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#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <assert.h>
#include <string.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;
}
int port = 0;
if(res->ai_family == AF_INET) port = ((struct sockaddr_in*)res->ai_addr)->sin_port;
else if(res->ai_family == AF_INET6) port = ((struct sockaddr_in6*)res->ai_addr)->sin6_port;
port = ntohs(port);
printf("hostname: %s, port: %d\n", hostname, port);
}
freeaddrinfo(result);
return EXIT_SUCCESS;
}
/* reproduce use of getaddrinfo as used by nmap 7.91's canonicalize_address */
int canonicalize_address(struct sockaddr_storage *ss, struct sockaddr_storage *output) {
char canonical_ip_string[NI_MAXHOST];
struct addrinfo *ai;
int rc;
/* Convert address to string. */
rc = getnameinfo((struct sockaddr *) ss, sizeof(*ss),
canonical_ip_string, sizeof(canonical_ip_string), NULL, 0, NI_NUMERICHOST);
assert(rc == 0);
struct addrinfo hints = {
.ai_family = ss->ss_family,
.ai_socktype = SOCK_DGRAM,
.ai_flags = AI_NUMERICHOST,
};
rc = getaddrinfo(canonical_ip_string, NULL, &hints, &ai);
if (rc != 0 || ai == NULL)
return -1;
assert(ai->ai_addrlen > 0 && ai->ai_addrlen <= (int) sizeof(*output));
memcpy(output, ai->ai_addr, ai->ai_addrlen);
freeaddrinfo(ai);
return 0;
}
int main(void) {
int ret;
ret = doit("www.example.com", NULL);
ret = doit("www.example.com", "80");
struct sockaddr_storage o, ss = {.ss_family = PF_INET};
struct sockaddr_in *v4 = &ss;
struct sockaddr_in6 *v6 = &ss;
memcpy(&v4->sin_addr, "\x7f\0\0\1", 4);
ret = canonicalize_address(&ss, &o);
assert (ret == 0);
ss.ss_family = PF_INET6;
memcpy(&v6->sin6_addr, "\0\0\0\0" "\0\0\0\0" "\0\0\0\0""\0\0\0\1", 16);
ret = canonicalize_address(&ss, &o);
assert (ret == 0);
return ret;
}
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