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freebsd-dev/sys/netinet/accf_dns.c

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Add an accept filter for TCP based DNS requests. It waits until the whole first request is present before returning from accept.
2008-07-18 14:44:51 +00:00
/*
* Copyright (C) 2007 David Malone <dwmalone@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.
*
* $FreeBSD$
*/
#define ACCEPT_FILTER_MOD
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/socketvar.h>
/* check for full DNS request */
Rework socket upcalls to close some races with setup/teardown of upcalls. - Each socket upcall is now invoked with the appropriate socket buffer locked. It is not permissible to call soisconnected() with this lock held; however, so socket upcalls now return an integer value. The two possible values are SU_OK and SU_ISCONNECTED. If an upcall returns SU_ISCONNECTED, then the soisconnected() will be invoked on the socket after the socket buffer lock is dropped. - A new API is provided for setting and clearing socket upcalls. The API consists of soupcall_set() and soupcall_clear(). - To simplify locking, each socket buffer now has a separate upcall. - When a socket upcall returns SU_ISCONNECTED, the upcall is cleared from the receive socket buffer automatically. Note that a SO_SND upcall should never return SU_ISCONNECTED. - All this means that accept filters should now return SU_ISCONNECTED instead of calling soisconnected() directly. They also no longer need to explicitly clear the upcall on the new socket. - The HTTP accept filter still uses soupcall_set() to manage its internal state machine, but other accept filters no longer have any explicit knowlege of socket upcall internals aside from their return value. - The various RPC client upcalls currently drop the socket buffer lock while invoking soreceive() as a temporary band-aid. The plan for the future is to add a new flag to allow soreceive() to be called with the socket buffer locked. - The AIO callback for socket I/O is now also invoked with the socket buffer locked. Previously sowakeup() would drop the socket buffer lock only to call aio_swake() which immediately re-acquired the socket buffer lock for the duration of the function call. Discussed with: rwatson, rmacklem
2009-06-01 21:17:03 +00:00
static int sohasdns(struct socket *so, void *arg, int waitflag);
Add an accept filter for TCP based DNS requests. It waits until the whole first request is present before returning from accept.
2008-07-18 14:44:51 +00:00
struct packet {
struct mbuf *m; /* Current mbuf. */
struct mbuf *n; /* nextpkt mbuf. */
unsigned long moff; /* Offset of the beginning of m. */
unsigned long offset; /* Which offset we are working at. */
unsigned long len; /* The number of bytes we have to play with. */
};
#define DNS_OK 0
#define DNS_WAIT -1
#define DNS_RUN -2
/* check we can skip over various parts of DNS request */
static int skippacket(struct sockbuf *sb);
static struct accept_filter accf_dns_filter = {
"dnsready",
sohasdns,
NULL,
NULL
};
static moduledata_t accf_dns_mod = {
"accf_dns",
accept_filt_generic_mod_event,
&accf_dns_filter
};
DECLARE_MODULE(accf_dns, accf_dns_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
Rework socket upcalls to close some races with setup/teardown of upcalls. - Each socket upcall is now invoked with the appropriate socket buffer locked. It is not permissible to call soisconnected() with this lock held; however, so socket upcalls now return an integer value. The two possible values are SU_OK and SU_ISCONNECTED. If an upcall returns SU_ISCONNECTED, then the soisconnected() will be invoked on the socket after the socket buffer lock is dropped. - A new API is provided for setting and clearing socket upcalls. The API consists of soupcall_set() and soupcall_clear(). - To simplify locking, each socket buffer now has a separate upcall. - When a socket upcall returns SU_ISCONNECTED, the upcall is cleared from the receive socket buffer automatically. Note that a SO_SND upcall should never return SU_ISCONNECTED. - All this means that accept filters should now return SU_ISCONNECTED instead of calling soisconnected() directly. They also no longer need to explicitly clear the upcall on the new socket. - The HTTP accept filter still uses soupcall_set() to manage its internal state machine, but other accept filters no longer have any explicit knowlege of socket upcall internals aside from their return value. - The various RPC client upcalls currently drop the socket buffer lock while invoking soreceive() as a temporary band-aid. The plan for the future is to add a new flag to allow soreceive() to be called with the socket buffer locked. - The AIO callback for socket I/O is now also invoked with the socket buffer locked. Previously sowakeup() would drop the socket buffer lock only to call aio_swake() which immediately re-acquired the socket buffer lock for the duration of the function call. Discussed with: rwatson, rmacklem
2009-06-01 21:17:03 +00:00
static int
Add an accept filter for TCP based DNS requests. It waits until the whole first request is present before returning from accept.
2008-07-18 14:44:51 +00:00
sohasdns(struct socket *so, void *arg, int waitflag)
{
struct sockbuf *sb = &so->so_rcv;
/* If the socket is full, we're ready. */
if (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax)
goto ready;
Correct the sense of a test so that this filter always waits for the full request to arrive. Previously it would end up returning as soon as the request length stored in the first two bytes had arrived. Reviewed by: dwmalone MFC after: 1 week
2009-05-26 20:00:30 +00:00
/* Check to see if we have a request. */
Add an accept filter for TCP based DNS requests. It waits until the whole first request is present before returning from accept.
