network.c

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/*
 *  PostgreSQL type definitions for the INET and CIDR types.
 *
 *  src/backend/utils/adt/network.c
 *
 *  Jon Postel RIP 16 Oct 1998
 */

#include "postgres.h"

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

#include "access/stratnum.h"
#include "catalog/pg_opfamily.h"
#include "catalog/pg_type.h"
#include "common/ip.h"
#include "lib/hyperloglog.h"
#include "libpq/libpq-be.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "nodes/supportnodes.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/hashutils.h"
#include "utils/inet.h"
#include "utils/lsyscache.h"
#include "utils/sortsupport.h"


/*
 * An IPv4 netmask size is a value in the range of 0 - 32, which is
 * represented with 6 bits in inet/cidr abbreviated keys where possible.
 *
 * An IPv4 inet/cidr abbreviated key can use up to 25 bits for subnet
 * component.
 */
#define ABBREV_BITS_INET4_NETMASK_SIZE  6
#define ABBREV_BITS_INET4_SUBNET        25

/* sortsupport for inet/cidr */
typedef struct
{
    int64       input_count;    /* number of non-null values seen */
    bool        estimating;     /* true if estimating cardinality */

    hyperLogLogState abbr_card; /* cardinality estimator */
} network_sortsupport_state;

static int32 network_cmp_internal(inet *a1, inet *a2);
static int  network_fast_cmp(Datum x, Datum y, SortSupport ssup);
static int  network_cmp_abbrev(Datum x, Datum y, SortSupport ssup);
static bool network_abbrev_abort(int memtupcount, SortSupport ssup);
static Datum network_abbrev_convert(Datum original, SortSupport ssup);
static List *match_network_function(Node *leftop,
                                    Node *rightop,
                                    int indexarg,
                                    Oid funcid,
                                    Oid opfamily);
static List *match_network_subset(Node *leftop,
                                  Node *rightop,
                                  bool is_eq,
                                  Oid opfamily);
static bool addressOK(unsigned char *a, int bits, int family);
static inet *internal_inetpl(inet *ip, int64 addend);


/*
 * Common INET/CIDR input routine
 */
static inet *
network_in(char *src, bool is_cidr)
{
    int         bits;
    inet       *dst;

    dst = (inet *) palloc0(sizeof(inet));

    /*
     * First, check to see if this is an IPv6 or IPv4 address.  IPv6 addresses
     * will have a : somewhere in them (several, in fact) so if there is one
     * present, assume it's V6, otherwise assume it's V4.
     */

    if (strchr(src, ':') != NULL)
        ip_family(dst) = PGSQL_AF_INET6;
    else
        ip_family(dst) = PGSQL_AF_INET;

    bits = pg_inet_net_pton(ip_family(dst), src, ip_addr(dst),
                            is_cidr ? ip_addrsize(dst) : -1);
    if ((bits < 0) || (bits > ip_maxbits(dst)))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
        /* translator: first %s is inet or cidr */
                 errmsg("invalid input syntax for type %s: \"%s\"",
                        is_cidr ? "cidr" : "inet", src)));

    /*
     * Error check: CIDR values must not have any bits set beyond the masklen.
     */
    if (is_cidr)
    {
        if (!addressOK(ip_addr(dst), bits, ip_family(dst)))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("invalid cidr value: \"%s\"", src),
                     errdetail("Value has bits set to right of mask.")));
    }

    ip_bits(dst) = bits;
    SET_INET_VARSIZE(dst);

    return dst;
}

Datum
inet_in(PG_FUNCTION_ARGS)
{
    char       *src = PG_GETARG_CSTRING(0);

    PG_RETURN_INET_P(network_in(src, false));
}

Datum
cidr_in(PG_FUNCTION_ARGS)
{
    char       *src = PG_GETARG_CSTRING(0);

    PG_RETURN_INET_P(network_in(src, true));
}


/*
 * Common INET/CIDR output routine
 */
static char *
network_out(inet *src, bool is_cidr)
{
    char        tmp[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];
    char       *dst;
    int         len;

    dst = pg_inet_net_ntop(ip_family(src), ip_addr(src), ip_bits(src),
                           tmp, sizeof(tmp));
    if (dst == NULL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("could not format inet value: %m")));

    /* For CIDR, add /n if not present */
    if (is_cidr && strchr(tmp, '/') == NULL)
    {
        len = strlen(tmp);
        snprintf(tmp + len, sizeof(tmp) - len, "/%u", ip_bits(src));
    }

    return pstrdup(tmp);
}

Datum
inet_out(PG_FUNCTION_ARGS)
{
    inet       *src = PG_GETARG_INET_PP(0);

    PG_RETURN_CSTRING(network_out(src, false));
}

Datum
cidr_out(PG_FUNCTION_ARGS)
{
    inet       *src = PG_GETARG_INET_PP(0);

    PG_RETURN_CSTRING(network_out(src, true));
}


/*
 *      network_recv        - converts external binary format to inet
 *
 * The external representation is (one byte apiece for)
 * family, bits, is_cidr, address length, address in network byte order.
 *
 * Presence of is_cidr is largely for historical reasons, though it might
 * allow some code-sharing on the client side.  We send it correctly on
 * output, but ignore the value on input.
 */
static inet *
network_recv(StringInfo buf, bool is_cidr)
{
    inet       *addr;
    char       *addrptr;
    int         bits;
    int         nb,
                i;

    /* make sure any unused bits in a CIDR value are zeroed */
    addr = (inet *) palloc0(sizeof(inet));

    ip_family(addr) = pq_getmsgbyte(buf);
    if (ip_family(addr) != PGSQL_AF_INET &&
        ip_family(addr) != PGSQL_AF_INET6)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
        /* translator: %s is inet or cidr */
                 errmsg("invalid address family in external \"%s\" value",
                        is_cidr ? "cidr" : "inet")));
    bits = pq_getmsgbyte(buf);
    if (bits < 0 || bits > ip_maxbits(addr))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
        /* translator: %s is inet or cidr */
                 errmsg("invalid bits in external \"%s\" value",
                        is_cidr ? "cidr" : "inet")));
    ip_bits(addr) = bits;
    i = pq_getmsgbyte(buf);     /* ignore is_cidr */
    nb = pq_getmsgbyte(buf);
    if (nb != ip_addrsize(addr))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
        /* translator: %s is inet or cidr */
                 errmsg("invalid length in external \"%s\" value",
                        is_cidr ? "cidr" : "inet")));

    addrptr = (char *) ip_addr(addr);
    for (i = 0; i < nb; i++)
        addrptr[i] = pq_getmsgbyte(buf);

    /*
     * Error check: CIDR values must not have any bits set beyond the masklen.
     */
    if (is_cidr)
    {
        if (!addressOK(ip_addr(addr), bits, ip_family(addr)))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                     errmsg("invalid external \"cidr\" value"),
                     errdetail("Value has bits set to right of mask.")));
    }

    SET_INET_VARSIZE(addr);

    return addr;
}

Datum
inet_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);

