text: /*
   * 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_ntop.c,v 1.7 2006/10/11 02:18:18 marka Exp $";
  #endif
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: releng/11.0/lib/libc/inet/inet_cidr_ntop.c 269867 2014-08-12 12:36:06Z ume $");
  
  #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 <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 char *
  inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size);
  static char *
  inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size);
  
  /*%
   * char *
   * inet_cidr_ntop(af, src, bits, dst, size)
   *	convert network address from network to presentation format.
   *	"src"'s size is determined from its "af".
   * return:
   *	pointer to dst, or NULL if an error occurred (check errno).
   * note:
   *	192.5.5.1/28 has a nonzero host part, which means it isn't a network
   *	as called for by inet_net_ntop() but it can be a host address with
   *	an included netmask.
   * author:
   *	Paul Vixie (ISC), October 1998
   */
  char *
  inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) {
  	switch (af) {
  	case AF_INET:
  		return (inet_cidr_ntop_ipv4(src, bits, dst, size));
  	case AF_INET6:
  		return (inet_cidr_ntop_ipv6(src, bits, dst, size));
  	default:
  		errno = EAFNOSUPPORT;
  		return (NULL);
  	}
  }
  
  static int
  decoct(const u_char *src, int bytes, char *dst, size_t size) {
  	char *odst = dst;
  	char *t;
  	int b;
  
  	for (b = 1; b <= bytes; b++) {
  		if (size < sizeof "255.")
  			return (0);
  		t = dst;
  		dst += SPRINTF((dst, "%u", *src++));
  		if (b != bytes) {
  			*dst++ = '.';
  			*dst = '\0';
  		}
  		size -= (size_t)(dst - t);
  	}
  	return (dst - odst);
  }
  
  /*%
   * static char *
   * inet_cidr_ntop_ipv4(src, bits, dst, size)
   *	convert IPv4 network address from network to presentation format.
   *	"src"'s size is determined from its "af".
   * return:
   *	pointer to dst, or NULL if an error occurred (check errno).
   * note:
   *	network byte order assumed.  this means 192.5.5.240/28 has
   *	0b11110000 in its fourth octet.
   * author:
   *	Paul Vixie (ISC), October 1998
   */
  static char *
  inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) {
  	char *odst = dst;
  	size_t len = 4;
  	size_t b;
  	size_t bytes;
  
  	if ((bits < -1) || (bits > 32)) {
  		errno = EINVAL;
  		return (NULL);
  	}
  
  	/* Find number of significant bytes in address. */
  	if (bits == -1)
  		len = 4;
  	else
  		for (len = 1, b = 1 ; b < 4U; b++)
  			if (*(src + b))
  				len = b + 1;
  
  	/* Format whole octets plus nonzero trailing octets. */
  	bytes = (((bits <= 0) ? 1 : bits) + 7) / 8;
  	if (len > bytes)
  		bytes = len;
  	b = decoct(src, bytes, dst, size);
  	if (b == 0U)
  		goto emsgsize;
  	dst += b;
  	size -= b;
  
  	if (bits != -1) {
  		/* Format CIDR /width. */
  		if (size < sizeof "/32")
  			goto emsgsize;
  		dst += SPRINTF((dst, "/%u", bits));
  	}
  
  	return (odst);
  
   emsgsize:
  	errno = EMSGSIZE;
  	return (NULL);
  }
   
  static char *
  inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_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:255.255.255.255/128"];
  	char *tp;
  	struct { int base, len; } best, cur;
  	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
  	int i;
  
  	if ((bits < -1) || (bits > 128)) {
  		errno = EINVAL;
  		return (NULL);
  	}
  
  	/*
  	 * 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 == 7 && words[7] != 0x0001) ||
  		    (best.len == 5 && words[5] == 0xffff))) {
  			int n;
  
  			if (src[15] || bits == -1 || bits > 120)
  				n = 4;
  			else if (src[14] || bits > 112)
  				n = 3;
  			else
  				n = 2;
  			n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp));
  			if (n == 0) {
  				errno = EMSGSIZE;
  				return (NULL);
  			}
  			tp += strlen(tp);
  			break;
  		}
  		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';
  
  	if (bits != -1)
  		tp += SPRINTF((tp, "/%u", bits));
  
  	/*
  	 * Check for overflow, copy, and we're done.
  	 */
  	if ((size_t)(tp - tmp) > size) {
  		errno = EMSGSIZE;
  		return (NULL);
  	}
  	strcpy(dst, tmp);
  	return (dst);
  }
  
  /*! \file */
  