Wireshark mailing list archives
Re: converting pcapng to pcap
From: sandra <deepaksoni1959 () yahoo com>
Date: Wed, 3 Apr 2013 09:27:24 +0000 (UTC)
Guy Harris <guy@...> writes:
Hi, I was searching for about pcap, so came across this link. I need to make
my own packet sniffer like tcpdump. I am aware of the list of functions used to read ,callback fns etc. I wanted to know the list of APIs been called for calling libpcap. Can somebody help
On Sep 28, 2012, at 2:01 PM, albert <alo@...> wrote:What/where is/are the function(s) that determine(s) whether the callback
for
next_packet_op is going to be pcap_dump() or some other higher level
routine ?
The next_packet_op is a *read* function, not a *write* function, so it would,
of course, not be set in
pcap_dump(), as that's a *write*-path routine. It's set in the open-for-reading path, either by pcap_check_header() if it's
a pcap file or
pcap_ng_check_header() if it's a pcap-ng file. The open-offline routines (pcap_open_offline() and pcap_fopen_offline()) try
calling each of the
routines in the check_headers[] array, to check whether the file is a file of
the routine's type. If so, the
routine sets the next_packet_op to the appropriate routine for that file type
and returns 1 to indicate
that the correct file type has been found.Is this a function that the user must supply ?No. That's all an internal detail of the current libpcap implementation, so
that programs do *not* have to
be changed in order to be able to read pcap-ng files. (The current libpcap
API limits what types of files can
be read - the link-layer header type is per-file, not per-packet or per-
interface, in the API, so it
doesn't support files with multiple link-layer header types - so *full*
support of pcap-ng files will
require an additional set of APIs, which programs *would* have to be changed
to use. The new APIs will still
support pcap, however; requiring programs to know whether they're reading
pcap or pcap-ng or... files is
an error.) ___________________________________________________________________________ Sent via: Wireshark-dev mailing list <wireshark-dev@...> Archives: http://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev mailto:wireshark-dev-request@...?subject=unsubscribe
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Current thread:
- Re: converting pcapng to pcap sandra (Apr 03)