[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[lwip-users] DHCP requesting additional options via option 55
From: |
Craig McQueen |
Subject: |
[lwip-users] DHCP requesting additional options via option 55 |
Date: |
Tue, 13 Nov 2018 03:02:18 +0000 |
I have tried using LWIP_HOOK_DHCP_APPEND_OPTIONS() and
LWIP_HOOK_DHCP_PARSE_OPTION() to request additional DHCP options from the
server, using DHCP option 55 (DHCP_OPTION_PARAMETER_REQUEST_LIST).
At first I thought it was working fine. But on closer examination, it seems the
server is not sending all requested options (e.g. options 3 and 6). That is
evidently because the DHCP request contains the option 55 twice (once from the
lwIP core code, a second time from my LWIP_HOOK_DHCP_APPEND_OPTIONS()).
According to the DHCP RFC 2131, " Options may appear only once, unless
otherwise specified in the options document." So I guess the DHCP server
(Microsoft in this case) is ignoring the first occurrence of option 55.
So, it would be good to improve the DHCP hook mechanism so that user code can
request additional options via option 55, without duplicating the option
contrary to the RFC. Ideally, it could be dynamic not a static array, so the
user code could decide at run-time which additional options are requested.
What would be a good way to improve the hook mechanism?
(I'm interested in contributing some code back to the lwIP project, as long as
I have a rough idea what would be accepted.)
--
Craig McQueen
- [lwip-users] DHCP requesting additional options via option 55,
Craig McQueen <=