49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <netdb.h>
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#include <netinet/in.h>
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#include <sys/socket.h>
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#ifndef NI_MAXHOST
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#define NI_MAXHOST 1025
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#endif
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static int doit(const char* host, const char* service) {
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struct addrinfo *result;
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struct addrinfo *res;
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int error;
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/* resolve the domain name into a list of addresses */
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error = getaddrinfo(host, service, NULL, &result);
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if (error != 0)
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{
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fprintf(stderr, "error in getaddrinfo: %s\n", gai_strerror(error));
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return EXIT_FAILURE;
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}
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/* loop over all returned results and do inverse lookup */
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for (res = result; res != NULL; res = res->ai_next)
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{
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char hostname[NI_MAXHOST] = "";
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error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
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if (error != 0)
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{
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fprintf(stderr, "error in getnameinfo: %s\n", gai_strerror(error));
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continue;
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}
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if (*hostname != '\0')
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printf("hostname: %s\n", hostname);
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}
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freeaddrinfo(result);
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return EXIT_SUCCESS;
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}
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int main(void) {
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int ret;
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ret = doit("www.example.com", NULL);
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ret = doit("www.example.com", "80");
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return ret;
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}
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