freebsd-dev/sys/net/bpfdesc.h
John Polstra 81bda851db Make bpf's read timeout feature work more correctly with
select/poll, and therefore with pthreads.  I doubt there is any way
to make this 100% semantically identical to the way it behaves in
unthreaded programs with blocking reads, but the solution here
should do the right thing for all reasonable usage patterns.

The basic idea is to schedule a callout for the read timeout when a
select/poll is done.  When the callout fires, it ends the select if
it is still in progress, or marks the state as "timed out" if the
select has already ended for some other reason.  Additional logic in
bpfread then does the right thing in the case where the timeout has
fired.

Note, I co-opted the bd_state member of the bpf_d structure.  It has
been present in the structure since the initial import of 4.4-lite,
but as far as I can tell it has never been used.

PR:		kern/22063 and bin/31649
MFC after:	3 days
2001-12-14 22:17:54 +00:00

121 lines
4.9 KiB
C

/*
* Copyright (c) 1990, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from the Stanford/CMU enet packet filter,
* (net/enet.c) distributed as part of 4.3BSD, and code contributed
* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
* Berkeley Laboratory.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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 BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)bpfdesc.h 8.1 (Berkeley) 6/10/93
*
* $FreeBSD$
*/
#ifndef _NET_BPFDESC_H_
#define _NET_BPFDESC_H_
#include <sys/callout.h>
#include <sys/selinfo.h>
/*
* Descriptor associated with each open bpf file.
*/
struct bpf_d {
struct bpf_d *bd_next; /* Linked list of descriptors */
/*
* Buffer slots: two mbuf clusters buffer the incoming packets.
* The model has three slots. Sbuf is always occupied.
* sbuf (store) - Receive interrupt puts packets here.
* hbuf (hold) - When sbuf is full, put cluster here and
* wakeup read (replace sbuf with fbuf).
* fbuf (free) - When read is done, put cluster here.
* On receiving, if sbuf is full and fbuf is 0, packet is dropped.
*/
caddr_t bd_sbuf; /* store slot */
caddr_t bd_hbuf; /* hold slot */
caddr_t bd_fbuf; /* free slot */
int bd_slen; /* current length of store buffer */
int bd_hlen; /* current length of hold buffer */
int bd_bufsize; /* absolute length of buffers */
struct bpf_if * bd_bif; /* interface descriptor */
u_long bd_rtout; /* Read timeout in 'ticks' */
struct bpf_insn *bd_filter; /* filter code */
u_long bd_rcount; /* number of packets received */
u_long bd_dcount; /* number of packets dropped */
u_char bd_promisc; /* true if listening promiscuously */
u_char bd_state; /* idle, waiting, or timed out */
u_char bd_immediate; /* true to return on packet arrival */
int bd_hdrcmplt; /* false to fill in src lladdr automatically */
int bd_seesent; /* true if bpf should see sent packets */
int bd_async; /* non-zero if packet reception should generate signal */
int bd_sig; /* signal to send upon packet reception */
struct sigio * bd_sigio; /* information for async I/O */
#if BSD < 199103
u_char bd_selcoll; /* true if selects collide */
int bd_timedout;
struct thread * bd_selthread; /* process that last selected us */
#else
u_char bd_pad; /* explicit alignment */
struct selinfo bd_sel; /* bsd select info */
#endif
struct mtx bd_mtx; /* mutex for this descriptor */
struct callout bd_callout; /* for BPF timeouts with select */
};
/* Values for bd_state */
#define BPF_IDLE 0 /* no select in progress */
#define BPF_WAITING 1 /* waiting for read timeout in select */
#define BPF_TIMED_OUT 2 /* read timeout has expired in select */
#define BPFD_LOCK(bd) mtx_lock(&(bd)->bd_mtx)
#define BPFD_UNLOCK(bd) mtx_unlock(&(bd)->bd_mtx)
/*
* Descriptor associated with each attached hardware interface.
*/
struct bpf_if {
struct bpf_if *bif_next; /* list of all interfaces */
struct bpf_d *bif_dlist; /* descriptor list */
u_int bif_dlt; /* link layer type */
u_int bif_hdrlen; /* length of header (with padding) */
struct ifnet *bif_ifp; /* corresponding interface */
struct mtx bif_mtx; /* mutex for interface */
};
#define BPFIF_LOCK(bif) mtx_lock(&(bif)->bif_mtx)
#define BPFIF_UNLOCK(bif) mtx_unlock(&(bif)->bif_mtx)
#endif