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