ioctl(sock, SIOCGIFHWADDR, &ifr) fails with 1.7

Fri Jun 12 12:30:00 GMT 2009

I used the following program to obtain mac address and ip of network
adpaters. It works fine with 1.5 but not with 1.7.
Output with 1.5:
sock=3
trying eth0
mac: 00.1f.3c.57.XX.XX, ip: XXX.XXX.XXX.XXX
trying eth1
mac: 00.1d.09.df.XX.XX, ip: XXX.XXX.XXX.XXX
trying eth2
mac: 08.00.27.00.XX.XX, ip: XXX.XXX.XXX.XXX
trying eth3
...
Output with 1.7:
sock=3
trying eth0
trying eth1
trying eth2
trying eth3
...
Any clue?
Frédéric
#include <iostream>
#include <iomanip>
#include <netdb.h>
#include <sys/ioctl.h>
#include <net/if.h>
void read_hwaddr(const struct ifreq &ifr) {
 std::cout << "mac: " ;
 const struct sockaddr &hwaddr=ifr.ifr_hwaddr ;
 for (size_t k=0 ; k<6 ; ++k) {
 if (k) std::cout << '.' ;
 unsigned int v=static_cast<unsigned char>(hwaddr.sa_data[k]) ;
 std::cout << std::hex << std::setw(2) <<
std::setfill('0') << static_cast<int>(v) ;
 }
}
void read_ip(const struct ifreq &ifr) {
 std::cout << "ip: " ;
 const struct sockaddr &addr=ifr.ifr_addr ;
 for (size_t k=0 ; k<4 ; ++k) {
 unsigned int v=static_cast<unsigned char>(addr.sa_data[k+2]) ;
 if (k) std::cout << '.' ;
 std::cout << std::dec << static_cast<int>(v) ;
 }
}
int main() {
 std::string eth("eth") ;
 struct protoent *proto=NULL ;
 if (proto=getprotobyname("tcp")) {
 int sock=socket(PF_INET, SOCK_STREAM, proto->p_proto) ;
 std::cout << "sock=" << sock << '\n' ;
 struct ifreq ifr ;
 for (char k='0' ; k<='9' ; ++k) {
 std::cout << "trying " << (eth+k) << '\n' ;
 std::memset(&ifr, 0, sizeof(struct ifreq)) ;
 std::strcpy(ifr.ifr_name, (eth+k).c_str()) ;
 // MAC address
 if (ioctl(sock, SIOCGIFHWADDR, &ifr)!=0) continue ;
 read_hwaddr(ifr) ;
 std::cout << ", " ;
 // IP address
 if (ioctl(sock, SIOCGIFADDR, &ifr)==0) read_ip(ifr) ;
 std::cout << '\n' ;
 }
 close(sock) ;
 }
 return 0 ;
}
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