1#include <features.h>
2#include <sys/socket.h>
3#include <arpa/inet.h>
4#include <errno.h>
5#include <stdio.h>
6#include <string.h>
7
8#if __GNUC__ < 4
9#define restrict
10#endif
11
12const char *__inet_ntop(int af, const void *restrict a0, char *restrict s, socklen_t l)
13{
14	const unsigned char *a = a0;
15	int i, j, max, best;
16	char buf[100];
17
18	switch (af) {
19	case AF_INET:
20		if (snprintf(s, l, "%d.%d.%d.%d", a[0],a[1],a[2],a[3]) < l)
21			return s;
22		break;
23	case AF_INET6:
24		if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\377\377", 12))
25			snprintf(buf, sizeof buf,
26				"%x:%x:%x:%x:%x:%x:%x:%x",
27				256*a[0]+a[1],256*a[2]+a[3],
28				256*a[4]+a[5],256*a[6]+a[7],
29				256*a[8]+a[9],256*a[10]+a[11],
30				256*a[12]+a[13],256*a[14]+a[15]);
31		else
32			snprintf(buf, sizeof buf,
33				"%x:%x:%x:%x:%x:%x:%d.%d.%d.%d",
34				256*a[0]+a[1],256*a[2]+a[3],
35				256*a[4]+a[5],256*a[6]+a[7],
36				256*a[8]+a[9],256*a[10]+a[11],
37				a[12],a[13],a[14],a[15]);
38		/* Replace longest /(^0|:)[:0]{2,}/ with "::" */
39		for (i=best=0, max=2; buf[i]; i++) {
40			if (i && buf[i] != ':') continue;
41			j = strspn(buf+i, ":0");
42			if (j>max) best=i, max=j;
43		}
44		if (max>3) {
45			buf[best] = buf[best+1] = ':';
46			memmove(buf+best+2, buf+best+max, i-best-max+1);
47		}
48		if (strlen(buf) < l) {
49			strcpy(s, buf);
50			return s;
51		}
52		break;
53	default:
54		errno = EAFNOSUPPORT;
55		return 0;
56	}
57	errno = ENOSPC;
58	return 0;
59}
60
61weak_alias(__inet_ntop, inet_ntop);
62