Checking for specific return errors in libpcap I/O functions

[Fernando Gont <fernando () gont com ar>]

Folks,

I was trying to check for specific errors in libpcap I/O functions such
as pcap_next_ex() and pcap_inject().

However, the relevant manpages indicate that these functions return -1
on error, and don't mention the setting of any "errno-like" variable
that specifies the specific error that occurred.

While there exist functions such as pcap_geterr() to print an
error-specific message, I'm rather interested in obtaining an error code
such that my program can act differently depending on the specific
return error.

If that's possible? If so, how?

FWIW, I've checked /usr/include/pcap/pcap.h, and while there exist error
codes such as:

#define PCAP_ERROR                      -1      /* generic error code */
#define PCAP_ERROR_BREAK                -2      /* loop terminated by pcap_breakloop */
[....]
#define PCAP_ERROR_IFACE_NOT_UP         -9      /* interface isn't up */

they don't seem to be returned when the corresponding error condition
occurs in pcap_next_ex() or other libpcap I/O functions. For instance,
if I take an interface down with ifconfig, pcap_next_ex() returns -1,
and not -9 (PCAP_ERROR_IFACE_NOT_UP).

Thanks!

Best regards,
-- 
Fernando Gont
e-mail: fernando () gont com ar || fgont () si6networks com
PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1



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