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.  netmask 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 multiple 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 PCAP_ERROR on failure. If PCAP_ERROR is returned,
       pcap_geterr(3PCAP) or pcap_perror(3PCAP) may be called with p as an argument to  fetch  or
       display the error text.

BACKWARD COMPATIBILITY

       The PCAP_NETMASK_UNKNOWN constant became available in libpcap release 1.1.0.

SEE ALSO

       pcap(3PCAP), pcap_setfilter(3PCAP), pcap_freecode(3PCAP)

                                          22 August 2018                      PCAP_COMPILE(3PCAP)