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49 lines
1.2 KiB
49 lines
1.2 KiB
/* |
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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 <net/if.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <sys/ioctl.h> |
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#include <sys/socket.h> |
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#include <sys/types.h> |
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#include <unistd.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 | SOCK_CLOEXEC, 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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close(fd); |
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return -1; |
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} |
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close(fd); |
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return if_mtu.ifr_mtu; |
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}
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