inet_ntop.h

Go to the documentation of this file.

/*
 * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1996-2001, 2003  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */
 
/*
 * WARNING: Don't even consider trying to compile this on a system where
 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
 */
 
static const char *inet_ntop4(const unsigned char *src, char *dst,
                              size_t size);
static const char *inet_ntop6(const unsigned char *src, char *dst,
                              size_t size);
 
static const char *
os_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 */
}
 
static const char *
inet_ntop4(const unsigned char *src, char *dst, size_t size)
{
    static const char fmt[] = "%u.%u.%u.%u";
    char tmp[sizeof("255.255.255.255")];
    size_t len;
 
    len = Q_snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
    if (len >= size) {
        /* errno = ENOSPC; */
        return (NULL);
    }
    strcpy(dst, tmp);
 
    return (dst);
}
 
static const char *
inet_ntop6(const unsigned char *src, char *dst, size_t size)
{
    char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
    struct {
        int base, len;
    } best, cur;
    unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
    int i;
 
    /*
     * Preprocess:
     *  Copy the input (bytewise) array into a wordwise array.
     *  Find the longest run of 0x00's in src[] for :: shorthanding.
     */
    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;
 
    /*
     * 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;
        }
        tp += sprintf(tp, "%x", words[i]); /* XXX */
    }
    /* 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 ((size_t)(tp - tmp) > size) {
        /* errno = ENOSPC; */
        return (NULL);
    }
    strcpy(dst, tmp);
    return (dst);
}