1 /* 2 * Copyright (c) 1998-1999, Craig Metz, All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. All advertising materials mentioning features or use of this software 13 * must display the following acknowledgement: 14 * This product includes software developed by Craig Metz and 15 * by other contributors. 16 * 4. Neither the name of the author nor the names of contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/types.h> 34 #include <stdlib.h> 35 #include <sys/socket.h> 36 #include <sys/ioctl.h> 37 #include <net/if.h> 38 #include <net/if_dl.h> 39 #include <string.h> 40 #include <unistd.h> 41 #include <errno.h> 42 43 unsigned int 44 if_nametoindex(const char *name) 45 { 46 int i, fd = -1, extra, len = 0; 47 struct ifconf ifconf; 48 char lastname[IFNAMSIZ], *thisname, *inbuf; 49 unsigned int index = 0; 50 struct sockaddr *sa; 51 void *p; 52 53 ifconf.ifc_buf = 0; 54 55 if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) 56 goto ret; 57 58 /* 59 * Try ifc_len == 0 hack first, to get the actual length. 60 * If that fails, revert to a loop which grows the ifc_buf 61 * until it is sufficiently large. 62 */ 63 extra = sizeof(struct ifreq); 64 while (1) { 65 ifconf.ifc_len = len; 66 if (ioctl(fd, SIOCGIFCONF, (void *) &ifconf) == -1 && 67 ifconf.ifc_buf) 68 goto ret; 69 if (ifconf.ifc_buf && 70 ifconf.ifc_len + extra < len) 71 break; 72 if (ifconf.ifc_buf) { 73 if (len == 0) 74 len = 4096; 75 ifconf.ifc_len = len *= 2; 76 } else { 77 len = ifconf.ifc_len; 78 extra = 0; 79 } 80 inbuf = realloc(ifconf.ifc_buf, ifconf.ifc_len); 81 if (inbuf == NULL) 82 goto ret; 83 ifconf.ifc_buf = inbuf; 84 } 85 86 i = 0; 87 p = ifconf.ifc_buf; 88 len = ifconf.ifc_len; 89 lastname[0] = 0; 90 lastname[sizeof(lastname)-1] = 0; 91 92 while (len > 0) { 93 if (len < IFNAMSIZ + sizeof(struct sockaddr)) 94 goto ret; 95 96 thisname = p; 97 if (strncmp(lastname, p, IFNAMSIZ)) { 98 if (!strcmp(lastname, name)) { 99 index = i; 100 goto ret; 101 } 102 memcpy(lastname, thisname, IFNAMSIZ); 103 i++; 104 } 105 106 len -= IFNAMSIZ; 107 p += IFNAMSIZ; 108 sa = (struct sockaddr *)p; 109 110 if (!strncmp(thisname, name, IFNAMSIZ) && 111 sa->sa_family == AF_LINK) { 112 struct sockaddr_dl *sd = p; 113 114 index = sd->sdl_index; 115 goto ret; 116 } 117 118 if (len < sa->sa_len) 119 goto ret; 120 len -= sa->sa_len; 121 p += sa->sa_len; 122 } 123 124 if (!strcmp(lastname, name)) 125 index = i; 126 127 ret: 128 if (fd != -1) 129 close(fd); 130 if (ifconf.ifc_buf) 131 free(ifconf.ifc_buf); 132 return index; 133 } 134