inet.c revision 39291
1/* 2 * Copyright (c) 1994, 1995, 1996, 1997, 1998 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 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. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the Computer Systems 16 * Engineering Group at Lawrence Berkeley Laboratory. 17 * 4. Neither the name of the University nor of the Laboratory may be used 18 * to endorse or promote products derived from this software without 19 * specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#ifndef lint 35static const char rcsid[] = 36 "@(#) $Header: inet.c,v 1.22 98/01/30 17:29:34 leres Exp $ (LBL)"; 37#endif 38 39#include <sys/param.h> 40#include <sys/file.h> 41#include <sys/ioctl.h> 42#include <sys/socket.h> 43#ifdef HAVE_SYS_SOCKIO_H 44#include <sys/sockio.h> 45#endif 46#include <sys/time.h> /* concession to AIX */ 47 48#if __STDC__ 49struct mbuf; 50struct rtentry; 51#endif 52 53#include <net/if.h> 54#include <netinet/in.h> 55 56#include <ctype.h> 57#include <errno.h> 58#include <memory.h> 59#include <stdio.h> 60#include <stdlib.h> 61#include <string.h> 62#include <unistd.h> 63 64#include "pcap-int.h" 65 66#include "gnuc.h" 67#ifdef HAVE_OS_PROTO_H 68#include "os-proto.h" 69#endif 70 71/* Not all systems have IFF_LOOPBACK */ 72#ifdef IFF_LOOPBACK 73#define ISLOOPBACK(p) ((p)->ifr_flags & IFF_LOOPBACK) 74#else 75#define ISLOOPBACK(p) ((p)->ifr_name[0] == 'l' && (p)->ifr_name[1] == 'o' && \ 76 (isdigit((p)->ifr_name[2]) || (p)->ifr_name[2] == '\0')) 77#endif 78 79/* 80 * Return the name of a network interface attached to the system, or NULL 81 * if none can be found. The interface must be configured up; the 82 * lowest unit number is preferred; loopback is ignored. 83 */ 84char * 85pcap_lookupdev(errbuf) 86 register char *errbuf; 87{ 88 register int fd, minunit, n; 89 register char *cp; 90 register struct ifreq *ifrp, *ifend, *ifnext, *mp; 91 struct ifconf ifc; 92 struct ifreq ibuf[16], ifr; 93 static char device[sizeof(ifrp->ifr_name) + 1]; 94 95 fd = socket(AF_INET, SOCK_DGRAM, 0); 96 if (fd < 0) { 97 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno)); 98 return (NULL); 99 } 100 ifc.ifc_len = sizeof ibuf; 101 ifc.ifc_buf = (caddr_t)ibuf; 102 103 memset((char *)ibuf, 0, sizeof(ibuf)); 104 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 || 105 ifc.ifc_len < sizeof(struct ifreq)) { 106 (void)sprintf(errbuf, "SIOCGIFCONF: %s", pcap_strerror(errno)); 107 (void)close(fd); 108 return (NULL); 109 } 110 ifrp = ibuf; 111 ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len); 112 113 mp = NULL; 114 minunit = 666; 115 for (; ifrp < ifend; ifrp = ifnext) { 116#ifdef HAVE_SOCKADDR_SA_LEN 117 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name); 118 if (n < sizeof(*ifrp)) 119 ifnext = ifrp + 1; 120 else 121 ifnext = (struct ifreq *)((char *)ifrp + n); 122 if (ifrp->ifr_addr.sa_family != AF_INET) 123 continue; 124#else 125 ifnext = ifrp + 1; 126#endif 127 /* 128 * Need a template to preserve address info that is 129 * used below to locate the next entry. (Otherwise, 130 * SIOCGIFFLAGS stomps over it because the requests 131 * are returned in a union.) 132 */ 133 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name)); 134 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) { 135 if (errno == ENXIO) 136 continue; 137 (void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s", 138 (int)sizeof(ifr.ifr_name), ifr.ifr_name, 139 pcap_strerror(errno)); 140 (void)close(fd); 141 return (NULL); 142 } 143 144 /* Must be up and not the loopback */ 145 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr)) 146 continue; 147 148 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp) 149 continue; 150 n = atoi(cp); 151 if (n < minunit) { 152 minunit = n; 153 mp = ifrp; 154 } 155 } 156 (void)close(fd); 157 if (mp == NULL) { 158 (void)strcpy(errbuf, "no suitable device found"); 159 return (NULL); 160 } 161 162 (void)strncpy(device, mp->ifr_name, sizeof(device) - 1); 163 device[sizeof(device) - 1] = '\0'; 164 return (device); 165} 166 167int 168pcap_lookupnet(device, netp, maskp, errbuf) 169 register char *device; 170 register bpf_u_int32 *netp, *maskp; 171 register char *errbuf; 172{ 173 register int fd; 174 register struct sockaddr_in *sin; 175 struct ifreq ifr; 176 177 fd = socket(AF_INET, SOCK_DGRAM, 0); 178 if (fd < 0) { 179 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno)); 180 return (-1); 181 } 182 memset(&ifr, 0, sizeof(ifr)); 183#ifdef linux 184 /* XXX Work around Linux kernel bug */ 185 ifr.ifr_addr.sa_family = AF_INET; 186#endif 187 (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 188 if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) { 189 (void)sprintf(errbuf, "SIOCGIFADDR: %s: %s", 190 device, pcap_strerror(errno)); 191 (void)close(fd); 192 return (-1); 193 } 194 sin = (struct sockaddr_in *)&ifr.ifr_addr; 195 *netp = sin->sin_addr.s_addr; 196 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) { 197 (void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s", 198 device, pcap_strerror(errno)); 199 (void)close(fd); 200 return (-1); 201 } 202 (void)close(fd); 203 *maskp = sin->sin_addr.s_addr; 204 if (*maskp == 0) { 205 if (IN_CLASSA(*netp)) 206 *maskp = IN_CLASSA_NET; 207 else if (IN_CLASSB(*netp)) 208 *maskp = IN_CLASSB_NET; 209 else if (IN_CLASSC(*netp)) 210 *maskp = IN_CLASSC_NET; 211 else { 212 (void)sprintf(errbuf, "inet class for 0x%x unknown", 213 *netp); 214 return (-1); 215 } 216 } 217 *netp &= *maskp; 218 return (0); 219} 220