1 /* $KAME: if_nameindex.c,v 1.8 2000/11/24 08:20:01 itojun Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-1-Clause
5 *
6 * Copyright (c) 1997, 2000
7 * Berkeley Software Design, Inc. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * BSDI Id: if_nameindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
28 */
29
30 #include <sys/types.h>
31 #include <sys/socket.h>
32 #include <net/if_dl.h>
33 #include <net/if.h>
34 #include <ifaddrs.h>
35 #include <stdlib.h>
36 #include <string.h>
37
38 /*
39 * From RFC 2553:
40 *
41 * 4.3 Return All Interface Names and Indexes
42 *
43 * The if_nameindex structure holds the information about a single
44 * interface and is defined as a result of including the <net/if.h>
45 * header.
46 *
47 * struct if_nameindex {
48 * unsigned int if_index;
49 * char *if_name;
50 * };
51 *
52 * The final function returns an array of if_nameindex structures, one
53 * structure per interface.
54 *
55 * struct if_nameindex *if_nameindex(void);
56 *
57 * The end of the array of structures is indicated by a structure with
58 * an if_index of 0 and an if_name of NULL. The function returns a NULL
59 * pointer upon an error, and would set errno to the appropriate value.
60 *
61 * The memory used for this array of structures along with the interface
62 * names pointed to by the if_name members is obtained dynamically.
63 * This memory is freed by the next function.
64 *
65 * 4.4. Free Memory
66 *
67 * The following function frees the dynamic memory that was allocated by
68 * if_nameindex().
69 *
70 * #include <net/if.h>
71 *
72 * void if_freenameindex(struct if_nameindex *ptr);
73 *
74 * The argument to this function must be a pointer that was returned by
75 * if_nameindex().
76 */
77
78 struct if_nameindex *
if_nameindex(void)79 if_nameindex(void)
80 {
81 struct ifaddrs *ifaddrs, *ifa;
82 unsigned int ni;
83 int nbytes;
84 struct if_nameindex *ifni, *ifni2;
85 char *cp;
86
87 if (getifaddrs(&ifaddrs) < 0)
88 return(NULL);
89
90 /*
91 * First, find out how many interfaces there are, and how
92 * much space we need for the string names.
93 */
94 ni = 0;
95 nbytes = 0;
96 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
97 if (ifa->ifa_addr &&
98 ifa->ifa_addr->sa_family == AF_LINK) {
99 nbytes += strlen(ifa->ifa_name) + 1;
100 ni++;
101 }
102 }
103
104 /*
105 * Next, allocate a chunk of memory, use the first part
106 * for the array of structures, and the last part for
107 * the strings.
108 */
109 cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes);
110 ifni = (struct if_nameindex *)cp;
111 if (ifni == NULL)
112 goto out;
113 cp += (ni + 1) * sizeof(struct if_nameindex);
114
115 /*
116 * Now just loop through the list of interfaces again,
117 * filling in the if_nameindex array and making copies
118 * of all the strings.
119 */
120 ifni2 = ifni;
121 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
122 if (ifa->ifa_addr &&
123 ifa->ifa_addr->sa_family == AF_LINK) {
124 ifni2->if_index =
125 LLINDEX((struct sockaddr_dl*)ifa->ifa_addr);
126 ifni2->if_name = cp;
127 strcpy(cp, ifa->ifa_name);
128 ifni2++;
129 cp += strlen(cp) + 1;
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
if_freenameindex(struct if_nameindex * ptr)143 if_freenameindex(struct if_nameindex *ptr)
144 {
145 free(ptr);
146 }
147