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