2 * Copyright (C) 2007 David Malone <dwmalone@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #define ACCEPT_FILTER_MOD
31 #include <sys/param.h>
32 #include <sys/kernel.h>
34 #include <sys/module.h>
35 #include <sys/signalvar.h>
36 #include <sys/sysctl.h>
37 #include <sys/socketvar.h>
39 /* check for full DNS request */
40 static int sohasdns(struct socket *so, void *arg, int waitflag);
43 struct mbuf *m; /* Current mbuf. */
44 struct mbuf *n; /* nextpkt mbuf. */
45 unsigned long moff; /* Offset of the beginning of m. */
46 unsigned long offset; /* Which offset we are working at. */
47 unsigned long len; /* The number of bytes we have to play with. */
54 /* check we can skip over various parts of DNS request */
55 static int skippacket(struct sockbuf *sb);
57 static struct accept_filter accf_dns_filter = {
64 static moduledata_t accf_dns_mod = {
66 accept_filt_generic_mod_event,
70 DECLARE_MODULE(accf_dns, accf_dns_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
73 sohasdns(struct socket *so, void *arg, int waitflag)
75 struct sockbuf *sb = &so->so_rcv;
77 /* If the socket is full, we're ready. */
78 if (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax)
81 /* Check to see if we have a request. */
82 if (skippacket(sb) == DNS_WAIT)
86 return (SU_ISCONNECTED);
89 #define GET8(p, val) do { \
90 if (p->offset < p->moff) \
92 while (p->offset >= p->moff + p->m->m_len) { \
93 p->moff += p->m->m_len; \
94 p->m = p->m->m_next; \
97 p->n = p->m->m_nextpkt; \
102 val = *(mtod(p->m, unsigned char *) + (p->offset - p->moff)); \
106 #define GET16(p, val) do { \
107 unsigned int v0, v1; \
110 val = v0 * 0x100 + v1; \
114 skippacket(struct sockbuf *sb) {
115 unsigned long packlen;
116 struct packet q, *p = &q;
122 q.n = q.m->m_nextpkt;
128 if (packlen + 2 > q.len)