inet.c revision 63696
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: /tcpdump/master/libpcap/inet.c,v 1.26 2000/01/14 23:55:31 mcr 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 char *buf; 93 struct ifreq ifr; 94 static char device[sizeof(ifrp->ifr_name) + 1]; 95 unsigned buf_size; 96 97 fd = socket(AF_INET, SOCK_DGRAM, 0); 98 if (fd < 0) { 99 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno)); 100 return (NULL); 101 } 102 103 buf_size = 8192; 104 105 for (;;) { 106 buf = malloc (buf_size); 107 if (buf == NULL) { 108 close (fd); 109 (void)sprintf(errbuf, "out of memory"); 110 return (NULL); 111 } 112 113 ifc.ifc_len = buf_size; 114 ifc.ifc_buf = buf; 115 memset (buf, 0, buf_size); 116 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0) { 117 free (buf); 118 (void)sprintf(errbuf, "SIOCGIFCONF: %s", 119 pcap_strerror(errno)); 120 (void)close(fd); 121 return (NULL); 122 } 123 if (ifc.ifc_len < buf_size) 124 break; 125 free (buf); 126 buf_size *= 2; 127 } 128 129 ifrp = (struct ifreq *)buf; 130 ifend = (struct ifreq *)(buf + ifc.ifc_len); 131 132 mp = NULL; 133 minunit = 666; 134 for (; ifrp < ifend; ifrp = ifnext) { 135#ifdef HAVE_SOCKADDR_SA_LEN 136 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name); 137 if (n < sizeof(*ifrp)) 138 ifnext = ifrp + 1; 139 else 140 ifnext = (struct ifreq *)((char *)ifrp + n); 141 if (ifrp->ifr_addr.sa_family != AF_INET) 142 continue; 143#else 144 ifnext = ifrp + 1; 145#endif 146 /* 147 * Need a template to preserve address info that is 148 * used below to locate the next entry. (Otherwise, 149 * SIOCGIFFLAGS stomps over it because the requests 150 * are returned in a union.) 151 */ 152 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name)); 153 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) { 154 if (errno == ENXIO) 155 continue; 156 (void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s", 157 (int)sizeof(ifr.ifr_name), ifr.ifr_name, 158 pcap_strerror(errno)); 159 (void)close(fd); 160 free (buf); 161 return (NULL); 162 } 163 164 /* Must be up and not the loopback */ 165 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr)) 166 continue; 167 168 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp) 169 continue; 170 n = atoi(cp); 171 if (n < minunit) { 172 minunit = n; 173 mp = ifrp; 174 } 175 } 176 (void)close(fd); 177 if (mp == NULL) { 178 (void)strcpy(errbuf, "no suitable device found"); 179 free(buf); 180 return (NULL); 181 } 182 183 (void)strncpy(device, mp->ifr_name, sizeof(device) - 1); 184 device[sizeof(device) - 1] = '\0'; 185 free(buf); 186 return (device); 187} 188 189int 190pcap_lookupnet(device, netp, maskp, errbuf) 191 register char *device; 192 register bpf_u_int32 *netp, *maskp; 193 register char *errbuf; 194{ 195 register int fd; 196 register struct sockaddr_in *sin; 197 struct ifreq ifr; 198 199 fd = socket(AF_INET, SOCK_DGRAM, 0); 200 if (fd < 0) { 201 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno)); 202 return (-1); 203 } 204 memset(&ifr, 0, sizeof(ifr)); 205#ifdef linux 206 /* XXX Work around Linux kernel bug */ 207 ifr.ifr_addr.sa_family = AF_INET; 208#endif 209 (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 210 if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) { 211 if (errno == EADDRNOTAVAIL) { 212 (void)sprintf(errbuf, "%s: no IPv4 address assigned", 213 device); 214 } else { 215 (void)sprintf(errbuf, "SIOCGIFADDR: %s: %s", 216 device, pcap_strerror(errno)); 217 } 218 (void)close(fd); 219 return (-1); 220 } 221 sin = (struct sockaddr_in *)&ifr.ifr_addr; 222 *netp = sin->sin_addr.s_addr; 223 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) { 224 (void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s", 225 device, pcap_strerror(errno)); 226 (void)close(fd); 227 return (-1); 228 } 229 (void)close(fd); 230 *maskp = sin->sin_addr.s_addr; 231 if (*maskp == 0) { 232 if (IN_CLASSA(*netp)) 233 *maskp = IN_CLASSA_NET; 234 else if (IN_CLASSB(*netp)) 235 *maskp = IN_CLASSB_NET; 236 else if (IN_CLASSC(*netp)) 237 *maskp = IN_CLASSC_NET; 238 else { 239 (void)sprintf(errbuf, "inet class for 0x%x unknown", 240 *netp); 241 return (-1); 242 } 243 } 244 *netp &= *maskp; 245 return (0); 246} 247