1180593Sdwmalone/* 2180593Sdwmalone * Copyright (C) 2007 David Malone <dwmalone@FreeBSD.org> 3180593Sdwmalone * All rights reserved. 4180593Sdwmalone * 5180593Sdwmalone * Redistribution and use in source and binary forms, with or without 6180593Sdwmalone * modification, are permitted provided that the following conditions 7180593Sdwmalone * are met: 8180593Sdwmalone * 1. Redistributions of source code must retain the above copyright 9180593Sdwmalone * notice, this list of conditions and the following disclaimer. 10180593Sdwmalone * 2. Redistributions in binary form must reproduce the above copyright 11180593Sdwmalone * notice, this list of conditions and the following disclaimer in the 12180593Sdwmalone * documentation and/or other materials provided with the distribution. 13180593Sdwmalone * 14180593Sdwmalone * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15180593Sdwmalone * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16180593Sdwmalone * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17180593Sdwmalone * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18180593Sdwmalone * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19180593Sdwmalone * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20180593Sdwmalone * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21180593Sdwmalone * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22180593Sdwmalone * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23180593Sdwmalone * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24180593Sdwmalone * SUCH DAMAGE. 25180593Sdwmalone * 26180593Sdwmalone * $FreeBSD$ 27180593Sdwmalone */ 28180593Sdwmalone 29180593Sdwmalone#define ACCEPT_FILTER_MOD 30180593Sdwmalone 31180593Sdwmalone#include <sys/param.h> 32180593Sdwmalone#include <sys/kernel.h> 33180593Sdwmalone#include <sys/mbuf.h> 34180593Sdwmalone#include <sys/module.h> 35180593Sdwmalone#include <sys/signalvar.h> 36180593Sdwmalone#include <sys/sysctl.h> 37180593Sdwmalone#include <sys/socketvar.h> 38180593Sdwmalone 39180593Sdwmalone/* check for full DNS request */ 40193272Sjhbstatic int sohasdns(struct socket *so, void *arg, int waitflag); 41180593Sdwmalone 42180593Sdwmalonestruct packet { 43180593Sdwmalone struct mbuf *m; /* Current mbuf. */ 44180593Sdwmalone struct mbuf *n; /* nextpkt mbuf. */ 45180593Sdwmalone unsigned long moff; /* Offset of the beginning of m. */ 46180593Sdwmalone unsigned long offset; /* Which offset we are working at. */ 47180593Sdwmalone unsigned long len; /* The number of bytes we have to play with. */ 48180593Sdwmalone}; 49180593Sdwmalone 50180593Sdwmalone#define DNS_OK 0 51180593Sdwmalone#define DNS_WAIT -1 52180593Sdwmalone#define DNS_RUN -2 53180593Sdwmalone 54180593Sdwmalone/* check we can skip over various parts of DNS request */ 55180593Sdwmalonestatic int skippacket(struct sockbuf *sb); 56180593Sdwmalone 57180593Sdwmalonestatic struct accept_filter accf_dns_filter = { 58180593Sdwmalone "dnsready", 59180593Sdwmalone sohasdns, 60180593Sdwmalone NULL, 61180593Sdwmalone NULL 62180593Sdwmalone}; 63180593Sdwmalone 64180593Sdwmalonestatic moduledata_t accf_dns_mod = { 65180593Sdwmalone "accf_dns", 66180593Sdwmalone accept_filt_generic_mod_event, 67180593Sdwmalone &accf_dns_filter 68180593Sdwmalone}; 69180593Sdwmalone 70180593SdwmaloneDECLARE_MODULE(accf_dns, accf_dns_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE); 71180593Sdwmalone 72193272Sjhbstatic int 73180593Sdwmalonesohasdns(struct socket *so, void *arg, int waitflag) 74180593Sdwmalone{ 75180593Sdwmalone struct sockbuf *sb = &so->so_rcv; 76180593Sdwmalone 77180593Sdwmalone /* If the socket is full, we're ready. */ 78180593Sdwmalone if (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax) 79180593Sdwmalone goto ready; 80180593Sdwmalone 81192848Sjhb /* Check to see if we have a request. */ 82180593Sdwmalone if (skippacket(sb) == DNS_WAIT) 83193272Sjhb return (SU_OK); 84180593Sdwmalone 85180593Sdwmaloneready: 86193272Sjhb return (SU_ISCONNECTED); 87180593Sdwmalone} 88180593Sdwmalone 89180593Sdwmalone#define GET8(p, val) do { \ 90180593Sdwmalone if (p->offset < p->moff) \ 91180593Sdwmalone return DNS_RUN; \ 92180593Sdwmalone while (p->offset >= p->moff + p->m->m_len) { \ 93180593Sdwmalone p->moff += p->m->m_len; \ 94180593Sdwmalone p->m = p->m->m_next; \ 95180593Sdwmalone if (p->m == NULL) { \ 96180593Sdwmalone p->m = p->n; \ 97180593Sdwmalone p->n = p->m->m_nextpkt; \ 98180593Sdwmalone } \ 99180593Sdwmalone if (p->m == NULL) \ 100180593Sdwmalone return DNS_WAIT; \ 101180593Sdwmalone } \ 102180593Sdwmalone val = *(mtod(p->m, unsigned char *) + (p->offset - p->moff)); \ 103180593Sdwmalone p->offset++; \ 104180593Sdwmalone } while (0) 105180593Sdwmalone 106180593Sdwmalone#define GET16(p, val) do { \ 107180593Sdwmalone unsigned int v0, v1; \ 108180593Sdwmalone GET8(p, v0); \ 109180593Sdwmalone GET8(p, v1); \ 110180593Sdwmalone val = v0 * 0x100 + v1; \ 111180593Sdwmalone } while (0) 112180593Sdwmalone 113180593Sdwmalonestatic int 114180593Sdwmaloneskippacket(struct sockbuf *sb) { 115180593Sdwmalone unsigned long packlen; 116180593Sdwmalone struct packet q, *p = &q; 117180593Sdwmalone 118180593Sdwmalone if (sb->sb_cc < 2) 119180593Sdwmalone return DNS_WAIT; 120180593Sdwmalone 121180593Sdwmalone q.m = sb->sb_mb; 122180593Sdwmalone q.n = q.m->m_nextpkt; 123180593Sdwmalone q.moff = 0; 124180593Sdwmalone q.offset = 0; 125180593Sdwmalone q.len = sb->sb_cc; 126180593Sdwmalone 127180593Sdwmalone GET16(p, packlen); 128192848Sjhb if (packlen + 2 > q.len) 129180593Sdwmalone return DNS_WAIT; 130180593Sdwmalone 131180593Sdwmalone return DNS_OK; 132180593Sdwmalone} 133