freebsd-dev/sys/netinet/libalias/alias_mod.c
Gleb Smirnoff 535e0a0981 Cleanup alias module handler register/unregister.
- Remove locking, since all module(9) events are running under &Giant.
- Use TAILQ for protocol handlers and fix a bug which led to
  infinite cycle. Bug found in VirtualBox [1]
- Simplify code everywhere.
- Fix documentation.

[1]  https://www.virtualbox.org/pipermail/vbox-dev/2013-November/011936.html

PR:		183792 [1]
Submitted by:	Valery Ushakov <uwe NetBSD.org> [1]
Sponsored by:	Nginx, Inc.
2013-12-25 03:24:20 +00:00

173 lines
4.0 KiB
C

/*-
* Copyright (c) 2005 Paolo Pisati <piso@FreeBSD.org>
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#ifdef _KERNEL
#include <sys/libkern.h>
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#else
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <errno.h>
#endif
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#ifdef _KERNEL
#include <netinet/libalias/alias_local.h>
#include <netinet/libalias/alias_mod.h>
#else
#include "alias_local.h"
#include "alias_mod.h"
#endif
/* Protocol and userland module handlers chains. */
static TAILQ_HEAD(handler_chain, proto_handler) handler_chain =
TAILQ_HEAD_INITIALIZER(handler_chain);
static int
attach_handler(struct proto_handler *p)
{
struct proto_handler *b;
TAILQ_FOREACH(b, &handler_chain, link) {
if ((b->pri == p->pri) &&
(b->dir == p->dir) &&
(b->proto == p->proto))
return (EEXIST);
if (b->pri > p->pri) {
TAILQ_INSERT_BEFORE(b, p, link);
return (0);
}
}
TAILQ_INSERT_TAIL(&handler_chain, p, link);
return (0);
}
int
LibAliasAttachHandlers(struct proto_handler *p)
{
int error;
while (p->dir != NODIR) {
error = attach_handler(p);
if (error)
return (error);
p++;
}
return (0);
}
/* XXXGL: should be void, but no good reason to break ABI */
int
LibAliasDetachHandlers(struct proto_handler *p)
{
while (p->dir != NODIR) {
TAILQ_REMOVE(&handler_chain, p, link);
p++;
}
return (0);
}
int
find_handler(int8_t dir, int8_t proto, struct libalias *la, struct ip *ip,
struct alias_data *ad)
{
struct proto_handler *p;
TAILQ_FOREACH(p, &handler_chain, link)
if ((p->dir & dir) && (p->proto & proto) &&
p->fingerprint(la, ad) == 0)
return (p->protohandler(la, ip, ad));
return (ENOENT);
}
struct proto_handler *
first_handler(void)
{
return (TAILQ_FIRST(&handler_chain));
}
#ifndef _KERNEL
/* Dll manipulation code - this code is not thread safe... */
SLIST_HEAD(dll_chain, dll) dll_chain = SLIST_HEAD_INITIALIZER(dll_chain);
int
attach_dll(struct dll *p)
{
struct dll *b;
SLIST_FOREACH(b, &dll_chain, next) {
if (!strncmp(b->name, p->name, DLL_LEN))
return (EEXIST); /* Dll name conflict. */
}
SLIST_INSERT_HEAD(&dll_chain, p, next);
return (0);
}
void *
detach_dll(char *p)
{
struct dll *b, *b_tmp;
void *error;
b = NULL;
error = NULL;
SLIST_FOREACH_SAFE(b, &dll_chain, next, b_tmp)
if (!strncmp(b->name, p, DLL_LEN)) {
SLIST_REMOVE(&dll_chain, b, dll, next);
error = b;
break;
}
return (error);
}
struct dll *
walk_dll_chain(void)
{
struct dll *t;
t = SLIST_FIRST(&dll_chain);
if (t == NULL)
return (NULL);
SLIST_REMOVE_HEAD(&dll_chain, next);
return (t);
}
#endif /* !_KERNEL */