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nic_bridge: drop 'gratuitous ARP' messages 

'Gratuitous ARP' broadcast messages are used to announce newly created
IP<->MAC address mappings to other hosts. nic_bridge-internal hosts
would expect a nic_bridge-internal MAC address in this message, whereas
external hosts would expect the NIC's MAC address in this message.
The simplest solution to this problem is to just drop those messages,
since they are not really necessary.

Fixes #709.
This commit is contained in:
Christian Prochaska 2013-04-08 18:10:47 +02:00 committed by Norman Feske
parent 242d51033f
commit 1500d59d0d
1 changed files with 12 additions and 0 deletions
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12
os/src/server/nic_bridge/component.cc
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@ -59,6 +59,18 @@ bool Session_component::Tx_handler::handle_arp(Ethernet_frame *eth, Genode::size
new (eth->data()) Arp_packet(size - sizeof(Ethernet_frame));
if (arp->ethernet_ipv4() &&
arp->opcode() == Arp_packet::REQUEST) {
/*
* 'Gratuitous ARP' broadcast messages are used to announce newly created
* IP<->MAC address mappings to other hosts. nic_bridge-internal hosts
* would expect a nic_bridge-internal MAC address in this message, whereas
* external hosts would expect the NIC's MAC address in this message.
* The simplest solution to this problem is to just drop those messages,
* since they are not really necessary.
*/
if (arp->src_ip() == arp->dst_ip())
return false;
Ipv4_address_node *node = Vlan::vlan()->ip_tree()->first();
if (node)
node = node->find_by_address(arp->dst_ip());