inet_aton.c

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/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2001 Charles Mott <cm@linktel.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include <sys/param.h>
#include <sys/ctype.h>
#include <sys/limits.h>
#include <sys/systm.h>
 
#include <netinet/in.h>
 
int
inet_aton(const char *cp, struct in_addr *addr)
{
        u_long parts[4];
        in_addr_t val;
        const char *c;
        char *endptr;
        int gotend, n;
 
        c = (const char *)cp;
        n = 0;
 
        /*
         * Run through the string, grabbing numbers until
         * the end of the string, or some error
         */
        gotend = 0;
        while (!gotend) {
                unsigned long l;
 
                l = strtoul(c, &endptr, 0);
 
                if (l == ULONG_MAX || (l == 0 && endptr == c))
                        return (0);
 
                val = (in_addr_t)l;
 
                /*
                 * If the whole string is invalid, endptr will equal
                 * c.. this way we can make sure someone hasn't
                 * gone '.12' or something which would get past
                 * the next check.
                 */
                if (endptr == c)
                        return (0);
                parts[n] = val;
                c = endptr;
 
                /* Check the next character past the previous number's end */
                switch (*c) {
                case '.' :
 
                        /* Make sure we only do 3 dots .. */
                        if (n == 3)     /* Whoops. Quit. */
                                return (0);
                        n++;
                        c++;
                        break;
 
                case '\0':
                        gotend = 1;
                        break;
 
                default:
                        if (isspace((unsigned char)*c)) {
                                gotend = 1;
                                break;
                        } else {
                                /* Invalid character, then fail. */
                                return (0);
                        }
                }
        }
 
        /* Concoct the address according to the number of parts specified. */
        switch (n) {
        case 0:                         /* a -- 32 bits */
 
                /*
                 * Nothing is necessary here.  Overflow checking was
                 * already done in strtoul().
                 */
                break;
        case 1:                         /* a.b -- 8.24 bits */
                if (val > 0xffffff || parts[0] > 0xff)
                        return (0);
                val |= parts[0] << 24;
                break;
 
        case 2:                         /* a.b.c -- 8.8.16 bits */
                if (val > 0xffff || parts[0] > 0xff || parts[1] > 0xff)
                        return (0);
                val |= (parts[0] << 24) | (parts[1] << 16);
                break;
 
        case 3:                         /* a.b.c.d -- 8.8.8.8 bits */
                if (val > 0xff || parts[0] > 0xff || parts[1] > 0xff ||
                    parts[2] > 0xff)
                        return (0);
                val |= (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8);
                break;
        }
 
        if (addr != NULL)
                addr->s_addr = htonl(val);
        return (1);
}