    PG_RETURN_INET_P(network_recv(buf, false));
}

Datum
cidr_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);

    PG_RETURN_INET_P(network_recv(buf, true));
}


/*
 *      network_send        - converts inet to binary format
 */
static bytea *
network_send(inet *addr, bool is_cidr)
{
    StringInfoData buf;
    char       *addrptr;
    int         nb,
                i;

    pq_begintypsend(&buf);
    pq_sendbyte(&buf, ip_family(addr));
    pq_sendbyte(&buf, ip_bits(addr));
    pq_sendbyte(&buf, is_cidr);
    nb = ip_addrsize(addr);
    if (nb < 0)
        nb = 0;
    pq_sendbyte(&buf, nb);
    addrptr = (char *) ip_addr(addr);
    for (i = 0; i < nb; i++)
        pq_sendbyte(&buf, addrptr[i]);
    return pq_endtypsend(&buf);
}

Datum
inet_send(PG_FUNCTION_ARGS)
{
    inet       *addr = PG_GETARG_INET_PP(0);

    PG_RETURN_BYTEA_P(network_send(addr, false));
}

Datum
cidr_send(PG_FUNCTION_ARGS)
{
    inet       *addr = PG_GETARG_INET_PP(0);

    PG_RETURN_BYTEA_P(network_send(addr, true));
}


Datum
inet_to_cidr(PG_FUNCTION_ARGS)
{
    inet       *src = PG_GETARG_INET_PP(0);
    int         bits;

    bits = ip_bits(src);

    /* safety check */
    if ((bits < 0) || (bits > ip_maxbits(src)))
        elog(ERROR, "invalid inet bit length: %d", bits);

    PG_RETURN_INET_P(cidr_set_masklen_internal(src, bits));
}

Datum
inet_set_masklen(PG_FUNCTION_ARGS)
{
    inet       *src = PG_GETARG_INET_PP(0);
    int         bits = PG_GETARG_INT32(1);
    inet       *dst;

    if (bits == -1)
        bits = ip_maxbits(src);

    if ((bits < 0) || (bits > ip_maxbits(src)))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid mask length: %d", bits)));

    /* clone the original data */
    dst = (inet *) palloc(VARSIZE_ANY(src));
    memcpy(dst, src, VARSIZE_ANY(src));

    ip_bits(dst) = bits;

    PG_RETURN_INET_P(dst);
}

Datum
cidr_set_masklen(PG_FUNCTION_ARGS)
{
    inet       *src = PG_GETARG_INET_PP(0);
    int         bits = PG_GETARG_INT32(1);

    if (bits == -1)
        bits = ip_maxbits(src);

    if ((bits < 0) || (bits > ip_maxbits(src)))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid mask length: %d", bits)));

    PG_RETURN_INET_P(cidr_set_masklen_internal(src, bits));
}

/*
 * Copy src and set mask length to 'bits' (which must be valid for the family)
 */
inet *
cidr_set_masklen_internal(const inet *src, int bits)
{
    inet       *dst = (inet *) palloc0(sizeof(inet));

    ip_family(dst) = ip_family(src);
    ip_bits(dst) = bits;

    if (bits > 0)
    {
        Assert(bits <= ip_maxbits(dst));

        /* Clone appropriate bytes of the address, leaving the rest 0 */
        memcpy(ip_addr(dst), ip_addr(src), (bits + 7) / 8);

        /* Clear any unwanted bits in the last partial byte */
        if (bits % 8)
            ip_addr(dst)[bits / 8] &= ~(0xFF >> (bits % 8));
    }

    /* Set varlena header correctly */
    SET_INET_VARSIZE(dst);

    return dst;
}

/*
 *  Basic comparison function for sorting and inet/cidr comparisons.
 *
 * Comparison is first on the common bits of the network part, then on
 * the length of the network part, and then on the whole unmasked address.
 * The effect is that the network part is the major sort key, and for
 * equal network parts we sort on the host part.  Note this is only sane
 * for CIDR if address bits to the right of the mask are guaranteed zero;
 * otherwise logically-equal CIDRs might compare different.
 */

static int32
network_cmp_internal(inet *a1, inet *a2)
{
    if (ip_family(a1) == ip_family(a2))
    {
        int         order;

        order = bitncmp(ip_addr(a1), ip_addr(a2),
                        Min(ip_bits(a1), ip_bits(a2)));
        if (order != 0)
            return order;
        order = ((int) ip_bits(a1)) - ((int) ip_bits(a2));
        if (order != 0)
            return order;
        return bitncmp(ip_addr(a1), ip_addr(a2), ip_maxbits(a1));
    }

    return ip_family(a1) - ip_family(a2);
}

Datum
network_cmp(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_INT32(network_cmp_internal(a1, a2));
}

/*
 * SortSupport strategy routine
 */
Datum
network_sortsupport(PG_FUNCTION_ARGS)
{
    SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);

    ssup->comparator = network_fast_cmp;
    ssup->ssup_extra = NULL;

    if (ssup->abbreviate)
    {
        network_sortsupport_state *uss;
        MemoryContext oldcontext;

        oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);

        uss = palloc(sizeof(network_sortsupport_state));
        uss->input_count = 0;
        uss->estimating = true;
        initHyperLogLog(&uss->abbr_card, 10);

        ssup->ssup_extra = uss;

        ssup->comparator = network_cmp_abbrev;
        ssup->abbrev_converter = network_abbrev_convert;
        ssup->abbrev_abort = network_abbrev_abort;
        ssup->abbrev_full_comparator = network_fast_cmp;

        MemoryContextSwitchTo(oldcontext);
    }

    PG_RETURN_VOID();
}

/*
 * SortSupport comparison func
 */
static int
network_fast_cmp(Datum x, Datum y, SortSupport ssup)
{
    inet       *arg1 = DatumGetInetPP(x);
    inet       *arg2 = DatumGetInetPP(y);

    return network_cmp_internal(arg1, arg2);
}

/*
 * Abbreviated key comparison func
 */
static int
network_cmp_abbrev(Datum x, Datum y, SortSupport ssup)
{
    if (x > y)
        return 1;
    else if (x == y)
        return 0;
    else
        return -1;
}

/*
 * Callback for estimating effectiveness of abbreviated key optimization.
 *
 * We pay no attention to the cardinality of the non-abbreviated data, because
 * there is no equality fast-path within authoritative inet comparator.
 */
static bool
network_abbrev_abort(int memtupcount, SortSupport ssup)
{
    network_sortsupport_state *uss = ssup->ssup_extra;
    double      abbr_card;

    if (memtupcount < 10000 || uss->input_count < 10000 || !uss->estimating)
        return false;

    abbr_card = estimateHyperLogLog(&uss->abbr_card);

