/*
 * 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/common/port/inet_net_ntop.cpp
 */

#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"
#include "knl/knl_variable.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

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((const unsigned char*)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((const unsigned char*)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 = NULL;
    const 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++ = '.';
        }
        errno_t rc = sprintf_s(dst, size, "%u", *src++);
        securec_check_ss_c(rc, "\0", "\0");
        dst += rc;
        size -= (size_t)(dst - t);
    }

    /* don't print masklen if 32 bits */
    if (bits != 32) {
        if (size <= sizeof "/32") {
            goto emsgsize;
        }
        errno_t rc = sprintf_s(dst, size, "/%d", bits);
        securec_check_ss_c(rc, "\0", "\0");
        dst += rc;
    }

    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 = NULL;
    int b;

    for (b = 1; b <= bytes; b++) {
        if (size <= sizeof "255.") {
            return (0);
        }
        t = dst;
        errno_t rc = sprintf_s(dst, size, "%u", *src++);
        securec_check_ss_c(rc, "\0", "\0");
        dst += rc;
        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 = NULL;
    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.
     */
    errno_t rc = memset_s(words, sizeof(words), '\0', sizeof(words));
    securec_check_c(rc, "\0", "\0");
    for (i = 0; i < NS_IN6ADDRSZ; i++) {
        words[i / 2] |= (src[i] << ((1 - ((unsigned int)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;
        }
        errno_t rc = sprintf_s(tp, size, "%x", words[i]);
        securec_check_ss_c(rc, "\0", "\0");
        tp += rc;
    }

    /* 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) {
        errno_t rc = sprintf_s(tp, size, "/%d", bits);
        securec_check_ss_c(rc, "\0", "\0");
        tp += rc;
    }

    /*
     * Check for overflow, copy, and we're done.
     */
    if ((size_t)(tp - tmp) > size) {
        errno = EMSGSIZE;
        return (NULL);
    }
    rc = strcpy_s(dst, size, tmp);
    securec_check_c(rc, "\0", "\0");
    return (dst);
}