removed ETHARP_TRUST_IP_MAC since it is insecure and we don't need it any more after implementing unicast ARP renewal towards arp entry timeout

CHANGELOG

@@ -328,6 +328,10 @@ HISTORY
 
   ++ Bugfixes:
 
+  2016-08-23: Simon Goldschmidt
+  * etharp: removed ETHARP_TRUST_IP_MAC since it is insecure and we don't need
+    it any more after implementing unicast ARP renewal towards arp entry timeout
+
   2016-07-20: Simon Goldschmidt
   * memp.h/.c: fixed bug #48442 (memp stats don't work for MEMP_MEM_MALLOC)
 

src/core/ipv4/etharp.c

@@ -616,56 +616,6 @@ etharp_get_entry(u8_t i, ip4_addr_t **ipaddr, struct netif **netif, struct eth_a
   }
 }
 
-#if ETHARP_TRUST_IP_MAC
-/**
- * Updates the ARP table using the given IP packet.
- *
- * Uses the incoming IP packet's source address to update the
- * ARP cache for the local network. The function does not alter
- * or free the packet. This function must be called before the
- * packet p is passed to the IP layer.
- *
- * @param netif The lwIP network interface on which the IP packet pbuf arrived.
- * @param p The IP packet that arrived on netif.
- *
- * @return NULL
- *
- * @see pbuf_free()
- */
-void
-etharp_ip_input(struct netif *netif, struct pbuf *p)
-{
-  struct eth_hdr *ethhdr;
-  struct ip_hdr *iphdr;
-  ip4_addr_t iphdr_src;
-  LWIP_ERROR("netif != NULL", (netif != NULL), return;);
-
-  /* Only insert an entry if the source IP address of the
-     incoming IP packet comes from a host on the local network. */
-  ethhdr = (struct eth_hdr *)p->payload;
-  iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
-#if ETHARP_SUPPORT_VLAN
-  if (ethhdr->type == PP_HTONS(ETHTYPE_VLAN)) {
-    iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
-  }
-#endif /* ETHARP_SUPPORT_VLAN */
-
-  ip4_addr_copy(iphdr_src, iphdr->src);
-
-  /* source is not on the local network? */
-  if (!ip4_addr_netcmp(&iphdr_src, netif_ip4_addr(netif), netif_ip4_netmask(netif))) {
-    /* do nothing */
-    return;
-  }
-
-  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
-  /* update the source IP address in the cache, if present */
-  /* @todo We could use ETHARP_FLAG_TRY_HARD if we think we are going to talk
-   * back soon (for example, if the destination IP address is ours. */
-  etharp_update_arp_entry(netif, &iphdr_src, &(ethhdr->src), ETHARP_FLAG_FIND_ONLY);
-}
-#endif /* ETHARP_TRUST_IP_MAC */
-
 /**
  * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache
  * send out queued IP packets. Updates cache with snooped address pairs.

src/include/lwip/etharp.h

@@ -94,7 +94,6 @@ err_t etharp_request(struct netif *netif, const ip4_addr_t *ipaddr);
  *  From RFC 3220 "IP Mobility Support for IPv4" section 4.6. */
 #define etharp_gratuitous(netif) etharp_request((netif), netif_ip4_addr(netif))
 void etharp_cleanup_netif(struct netif *netif);
-void etharp_ip_input(struct netif *netif, struct pbuf *p);
 
 #if ETHARP_SUPPORT_STATIC_ENTRIES
 err_t etharp_add_static_entry(const ip4_addr_t *ipaddr, struct eth_addr *ethaddr);

src/include/lwip/opt.h

@@ -576,20 +576,6 @@
 #define ARP_QUEUE_LEN                   3
 #endif
 
-/**
- * ETHARP_TRUST_IP_MAC==1: Incoming IP packets cause the ARP table to be
- * updated with the source MAC and IP addresses supplied in the packet.
- * You may want to disable this if you do not trust LAN peers to have the
- * correct addresses, or as a limited approach to attempt to handle
- * spoofing. If disabled, lwIP will need to make a new ARP request if
- * the peer is not already in the ARP table, adding a little latency.
- * The peer *is* in the ARP table if it requested our address before.
- * Also notice that this slows down input processing of every IP packet!
- */
-#if !defined ETHARP_TRUST_IP_MAC || defined __DOXYGEN__
-#define ETHARP_TRUST_IP_MAC             0
-#endif
-
 /**
  * ETHARP_SUPPORT_VLAN==1: support receiving and sending ethernet packets with
  * VLAN header. See the description of LWIP_HOOK_VLAN_CHECK and

src/netif/ethernet.c

@@ -157,10 +157,6 @@ ethernet_input(struct pbuf *p, struct netif *netif)
       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
         goto free_and_return;
       }
-#if ETHARP_TRUST_IP_MAC
-      /* update ARP table */
-      etharp_ip_input(netif, p);
-#endif /* ETHARP_TRUST_IP_MAC */
       /* skip Ethernet header */
       if ((p->len < ip_hdr_offset) || pbuf_header(p, (s16_t)-ip_hdr_offset)) {
         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,