#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <netinet/in.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#define MAX_V4_ADDR_LEN 16
const char * inet_ntop6(const struct in6_addr *addr, char *dst, socklen_t size);
const char * inet_ntop4(const struct in_addr *addr, char *dst, socklen_t size);
const char *
inet_ntop(int af, const void *addr, char *buf, socklen_t len)
{
if (addr && af == AF_INET6) return inet_ntop6(addr, buf, len);
if (addr && af == AF_INET) return inet_ntop4(addr, buf, len);
errno = EAFNOSUPPORT;
return NULL;
}
const char *
inet_ntop6(const struct in6_addr *addr, char *dst, socklen_t size)
{
const u_char *src = addr->__u6_addr.__u6_addr8;
char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
struct { int base, len; } best, cur;
u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
int i;
memset(words, '\0', sizeof words);
for (i = 0; i < NS_IN6ADDRSZ; i++)
words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
best.base = -1;
best.len = 0;
cur.base = -1;
cur.len = 0;
for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
if (words[i] == 0) {
if (cur.base == -1) {
cur.base = i;
cur.len = 1;
} else {
cur.len++;
}
} else {
if (cur.base != -1) {
if (best.base == -1 || cur.len > best.len)
best = cur;
cur.base = -1;
}
}
}
if (cur.base != -1) {
if (best.base == -1 || cur.len > best.len)
best = cur;
}
if (best.base != -1 && best.len < 2)
best.base = -1;
tp = tmp;
for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
if (best.base != -1 && i >= best.base &&
i < (best.base + best.len)) {
if (i == best.base)
*tp++ = ':';
continue;
}
if (i != 0)
*tp++ = ':';
if (i == 6 && best.base == 0 && (best.len == 6 ||
(best.len == 7 && words[7] != 0x0001) ||
(best.len == 5 && words[5] == 0xffff))) {
struct in_addr ipv4_addr;
memcpy(&ipv4_addr, src+12, sizeof(ipv4_addr));
if (!inet_ntop4(&ipv4_addr, tp, (socklen_t)sizeof(tmp) - (socklen_t)(tp - tmp))) {
errno = ENOSPC;
return (NULL);
}
tp += strlen(tp);
break;
}
tp += sprintf(tp, "%x", words[i]);
}
if (best.base != -1 && (best.base + best.len) ==
(NS_IN6ADDRSZ / NS_INT16SZ))
*tp++ = ':';
*tp++ = '\0';
if ((socklen_t)(tp - tmp) > size) {
errno = ENOSPC;
return (NULL);
}
strcpy(dst, tmp);
return (dst);
}
const char *
inet_ntop4(const struct in_addr *addr, char *dst, socklen_t size)
{
char tmp[MAX_V4_ADDR_LEN], *p;
const u_int8_t *ap = (u_int8_t *)&addr->s_addr;
int i;
size_t ql, len;
if (addr == NULL) {
errno = EAFNOSUPPORT;
return NULL;
}
if (dst == NULL) {
errno = ENOSPC;
return NULL;
}
memset(tmp, 0, MAX_V4_ADDR_LEN);
len = 4;
p = tmp;
for (i = 0; i < 4; i++, ap++) {
snprintf(p, 4, "%d", *ap);
ql = strlen(p);
len += ql;
p += ql;
if (i < 3) *p++ = '.';
}
if (len > size) {
errno = ENOSPC;
return NULL;
}
memcpy(dst, tmp, len);
return dst;
}