    /*
     * If we have >100k distinct values, then even if we were sorting many
     * billion rows we'd likely still break even, and the penalty of undoing
     * that many rows of abbrevs would probably not be worth it. At this point
     * we stop counting because we know that we're now fully committed.
     */
    if (abbr_card > 100000.0)
    {
#ifdef TRACE_SORT
        if (trace_sort)
            elog(LOG,
                 "network_abbrev: estimation ends at cardinality %f"
                 " after " INT64_FORMAT " values (%d rows)",
                 abbr_card, uss->input_count, memtupcount);
#endif
        uss->estimating = false;
        return false;
    }

    /*
     * Target minimum cardinality is 1 per ~2k of non-null inputs. 0.5 row
     * fudge factor allows us to abort earlier on genuinely pathological data
     * where we've had exactly one abbreviated value in the first 2k
     * (non-null) rows.
     */
    if (abbr_card < uss->input_count / 2000.0 + 0.5)
    {
#ifdef TRACE_SORT
        if (trace_sort)
            elog(LOG,
                 "network_abbrev: aborting abbreviation at cardinality %f"
                 " below threshold %f after " INT64_FORMAT " values (%d rows)",
                 abbr_card, uss->input_count / 2000.0 + 0.5, uss->input_count,
                 memtupcount);
#endif
        return true;
    }

#ifdef TRACE_SORT
    if (trace_sort)
        elog(LOG,
             "network_abbrev: cardinality %f after " INT64_FORMAT
             " values (%d rows)", abbr_card, uss->input_count, memtupcount);
#endif

    return false;
}

/*
 * SortSupport conversion routine. Converts original inet/cidr representation
 * to abbreviated key representation that works with simple 3-way unsigned int
 * comparisons. The network_cmp_internal() rules for sorting inet/cidr datums
 * are followed by abbreviated comparisons by an encoding scheme that
 * conditions keys through careful use of padding.
 *
 * Some background: inet values have three major components (take for example
 * the address 1.2.3.4/24):
 *
 *     * A network, or netmasked bits (1.2.3.0).
 *     * A netmask size (/24).
 *     * A subnet, or bits outside of the netmask (0.0.0.4).
 *
 * cidr values are the same except that with only the first two components --
 * all their subnet bits *must* be zero (1.2.3.0/24).
 *
 * IPv4 and IPv6 are identical in this makeup, with the difference being that
 * IPv4 addresses have a maximum of 32 bits compared to IPv6's 64 bits, so in
 * IPv6 each part may be larger.
 *
 * inet/cidr types compare using these sorting rules. If inequality is detected
 * at any step, comparison is finished. If any rule is a tie, the algorithm
 * drops through to the next to break it:
 *
 *     1. IPv4 always appears before IPv6.
 *     2. Network bits are compared.
 *     3. Netmask size is compared.
 *     4. All bits are compared (having made it here, we know that both
 *        netmasked bits and netmask size are equal, so we're in effect only
 *        comparing subnet bits).
 *
 * When generating abbreviated keys for SortSupport, we pack as much as we can
 * into a datum while ensuring that when comparing those keys as integers,
 * these rules will be respected. Exact contents depend on IP family and datum
 * size.
 *
 * IPv4
 * ----
 *
 * 4 byte datums:
 *
 * Start with 1 bit for the IP family (IPv4 or IPv6; this bit is present in
 * every case below) followed by all but 1 of the netmasked bits.
 *
 * +----------+---------------------+
 * | 1 bit IP |   31 bits network   |     (1 bit network
 * |  family  |     (truncated)     |      omitted)
 * +----------+---------------------+
 *
 * 8 byte datums:
 *
 * We have space to store all netmasked bits, followed by the netmask size,
 * followed by 25 bits of the subnet (25 bits is usually more than enough in
 * practice). cidr datums always have all-zero subnet bits.
 *
 * +----------+-----------------------+--------------+--------------------+
 * | 1 bit IP |    32 bits network    |    6 bits    |   25 bits subnet   |
 * |  family  |        (full)         | network size |    (truncated)     |
 * +----------+-----------------------+--------------+--------------------+
 *
 * IPv6
 * ----
 *
 * 4 byte datums:
 *
 * +----------+---------------------+
 * | 1 bit IP |   31 bits network   |    (up to 97 bits
 * |  family  |     (truncated)     |   network omitted)
 * +----------+---------------------+
 *
 * 8 byte datums:
 *
 * +----------+---------------------------------+
 * | 1 bit IP |         63 bits network         |    (up to 65 bits
 * |  family  |           (truncated)           |   network omitted)
 * +----------+---------------------------------+
 */
static Datum
network_abbrev_convert(Datum original, SortSupport ssup)
{
    network_sortsupport_state *uss = ssup->ssup_extra;
    inet       *authoritative = DatumGetInetPP(original);
    Datum       res,
                ipaddr_datum,
                subnet_bitmask,
                network;
    int         subnet_size;

    Assert(ip_family(authoritative) == PGSQL_AF_INET ||
           ip_family(authoritative) == PGSQL_AF_INET6);

    /*
     * Get an unsigned integer representation of the IP address by taking its
     * first 4 or 8 bytes. Always take all 4 bytes of an IPv4 address. Take
     * the first 8 bytes of an IPv6 address with an 8 byte datum and 4 bytes
     * otherwise.
     *
     * We're consuming an array of unsigned char, so byteswap on little endian
     * systems (an inet's ipaddr field stores the most significant byte
     * first).
     */
    if (ip_family(authoritative) == PGSQL_AF_INET)
    {
        uint32      ipaddr_datum32;

        memcpy(&ipaddr_datum32, ip_addr(authoritative), sizeof(uint32));

        /* Must byteswap on little-endian machines */
#ifndef WORDS_BIGENDIAN
        ipaddr_datum = pg_bswap32(ipaddr_datum32);
#else
        ipaddr_datum = ipaddr_datum32;
#endif

        /* Initialize result without setting ipfamily bit */
        res = (Datum) 0;
    }
    else
    {
        memcpy(&ipaddr_datum, ip_addr(authoritative), sizeof(Datum));

        /* Must byteswap on little-endian machines */
        ipaddr_datum = DatumBigEndianToNative(ipaddr_datum);

        /* Initialize result with ipfamily (most significant) bit set */
        res = ((Datum) 1) << (SIZEOF_DATUM * BITS_PER_BYTE - 1);
    }

