68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
#include <sys/socket.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <netdb.h>
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#include <string.h>
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#include <stdlib.h>
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#define SIZE 4096
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#define exit_code_func_msg(c,f,m) \
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do \
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{ \
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printf ("error %d: %s: %s\n", c, f, m); \
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exit (1); \
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} \
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while (0)
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static void
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get_canon_name (char *hostname, int af)
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{
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struct addrinfo hints, *result, *current;
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int error;
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memset (&hints, 0, sizeof (hints));
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hints.ai_family = af;
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hints.ai_socktype = SOCK_DGRAM;
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hints.ai_flags = AI_CANONNAME;
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error = getaddrinfo (hostname, NULL, &hints, &result);
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if (error != 0)
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exit_code_func_msg (error, "getaddrinfo", gai_strerror (error));
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if (result->ai_canonname == NULL)
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exit_code_func_msg (-1, "getaddrinfo", "No canonical name returned");
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for (current = result;
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current != NULL && current->ai_canonname != NULL;
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current = current->ai_next)
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printf ("%s\n", current->ai_canonname);
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freeaddrinfo (result);
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return;
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}
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int
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main (int argc, char **argv)
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{
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char hostname[SIZE];
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int error;
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error = gethostname (hostname, SIZE);
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if (error)
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exit_code_func_msg (error, "gethostname", "");
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printf ("%s\n", hostname);
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get_canon_name (hostname, AF_INET);
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get_canon_name (hostname, AF_INET6);
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get_canon_name (hostname, AF_UNSPEC);
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return 0;
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}
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