/*      $OpenBSD: inet_net_ntop.c,v 1.9 2019/07/03 03:24:04 deraadt Exp $       */

/*
 * Copyright (c) 2012 by Gilles Chehade <gilles@openbsd.org>
 * Copyright (c) 1996 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

#include "port_before.h"

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

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "port_after.h"

#ifdef __weak_alias
__weak_alias(inet_net_ntop,_inet_net_ntop)
#endif

static char *inet_net_ntop_ipv4(const u_char *, int, char *, size_t);
static char *inet_net_ntop_ipv6(const u_char *, int, char *, size_t);

/*
 * char *
 * inet_net_ntop(af, src, bits, dst, size)
 *      convert network number from network to presentation format.
 *      generates CIDR style result always.
 * return:
 *      pointer to dst, or NULL if an error occurred (check errno).
 * author:
 *      Paul Vixie (ISC), July 1996
 */
char *
inet_net_ntop(int af, const void *src, int bits, char *dst, size_t size)
{
        switch (af) {
        case AF_INET:
                return (inet_net_ntop_ipv4(src, bits, dst, size));
        case AF_INET6:
                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 number from network to presentation format.
 *      generates CIDR style result always.
 * 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
 *      0x11110000 in its fourth octet.
 * author:
 *      Paul Vixie (ISC), July 1996
 */
static char *
inet_net_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size)
{
        char *odst = dst;
        u_int m;
        int b;
        char *ep;
        int advance;

        ep = dst + size;
        if (ep <= dst)
                goto emsgsize;

        if (bits < 0 || bits > 32) {
                errno = EINVAL;
                return (NULL);
        }
        if (bits == 0) {
                if (ep - dst < sizeof "0")
                        goto emsgsize;
                *dst++ = '0';
                *dst = '\0';
        }

        /* Format whole octets. */
        for (b = bits / 8; b > 0; b--) {
                if (ep - dst < sizeof "255.")
                        goto emsgsize;
                advance = snprintf(dst, ep - dst, "%u", *src++);
                if (advance <= 0 || advance >= ep - dst)
                        goto emsgsize;
                dst += advance;
                if (b > 1) {
                        if (dst + 1 >= ep)
                                goto emsgsize;
                        *dst++ = '.';
                        *dst = '\0';
                }
        }

        /* Format partial octet. */
        b = bits % 8;
        if (b > 0) {
                if (ep - dst < sizeof ".255")
                        goto emsgsize;
                if (dst != odst)
                        *dst++ = '.';
                m = ((1 << b) - 1) << (8 - b);
                advance = snprintf(dst, ep - dst, "%u", *src & m);
                if (advance <= 0 || advance >= ep - dst)
                        goto emsgsize;
                dst += advance;
        }

        /* Format CIDR /width. */
        if (ep - dst < sizeof "/32")
                goto emsgsize;
        advance = snprintf(dst, ep - dst, "/%u", bits);
        if (advance <= 0 || advance >= ep - dst)
                goto emsgsize;
        dst += advance;
        return (odst);

 emsgsize:
        errno = EMSGSIZE;
        return (NULL);
}

static char *
inet_net_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size)
{
        int     ret;
        char    buf[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255:255:255:255/128")];

        if (bits < 0 || bits > 128) {
                errno = EINVAL;
                return (NULL);
        }

        if (inet_ntop(AF_INET6, src, buf, size) == NULL)
                return (NULL);

        ret = snprintf(dst, size, "%s/%d", buf, bits);
        if (ret < 0 || ret >= size) {
                errno = EMSGSIZE;
                return (NULL);
        }

        return (dst);
}

#undef inet_net_ntop
#pragma weak inet_net_ntop = __inet_net_ntop