2009-07-21 18:26:53 +00:00
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// vim:ts=8:expandtab
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2009-07-21 17:07:30 +00:00
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netdb.h>
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#include <string.h>
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#include <arpa/inet.h>
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/*
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* Returns the IPv6 address with which you have connectivity at the moment.
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*
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*/
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const char *get_ipv6_addr() {
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2009-07-21 18:26:53 +00:00
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static char buf[INET6_ADDRSTRLEN+1];
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struct addrinfo hints;
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struct addrinfo *result, *resp;
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int fd;
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memset(&hints, 0, sizeof(struct addrinfo));
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hints.ai_family = AF_INET6;
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2009-07-21 18:35:19 +00:00
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/* We resolve the K root server to get a public IPv6 address. You can
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* replace this with any other host which has an AAAA record, but the
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* K root server is a pretty safe bet. */
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2009-07-21 18:26:53 +00:00
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if (getaddrinfo("k.root-servers.net", "domain", &hints, &result) != 0) {
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2009-08-23 18:20:52 +00:00
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/* We don’t display the error here because most
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* likely, there just is no connectivity.
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* Thus, don’t spam the user’s console. */
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2009-09-11 19:41:22 +00:00
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return "no IPv6";
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2009-07-21 18:26:53 +00:00
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}
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for (resp = result; resp != NULL; resp = resp->ai_next) {
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2009-07-21 18:35:19 +00:00
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if ((fd = socket(resp->ai_family, SOCK_DGRAM, 0)) == -1) {
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2009-07-21 18:26:53 +00:00
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perror("socket()");
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continue;
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}
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2009-07-21 18:35:19 +00:00
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/* Since the socket was created with SOCK_DGRAM, this is
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* actually not establishing a connection or generating
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* any other network traffic. Instead, as a side-effect,
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* it saves the local address with which packets would
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* be sent to the destination. */
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2009-07-21 18:26:53 +00:00
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if (connect(fd, resp->ai_addr, resp->ai_addrlen) == -1) {
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2009-07-25 19:23:39 +00:00
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/* We don’t display the error here because most
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* likely, there just is no IPv6 connectivity.
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* Thus, don’t spam the user’s console but just
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* try the next address. */
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2009-07-21 18:35:19 +00:00
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(void)close(fd);
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2009-07-21 18:26:53 +00:00
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continue;
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}
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struct sockaddr_storage local;
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socklen_t local_len = sizeof(struct sockaddr_storage);
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if (getsockname(fd, (struct sockaddr*)&local, &local_len) == -1) {
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perror("getsockname()");
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2009-07-21 18:35:19 +00:00
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(void)close(fd);
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2009-09-11 19:41:22 +00:00
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return "no IPv6";
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2009-07-21 18:26:53 +00:00
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}
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2009-07-21 18:35:19 +00:00
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(void)close(fd);
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2009-07-21 18:26:53 +00:00
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memset(buf, 0, INET6_ADDRSTRLEN + 1);
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int ret;
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2009-07-21 18:35:19 +00:00
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if ((ret = getnameinfo((struct sockaddr*)&local, local_len,
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buf, sizeof(buf), NULL, 0,
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NI_NUMERICHOST)) != 0) {
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2009-07-21 18:26:53 +00:00
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fprintf(stderr, "getnameinfo(): %s\n", gai_strerror(ret));
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2009-09-11 19:41:22 +00:00
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return "no IPv6";
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2009-07-21 18:26:53 +00:00
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}
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free(result);
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return buf;
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}
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free(result);
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2009-09-11 19:41:22 +00:00
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return "no IPv6";
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2009-07-21 17:07:30 +00:00
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}
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