1 /* $KAME: if_nameindex.c,v 1.8 2000/11/24 08:20:01 itojun Exp $ */
4 * SPDX-License-Identifier: BSD-1-Clause
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27 * BSDI Id: if_nameindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
30 #include <sys/types.h>
31 #include <sys/socket.h>
32 #include <net/if_dl.h>
41 * 4.3 Return All Interface Names and Indexes
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>
47 * struct if_nameindex {
48 * unsigned int if_index;
52 * The final function returns an array of if_nameindex structures, one
53 * structure per interface.
55 * struct if_nameindex *if_nameindex(void);
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.
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.
67 * The following function frees the dynamic memory that was allocated by
72 * void if_freenameindex(struct if_nameindex *ptr);
74 * The argument to this function must be a pointer that was returned by
81 struct ifaddrs *ifaddrs, *ifa;
84 struct if_nameindex *ifni, *ifni2;
87 if (getifaddrs(&ifaddrs) < 0)
91 * First, find out how many interfaces there are, and how
92 * much space we need for the string names.
96 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
98 ifa->ifa_addr->sa_family == AF_LINK) {
99 nbytes += strlen(ifa->ifa_name) + 1;
105 * Next, allocate a chunk of memory, use the first part
106 * for the array of structures, and the last part for
109 cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes);
110 ifni = (struct if_nameindex *)cp;
113 cp += (ni + 1) * sizeof(struct if_nameindex);
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.
121 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
123 ifa->ifa_addr->sa_family == AF_LINK) {
125 LLINDEX((struct sockaddr_dl*)ifa->ifa_addr);
127 strcpy(cp, ifa->ifa_name);
129 cp += strlen(cp) + 1;
133 * Finally, don't forget to terminate the array.
136 ifni2->if_name = NULL;
138 freeifaddrs(ifaddrs);
143 if_freenameindex(struct if_nameindex *ptr)