f342fce2 |
1 | #include <errno.h> |
2 | #include <stdio.h> |
3 | #include <stdlib.h> |
4 | #include <string.h> |
5 | |
6 | #include <sys/types.h> |
7 | #include <unistd.h> |
8 | #include <sys/socket.h> |
9 | #include <netinet/in.h> |
10 | #include <net/if.h> |
11 | #include <sys/ioctl.h> |
12 | |
13 | int main(int argc, char *argv[]) |
14 | { |
15 | int fd; |
16 | struct ifreq ifr; |
17 | if (argc != 2) { |
18 | fprintf(stderr, "usage: %s IFACE\n", argv[0]); |
19 | exit(1); |
20 | } |
21 | if (strlen(argv[1]) >= sizeof(ifr.ifr_name)) { |
22 | fprintf(stderr, "%s: interface name `%s' too long\n", argv[0], argv[1]); |
23 | exit(1); |
24 | } |
25 | if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0) { |
26 | fprintf(stderr, "%s: socket: %s\n", argv[0], strerror(errno)); |
27 | exit(1); |
28 | } |
29 | strcpy(ifr.ifr_name, argv[1]); |
30 | if (ioctl(fd, SIOCGIFMTU, &ifr)) { |
31 | fprintf(stderr, "%s: ioctl(SIOCGIFMTU): %s\n", argv[0], strerror(errno)); |
32 | exit(1); |
33 | } |
34 | printf("%d\n", ifr.ifr_mtu); |
35 | return (0); |
36 | } |