inet.c revision 17683
1/* 2 * Copyright (c) 1994, 1995, 1996 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 char rcsid[] = 36 "@(#) $Header: inet.c,v 1.18 96/07/15 00:48:49 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) (strcmp((p)->ifr_name, "lo0") == 0) 76#endif 77 78/* 79 * Return the name of a network interface attached to the system, or NULL 80 * if none can be found. The interface must be configured up; the 81 * lowest unit number is preferred; loopback is ignored. 82 */ 83char * 84pcap_lookupdev(errbuf) 85 register char *errbuf; 86{ 87 register int fd, minunit, n; 88 register char *cp; 89 register struct ifreq *ifrp, *ifend, *ifnext, *mp; 90 struct ifconf ifc; 91 struct ifreq ibuf[16], ifr; 92 static char device[sizeof(ifrp->ifr_name) + 1]; 93 94 fd = socket(AF_INET, SOCK_DGRAM, 0); 95 if (fd < 0) { 96 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno)); 97 return (NULL); 98 } 99 ifc.ifc_len = sizeof ibuf; 100 ifc.ifc_buf = (caddr_t)ibuf; 101 102 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 || 103 ifc.ifc_len < sizeof(struct ifreq)) { 104 (void)sprintf(errbuf, "SIOCGIFCONF: %s", pcap_strerror(errno)); 105 (void)close(fd); 106 return (NULL); 107 } 108 ifrp = ibuf; 109 ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len); 110 111 mp = NULL; 112 minunit = 666; 113 for (; ifrp < ifend; ifrp = ifnext) { 114#ifdef HAVE_SOCKADDR_SA_LEN 115 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name); 116 if (n < sizeof(*ifrp)) 117 ifnext = ifrp + 1; 118 else 119 ifnext = (struct ifreq *)((char *)ifrp + n); 120 if (ifrp->ifr_addr.sa_family != AF_INET) 121 continue; 122#else 123 ifnext = ifrp + 1; 124#endif 125 /* 126 * Need a template to preserve address info that is 127 * used below to locate the next entry. (Otherwise, 128 * SIOCGIFFLAGS stomps over it because the requests 129 * are returned in a union.) 130 */ 131 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name)); 132 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) { 133 (void)sprintf(errbuf, "SIOCGIFFLAGS: %s", 134 pcap_strerror(errno)); 135 (void)close(fd); 136 return (NULL); 137 } 138 139 /* Must be up and not the loopback */ 140 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr)) 141 continue; 142 143 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp) 144 continue; 145 n = atoi(cp); 146 if (n < minunit) { 147 minunit = n; 148 mp = ifrp; 149 } 150 } 151 (void)close(fd); 152 if (mp == NULL) { 153 (void)strcpy(errbuf, "no suitable device found"); 154 return (NULL); 155 } 156 157 (void)strncpy(device, mp->ifr_name, sizeof(device) - 1); 158 device[sizeof(device) - 1] = '\0'; 159 return (device); 160} 161 162int 163pcap_lookupnet(device, netp, maskp, errbuf) 164 register char *device; 165 register bpf_u_int32 *netp, *maskp; 166 register char *errbuf; 167{ 168 register int fd; 169 register struct sockaddr_in *sin; 170 struct ifreq ifr; 171 172 fd = socket(AF_INET, SOCK_DGRAM, 0); 173 if (fd < 0) { 174 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno)); 175 return (-1); 176 } 177 memset(&ifr, 0, sizeof(ifr)); 178#ifdef linux 179 /* XXX Work around Linux kernel bug */ 180 ifr.ifr_addr.sa_family = AF_INET; 181#endif 182 (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 183 if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) { 184 (void)sprintf(errbuf, "SIOCGIFADDR: %s: %s", 185 device, pcap_strerror(errno)); 186 (void)close(fd); 187 return (-1); 188 } 189 sin = (struct sockaddr_in *)&ifr.ifr_addr; 190 *netp = sin->sin_addr.s_addr; 191 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) { 192 (void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s", 193 device, pcap_strerror(errno)); 194 (void)close(fd); 195 return (-1); 196 } 197 (void)close(fd); 198 *maskp = sin->sin_addr.s_addr; 199 if (*maskp == 0) { 200 if (IN_CLASSA(*netp)) 201 *maskp = IN_CLASSA_NET; 202 else if (IN_CLASSB(*netp)) 203 *maskp = IN_CLASSB_NET; 204 else if (IN_CLASSC(*netp)) 205 *maskp = IN_CLASSC_NET; 206 else { 207 (void)sprintf(errbuf, "inet class for 0x%x unknown", 208 *netp); 209 return (-1); 210 } 211 } 212 *netp &= *maskp; 213 return (0); 214} 215