1 /* $OpenBSD: if_nameindex.c,v 1.10 2010/09/24 13:29:29 claudio Exp $ */ 2 /* $KAME: if_nameindex.c,v 1.7 2000/11/24 08:17:20 itojun Exp $ */ 3 4 /*- 5 * Copyright (c) 1997, 2000 6 * Berkeley Software Design, Inc. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 14 * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * BSDI Id: if_nameindex.c,v 2.3 2000/04/17 22:38:05 dab Exp 27 */ 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <net/if_dl.h> 32 #include <net/if.h> 33 #include <ifaddrs.h> 34 #include <stdlib.h> 35 #include <string.h> 36 37 /* 38 * From RFC 2553: 39 * 40 * 4.3 Return All Interface Names and Indexes 41 * 42 * The if_nameindex structure holds the information about a single 43 * interface and is defined as a result of including the <net/if.h> 44 * header. 45 * 46 * struct if_nameindex { 47 * unsigned int if_index; 48 * char *if_name; 49 * }; 50 * 51 * The final function returns an array of if_nameindex structures, one 52 * structure per interface. 53 * 54 * struct if_nameindex *if_nameindex(void); 55 * 56 * The end of the array of structures is indicated by a structure with 57 * an if_index of 0 and an if_name of NULL. The function returns a NULL 58 * pointer upon an error, and would set errno to the appropriate value. 59 * 60 * The memory used for this array of structures along with the interface 61 * names pointed to by the if_name members is obtained dynamically. 62 * This memory is freed by the next function. 63 * 64 * 4.4. Free Memory 65 * 66 * The following function frees the dynamic memory that was allocated by 67 * if_nameindex(). 68 * 69 * #include <net/if.h> 70 * 71 * void if_freenameindex(struct if_nameindex *ptr); 72 * 73 * The argument to this function must be a pointer that was returned by 74 * if_nameindex(). 75 */ 76 77 struct if_nameindex * 78 if_nameindex(void) 79 { 80 struct ifaddrs *ifaddrs, *ifa; 81 unsigned int ni; 82 size_t nbytes; 83 struct if_nameindex *ifni, *ifni2; 84 char *cp; 85 86 if (getifaddrs(&ifaddrs) < 0) 87 return(NULL); 88 89 /* 90 * First, find out how many interfaces there are, and how 91 * much space we need for the string names. 92 */ 93 ni = 0; 94 nbytes = 0; 95 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 96 if (ifa->ifa_addr && 97 ifa->ifa_addr->sa_family == AF_LINK) { 98 nbytes += strlen(ifa->ifa_name) + 1; 99 ni++; 100 } 101 } 102 103 /* 104 * Next, allocate a chunk of memory, use the first part 105 * for the array of structures, and the last part for 106 * the strings. 107 */ 108 cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes); 109 ifni = (struct if_nameindex *)cp; 110 if (ifni == NULL) 111 goto out; 112 cp += (ni + 1) * sizeof(struct if_nameindex); 113 114 /* 115 * Now just loop through the list of interfaces again, 116 * filling in the if_nameindex array and making copies 117 * of all the strings. 118 */ 119 ifni2 = ifni; 120 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 121 if (ifa->ifa_addr && 122 ifa->ifa_addr->sa_family == AF_LINK) { 123 ifni2->if_index = 124 ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index; 125 ifni2->if_name = cp; 126 nbytes = strlen(ifa->ifa_name) + 1; 127 memcpy(cp, ifa->ifa_name, nbytes); 128 ifni2++; 129 cp += nbytes; 130 } 131 } 132 /* 133 * Finally, don't forget to terminate the array. 134 */ 135 ifni2->if_index = 0; 136 ifni2->if_name = NULL; 137 out: 138 freeifaddrs(ifaddrs); 139 return(ifni); 140 } 141 142 void 143 if_freenameindex(struct if_nameindex *ptr) 144 { 145 free(ptr); 146 } 147