setting mac address for a host in C (dhcpctl.h)

[Johnson koil Raj]

Hi Peter,

     Thanks for correcting me.

  I have changed and tried as you suggestion.

   memset (&macaddrstring, 0, sizeof macaddrstring);
   omapi_data_string_new (&macaddrstring, 18, MDL);
   memcpy(macaddrstring->value, "00:0c:26:22:bf:c3", 18);
   dhcpctl_set_string_value (host, macaddrstring, "hardware-address");

But still the mac address is not getting set proper.

host testomapihost {
   dynamic;
   hardware ethernet 01;
   fixed-address 192.168.10.123;
}

  Still I am missing some thing.


Thanks,
Johnson

----------------------------------------------------------------------
> Message: 1
> Date: Wed, 29 Jun 2011 00:01:42 +0200
> From: Peter Rathlev<peter at rathlev.dk>
> Subject: Re: setting mac address for a host in C (dhcpctl.h)
> To: Users of ISC DHCP<dhcp-users at lists.isc.org>
> Message-ID:<1309298502.11298.10.camel at abehat.dyn.net.rm.dk>
> Content-Type: text/plain; charset="UTF-8"
>
> On Tue, 2011-06-28 at 18:35 +0530, Johnson koil Raj wrote:
>> I am working on dhcpd api by using dhcpctl.h. I am trying to assign
>> static IPs for machines when its hostname and mac-address was provided.
>> I have tried so far. When I tried to add a new host detail. The
>> mac-address alone not assigned properly. Some junk value it is giving.
>> The code what I have used is below.
> I don't want to sound harsh, but have you considered if you're really
> doing the right thing here? Trying to hack together some C code yourself
> can be dangerous if you don't master the basic concepts.
>
>>       dhcpctl_data_string macaddrstring = NULL;
>>       memset (&macaddrstring, 0, sizeof macaddrstring);
>>       omapi_data_string_new (&macaddrstring, 16, MDL);
>>       memcpy(macaddrstring->value, "00:0c:26:22:bf:c3", 16);
>>       status = dhcpctl_set_value (host, macaddrstring, "hardware-address");
>>
>> I am seeing following value in lease file.
>>
>> host testomapihost {
>>     dynamic;
>>     hardware ethernet 31:30:30:3a:30:63:3a:32:36:3a:32:32:3a:62:66:3a;
>>     fixed-address 192.168.10.123;
>> }
> This should give you the clue. Look at what the string "00:0c:26..."
> translates to in hex: "30 30 3a 30 63 3a 32 36 ...". That's probably not
> a coincidence.
>
> Looking closer at the lines above:
>
>       memcpy(macaddrstring->value, "00:0c:26:22:bf:c3", 16);
>
> That string isn't 16 bytes. It's 18 bytes including the terminating nul
> character. And keep in mind that "correcting" the length parameter will
> not help you.
>
>       status = dhcpctl_set_value (host, macaddrstring, "hardware-address");
>
> You probably want to use dhcpctl_set_string_value instead.
>
> Beware that you're probably in the process of creating a piece of
> software that you should never ever try to run as root on anything.


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