    /*
     * ipaddr_datum must be "split": high order bits go in "network" component
     * of abbreviated key (often with zeroed bits at the end due to masking),
     * while low order bits go in "subnet" component when there is space for
     * one. This is often accomplished by generating a temp datum subnet
     * bitmask, which we may reuse later when generating the subnet bits
     * themselves.  (Note that subnet bits are only used with IPv4 datums on
     * platforms where datum is 8 bytes.)
     *
     * The number of bits in subnet is used to generate a datum subnet
     * bitmask. For example, with a /24 IPv4 datum there are 8 subnet bits
     * (since 32 - 24 is 8), so the final subnet bitmask is B'1111 1111'. We
     * need explicit handling for cases where the ipaddr bits cannot all fit
     * in a datum, though (otherwise we'd incorrectly mask the network
     * component with IPv6 values).
     */
    subnet_size = ip_maxbits(authoritative) - ip_bits(authoritative);
    Assert(subnet_size >= 0);
    /* subnet size must work with prefix ipaddr cases */
    subnet_size %= SIZEOF_DATUM * BITS_PER_BYTE;
    if (ip_bits(authoritative) == 0)
    {
        /* Fit as many ipaddr bits as possible into subnet */
        subnet_bitmask = ((Datum) 0) - 1;
        network = 0;
    }
    else if (ip_bits(authoritative) < SIZEOF_DATUM * BITS_PER_BYTE)
    {
        /* Split ipaddr bits between network and subnet */
        subnet_bitmask = (((Datum) 1) << subnet_size) - 1;
        network = ipaddr_datum & ~subnet_bitmask;
    }
    else
    {
        /* Fit as many ipaddr bits as possible into network */
        subnet_bitmask = 0;
        network = ipaddr_datum;
    }

#if SIZEOF_DATUM == 8
    if (ip_family(authoritative) == PGSQL_AF_INET)
    {
        /*
         * IPv4 with 8 byte datums: keep all 32 netmasked bits, netmask size,
         * and most significant 25 subnet bits
         */
        Datum       netmask_size = (Datum) ip_bits(authoritative);
        Datum       subnet;

        /*
         * Shift left 31 bits: 6 bits netmask size + 25 subnet bits.
         *
         * We don't make any distinction between network bits that are zero
         * due to masking and "true"/non-masked zero bits.  An abbreviated
         * comparison that is resolved by comparing a non-masked and non-zero
         * bit to a masked/zeroed bit is effectively resolved based on
         * ip_bits(), even though the comparison won't reach the netmask_size
         * bits.
         */
        network <<= (ABBREV_BITS_INET4_NETMASK_SIZE +
                     ABBREV_BITS_INET4_SUBNET);

        /* Shift size to make room for subnet bits at the end */
        netmask_size <<= ABBREV_BITS_INET4_SUBNET;

        /* Extract subnet bits without shifting them */
        subnet = ipaddr_datum & subnet_bitmask;

        /*
         * If we have more than 25 subnet bits, we can't fit everything. Shift
         * subnet down to avoid clobbering bits that are only supposed to be
         * used for netmask_size.
         *
         * Discarding the least significant subnet bits like this is correct
         * because abbreviated comparisons that are resolved at the subnet
         * level must have had equal netmask_size/ip_bits() values in order to
         * get that far.
         */
        if (subnet_size > ABBREV_BITS_INET4_SUBNET)
            subnet >>= subnet_size - ABBREV_BITS_INET4_SUBNET;

        /*
         * Assemble the final abbreviated key without clobbering the ipfamily
         * bit that must remain a zero.
         */
        res |= network | netmask_size | subnet;
    }
    else
#endif
    {
        /*
         * 4 byte datums, or IPv6 with 8 byte datums: Use as many of the
         * netmasked bits as will fit in final abbreviated key. Avoid
         * clobbering the ipfamily bit that was set earlier.
         */
        res |= network >> 1;
    }

    uss->input_count += 1;

    /* Hash abbreviated key */
    if (uss->estimating)
    {
        uint32      tmp;

#if SIZEOF_DATUM == 8
        tmp = (uint32) res ^ (uint32) ((uint64) res >> 32);
#else                           /* SIZEOF_DATUM != 8 */
        tmp = (uint32) res;
#endif

        addHyperLogLog(&uss->abbr_card, DatumGetUInt32(hash_uint32(tmp)));
    }

    return res;
}

/*
 *  Boolean ordering tests.
 */
Datum
network_lt(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_BOOL(network_cmp_internal(a1, a2) < 0);
}

Datum
network_le(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_BOOL(network_cmp_internal(a1, a2) <= 0);
}

Datum
network_eq(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_BOOL(network_cmp_internal(a1, a2) == 0);
}

Datum
network_ge(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_BOOL(network_cmp_internal(a1, a2) >= 0);
}

Datum
network_gt(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_BOOL(network_cmp_internal(a1, a2) > 0);
}

Datum
network_ne(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_BOOL(network_cmp_internal(a1, a2) != 0);
}

/*
 * MIN/MAX support functions.
 */
Datum
network_smaller(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    if (network_cmp_internal(a1, a2) < 0)
        PG_RETURN_INET_P(a1);
    else
        PG_RETURN_INET_P(a2);
}

Datum
network_larger(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    if (network_cmp_internal(a1, a2) > 0)
        PG_RETURN_INET_P(a1);
    else
        PG_RETURN_INET_P(a2);
}

/*
 * Support function for hash indexes on inet/cidr.
 */
Datum
hashinet(PG_FUNCTION_ARGS)
{
    inet       *addr = PG_GETARG_INET_PP(0);
    int         addrsize = ip_addrsize(addr);

    /* XXX this assumes there are no pad bytes in the data structure */
    return hash_any((unsigned char *) VARDATA_ANY(addr), addrsize + 2);
}

Datum
hashinetextended(PG_FUNCTION_ARGS)
{
    inet       *addr = PG_GETARG_INET_PP(0);
    int         addrsize = ip_addrsize(addr);

    return hash_any_extended((unsigned char *) VARDATA_ANY(addr), addrsize + 2,
                             PG_GETARG_INT64(1));
}

/*
 *  Boolean network-inclusion tests.
 */
Datum
network_sub(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    if (ip_family(a1) == ip_family(a2))
    {
        PG_RETURN_BOOL(ip_bits(a1) > ip_bits(a2) &&
                       bitncmp(ip_addr(a1), ip_addr(a2), ip_bits(a2)) == 0);
    }

    PG_RETURN_BOOL(false);
}

Datum
network_subeq(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    if (ip_family(a1) == ip_family(a2))
    {
        PG_RETURN_BOOL(ip_bits(a1) >= ip_bits(a2) &&
                       bitncmp(ip_addr(a1), ip_addr(a2), ip_bits(a2)) == 0);
    }

    PG_RETURN_BOOL(false);
}

Datum
network_sup(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    if (ip_family(a1) == ip_family(a2))
    {
        PG_RETURN_BOOL(ip_bits(a1) < ip_bits(a2) &&
                       bitncmp(ip_addr(a1), ip_addr(a2), ip_bits(a1)) == 0);
    }

    PG_RETURN_BOOL(false);
}

Datum
network_supeq(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    if (ip_family(a1) == ip_family(a2))
    {
        PG_RETURN_BOOL(ip_bits(a1) <= ip_bits(a2) &&
                       bitncmp(ip_addr(a1), ip_addr(a2), ip_bits(a1)) == 0);
    }

    PG_RETURN_BOOL(false);
}

Datum
network_overlap(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    if (ip_family(a1) == ip_family(a2))
    {
        PG_RETURN_BOOL(bitncmp(ip_addr(a1), ip_addr(a2),
                               Min(ip_bits(a1), ip_bits(a2))) == 0);
    }

