[C++知识库]inet_ntop6 源码

#if defined(_WIN32) || defined(_WIN64)//Windows includes
#include <ws2tcpip.h>
#include <string.h>
#include <stdio.h>
#include "inet_ntop.h"
#ifdef __cplusplus
   // extern "C" {
#endif
static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size)
{
    struct in_addr tmp;
    memcpy(&tmp,src,sizeof(struct in_addr));
    return strncpy(dst,inet_ntoa(tmp),size);
}
static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size);


#define NS_INT16SZ	2
#define NS_IN6ADDRSZ	16
/* char *
 * inet_ntop(af, src, dst, size)
 *	convert a network format address to presentation format.
 * return:
 *	pointer to presentation format address (`dst'), or NULL (see errno).
 * author:
 *	Paul Vixie, 1996.
 */
const char *
inet_ntop (int af, const void *src, char *dst, socklen_t size)
{
    switch (af) {
    case AF_INET:
        return (inet_ntop4((const u_char *)src, dst, size));
    case AF_INET6:
        return (inet_ntop6((const u_char *)src, dst, size));
    default:
        return (NULL);
    }
    /* NOTREACHED */
}
#include <QDebug>
/* const char *
 * inet_ntop6(src, dst, size)
 *	convert IPv6 binary address into presentation (printable) format
 * author:
 *	Paul Vixie, 1996.
 */
static const char *
inet_ntop6 (const u_char *src, char *dst, socklen_t size)
{
    /*
     * Note that int32_t and int16_t need only be "at least" large enough
     * to contain a value of the specified size.  On some systems, like
     * Crays, there is no such thing as an integer variable with 16 bits.
     * Keep this in mind if you think this function should have been coded
     * to use pointer overlays.  All the world's not a VAX.
     */
    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];
    uint16_t *words = (uint16_t *)src;
    int i;

    /*
     * Preprocess:
     *	Copy the input (bytewise) array into a wordwise array.
     *	Find the longest run of 0x00's in src[] for :: shorthanding.
     */
    best.base = -1;
    cur.base = -1;
    best.len = 0;
    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;

    /*
     * Format the result.
     */
    tp = tmp;
    for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
        /* Are we inside the best run of 0x00's? */
        if (best.base != -1 && i >= best.base &&
            i < (best.base + best.len)) {
            if (i == best.base)
                *tp++ = ':';
            continue;
        }
        /* Are we following an initial run of 0x00s or any real hex? */
        if (i != 0)
            *tp++ = ':';
        /* 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+12, tp, sizeof tmp - (tp - tmp)))
                return (NULL);
            tp += strlen(tp);
            break;
        }
       // qDebug() << "words[i]=" << words[i] ;
        tp += sprintf(tp,"%x",words[i]);
    }
    /* Was it a trailing run of 0x00's? */
    if (best.base != -1 && (best.base + best.len) ==
        (NS_IN6ADDRSZ / NS_INT16SZ))
        *tp++ = ':';
    *tp++ = '\0';

    /*
     * Check for overflow, copy, and we're done.
     */
    if ((socklen_t)(tp - tmp) > size) {
        return (NULL);
    }
    return strcpy(dst, tmp);
}

#ifdef __cplusplus
  //  }
#endif
#endif