windows inet_ntop inet_pton可参考linux下的实现

q989

文章转载自：罗索实验室 [http://www.rosoo.net/a/201102/10957.html]

linux下这两个函数可以直接调用，windows没有实现这两个函数，需要自己实现
#ifdef _WIN32
static const char *  inet_ntop4(const u_char *src, char *dst, size_t size)
{  
static const char fmt[] = "%u.%u.%u.%u";  
char tmp[sizeof("255.255.255.255")];  
int l;
l = _snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
if (l <= 0 || l >= size)
{   
  return (NULL);  
}  
strncpy(dst, tmp, size);  
return (dst);
}
static const char *  inet_ntop6(const u_char *src, char *dst, size_t size)
{
char tmp[sizeof &quot;ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255&quot;];  
char *tp, *ep;  
struct
{
int base, len;
} best, cur;  
u_int words[IN6ADDRSZ / INT16SZ];  
int i;
int advance;  
memset(words, '\0', sizeof(words));  
for (i = 0; i < IN6ADDRSZ; i&#43;&#43;)
words[i / 2] |= (src << ((1 - (i % 2)) << 3));
best.base = -1;
cur.base = -1;
for (i = 0; i < (IN6ADDRSZ / INT16SZ); i&#43;&#43;) {
if (words == 0) {
if (cur.base == -1)
cur.base = i, cur.len = 1;  
else
cur.len&#43;&#43;;
}
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;
ep = tmp &#43; sizeof(tmp);
for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i&#43;&#43;) {
/** Are we inside the best run of 0x00's? */
if (best.base != -1 && i >= best.base &&
i < (best.base &#43; best.len)) {
if (i == best.base) {
if (tp &#43; 1 >= ep)  
return (NULL);
*tp&#43;&#43; = ':';
}
continue;
}
/** Are we following an initial run of 0x00s or any real hex? */
if (i != 0) {
if (tp &#43; 1 >= ep)
return (NULL);
*tp&#43;&#43; = ':';
}
/** Is this address an encapsulated IPv4? */
if (i == 6 && best.base == 0 &&
(best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
if (!inet_ntop4(src&#43;12, tp, (size_t)(ep - tp)))
return (NULL);
tp &#43;= strlen(tp);
break;
}
advance = snprintf(tp, ep - tp, &quot;%x&quot;, words);
if (advance <= 0 || advance >= ep - tp)
return (NULL);
tp &#43;= advance;
}
/** Was it a trailing run of 0x00's? */
if (best.base != -1 && (best.base &#43; best.len) == (IN6ADDRSZ / INT16SZ)) {
if (tp &#43; 1 >= ep)
return (NULL);
*tp&#43;&#43; = ':';
}
if (tp &#43; 1 >= ep)
return (NULL);
*tp&#43;&#43; = '\0';

/**
* Check for overflow, copy, and we're done.
*/
if ((size_t)(tp - tmp) > size) {
errno = ENOSPC;  
return (NULL);
}
strlcpy(dst, tmp, size);
return (dst);
}  
const char *  inet_ntop(int af, const void *src, char *dst, size_t size)
{
switch (af) {
case AF_INET:
return (inet_ntop4(src, dst, size));
case AF_INET6:
return (inet_ntop6(src, dst, size));
default:
errno = EAFNOSUPPORT;
return (NULL);  
}
/** NOTREACHED */
}
#endif