text: /* From openssh4.3p2 compat/inet_aton.c */
  /*
   * Copyright (c) 1983, 1990, 1993
   *    The Regents of the University of California.  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.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
   * -
   * Portions Copyright (c) 1993 by Digital Equipment Corporation.
   * 
   * 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, and that
   * the name of Digital Equipment Corporation not be used in advertising or
   * publicity pertaining to distribution of the document or software without
   * specific, written prior permission.
   * 
   * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
   * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
   * CORPORATION 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.
   * -
   * --Copyright--
   */
  
  /* OPENBSD ORIGINAL: lib/libc/net/inet_addr.c */
  
  #include <config.h>
  
  #if !defined(HAVE_INET_ATON)
  
  #include <sys/types.h>
  #include <sys/param.h>
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  #ifdef HAVE_ARPA_INET_H
  #include <arpa/inet.h>
  #endif
  #include <ctype.h>
  
  #if 0
  /*
   * Ascii internet address interpretation routine.
   * The value returned is in network order.
   */
  in_addr_t
  inet_addr(const char *cp)
  {
  	struct in_addr val;
  
  	if (inet_aton(cp, &val))
  		return (val.s_addr);
  	return (INADDR_NONE);
  }
  #endif
  
  /* 
   * Check whether "cp" is a valid ascii representation
   * of an Internet address and convert to a binary address.
   * Returns 1 if the address is valid, 0 if not.
   * This replaces inet_addr, the return value from which
   * cannot distinguish between failure and a local broadcast address.
   */
  int
  inet_aton(const char *cp, struct in_addr *addr)
  {
  	uint32_t val;
  	int base, n;
  	char c;
  	unsigned int parts[4];
  	unsigned int *pp = parts;
  
  	c = *cp;
  	for (;;) {
  		/*
  		 * Collect number up to ``.''.
  		 * Values are specified as for C:
  		 * 0x=hex, 0=octal, isdigit=decimal.
  		 */
  		if (!isdigit((unsigned char)c))
  			return (0);
  		val = 0; base = 10;
  		if (c == '0') {
  			c = *++cp;
  			if (c == 'x' || c == 'X')
  				base = 16, c = *++cp;
  			else
  				base = 8;
  		}
  		for (;;) {
  			if (isascii((unsigned char)c) && isdigit((unsigned char)c)) {
  				val = (val * base) + (c - '0');
  				c = *++cp;
  			} else if (base == 16 && isascii((unsigned char)c) && isxdigit((unsigned char)c)) {
  				val = (val << 4) |
  					(c + 10 - (islower((unsigned char)c) ? 'a' : 'A'));
  				c = *++cp;
  			} else
  				break;
  		}
  		if (c == '.') {
  			/*
  			 * Internet format:
  			 *	a.b.c.d
  			 *	a.b.c	(with c treated as 16 bits)
  			 *	a.b	(with b treated as 24 bits)
  			 */
  			if (pp >= parts + 3)
  				return (0);
  			*pp++ = val;
  			c = *++cp;
  		} else
  			break;
  	}
  	/*
  	 * Check for trailing characters.
  	 */
  	if (c != '\0' && (!isascii((unsigned char)c) || !isspace((unsigned char)c)))
  		return (0);
  	/*
  	 * Concoct the address according to
  	 * the number of parts specified.
  	 */
  	n = pp - parts + 1;
  	switch (n) {
  
  	case 0:
  		return (0);		/* initial nondigit */
  
  	case 1:				/* a -- 32 bits */
  		break;
  
  	case 2:				/* a.b -- 8.24 bits */
  		if ((val > 0xffffff) || (parts[0] > 0xff))
  			return (0);
  		val |= parts[0] << 24;
  		break;
  
  	case 3:				/* 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 4:				/* 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)
  		addr->s_addr = htonl(val);
  	return (1);
  }
  
  #endif /* !defined(HAVE_INET_ATON) */
  