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