pcap_findalldevs(3) - NetBSD Manual Pages

PCAP_FINDALLDEVS(3)                                        PCAP_FINDALLDEVS(3)




NAME

       pcap_findalldevs, pcap_freealldevs - get a list of capture devices, and
       free that list


SYNOPSIS

       #include <pcap/pcap.h>

       char errbuf[PCAP_ERRBUF_SIZE];

       int pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf);
       void pcap_freealldevs(pcap_if_t *alldevs);


DESCRIPTION

       pcap_findalldevs() constructs a list of network  devices  that  can  be
       opened with pcap_create() and pcap_activate() or with pcap_open_live().
       (Note that there may be network devices that cannot be  opened  by  the
       process  calling pcap_findalldevs(), because, for example, that process
       does not have sufficient privileges to open them for capturing; if  so,
       those devices will not appear on the list.)  If pcap_findalldevs() suc-
       ceeds, the pointer pointed to by alldevsp is set to point to the  first
       element  of the list, or to NULL if no devices were found (this is con-
       sidered success).  Each element of the list is of type  pcap_if_t,  and
       has the following members:

              next   if  not  NULL, a pointer to the next element in the list;
                     NULL for the last element of the list

              name   a pointer to a string giving a name  for  the  device  to
                     pass to pcap_open_live()

              description
                     if  not  NULL, a pointer to a string giving a human-read-
                     able description of the device

              addresses
                     a pointer to the first  element  of  a  list  of  network
                     addresses  for  the  device, or NULL if the device has no
                     addresses

              flags  device flags:

                     PCAP_IF_LOOPBACK
                            set if the device is a loopback interface

                     PCAP_IF_UP
                            set if the device is up

                     PCAP_IF_RUNNING
                            set if the device is running

       Each element of the list of addresses is of type pcap_addr_t,  and  has
       the following members:

              next   if  not  NULL, a pointer to the next element in the list;
                     NULL for the last element of the list

              addr   a pointer to a struct sockaddr containing an address

              netmask
                     if not NULL, a pointer to a struct sockaddr that contains
                     the  netmask  corresponding  to the address pointed to by
                     addr

              broadaddr
                     if not NULL, a pointer to a struct sockaddr that contains
                     the   broadcast  address  corresponding  to  the  address
                     pointed to by addr; may be null  if  the  device  doesn't
                     support broadcasts

              dstaddr
                     if not NULL, a pointer to a struct sockaddr that contains
                     the destination  address  corresponding  to  the  address
                     pointed  to  by  addr;  may be null if the device isn't a
                     point-to-point interface

       Note that the  addresses  in  the  list  of  addresses  might  be  IPv4
       addresses, IPv6 addresses, or some other type of addresses, so you must
       check the sa_family member of the struct sockaddr  before  interpreting
       the  contents  of the address; do not assume that the addresses are all
       IPv4 addresses, or even all IPv4 or  IPv6  addresses.   IPv4  addresses
       have  the  value AF_INET, IPv6 addresses have the value AF_INET6 (which
       older operating systems that don't support IPv6 might not define),  and
       other  addresses  have  other  values.   Whether  other  addresses  are
       returned, and what types they might have  is  platform-dependent.   For
       IPv4 addresses, the struct sockaddr pointer can be interpreted as if it
       pointed to a struct sockaddr_in; for IPv6 addresses, it can  be  inter-
       preted as if it pointed to a struct sockaddr_in6.

       The  list of devices must be freed with pcap_freealldevs(), which frees
       the list pointed to by alldevs.


RETURN VALUE

       pcap_findalldevs() returns 0 on success and -1  on  failure;  as  indi-
       cated,  finding  no devices is considered success, rather than failure,
       so 0 will be returned in that case.   If  -1  is  returned,  errbuf  is
       filled  in  with an appropriate error message.  errbuf is assumed to be
       able to hold at least PCAP_ERRBUF_SIZE chars.


SEE ALSO

       pcap(3), pcap_create(3), pcap_activate(3), pcap_open_live(3)



                                 7 April 2014              PCAP_FINDALLDEVS(3)