    PG_RETURN_BOOL(false);
}

/*
 * Planner support function for network subset/superset operators
 */
Datum
network_subset_support(PG_FUNCTION_ARGS)
{
    Node       *rawreq = (Node *) PG_GETARG_POINTER(0);
    Node       *ret = NULL;

    if (IsA(rawreq, SupportRequestIndexCondition))
    {
        /* Try to convert operator/function call to index conditions */
        SupportRequestIndexCondition *req = (SupportRequestIndexCondition *) rawreq;

        if (is_opclause(req->node))
        {
            OpExpr     *clause = (OpExpr *) req->node;

            Assert(list_length(clause->args) == 2);
            ret = (Node *)
                match_network_function((Node *) linitial(clause->args),
                                       (Node *) lsecond(clause->args),
                                       req->indexarg,
                                       req->funcid,
                                       req->opfamily);
        }
        else if (is_funcclause(req->node))  /* be paranoid */
        {
            FuncExpr   *clause = (FuncExpr *) req->node;

            Assert(list_length(clause->args) == 2);
            ret = (Node *)
                match_network_function((Node *) linitial(clause->args),
                                       (Node *) lsecond(clause->args),
                                       req->indexarg,
                                       req->funcid,
                                       req->opfamily);
        }
    }

    PG_RETURN_POINTER(ret);
}

/*
 * match_network_function
 *    Try to generate an indexqual for a network subset/superset function.
 *
 * This layer is just concerned with identifying the function and swapping
 * the arguments if necessary.
 */
static List *
match_network_function(Node *leftop,
                       Node *rightop,
                       int indexarg,
                       Oid funcid,
                       Oid opfamily)
{
    switch (funcid)
    {
        case F_NETWORK_SUB:
            /* indexkey must be on the left */
            if (indexarg != 0)
                return NIL;
            return match_network_subset(leftop, rightop, false, opfamily);

        case F_NETWORK_SUBEQ:
            /* indexkey must be on the left */
            if (indexarg != 0)
                return NIL;
            return match_network_subset(leftop, rightop, true, opfamily);

        case F_NETWORK_SUP:
            /* indexkey must be on the right */
            if (indexarg != 1)
                return NIL;
            return match_network_subset(rightop, leftop, false, opfamily);

        case F_NETWORK_SUPEQ:
            /* indexkey must be on the right */
            if (indexarg != 1)
                return NIL;
            return match_network_subset(rightop, leftop, true, opfamily);

        default:

            /*
             * We'd only get here if somebody attached this support function
             * to an unexpected function.  Maybe we should complain, but for
             * now, do nothing.
             */
            return NIL;
    }
}

/*
 * match_network_subset
 *    Try to generate an indexqual for a network subset function.
 */
static List *
match_network_subset(Node *leftop,
                     Node *rightop,
                     bool is_eq,
                     Oid opfamily)
{
    List       *result;
    Datum       rightopval;
    Oid         datatype = INETOID;
    Oid         opr1oid;
    Oid         opr2oid;
    Datum       opr1right;
    Datum       opr2right;
    Expr       *expr;

    /*
     * Can't do anything with a non-constant or NULL comparison value.
     *
     * Note that since we restrict ourselves to cases with a hard constant on
     * the RHS, it's a-fortiori a pseudoconstant, and we don't need to worry
     * about verifying that.
     */
    if (!IsA(rightop, Const) ||
        ((Const *) rightop)->constisnull)
        return NIL;
    rightopval = ((Const *) rightop)->constvalue;

    /*
     * Must check that index's opfamily supports the operators we will want to
     * apply.
     *
     * We insist on the opfamily being the specific one we expect, else we'd
     * do the wrong thing if someone were to make a reverse-sort opfamily with
     * the same operators.
     */
    if (opfamily != NETWORK_BTREE_FAM_OID)
        return NIL;

    /*
     * create clause "key >= network_scan_first( rightopval )", or ">" if the
     * operator disallows equality.
     *
     * Note: seeing that this function supports only fixed values for opfamily
     * and datatype, we could just hard-wire the operator OIDs instead of
     * looking them up.  But for now it seems better to be general.
     */
    if (is_eq)
    {
        opr1oid = get_opfamily_member(opfamily, datatype, datatype,
                                      BTGreaterEqualStrategyNumber);
        if (opr1oid == InvalidOid)
            elog(ERROR, "no >= operator for opfamily %u", opfamily);
    }
    else
    {
        opr1oid = get_opfamily_member(opfamily, datatype, datatype,
                                      BTGreaterStrategyNumber);
        if (opr1oid == InvalidOid)
            elog(ERROR, "no > operator for opfamily %u", opfamily);
    }

    opr1right = network_scan_first(rightopval);

    expr = make_opclause(opr1oid, BOOLOID, false,
                         (Expr *) leftop,
                         (Expr *) makeConst(datatype, -1,
                                            InvalidOid, /* not collatable */
                                            -1, opr1right,
                                            false, false),
                         InvalidOid, InvalidOid);
    result = list_make1(expr);

    /* create clause "key <= network_scan_last( rightopval )" */

    opr2oid = get_opfamily_member(opfamily, datatype, datatype,
                                  BTLessEqualStrategyNumber);
    if (opr2oid == InvalidOid)
        elog(ERROR, "no <= operator for opfamily %u", opfamily);

    opr2right = network_scan_last(rightopval);

    expr = make_opclause(opr2oid, BOOLOID, false,
                         (Expr *) leftop,
                         (Expr *) makeConst(datatype, -1,
                                            InvalidOid, /* not collatable */
                                            -1, opr2right,
                                            false, false),
                         InvalidOid, InvalidOid);
    result = lappend(result, expr);

    return result;
}


/*
 * Extract data from a network datatype.
 */
Datum
network_host(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    char       *ptr;
    char        tmp[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];

    /* force display of max bits, regardless of masklen... */
    if (pg_inet_net_ntop(ip_family(ip), ip_addr(ip), ip_maxbits(ip),
                         tmp, sizeof(tmp)) == NULL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("could not format inet value: %m")));

    /* Suppress /n if present (shouldn't happen now) */
    if ((ptr = strchr(tmp, '/')) != NULL)
        *ptr = '\0';

    PG_RETURN_TEXT_P(cstring_to_text(tmp));
}

/*
 * network_show implements the inet and cidr casts to text.  This is not
 * quite the same behavior as network_out, hence we can't drop it in favor
 * of CoerceViaIO.
 */
Datum
network_show(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    int         len;
    char        tmp[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];

    if (pg_inet_net_ntop(ip_family(ip), ip_addr(ip), ip_maxbits(ip),
                         tmp, sizeof(tmp)) == NULL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("could not format inet value: %m")));

    /* Add /n if not present (which it won't be) */
    if (strchr(tmp, '/') == NULL)
    {
        len = strlen(tmp);
        snprintf(tmp + len, sizeof(tmp) - len, "/%u", ip_bits(ip));
    }

