arp: remove gethostby*() calls

[bses30074_gmail.com]

Summary

1. Use getaddrinfo to replace gethostbyname.
2. Use getnameinfo with NI_NAMEREQD flag to replace gethostbyaddr.

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Fix file permission.

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usr.sbin/arp/arp.c

262–263

Should I use memset to replace the bzero function?

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This comment was removed by bses30074_gmail.com.

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Revise error code

We should use EAI_AGAIN instead of TRY_AGAIN error code while using getnameinfo.

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• Remove for loop

[hrs]

The change basically looks good to me, but I added some comments.

usr.sbin/arp/arp.c

263

hints = (struct addrinfo){
    .ai_family = AF_INET
};

is enough for memset() + assignments.

619

sizeof() should be replaced with addr->sin_len.

I would recommend to change the type of addr to struct sockaddr, and define struct sockaddr_in *sin = (struct sockaddr_in *)addr at the top of this function to use it as sockaddr_in. This requires additional changes in search() and action_fn, though.

usr.sbin/arp/arp_netlink.c

187

The same as arp.c