/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1996,1999 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.
 *
 *	  src/backend/utils/adt/inet_net_ntop.c
 */

#if defined(LIBC_SCCS) && !defined(lint)
static const char rcsid[] = "Id: inet_net_ntop.c,v 1.1.2.2 2004/03/09 09:17:27 marka Exp $";
#endif

#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

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

#ifndef FRONTEND
#include "utils/inet.h"
#else
/*
 * In a frontend build, we can't include inet.h, but we still need to have
 * sensible definitions of these two constants.  Note that inet_net_ntop()
 * assumes that PGSQL_AF_INET is equal to AF_INET.
 */
#define PGSQL_AF_INET	(AF_INET + 0)
#define PGSQL_AF_INET6	(AF_INET + 1)
#endif


#define NS_IN6ADDRSZ 16
#define NS_INT16SZ 2

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

static char *inet_net_ntop_ipv4(const u_char *src, int bits,
				   char *dst, size_t size);
static char *inet_net_ntop_ipv6(const u_char *src, int bits,
				   char *dst, size_t size);


/*
 * char *
 * inet_net_ntop(af, src, bits, dst, size)
 *	convert host/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_pton() but it can be a host address with
 *	an included netmask.
 * author:
 *	Paul Vixie (ISC), October 1998
 */
char *
inet_net_ntop(int af, const void *src, int bits, char *dst, size_t size)
{
	/*
	 * We need to cover both the address family constants used by the PG
	 * inet type (PGSQL_AF_INET and PGSQL_AF_INET6) and those used by the
	 * system libraries (AF_INET and AF_INET6).  We can safely assume
	 * PGSQL_AF_INET == AF_INET, but the INET6 constants are very likely
	 * to be different.  If AF_INET6 isn't defined, silently ignore it.
	 */
	switch (af)
	{
		case PGSQL_AF_INET:
			return (inet_net_ntop_ipv4(src, bits, dst, size));
		case PGSQL_AF_INET6:
#if defined(AF_INET6) && AF_INET6 != PGSQL_AF_INET6
		case AF_INET6:
#endif
			return (inet_net_ntop_ipv6(src, bits, dst, size));
		default:
			errno = EAFNOSUPPORT;
			return (NULL);
	}
}

/*
 * static char *
 * inet_net_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_net_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size)
{
	char	   *odst = dst;
	char	   *t;
	int			len = 4;
	int			b;

	if (bits < 0 || bits > 32)
	{
		errno = EINVAL;
		return (NULL);
	}

	/* Always format all four octets, regardless of mask length. */
	for (b = len; b > 0; b--)
	{
		if (size <= sizeof ".255")
			goto emsgsize;
		t = dst;
		if (dst != odst)
			*dst++ = '.';
		dst += SPRINTF((dst, "%u", *src++));
		size -= (size_t) (dst - t);
	}

	/* don't print masklen if 32 bits */
	if (bits != 32)
	{
		if (size <= sizeof "/32")
			goto emsgsize;
		dst += SPRINTF((dst, "/%u", bits));
	}

	return (odst);

emsgsize:
	errno = EMSGSIZE;
	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_net_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;
	cur.base = -1;
	best.len = 0;
	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;

			n = decoct(src + 12, 4, 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 && bits != 128)
		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);
}
