On Jan 24, 2016, at 7:47 PM, Yang Luo <[email protected]> wrote:
> My ubuntu 14.04 shows the lines below, so I think it doesn't support
> IFF_LOOPBACK.
> root@ly-controller:~# ifconfig lo
> lo Link encap:Local Loopback
>
> inet addr:127.0.0.1 Mask:255.0.0.0
> inet6 addr: ::1/128 Scope:Host
> UP LOOPBACK RUNNING MTU:65536 Metric:1
^^^^^^^^^
> RX packets:10580846 errors:0 dropped:0 overruns:0 frame:0
> TX packets:10580846 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:2877631654 (2.8 GB) TX bytes:2877631654 (2.8 GB)
No, it *does* support it.
> However Windows supports it.
Yes, there's an IFF_LOOPBACK flag in Winsock:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms738568(v=vs.85).aspx
But is it actually set for any interface, or is it just provided for source
compatibility with various UN*Xes?
> <image.png>
>
> I have analyzed the code related to me. Currently my code is in
> inet.c----add_or_find_if. It has curdev->flags and this must be set. What
> pcap-win32.c has is pcap_create and pcap_activate_win32, called by
> pcap_open_live which is called by add_or_find_if. If I make the change in
> pcap-win32.c, the code would be very ugly.
In the current version of the code on the trunk, which I just checked in,
add_or_find_if() takes PCAP_IF_ flags, rather than IFF_ flags, as arguments.
In pcap_add_if_win32(), check whether the interface is a loopback interface
and, if it is, pass PCAP_IF_LOOPBACK to add_or_find_if(), otherwise pass 0.
(There appear to be OIDs that will determine whether the interface is "working"
or not, but 1) they appear to be different in NDIS 5 and NDIS 6 and 2) they
don't separate "up" and "running", so you could only use them to determine
whether to pass PCAP_IF_UP|PCAP_IF_RUNNING, possibly combined with
PCAP_IF_LOOPBACK, or just 0, possibly combined with PCAP_IF_LOOPBACK.)
> Maybe I should just put my code in inet.c and wrap it with #ifdef WIN32 macro?
No - see above.
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