"getifaddrs()"), after processing the list returned by SIOCGIFCONF, scan
"/proc/net/dev" for interface names, and add to the list of interfaces
entries for those interfaces, with no associated addresses (if the
interfaces were already added, with addresses, from the list returned by
SIOCGIFCONF, they won't get added again).
Clean up the error handling a bit.
whether we have "freeifaddrs()" (we don't check whether we have
"getifaddrs()", and if we have "getifaddrs()" but not "freeifaddrs()",
we're stuck with leaking memory).
Give the "any" device an instance number of INT_MAX, so it shows up
after all other non-loopback devices.
"getifaddrs()" sometimes appears to supply a destination address even
for non-point-to-point interfaces (it did so on a FreeBSD 4.1 system);
don't use the broadcast address it supplies if an interface isn't a
broadcast interface, and don't use the destination address it supplies
if an interface isn't a point-to-point interface.
If we had an error constructing the list of interfaces, don't attempt to
add the "any" device to the list.
SOL_PACKET/PACKET_STATISTICS "getsockopt()" call, on Linux kernels that
support it, to get packet statistics, so that we can report the number
of dropped packets, and always use <linux/if_packet.h> to get
definitions for PF_PACKET sockets, so that we don't depend on glibc's
header files having been updated to support all the latest shiniest
kernel features (many systems with 2.4[.x] kernels don't have a
<netpacket/packet.h> that defines "struct tpacket_stats", for example,
so we wouldn't have been able to support that kernel feature on those
systems).
fenner