getting interface MAC addr from C

2006-08-04 Thread Mario Lobo 
Hi;

Would anyone have a tip on how to get the MAC from a C program?

I tried:

struct ifreq ifreq;
unsigned char *hw;

strcpy(ifreq.ifr_name, rl0);
ioctl(fd, SIOCGIFMAC, ifreq);
hw = ifreq.ifr_ifru.ifru_data; 

but i don't know if this is right or, if it is, where to get the MAC from the 
structure. I doesn't issue any error compiling or running though.

In linux i used:

struct ifreq ifreq;
unsigned char *hw;

strcpy(ifreq.ifr_name, rl0);
ioctl(fd, SIOCGIFHWADDR, ifreq);
hw = ifreq.ifr_hwaddr.sa_data;

Thanks,

Mario
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Re: getting interface MAC addr from C

2006-08-04 Thread Robert Watson 

On Fri, 4 Aug 2006, Mario Lobo wrote:


Would anyone have a tip on how to get the MAC from a C program?

I tried:

   struct ifreq ifreq;
   unsigned char *hw;

   strcpy(ifreq.ifr_name, rl0);
   ioctl(fd, SIOCGIFMAC, ifreq);
   hw = ifreq.ifr_ifru.ifru_data; 

but i don't know if this is right or, if it is, where to get the MAC from 
the structure. I doesn't issue any error compiling or running though.


Usually the general purpose interface recommended for inspecting interface 
information is getifaddrs(), which will build a userspace list of interfaces 
and their various addresses, including link-layer addresses.  Something like 
the above will work, but may not be preferred.


Robert N M Watson
Computer Laboratory
University of Cambridge



In linux i used:

   struct ifreq ifreq;
   unsigned char *hw;

   strcpy(ifreq.ifr_name, rl0);
   ioctl(fd, SIOCGIFHWADDR, ifreq);
   hw = ifreq.ifr_hwaddr.sa_data;

Thanks,

Mario
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Re: getting interface MAC addr from C

2006-08-04 Thread Michal Mertl 
Mario Lobo wrote:
 Hi;
 
 Would anyone have a tip on how to get the MAC from a C program?
 
 I tried:
 
 struct ifreq ifreq;
 unsigned char *hw;
 
 strcpy(ifreq.ifr_name, rl0);
 ioctl(fd, SIOCGIFMAC, ifreq);
 hw = ifreq.ifr_ifru.ifru_data; 

This is probably very far from what you want. MAC stands here for MAC(4)
- e.g. security related stuff as opposed to something network (did you
read MAC as Media Access Control?).

I don't know it that is the easiest/right way to get this information
but you can use getifaddrs(3). Attached find a simple program which
prints out the interfaces and their MAC addresses using getifaddrs().
The code for getting the printable address is taken from function
fmt_sockaddr() from src/usr.bin/netstat/route.c.

You can also probably use SIOCGIFADDR with the right socket passed in as
fd or with sysctl(3) (int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK,
NET_RT_IFLIST, 0}).

 but i don't know if this is right or, if it is, where to get the MAC from the 
 structure. I doesn't issue any error compiling or running though.
 
 In linux i used:
 
 struct ifreq ifreq;
 unsigned char *hw;
 
 strcpy(ifreq.ifr_name, rl0);
 ioctl(fd, SIOCGIFHWADDR, ifreq);
 hw = ifreq.ifr_hwaddr.sa_data;
 
 Thanks,
 
 Mario
 

HTH

Michal
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