Re^2: Of Net::Arp and Hashes

I confirmed (sort of, read on) that commenting out the $ipaddr2 line causes it to fail. After commenting out the $ipaddr2 assignment, the second arp_lookup() still worked. This was odd to me since I tested the snippet a bunch before I posted. I looked further up to the first print. Upon commenting out the first print, the second arp_lookup() failed to work. If I comment out the first print and the $ipaddr2 assignment, the second arp_lookup() no longer works. Odd.

Comment on Re^2: Of Net::Arp and Hashes

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Re^3: Of Net::Arp and Hashes by japhy (Canon) on Jan 13, 2006 at 18:39 UTC
I think there's a bug in the XS code: `char * arp_lookup(dev, ip, mac) unsigned char dev; unsigned char ip; unsigned char mac; CODE: char tmp[20]; if(SOCK_TYPE == SOCK_RAW) { arp_lookup_bsd(dev,ip,tmp); } else { arp_lookup_linux(dev,ip,tmp); } mac = tmp; OUTPUT: mac` [download] That's the XS that handles arp_lookup(). Notice that it creates `char tmp[20]` without ever assigning anything to it (such as ""). I'm not a C guru, but that's a definite NO-NO. Because in the arp_lookup_linux() code, we have: `int arp_lookup_linux(char dev, char ip, char mac) { FILE fp; char ipaddr[100]; char line[200]; char hwa[100]; char mask[100]; char device[100]; int num, type, flags; if(strlen(mac) > 0) strcpy(mac,"unkown"); else return -1;` [download] which leads me to believe -1 is being returned. I just think it's suspect. Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart*	[reply] [d/l] [select]

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Re^3: Of Net::Arp and Hashes
by japhy (Canon) on Jan 13, 2006 at 18:39 UTC

char *
arp_lookup(dev, ip, mac)
    unsigned char *dev;
    unsigned char *ip;
    unsigned char *mac;
    CODE:
      char tmp[20];

      if(SOCK_TYPE == SOCK_RAW)
      {
        arp_lookup_bsd(dev,ip,tmp);
      }
      else
      {
        arp_lookup_linux(dev,ip,tmp);
      }

      mac = tmp;

    OUTPUT:
    mac
[download]

char tmp[20]

int arp_lookup_linux(char *dev, char *ip, char *mac)
{
  FILE *fp;
  char ipaddr[100];
  char line[200];
  char hwa[100];
  char mask[100];
  char device[100];
  int num, type, flags;
  
  if(strlen(mac) > 0)
    strcpy(mac,"unkown");
  else
    return -1;
[download]

Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

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