common/inet/inet_cidr_pton.c

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1998,1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static const char rcsid[] = "$Id: inet_cidr_pton.c,v 1.6 2005/04/27 04:56:19 sra Exp $";
#endif

#include "port_before.h"

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>

#include <isc/assertions.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "port_after.h"

#ifdef SPRINTF_CHAR
# define SPRINTF(x) strlen(sprintf/**/x)
#else
# define SPRINTF(x) ((size_t)sprintf x)
#endif

static int  inet_cidr_pton_ipv4 __P((const char *src, u_char *dst,
                     int *bits, int ipv6));
static int  inet_cidr_pton_ipv6 __P((const char *src, u_char *dst,
                     int *bits));

static int  getbits(const char *, int ipv6);

/*%
 * int
 * inet_cidr_pton(af, src, dst, *bits)
 *  convert network address from presentation to network format.
 *  accepts inet_pton()'s input for this "af" plus trailing "/CIDR".
 *  "dst" is assumed large enough for its "af".  "bits" is set to the
 *  /CIDR prefix length, which can have defaults (like /32 for IPv4).
 * return:
 *  -1 if an error occurred (inspect errno; ENOENT means bad format).
 *  0 if successful conversion occurred.
 * note:
 *  192.5.5.1/28 has a nonzero host part, which means it isn't a network
 *  as called for by inet_net_pton() but it can be a host address with
 *  an included netmask.
 * author:
 *  Paul Vixie (ISC), October 1998
 */
int
inet_cidr_pton(int af, const char *src, void *dst, int *bits) {
    switch (af) {
    case AF_INET:
        return (inet_cidr_pton_ipv4(src, dst, bits, 0));
    case AF_INET6:
        return (inet_cidr_pton_ipv6(src, dst, bits));
    default:
        errno = EAFNOSUPPORT;
        return (-1);
    }
}

static const char digits[] = "0123456789";

static int
inet_cidr_pton_ipv4(const char *src, u_char *dst, int *pbits, int ipv6) {
    const u_char *odst = dst;
    int n, ch, tmp, bits;
    size_t size = 4;

    /* Get the mantissa. */
    while (ch = *src++, (isascii(ch) && isdigit(ch))) {
        tmp = 0;
        do {
            n = strchr(digits, ch) - digits;
            INSIST(n >= 0 && n <= 9);
            tmp *= 10;
            tmp += n;
            if (tmp > 255)
                goto enoent;
        } while ((ch = *src++) != '\0' && isascii(ch) && isdigit(ch));
        if (size-- == 0U)
            goto emsgsize;
        *dst++ = (u_char) tmp;
        if (ch == '\0' || ch == '/')
            break;
        if (ch != '.')
            goto enoent;
    }

    /* Get the prefix length if any. */
    bits = -1;
    if (ch == '/' && dst > odst) {
        bits = getbits(src, ipv6);
        if (bits == -2)
            goto enoent;
    } else if (ch != '\0')
        goto enoent;

    /* Prefix length can default to /32 only if all four octets spec'd. */
    if (bits == -1) {
        if (dst - odst == 4)
            bits = ipv6 ? 128 : 32;
        else
            goto enoent;
    }

    /* If nothing was written to the destination, we found no address. */
    if (dst == odst)
        goto enoent;

    /* If prefix length overspecifies mantissa, life is bad. */
    if (((bits - (ipv6 ? 96 : 0)) / 8) > (dst - odst))
        goto enoent;

    /* Extend address to four octets. */
    while (size-- > 0U)
        *dst++ = 0;

    *pbits = bits;
    return (0);

 enoent:
    errno = ENOENT;
    return (-1);

 emsgsize:
    errno = EMSGSIZE;
    return (-1);
}

static int
inet_cidr_pton_ipv6(const char *src, u_char *dst, int *pbits) {
    static const char xdigits_l[] = "0123456789abcdef",
              xdigits_u[] = "0123456789ABCDEF";
    u_char tmp[NS_IN6ADDRSZ], *tp, *endp, *colonp;
    const char *xdigits, *curtok;
    int ch, saw_xdigit;
    u_int val;
    int bits;

    memset((tp = tmp), '\0', NS_IN6ADDRSZ);
    endp = tp + NS_IN6ADDRSZ;
    colonp = NULL;
    /* Leading :: requires some special handling. */
    if (*src == ':')
        if (*++src != ':')
            return (0);
    curtok = src;
    saw_xdigit = 0;
    val = 0;
    bits = -1;
    while ((ch = *src++) != '\0') {
        const char *pch;

        if ((pch = strchr((xdigits = xdigits_l), ch)) == NULL)
            pch = strchr((xdigits = xdigits_u), ch);
        if (pch != NULL) {
            val <<= 4;
            val |= (pch - xdigits);
            if (val > 0xffff)
                return (0);
            saw_xdigit = 1;
            continue;
        }
        if (ch == ':') {
            curtok = src;
            if (!saw_xdigit) {
                if (colonp)
                    return (0);
                colonp = tp;
                continue;
            } else if (*src == '\0') {
                return (0);
            }
            if (tp + NS_INT16SZ > endp)
                return (0);
            *tp++ = (u_char) (val >> 8) & 0xff;
            *tp++ = (u_char) val & 0xff;
            saw_xdigit = 0;
            val = 0;
            continue;
        }
        if (ch == '.' && ((tp + NS_INADDRSZ) <= endp) &&
            inet_cidr_pton_ipv4(curtok, tp, &bits, 1) == 0) {
            tp += NS_INADDRSZ;
            saw_xdigit = 0;
            break;  /*%< '\\0' was seen by inet_pton4(). */
        }
        if (ch == '/') {
            bits = getbits(src, 1);
            if (bits == -2)
                goto enoent;
            break;
        }
        goto enoent;
    }
    if (saw_xdigit) {
        if (tp + NS_INT16SZ > endp)
            goto emsgsize;
        *tp++ = (u_char) (val >> 8) & 0xff;
        *tp++ = (u_char) val & 0xff;
    }
    if (colonp != NULL) {
        /*
         * Since some memmove()'s erroneously fail to handle
         * overlapping regions, we'll do the shift by hand.
         */
        const int n = tp - colonp;
        int i;

        if (tp == endp)
            goto enoent;
        for (i = 1; i <= n; i++) {
            endp[- i] = colonp[n - i];
            colonp[n - i] = 0;
        }
        tp = endp;
    }

    memcpy(dst, tmp, NS_IN6ADDRSZ);

    *pbits = bits;
    return (0);

 enoent:
    errno = ENOENT;
    return (-1);

 emsgsize:
    errno = EMSGSIZE;
    return (-1);
}

static int
getbits(const char *src, int ipv6) {
    int bits = 0;
    char *cp, ch;

    if (*src == '\0')           /*%< syntax */
        return (-2);
    do {
        ch = *src++;
        cp = strchr(digits, ch);
        if (cp == NULL)         /*%< syntax */
            return (-2);
        bits *= 10;
        bits += cp - digits;
        if (bits == 0 && *src != '\0')  /*%< no leading zeros */
            return (-2);
        if (bits > (ipv6 ? 128 : 32))   /*%< range error */
            return (-2);
    } while (*src != '\0');

    return (bits);
}

/*! \file */