    PG_RETURN_TEXT_P(cstring_to_text(tmp));
}

Datum
inet_abbrev(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    char       *dst;
    char        tmp[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];

    dst = pg_inet_net_ntop(ip_family(ip), ip_addr(ip),
                           ip_bits(ip), tmp, sizeof(tmp));

    if (dst == NULL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("could not format inet value: %m")));

    PG_RETURN_TEXT_P(cstring_to_text(tmp));
}

Datum
cidr_abbrev(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    char       *dst;
    char        tmp[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];

    dst = pg_inet_cidr_ntop(ip_family(ip), ip_addr(ip),
                            ip_bits(ip), tmp, sizeof(tmp));

    if (dst == NULL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("could not format cidr value: %m")));

    PG_RETURN_TEXT_P(cstring_to_text(tmp));
}

Datum
network_masklen(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);

    PG_RETURN_INT32(ip_bits(ip));
}

Datum
network_family(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);

    switch (ip_family(ip))
    {
        case PGSQL_AF_INET:
            PG_RETURN_INT32(4);
            break;
        case PGSQL_AF_INET6:
            PG_RETURN_INT32(6);
            break;
        default:
            PG_RETURN_INT32(0);
            break;
    }
}

Datum
network_broadcast(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *dst;
    int         byte;
    int         bits;
    int         maxbytes;
    unsigned char mask;
    unsigned char *a,
               *b;

    /* make sure any unused bits are zeroed */
    dst = (inet *) palloc0(sizeof(inet));

    maxbytes = ip_addrsize(ip);
    bits = ip_bits(ip);
    a = ip_addr(ip);
    b = ip_addr(dst);

    for (byte = 0; byte < maxbytes; byte++)
    {
        if (bits >= 8)
        {
            mask = 0x00;
            bits -= 8;
        }
        else if (bits == 0)
            mask = 0xff;
        else
        {
            mask = 0xff >> bits;
            bits = 0;
        }

        b[byte] = a[byte] | mask;
    }

    ip_family(dst) = ip_family(ip);
    ip_bits(dst) = ip_bits(ip);
    SET_INET_VARSIZE(dst);

    PG_RETURN_INET_P(dst);
}

Datum
network_network(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *dst;
    int         byte;
    int         bits;
    unsigned char mask;
    unsigned char *a,
               *b;

    /* make sure any unused bits are zeroed */
    dst = (inet *) palloc0(sizeof(inet));

    bits = ip_bits(ip);
    a = ip_addr(ip);
    b = ip_addr(dst);

    byte = 0;

    while (bits)
    {
        if (bits >= 8)
        {
            mask = 0xff;
            bits -= 8;
        }
        else
        {
            mask = 0xff << (8 - bits);
            bits = 0;
        }

        b[byte] = a[byte] & mask;
        byte++;
    }

    ip_family(dst) = ip_family(ip);
    ip_bits(dst) = ip_bits(ip);
    SET_INET_VARSIZE(dst);

    PG_RETURN_INET_P(dst);
}

Datum
network_netmask(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *dst;
    int         byte;
    int         bits;
    unsigned char mask;
    unsigned char *b;

    /* make sure any unused bits are zeroed */
    dst = (inet *) palloc0(sizeof(inet));

    bits = ip_bits(ip);
    b = ip_addr(dst);

    byte = 0;

    while (bits)
    {
        if (bits >= 8)
        {
            mask = 0xff;
            bits -= 8;
        }
        else
        {
            mask = 0xff << (8 - bits);
            bits = 0;
        }

        b[byte] = mask;
        byte++;
    }

    ip_family(dst) = ip_family(ip);
    ip_bits(dst) = ip_maxbits(ip);
    SET_INET_VARSIZE(dst);

    PG_RETURN_INET_P(dst);
}

Datum
network_hostmask(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *dst;
    int         byte;
    int         bits;
    int         maxbytes;
    unsigned char mask;
    unsigned char *b;

    /* make sure any unused bits are zeroed */
    dst = (inet *) palloc0(sizeof(inet));

    maxbytes = ip_addrsize(ip);
    bits = ip_maxbits(ip) - ip_bits(ip);
    b = ip_addr(dst);

    byte = maxbytes - 1;

    while (bits)
    {
        if (bits >= 8)
        {
            mask = 0xff;
            bits -= 8;
        }
        else
        {
            mask = 0xff >> (8 - bits);
            bits = 0;
        }

        b[byte] = mask;
        byte--;
    }

    ip_family(dst) = ip_family(ip);
    ip_bits(dst) = ip_maxbits(ip);
    SET_INET_VARSIZE(dst);

    PG_RETURN_INET_P(dst);
}

/*
 * Returns true if the addresses are from the same family, or false.  Used to
 * check that we can create a network which contains both of the networks.
 */
Datum
inet_same_family(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0);
    inet       *a2 = PG_GETARG_INET_PP(1);

    PG_RETURN_BOOL(ip_family(a1) == ip_family(a2));
}

/*
 * Returns the smallest CIDR which contains both of the inputs.
 */
Datum
inet_merge(PG_FUNCTION_ARGS)
{
    inet       *a1 = PG_GETARG_INET_PP(0),
               *a2 = PG_GETARG_INET_PP(1);
    int         commonbits;

    if (ip_family(a1) != ip_family(a2))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("cannot merge addresses from different families")));

    commonbits = bitncommon(ip_addr(a1), ip_addr(a2),
                            Min(ip_bits(a1), ip_bits(a2)));

    PG_RETURN_INET_P(cidr_set_masklen_internal(a1, commonbits));
}

/*
 * Convert a value of a network datatype to an approximate scalar value.
 * This is used for estimating selectivities of inequality operators
 * involving network types.
 *
 * On failure (e.g., unsupported typid), set *failure to true;
 * otherwise, that variable is not changed.
 */
double
convert_network_to_scalar(Datum value, Oid typid, bool *failure)
{
    switch (typid)
    {
        case INETOID:
        case CIDROID:
            {
                inet       *ip = DatumGetInetPP(value);
                int         len;
                double      res;
                int         i;

                /*
                 * Note that we don't use the full address for IPv6.
                 */
                if (ip_family(ip) == PGSQL_AF_INET)
                    len = 4;
                else
                    len = 5;

                res = ip_family(ip);
                for (i = 0; i < len; i++)
                {
                    res *= 256;
                    res += ip_addr(ip)[i];
                }
                return res;
            }
        case MACADDROID:
            {
                macaddr    *mac = DatumGetMacaddrP(value);
                double      res;

                res = (mac->a << 16) | (mac->b << 8) | (mac->c);
                res *= 256 * 256 * 256;
                res += (mac->d << 16) | (mac->e << 8) | (mac->f);
                return res;
            }
        case MACADDR8OID:
            {
                macaddr8   *mac = DatumGetMacaddr8P(value);
                double      res;

                res = (mac->a << 24) | (mac->b << 16) | (mac->c << 8) | (mac->d);
                res *= ((double) 256) * 256 * 256 * 256;
                res += (mac->e << 24) | (mac->f << 16) | (mac->g << 8) | (mac->h);
                return res;
            }
    }

