 +0100
@@ -29,6 +29,7 @@
 
 static struct pico_queue pending;
 static int pending_timer_on = 0;
+static int max_arp_reqs = PICO_ARP_MAX_RATE;
 
 void check_pending(pico_time now, void *_unused)
 {
@@ -46,6 +47,20 @@
     pico_timer_add(PICO_ARP_RETRY, &check_pending, NULL);
 }
 
+static void update_max_arp_reqs(pico_time now, void *unused)
+{
+    IGNORE_PARAMETER(now);
+    IGNORE_PARAMETER(unused);
+    if (max_arp_reqs < PICO_ARP_MAX_RATE)
+        max_arp_reqs++;
+
+    pico_timer_add(PICO_ARP_INTERVAL / PICO_ARP_MAX_RATE, &update_max_arp_reqs, NULL);
+}
+
+void pico_arp_init()
+{
+    pico_timer_add(PICO_ARP_INTERVAL / PICO_ARP_MAX_RATE, &update_max_arp_reqs, NULL);
+}
 
 struct
 __attribute__ ((__packed__))
@@ -81,6 +96,7 @@
     int arp_status;
     pico_time timestamp;
     struct pico_device *dev;
+    struct pico_timer *timer;
 };
 
 
@@ -229,16 +245,36 @@
 {
     struct pico_arp_hdr *hdr;
     struct pico_arp search, *found, *new = NULL;
+    struct pico_ip4 me;
+    struct pico_device *link_dev;
+    struct pico_eth_hdr *eh;
     int ret = -1;
     hdr = (struct pico_arp_hdr *) f->net_hdr;
+    me.addr = hdr->dst.addr;
+    eh = (struct pico_eth_hdr *)f->datalink_hdr;
 
     if (!hdr)
         goto end;
 
     /* Validate the incoming arp packet */
+
+    /* Check the hardware type and protocol */
     if ((hdr->htype != PICO_ARP_HTYPE_ETH) || (hdr->ptype != PICO_IDETH_IPV4))
         goto end;
 
+    /* The source mac address must not be a multicast or broadcast address */
+    if (hdr->s_mac[0] & 0x01)
+        goto end;
+
+    /* Prevent ARP flooding */
+    link_dev = pico_ipv4_link_find(&me);
+    if ((link_dev == f->dev) && (hdr->opcode == PICO_ARP_REQUEST)) {
+        if (max_arp_reqs == 0)
+            goto end;
+        else
+            max_arp_reqs--;
+    }
+
     if (conflict_ipv4.conflict != NULL)
     {
         if ((conflict_ipv4.ip.addr == hdr->src.addr) && (memcmp(hdr->s_mac, conflict_ipv4.mac.addr, 6) != 0))
@@ -250,40 +286,47 @@
     memcpy(search.eth.addr, hdr->s_mac, PICO_SIZE_ETH);
 
     /* Search for already existing entry */
+    found = pico_tree_findKey(&arp_tree, &search);
+    if (found) {
+        if (found->arp_status == PICO_ARP_STATUS_STALE) {
+            /* Replace if stale */
+            new = found;
 
-    found = pico_tree_findKey(&arp_tree, &search);
+            pico_tree_delete(&arp_tree, new);
+        }
+        else {
+            /* Update mac address */
+            memcpy(found->eth.addr, hdr->s_mac, PICO_SIZE_ETH);
+
+            /* Refresh timeout & update timestamp*/
+            pico_timer_cancel(found->timer);
+            found->timer = pico_timer_add(PICO_ARP_TIMEOUT, arp_expire, found);
+            found->timestamp = PICO_TIME();
+        }
+    }
+
+    /* Check if we are the target IP address */
+    if (link_dev != f->dev)
+        goto end;
+
+    /* If no existing entry was found, create a new entry */
     if (!found) {
         new = pico_zalloc(sizeof(struct pico_arp));
         if (!new)
             goto end;
 
         new->ipv4.addr = hdr->src.addr;
+        memcpy(new->eth.addr, hdr->s_mac, PICO_SIZE_ETH);
+        new->dev = f->dev;
     }
-    else if (found->arp_status == PICO_ARP_STATUS_STALE) {
-        /* Replace if stale */
-        new = found;
 
-        pico_tree_delete(&arp_tree, new);
-    }
+    if (new)
+        pico_arp_add_entry(new);
 
     ret = 0;
 
-    if (new) {
-        memcpy(new->eth.addr, hdr->s_mac, PICO_SIZE_ETH);
-        new->dev = f->dev;
-        pico_arp_add_entry(new);
-    }
-
+    /* If the packet is a request, send a reply */
     if (hdr->opcode == PICO_ARP_REQUEST) {
-        struct pico_ip4 me;
-        struct pico_eth_hdr *eh = (struct pico_eth_hdr *)f->datalink_hdr;
-        struct pico_device *link_dev;
-        me.addr = hdr->dst.addr;
-
-        link_dev = pico_ipv4_link_find(&me);
-        if (link_dev != f->dev)
-            goto end;
-
         hdr->opcode = PICO_ARP_REPLY;
         memcpy(hdr->d_mac, hdr->s_mac, PICO_SIZE_ETH);
         memcpy(hdr->s_mac, f->dev->eth->mac.addr, PICO_SIZE_ETH);