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[dhcp] Request broadcast responses when we already have an IPv4 address

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FCoE requires the use of multiple local unicast link-layer addresses.
To avoid the complexity of managing multiple addresses, iPXE operates
in promiscuous mode.  As a consequence, any unicast packets with
non-matching IPv4 addresses are rejected at the IPv4 layer (rather
than at the link layer).

This can cause problems when issuing a second DHCP request: if the
address chosen by the DHCP server does not match the existing address,
then the DHCP response will itself be rejected.

Fix by requesting a broadcast response from the DHCP server if the
network interface already has any IPv4 addresses.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2012-06-20 11:56:43 +01:00
parent b9ef880c8d
commit c0942408b7
3 changed files with 10 additions and 1 deletions
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7
src/net/udp/dhcp.c
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@@ -941,6 +941,13 @@ int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
&dhcphdr->flags );
memcpy ( dhcphdr->options, options, options_len );
/* If the network device already has an IPv4 address then
* unicast responses from the DHCP server may be rejected, so
* request broadcast responses.
*/
if ( ipv4_has_any_addr ( netdev ) )
dhcphdr->flags |= htons ( BOOTP_FL_BROADCAST );
/* Initialise DHCP packet structure */
memset ( dhcppkt, 0, sizeof ( *dhcppkt ) );
dhcppkt_init ( dhcppkt, data, max_len );