    *failure = true;
    return 0;
}

/*
 * int
 * bitncmp(l, r, n)
 *      compare bit masks l and r, for n bits.
 * return:
 *      <0, >0, or 0 in the libc tradition.
 * note:
 *      network byte order assumed.  this means 192.5.5.240/28 has
 *      0x11110000 in its fourth octet.
 * author:
 *      Paul Vixie (ISC), June 1996
 */
int
bitncmp(const unsigned char *l, const unsigned char *r, int n)
{
    unsigned int lb,
                rb;
    int         x,
                b;

    b = n / 8;
    x = memcmp(l, r, b);
    if (x || (n % 8) == 0)
        return x;

    lb = l[b];
    rb = r[b];
    for (b = n % 8; b > 0; b--)
    {
        if (IS_HIGHBIT_SET(lb) != IS_HIGHBIT_SET(rb))
        {
            if (IS_HIGHBIT_SET(lb))
                return 1;
            return -1;
        }
        lb <<= 1;
        rb <<= 1;
    }
    return 0;
}

/*
 * bitncommon: compare bit masks l and r, for up to n bits.
 *
 * Returns the number of leading bits that match (0 to n).
 */
int
bitncommon(const unsigned char *l, const unsigned char *r, int n)
{
    int         byte,
                nbits;

    /* number of bits to examine in last byte */
    nbits = n % 8;

    /* check whole bytes */
    for (byte = 0; byte < n / 8; byte++)
    {
        if (l[byte] != r[byte])
        {
            /* at least one bit in the last byte is not common */
            nbits = 7;
            break;
        }
    }

    /* check bits in last partial byte */
    if (nbits != 0)
    {
        /* calculate diff of first non-matching bytes */
        unsigned int diff = l[byte] ^ r[byte];

        /* compare the bits from the most to the least */
        while ((diff >> (8 - nbits)) != 0)
            nbits--;
    }

    return (8 * byte) + nbits;
}


/*
 * Verify a CIDR address is OK (doesn't have bits set past the masklen)
 */
static bool
addressOK(unsigned char *a, int bits, int family)
{
    int         byte;
    int         nbits;
    int         maxbits;
    int         maxbytes;
    unsigned char mask;

    if (family == PGSQL_AF_INET)
    {
        maxbits = 32;
        maxbytes = 4;
    }
    else
    {
        maxbits = 128;
        maxbytes = 16;
    }
    Assert(bits <= maxbits);

    if (bits == maxbits)
        return true;

    byte = bits / 8;

    nbits = bits % 8;
    mask = 0xff;
    if (bits != 0)
        mask >>= nbits;

    while (byte < maxbytes)
    {
        if ((a[byte] & mask) != 0)
            return false;
        mask = 0xff;
        byte++;
    }

    return true;
}


/*
 * These functions are used by planner to generate indexscan limits
 * for clauses a << b and a <<= b
 */

/* return the minimal value for an IP on a given network */
Datum
network_scan_first(Datum in)
{
    return DirectFunctionCall1(network_network, in);
}

/*
 * return "last" IP on a given network. It's the broadcast address,
 * however, masklen has to be set to its max bits, since
 * 192.168.0.255/24 is considered less than 192.168.0.255/32
 *
 * inet_set_masklen() hacked to max out the masklength to 128 for IPv6
 * and 32 for IPv4 when given '-1' as argument.
 */
Datum
network_scan_last(Datum in)
{
    return DirectFunctionCall2(inet_set_masklen,
                               DirectFunctionCall1(network_broadcast, in),
                               Int32GetDatum(-1));
}


/*
 * IP address that the client is connecting from (NULL if Unix socket)
 */
Datum
inet_client_addr(PG_FUNCTION_ARGS)
{
    Port       *port = MyProcPort;
    char        remote_host[NI_MAXHOST];
    int         ret;

    if (port == NULL)
        PG_RETURN_NULL();

    switch (port->raddr.addr.ss_family)
    {
        case AF_INET:
#ifdef HAVE_IPV6
        case AF_INET6:
#endif
            break;
        default:
            PG_RETURN_NULL();
    }

    remote_host[0] = '\0';

    ret = pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen,
                             remote_host, sizeof(remote_host),
                             NULL, 0,
                             NI_NUMERICHOST | NI_NUMERICSERV);
    if (ret != 0)
        PG_RETURN_NULL();

    clean_ipv6_addr(port->raddr.addr.ss_family, remote_host);

    PG_RETURN_INET_P(network_in(remote_host, false));
}


/*
 * port that the client is connecting from (NULL if Unix socket)
 */
Datum
inet_client_port(PG_FUNCTION_ARGS)
{
    Port       *port = MyProcPort;
    char        remote_port[NI_MAXSERV];
    int         ret;

    if (port == NULL)
        PG_RETURN_NULL();

    switch (port->raddr.addr.ss_family)
    {
        case AF_INET:
#ifdef HAVE_IPV6
        case AF_INET6:
#endif
            break;
        default:
            PG_RETURN_NULL();
    }

    remote_port[0] = '\0';

    ret = pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen,
                             NULL, 0,
                             remote_port, sizeof(remote_port),
                             NI_NUMERICHOST | NI_NUMERICSERV);
    if (ret != 0)
        PG_RETURN_NULL();

    PG_RETURN_DATUM(DirectFunctionCall1(int4in, CStringGetDatum(remote_port)));
}


/*
 * IP address that the server accepted the connection on (NULL if Unix socket)
 */
Datum
inet_server_addr(PG_FUNCTION_ARGS)
{
    Port       *port = MyProcPort;
    char        local_host[NI_MAXHOST];
    int         ret;

    if (port == NULL)
        PG_RETURN_NULL();

    switch (port->laddr.addr.ss_family)
    {
        case AF_INET:
#ifdef HAVE_IPV6
        case AF_INET6:
#endif
            break;
        default:
            PG_RETURN_NULL();
    }

    local_host[0] = '\0';

    ret = pg_getnameinfo_all(&port->laddr.addr, port->laddr.salen,
                             local_host, sizeof(local_host),
                             NULL, 0,
                             NI_NUMERICHOST | NI_NUMERICSERV);
    if (ret != 0)
        PG_RETURN_NULL();

    clean_ipv6_addr(port->laddr.addr.ss_family, local_host);

    PG_RETURN_INET_P(network_in(local_host, false));
}


/*
 * port that the server accepted the connection on (NULL if Unix socket)
 */
Datum
inet_server_port(PG_FUNCTION_ARGS)
{
    Port       *port = MyProcPort;
    char        local_port[NI_MAXSERV];
    int         ret;

    if (port == NULL)
        PG_RETURN_NULL();

    switch (port->laddr.addr.ss_family)
    {
        case AF_INET:
#ifdef HAVE_IPV6
        case AF_INET6:
#endif
            break;
        default:
            PG_RETURN_NULL();
    }

    local_port[0] = '\0';

    ret = pg_getnameinfo_all(&port->laddr.addr, port->laddr.salen,
                             NULL, 0,
                             local_port, sizeof(local_port),
                             NI_NUMERICHOST | NI_NUMERICSERV);
    if (ret != 0)
        PG_RETURN_NULL();