2008-07-18 14:44:51 +00:00
if (skippacket(sb) == DNS_WAIT)
Rework socket upcalls to close some races with setup/teardown of upcalls. - Each socket upcall is now invoked with the appropriate socket buffer locked. It is not permissible to call soisconnected() with this lock held; however, so socket upcalls now return an integer value. The two possible values are SU_OK and SU_ISCONNECTED. If an upcall returns SU_ISCONNECTED, then the soisconnected() will be invoked on the socket after the socket buffer lock is dropped. - A new API is provided for setting and clearing socket upcalls. The API consists of soupcall_set() and soupcall_clear(). - To simplify locking, each socket buffer now has a separate upcall. - When a socket upcall returns SU_ISCONNECTED, the upcall is cleared from the receive socket buffer automatically. Note that a SO_SND upcall should never return SU_ISCONNECTED. - All this means that accept filters should now return SU_ISCONNECTED instead of calling soisconnected() directly. They also no longer need to explicitly clear the upcall on the new socket. - The HTTP accept filter still uses soupcall_set() to manage its internal state machine, but other accept filters no longer have any explicit knowlege of socket upcall internals aside from their return value. - The various RPC client upcalls currently drop the socket buffer lock while invoking soreceive() as a temporary band-aid. The plan for the future is to add a new flag to allow soreceive() to be called with the socket buffer locked. - The AIO callback for socket I/O is now also invoked with the socket buffer locked. Previously sowakeup() would drop the socket buffer lock only to call aio_swake() which immediately re-acquired the socket buffer lock for the duration of the function call. Discussed with: rwatson, rmacklem
2009-06-01 21:17:03 +00:00
return (SU_OK);
Add an accept filter for TCP based DNS requests. It waits until the whole first request is present before returning from accept.
2008-07-18 14:44:51 +00:00
ready:
Rework socket upcalls to close some races with setup/teardown of upcalls. - Each socket upcall is now invoked with the appropriate socket buffer locked. It is not permissible to call soisconnected() with this lock held; however, so socket upcalls now return an integer value. The two possible values are SU_OK and SU_ISCONNECTED. If an upcall returns SU_ISCONNECTED, then the soisconnected() will be invoked on the socket after the socket buffer lock is dropped. - A new API is provided for setting and clearing socket upcalls. The API consists of soupcall_set() and soupcall_clear(). - To simplify locking, each socket buffer now has a separate upcall. - When a socket upcall returns SU_ISCONNECTED, the upcall is cleared from the receive socket buffer automatically. Note that a SO_SND upcall should never return SU_ISCONNECTED. - All this means that accept filters should now return SU_ISCONNECTED instead of calling soisconnected() directly. They also no longer need to explicitly clear the upcall on the new socket. - The HTTP accept filter still uses soupcall_set() to manage its internal state machine, but other accept filters no longer have any explicit knowlege of socket upcall internals aside from their return value. - The various RPC client upcalls currently drop the socket buffer lock while invoking soreceive() as a temporary band-aid. The plan for the future is to add a new flag to allow soreceive() to be called with the socket buffer locked. - The AIO callback for socket I/O is now also invoked with the socket buffer locked. Previously sowakeup() would drop the socket buffer lock only to call aio_swake() which immediately re-acquired the socket buffer lock for the duration of the function call. Discussed with: rwatson, rmacklem
2009-06-01 21:17:03 +00:00
return (SU_ISCONNECTED);
Add an accept filter for TCP based DNS requests. It waits until the whole first request is present before returning from accept.
2008-07-18 14:44:51 +00:00
}
#define GET8(p, val) do { \
if (p->offset < p->moff) \
return DNS_RUN; \
while (p->offset >= p->moff + p->m->m_len) { \
p->moff += p->m->m_len; \
p->m = p->m->m_next; \
if (p->m == NULL) { \
p->m = p->n; \
p->n = p->m->m_nextpkt; \
} \
if (p->m == NULL) \
return DNS_WAIT; \
} \
val = *(mtod(p->m, unsigned char *) + (p->offset - p->moff)); \
p->offset++; \
} while (0)
#define GET16(p, val) do { \
unsigned int v0, v1; \
GET8(p, v0); \
GET8(p, v1); \
val = v0 * 0x100 + v1; \
} while (0)
static int
skippacket(struct sockbuf *sb) {
unsigned long packlen;
struct packet q, *p = &q;
if (sb->sb_cc < 2)
return DNS_WAIT;
q.m = sb->sb_mb;
q.n = q.m->m_nextpkt;
q.moff = 0;
q.offset = 0;
q.len = sb->sb_cc;
GET16(p, packlen);
Correct the sense of a test so that this filter always waits for the full request to arrive. Previously it would end up returning as soon as the request length stored in the first two bytes had arrived. Reviewed by: dwmalone MFC after: 1 week
2009-05-26 20:00:30 +00:00
if (packlen + 2 > q.len)
Add an accept filter for TCP based DNS requests. It waits until the whole first request is present before returning from accept.
2008-07-18 14:44:51 +00:00
return DNS_WAIT;
return DNS_OK;
}
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