1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
|
// vim:ts=8:expandtab
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <arpa/inet.h>
static void print_sockname(int fd) {
static char buf[INET6_ADDRSTRLEN+1];
struct sockaddr_storage local;
int ret;
socklen_t local_len = sizeof(struct sockaddr_storage);
if (getsockname(fd, (struct sockaddr*)&local, &local_len) == -1) {
perror("getsockname()");
(void)close(fd);
printf("no IPv6");
return;
}
memset(buf, 0, INET6_ADDRSTRLEN + 1);
if ((ret = getnameinfo((struct sockaddr*)&local, local_len,
buf, sizeof(buf), NULL, 0,
NI_NUMERICHOST)) != 0) {
fprintf(stderr, "getnameinfo(): %s\n", gai_strerror(ret));
printf("no IPv6");
return;
}
printf("%s", buf);
}
/*
* Returns the IPv6 address with which you have connectivity at the moment.
*
*/
static void print_ipv6_addr() {
struct addrinfo hints;
struct addrinfo *result, *resp;
static int fd = -1;
/* To save dns lookups (if they are not cached locally) and creating
* sockets, we save the fd and keep it open. */
if (fd > -1) {
print_sockname(fd);
return;
}
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_INET6;
/* We resolve the K root server to get a public IPv6 address. You can
* replace this with any other host which has an AAAA record, but the
* K root server is a pretty safe bet. */
if (getaddrinfo("k.root-servers.net", "domain", &hints, &result) != 0) {
/* We don’t display the error here because most
* likely, there just is no connectivity.
* Thus, don’t spam the user’s console. */
printf("no IPv6");
return;
}
for (resp = result; resp != NULL; resp = resp->ai_next) {
if ((fd = socket(resp->ai_family, SOCK_DGRAM, 0)) == -1) {
perror("socket()");
continue;
}
/* Since the socket was created with SOCK_DGRAM, this is
* actually not establishing a connection or generating
* any other network traffic. Instead, as a side-effect,
* it saves the local address with which packets would
* be sent to the destination. */
if (connect(fd, resp->ai_addr, resp->ai_addrlen) == -1) {
/* We don’t display the error here because most
* likely, there just is no IPv6 connectivity.
* Thus, don’t spam the user’s console but just
* try the next address. */
(void)close(fd);
continue;
}
free(result);
print_sockname(fd);
return;
}
free(result);
printf("no IPv6");
}
void print_ipv6_info(const char *format) {
const char *walk;
for (walk = format; *walk != '\0'; walk++) {
if (*walk != '%') {
putchar(*walk);
continue;
}
if (strncmp(walk+1, "ip", strlen("ip")) == 0) {
print_ipv6_addr();
walk += strlen("ip");
}
}
}
|
