Split the pcap(3) man page into a bunch of individual man pages for

functions plus an overall man page for libpcap, and put them all into
section 3PCAP.  That means you can actually do "man pcap_open_live" and
get something meaningful, rather than having to do "man pcap" and then
scroll through all the other stuff in the man page.

1 files changed, 164 insertions, 0 deletions

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+.\" @(#) $Header: /tcpdump/master/libpcap/pcap_loop.3pcap,v 1.1 2008-04-05 20:19:42 guy Exp $
+.\"
+.\" Copyright (c) 1994, 1996, 1997
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that: (1) source code distributions
+.\" retain the above copyright notice and this paragraph in its entirety, (2)
+.\" distributions including binary code include the above copyright notice and
+.\" this paragraph in its entirety in the documentation or other materials
+.\" provided with the distribution, and (3) all advertising materials mentioning
+.\" features or use of this software display the following acknowledgement:
+.\" ``This product includes software developed by the University of California,
+.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+.\" the University nor the names of its contributors may be used to endorse
+.\" or promote products derived from this software without specific prior
+.\" written permission.
+.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+.\"
+.TH PCAP_LOOP 3PCAP "4 April 2008"
+.SH NAME
+pcap_loop, pcap_dispatch \- process packets from a live capture or savefile
+.SH SYNOPSIS
+.nf
+.ft B
+#include <pcap.h>
+.ft
+.LP
+.ft B
+typedef void (*pcap_handler)(u_char *user, const struct pcap_pkthdr *h,
+.ti +8
+			     const u_char *bytes);
+.ft
+.LP
+.ft B
+int pcap_loop(pcap_t *p, int cnt,
+.ti +8
+pcap_handler callback, u_char *user);
+int pcap_dispatch(pcap_t *p, int cnt,
+.ti +8
+pcap_handler callback, u_char *user);
+.ft
+.fi
+.SH DESCRIPTION
+.B pcap_loop()
+processes packets from a live capture or ``savefile'' until
+.I cnt
+packets are processed, the end of the ``savefile'' is
+reached when reading from a ``savefile'',
+.B pcap_breakloop()
+is called, or an error occurs.
+It does
+.B not
+return when live read timeouts occur.
+A value of \-1 or 0 for
+.I cnt
+is equivalent to infinity, so that packets are processed until another
+ending condition occurs.
+.PP
+.B pcap_dispatch()
+processes packets from a live capture or ``savefile'' until
+.I cnt
+packets are processed, the end of the current bufferful of packets is
+reached when doing a live capture, the end of the ``savefile'' is
+reached when reading from a ``savefile'',
+.B pcap_breakloop()
+is called, or an error occurs.
+Thus, when doing a live capture,
+.I cnt
+is the maximum number of packets to process before returning, but is not
+a minimum number; when reading a live capture, only one
+bufferful of packets is read at a time, so fewer than
+.I cnt
+packets may be processed. A value of \-1 or 0 for
+.I cnt
+causes all the packets received in one buffer to be processed when
+reading a live capture, and causes all the packets in the file to be
+processed when reading a ``savefile''.
+.PP
+.ft B
+(In older versions of libpcap, the behavior when
+\fIcnt\fP
+was 0 was undefined; different platforms and devices behaved
+differently, so code that must work with older versions of libpcap
+should use \-1, nor 0, as the value of
+\fIcnt\fP.)
+.ft R
+.PP
+.I callback
+specifies a routine to be called with three arguments:
+a
+.I u_char
+pointer which is passed in the
+.I user
+argument to
+.B pcap_loop()
+or
+.BR pcap_dispatch() ,
+a
+.I const struct pcap_pkthdr
+pointer pointing to the packet time stamp and lengths, and a
+.I const u_char
+pointer to the first
+.B caplen
+(as given in the
+.I struct pcap_pkthdr
+a pointer to which is passed to the callback routine)
+bytes of data from the packet.
+.PP
+.BR NOTE :
+when reading a live capture,
+.B pcap_dispatch()
+will not necessarily return when the read times out; on some platforms,
+the read timeout isn't supported, and, on other platforms, the timer
+doesn't start until at least one packet arrives.  This means that the
+read timeout should
+.B NOT
+be used in, for example, an interactive application, to allow the packet
+capture loop to ``poll'' for user input periodically, as there's no
+guarantee that
+.B pcap_dispatch()
+will return after the timeout expires.
+.SH RETURN VALUE
+.B pcap_loop()
+returns 0 if
+.I cnt
+is exhausted, \-1 if an error occurs, or \-2 if the loop terminated due
+to a call to
+.B pcap_breakloop()
+before any packets were processed.
+It does
+.B not
+return when live read timeouts occur; instead, it attempts to read more
+packets.
+.PP
+.B pcap_dispatch()
+returns the number of packets processed on success; this can be 0 if no
+packets were read from a live capture (if, for example, they were
+discarded because they didn't pass the packet filter, or if, on
+platforms that support a read timeout that starts before any packets
+arrive, the timeout expires before any packets arrive, or if the file
+descriptor for the capture device is in non-blocking mode and no packets
+were available to be read) or if no more packets are available in a
+``savefile.''  It returns \-1 if an error occurs or \-2 if the loop
+terminated due to a call to
+.B pcap_breakloop()
+before any packets were processed.
+.ft B
+If your application uses pcap_breakloop(),
+make sure that you explicitly check for \-1 and \-2, rather than just
+checking for a return value < 0.
+.ft R
+.PP
+If \-1 is returned,
+.B pcap_geterr()
+or
+.B pcap_perror()
+may be called with
+.I p
+as an argument to fetch or display the error text.
+.SH SEE ALSO
+pcap_geterr(3PCAP), pcap_breakloop(3PCAP)