Re: [PATCH]: pcap and zero copy.

["Gisle Vanem" <giva () bgnett no>]

"Yoann Vandoorselaere" <yoann () prelude-ids org> said:

> here is a patch I made to libpcap, permitting zero copy by allowing the
> calling application to specify it's own allocation/freeing function for
> the packet buffer, and the pcap header.

I didn't see any patch for pcap-win32.c, but  not sure it's possible with
a zero-copy here. Except maybe using shared memory or overlapped
I/O.

> This patch was done in a way that it won't break the existing libpcap
> API (except for the pcap_next function, but I could simply remove the

I agree that many args should be 'const'ed, but your patch will break e.g. 
Ethereal that binds to libpcap functions via dynamic lib-loading and function-
pointers.

--- libpcap-0.7.2/pcap-int.h    2001-08-24 09:46:52.000000000 +0200
+++ libpcap/pcap-int.h  2003-10-05 23:30:22.000000000 +0200
@@ -117,6 +117,23 @@ struct pcap_timeval {
     bpf_int32 tv_usec;         /* microseconds */
 };

+
+        struct buffer_head {
+                int refcount;
+                unsigned char buf[0];
+        };
+

Not all compilers support zero-sized arrays.

--gv

-
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