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