udhcpc: option -x OPT:VAL clarification
Denys Vlasenko
vda.linux at googlemail.com
Sun Dec 5 22:22:02 UTC 2010
On Sunday 05 December 2010 20:05, Abdoulaye Walsimou GAYE wrote:
> Can someone clarify usage of -x OPT:VAL please?
$ udhcpc --help
BusyBox v1.18.0 (2010-11-23 00:11:12 CET) multi-call binary.
Usage: udhcpc [-fbnqvoCR] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]
[-H HOSTNAME] [-V VENDOR] [-x OPT:VAL]... [-O OPT]...
...
-x OPT:VAL Include option OPT in sent packets (cumulative)
Examples of string, numeric, and hex byte opts:
-x hostname:bbox - option 12
-x lease:3600 - option 51 (lease time)
-x 0x3d:0100BEEFC0FFEE - option 61 (client id)
Is this text unclear?
Please provide question(s) it doesn't answer.
> I my case I want to use it to encode dhcp option 125[1], vendor
> identifying vendor options.
Use -x 125:foo then.
> I want to know how VAL need to be in order to send dhcp option 125.
>
> from [1] ----------------------------------------------------
> The format of the V-I Vendor-specific Information option is as
> follows:
> 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | option-code | option-len |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | enterprise-number1 |
> | |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | data-len1 | |
> +-+-+-+-+-+-+-+-+ option-data1 |
Well, the picture seems to be garbled. "option-data1" looks strange.
Ypou meant:
The format of the V-I Vendor Class option is as follows:
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| enterprise-number1 |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| data-len1 | |
+-+-+-+-+-+-+-+-+ |
/ vendor-class-data1 /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
| enterprise-number2 | ^
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| data-len2 | | optional
+-+-+-+-+-+-+-+-+ | |
/ vendor-class-data2 / |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ ... ~ V
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
Since enterprise-number1, data-len1, vendor-class-data1
are likely to be nonrepresentable as strings,
encode them as hex bytes:
-x 125:010203040506070809
replace 01 with the value of 1st byte, 02 with with the value
of 2nd one and so on.
--
vda
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