[lwip-devel] [bug #29072] DHCPDISCOVER doesn't have ciaddr == 0

[Bill Auerbach]

Follow-up Comment #7, bug #29072 (project lwip):

Ok, checked my code.  I do dhcp_start and if I don't get an IP address in 5
seconds, I do netif_set_addr to a static fallback (but didn't do a
dhcp_stop).

What you're seeing does look incorrect from what I see in the RFC.  RFC2131
covers a lot of points for both DHCP client and server.

This brings up 3 points:

1.  Should netif_set_addr call dhcp_stop?  If netif_set_addr is called
without stopping, DHCP can come along and change it.  If netif_set_addr is
used internally calling dhcp_stop would be a problem.

2.  Should netif_set_addr call dhcp_inform?

3.  This is the part I mentioned where lwIP might not be RFC compliant: The
RFC states that if an interface has an IP address and later if DHCP offers an
IP address, the address must be taken, but the original connections must not
be broken or changed. I believe the bug is that we do change the netif IP
address and lwIP will break open connections on the pre-DHCP-assigned address.

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