1 /* 2 * Copyright (c) 2008 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/usr.sbin/vknetd/filter.c,v 1.2 2008/05/27 22:47:16 dillon Exp $ 35 */ 36 /* 37 * Bridging code (serialized) 38 */ 39 #include "vknetd.h" 40 #include <netinet/ip.h> 41 42 /* 43 * Return on-zero if the packet should be passed through, zero if it should 44 * be discarded. 45 */ 46 int 47 filter_ok(u_int8_t *pkt, int bytes) 48 { 49 struct ip *ip; 50 u_int16_t ether_type; 51 52 if (bytes < 12 + 2 + 20) 53 return(0); 54 55 /* 56 * Allow only ARP and IP packetes 57 */ 58 ether_type = ntohs(*(u_int16_t *)(pkt + 12)); 59 if (ether_type == ETHERTYPE_ARP) 60 return(1); 61 if (ether_type != ETHERTYPE_IP) 62 return(0); 63 64 /* 65 * Allow only ICMP, TCP, and UDP protocols. 66 */ 67 ip = (void *)(pkt + 14); 68 69 switch(ip->ip_p) { 70 case 1: /* ICMP */ 71 /* XXX fix me */ 72 break; 73 case 6: /* TCP */ 74 case 17: /* UDP */ 75 /* 76 * ip_src must represent our network. 77 */ 78 if ((ip->ip_src.s_addr & NetMask.s_addr) != 79 (NetAddress.s_addr & NetMask.s_addr)) { 80 fprintf(stderr, "Filtered Address: %08x\n", 81 ntohl(ip->ip_src.s_addr)); 82 return(0); 83 } 84 break; 85 default: 86 return(0); 87 } 88 return(1); 89 } 90 91