    PG_RETURN_DATUM(DirectFunctionCall1(int4in, CStringGetDatum(local_port)));
}


Datum
inetnot(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *dst;

    dst = (inet *) palloc0(sizeof(inet));

    {
        int         nb = ip_addrsize(ip);
        unsigned char *pip = ip_addr(ip);
        unsigned char *pdst = ip_addr(dst);

        while (nb-- > 0)
            pdst[nb] = ~pip[nb];
    }
    ip_bits(dst) = ip_bits(ip);

    ip_family(dst) = ip_family(ip);
    SET_INET_VARSIZE(dst);

    PG_RETURN_INET_P(dst);
}


Datum
inetand(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *ip2 = PG_GETARG_INET_PP(1);
    inet       *dst;

    dst = (inet *) palloc0(sizeof(inet));

    if (ip_family(ip) != ip_family(ip2))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("cannot AND inet values of different sizes")));
    else
    {
        int         nb = ip_addrsize(ip);
        unsigned char *pip = ip_addr(ip);
        unsigned char *pip2 = ip_addr(ip2);
        unsigned char *pdst = ip_addr(dst);

        while (nb-- > 0)
            pdst[nb] = pip[nb] & pip2[nb];
    }
    ip_bits(dst) = Max(ip_bits(ip), ip_bits(ip2));

    ip_family(dst) = ip_family(ip);
    SET_INET_VARSIZE(dst);

    PG_RETURN_INET_P(dst);
}


Datum
inetor(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *ip2 = PG_GETARG_INET_PP(1);
    inet       *dst;

    dst = (inet *) palloc0(sizeof(inet));

    if (ip_family(ip) != ip_family(ip2))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("cannot OR inet values of different sizes")));
    else
    {
        int         nb = ip_addrsize(ip);
        unsigned char *pip = ip_addr(ip);
        unsigned char *pip2 = ip_addr(ip2);
        unsigned char *pdst = ip_addr(dst);

        while (nb-- > 0)
            pdst[nb] = pip[nb] | pip2[nb];
    }
    ip_bits(dst) = Max(ip_bits(ip), ip_bits(ip2));

    ip_family(dst) = ip_family(ip);
    SET_INET_VARSIZE(dst);

    PG_RETURN_INET_P(dst);
}


static inet *
internal_inetpl(inet *ip, int64 addend)
{
    inet       *dst;

    dst = (inet *) palloc0(sizeof(inet));

    {
        int         nb = ip_addrsize(ip);
        unsigned char *pip = ip_addr(ip);
        unsigned char *pdst = ip_addr(dst);
        int         carry = 0;

        while (nb-- > 0)
        {
            carry = pip[nb] + (int) (addend & 0xFF) + carry;
            pdst[nb] = (unsigned char) (carry & 0xFF);
            carry >>= 8;

            /*
             * We have to be careful about right-shifting addend because
             * right-shift isn't portable for negative values, while simply
             * dividing by 256 doesn't work (the standard rounding is in the
             * wrong direction, besides which there may be machines out there
             * that round the wrong way).  So, explicitly clear the low-order
             * byte to remove any doubt about the correct result of the
             * division, and then divide rather than shift.
             */
            addend &= ~((int64) 0xFF);
            addend /= 0x100;
        }

        /*
         * At this point we should have addend and carry both zero if original
         * addend was >= 0, or addend -1 and carry 1 if original addend was <
         * 0.  Anything else means overflow.
         */
        if (!((addend == 0 && carry == 0) ||
              (addend == -1 && carry == 1)))
            ereport(ERROR,
                    (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                     errmsg("result is out of range")));
    }

    ip_bits(dst) = ip_bits(ip);
    ip_family(dst) = ip_family(ip);
    SET_INET_VARSIZE(dst);

    return dst;
}


Datum
inetpl(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    int64       addend = PG_GETARG_INT64(1);

    PG_RETURN_INET_P(internal_inetpl(ip, addend));
}


Datum
inetmi_int8(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    int64       addend = PG_GETARG_INT64(1);

    PG_RETURN_INET_P(internal_inetpl(ip, -addend));
}


Datum
inetmi(PG_FUNCTION_ARGS)
{
    inet       *ip = PG_GETARG_INET_PP(0);
    inet       *ip2 = PG_GETARG_INET_PP(1);
    int64       res = 0;

    if (ip_family(ip) != ip_family(ip2))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("cannot subtract inet values of different sizes")));
    else
    {
        /*
         * We form the difference using the traditional complement, increment,
         * and add rule, with the increment part being handled by starting the
         * carry off at 1.  If you don't think integer arithmetic is done in
         * two's complement, too bad.
         */
        int         nb = ip_addrsize(ip);
        int         byte = 0;
        unsigned char *pip = ip_addr(ip);
        unsigned char *pip2 = ip_addr(ip2);
        int         carry = 1;

        while (nb-- > 0)
        {
            int         lobyte;

            carry = pip[nb] + (~pip2[nb] & 0xFF) + carry;
            lobyte = carry & 0xFF;
            if (byte < sizeof(int64))
            {
                res |= ((int64) lobyte) << (byte * 8);
            }
            else
            {
                /*
                 * Input wider than int64: check for overflow.  All bytes to
                 * the left of what will fit should be 0 or 0xFF, depending on
                 * sign of the now-complete result.
                 */
                if ((res < 0) ? (lobyte != 0xFF) : (lobyte != 0))
                    ereport(ERROR,
                            (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                             errmsg("result is out of range")));
            }
            carry >>= 8;
            byte++;
        }

        /*
         * If input is narrower than int64, overflow is not possible, but we
         * have to do proper sign extension.
         */
        if (carry == 0 && byte < sizeof(int64))
            res |= ((uint64) (int64) -1) << (byte * 8);
    }

    PG_RETURN_INT64(res);
}


/*
 * clean_ipv6_addr --- remove any '%zone' part from an IPv6 address string
 *
 * XXX This should go away someday!
 *
 * This is a kluge needed because we don't yet support zones in stored inet
 * values.  Since the result of getnameinfo() might include a zone spec,
 * call this to remove it anywhere we want to feed getnameinfo's output to
 * network_in.  Beats failing entirely.
 *
 * An alternative approach would be to let network_in ignore %-parts for
 * itself, but that would mean we'd silently drop zone specs in user input,
 * which seems not such a good idea.
 */
void
clean_ipv6_addr(int addr_family, char *addr)
{
#ifdef HAVE_IPV6
    if (addr_family == AF_INET6)
    {
        char       *pct = strchr(addr, '%');

        if (pct)
            *pct = '\0';
    }
#endif
}