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/*
* Copyright 2011 Daniel Drown
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* mtu.c - get interface mtu
*/
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include "mtu.h"
/* function: getifmtu
* returns the interface mtu or -1 on failure
* ifname - interface name
*/
int getifmtu(const char *ifname) {
int fd;
struct ifreq if_mtu;
fd = socket(AF_INET, SOCK_STREAM, 0);
if(fd < 0) {
return -1;
}
strncpy(if_mtu.ifr_name, ifname, IFNAMSIZ);
if_mtu.ifr_name[IFNAMSIZ - 1] = '\0';
if(ioctl(fd, SIOCGIFMTU, &if_mtu) < 0) {
return -1;
}
return if_mtu.ifr_mtu;
}
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