... or am I doing something stupid?
Sorry for the long mail, hopefully it will explain the issue thoroughly.
I am trying to develop a plugin (hook) that will replace certain
config-"variables" based on the incoming DHCP-request.
The plugin lives here: https://github.com/Olen/kea_hooks
And the relevant part is in pk4_send.cc
When the server receives a DHCP-request with Option82.2 set, it will
send back a DHCP-reply with Option43.1 set to the same value.
But for some reason, the Reply is sent back to the client with the
_wrong_ content.
The request comes in:
options:
type=050, len=004: 172.19.12.130 (ipv4-address)
type=053, len=001: 3 (uint8)
type=054, len=004: 172.29.148.250 (ipv4-address)
type=082, len=023:,
options:
type=001, len=010: 67:65:2d:30:2f:30:2f:34:3a:31
type=002, len=009: 74:65:73:74:2d:63:70:65:34
Option82.002 equals "test-cpe4" (hex encoded)
The server then replies with:
options:
type=001, len=004: 4294967040 (uint32)
type=003, len=004: 172.19.12.1
type=006, len=008: 172.29.131.100 172.29.131.200
type=042, len=004: 172.19.8.3
type=043, len=037:,
options:
type=001, len=009: "test-cpe2" (string)
- "test-cpe2" was the _first_ test i ran after restarting Kea. No
matter what I put in Option82, it will always reply with "test-cpe2".
My config file contains the following:
"name": "config-file-name",
"code": 1,
"space": "vendor-encapsulated-options-space",
"csv-format": true,
"data": "@OPTION_82_2@"
So I look in my code, and in pkt4_send I try to do the following:
(Only the relevant parts of the code is quoted)
I get the packet-pointer:
Pkt4Ptr response4_ptr;
handle.getArgument("response4", response4_ptr);
I try to read the contents of Option43.1:
OptionPtr opt_ptr = response4_ptr->getOption(opt_code);
OptionPtr sub_ptr = opt_ptr->getOption(sub_code);
option_data = sub_ptr->toString();
debug("Returning data: " << option_data << "\n")
<------- A
Then I try to replace the "variable" with the correct value:
string placeholder = "@OPTION_82_2@";
string replace_with = <data from Option82_2>
option_data.replace(option_data.find(placeholder), placeholder.size(),
replace_with);
I have added a lot of debug to the code, and the first time after a
restart, I see the following:
in: @OPTION_82_2@ = test-cpe2
Getting writable option 43.1
Getting option: 43.1
Returning data: cpe/config?hostname=@OPTION_82_2@
<------ B
Replacing @OPTION_82_2@ with test-cpe2 in option
cpe/config?hostname=@OPTION_82_2@
New option-value: cpe/config?hostname=test-cpe2
Adding option-value: cpe/config?hostname=test-cpe2 in 43.1
Option added
And everything works fine.
But any later DHCP-request will give the following:
in: @OPTION_82_2@ = test-cpe4
Getting writable option 43.1
Getting option: 43.1
Returning data: cpe/config?hostname=test-cpe2
<------ C
A is the debug line resulting it the two outputs B and C
B is first run - the response4_ptr->getOption returns the Option-value
from the config-file
C is the second run. Now response4_ptr is _not_ fresh from the config,
but contains values from the previous dhcp-reply.
What do I need to do to make sure respones4_ptr contains a "fresh"
packet, without any left overs from the old packets?
/Ola (T)
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