pcap_compile(3) - NetBSD Manual Pages

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PCAP_COMPILE(3)                                                PCAP_COMPILE(3)




NAME

       pcap_compile - compile a filter expression


SYNOPSIS

       #include <pcap/pcap.h>

       int pcap_compile(pcap_t *p, struct bpf_program *fp,
               const char *str, int optimize, bpf_u_int32 netmask);


DESCRIPTION

       pcap_compile() is used to compile the string str into a filter program.
       See pcap-filter(7) for the syntax of that string.  program is a pointer
       to  a  bpf_program struct and is filled in by pcap_compile().  optimize
       controls whether optimization on the resulting code is performed.  net-
       mask  specifies  the  IPv4  netmask of the network on which packets are
       being captured; it is  used  only  when  checking  for  IPv4  broadcast
       addresses  in  the  filter  program.   If the netmask of the network on
       which packets are being captured isn't known  to  the  program,  or  if
       packets are being captured on the Linux "any" pseudo-interface that can
       capture on more than one network, a value of  PCAP_NETMASK_UNKNOWN  can
       be  supplied;  tests for IPv4 broadcast addresses will fail to compile,
       but all other tests in the filter program will be OK.

       NOTE: in libpcap 1.8.0 and later, pcap_compile() can be used in  multi-
       ple  threads  within a single process.  However, in earlier versions of
       libpcap, it is not safe to use pcap_compile() in multiple threads in  a
       single  process without some form of mutual exclusion allowing only one
       thread to call it at any given time.


RETURN VALUE

       pcap_compile() returns 0 on success  and  -1  on  failure.   If  -1  is
       returned,  pcap_geterr()  or  pcap_perror()  may be called with p as an
       argument to fetch or display the error text.


SEE ALSO

       pcap(3), pcap_setfilter(3), pcap_freecode(3), pcap_geterr(3), pcap-filter(7)
       



                                 24 March 2017                 PCAP_COMPILE(3)