class NetStat {

    private static final Logger LOG = LoggerFactory.getLogger(NetStat.class);

    private static final int CTL_NET = 4;
    private static final int PF_ROUTE = 17;
    private static final int NET_RT_IFLIST2 = 6;
    private static final int RTM_IFINFO2 = 0x12;

    private NetStat() {
    }

    /**
     * Map data for network interfaces.
     *
     * @param index If positive, limit the map to only return data for this interface index. If negative, returns data
     *              for all indices.
     *
     * @return a map of {@link IFdata} object indexed by the interface index, encapsulating the stats
     */
    public static Map<Integer, IFdata> queryIFdata(int index) {<FILL_FUNCTION_BODY>}

    /**
     * Class to encapsulate IF data for method return
     */
    @Immutable
    public static class IFdata {
        private final int ifType;
        private final long oPackets;
        private final long iPackets;
        private final long oBytes;
        private final long iBytes;
        private final long oErrors;
        private final long iErrors;
        private final long collisions;
        private final long iDrops;
        private final long speed;
        private final long timeStamp;

        IFdata(int ifType, // NOSONAR squid:S00107
                long oPackets, long iPackets, long oBytes, long iBytes, long oErrors, long iErrors, long collisions,
                long iDrops, long speed, long timeStamp) {
            this.ifType = ifType;
            this.oPackets = oPackets & 0xffffffffL;
            this.iPackets = iPackets & 0xffffffffL;
            this.oBytes = oBytes & 0xffffffffL;
            this.iBytes = iBytes & 0xffffffffL;
            this.oErrors = oErrors & 0xffffffffL;
            this.iErrors = iErrors & 0xffffffffL;
            this.collisions = collisions & 0xffffffffL;
            this.iDrops = iDrops & 0xffffffffL;
            this.speed = speed & 0xffffffffL;
            this.timeStamp = timeStamp;
        }

        /**
         * @return the ifType
         */
        public int getIfType() {
            return ifType;
        }

        /**
         * @return the oPackets
         */
        public long getOPackets() {
            return oPackets;
        }

        /**
         * @return the iPackets
         */
        public long getIPackets() {
            return iPackets;
        }

        /**
         * @return the oBytes
         */
        public long getOBytes() {
            return oBytes;
        }

        /**
         * @return the iBytes
         */
        public long getIBytes() {
            return iBytes;
        }

        /**
         * @return the oErrors
         */
        public long getOErrors() {
            return oErrors;
        }

        /**
         * @return the iErrors
         */
        public long getIErrors() {
            return iErrors;
        }

        /**
         * @return the collisions
         */
        public long getCollisions() {
            return collisions;
        }

        /**
         * @return the iDrops
         */
        public long getIDrops() {
            return iDrops;
        }

        /**
         * @return the speed
         */
        public long getSpeed() {
            return speed;
        }

        /**
         * @return the timeStamp
         */
        public long getTimeStamp() {
            return timeStamp;
        }
    }
}

        // Ported from source code of "netstat -ir". See
        // https://opensource.apple.com/source/network_cmds/network_cmds-457/netstat.tproj/if.c
        Map<Integer, IFdata> data = new HashMap<>();
        // Get buffer of all interface information
        int[] mib = { CTL_NET, PF_ROUTE, 0, 0, NET_RT_IFLIST2, 0 };
        try (CloseableSizeTByReference len = new CloseableSizeTByReference()) {
            if (0 != SystemB.INSTANCE.sysctl(mib, 6, null, len, null, size_t.ZERO)) {
                LOG.error("Didn't get buffer length for IFLIST2");
                return data;
            }
            try (Memory buf = new Memory(len.longValue())) {
                if (0 != SystemB.INSTANCE.sysctl(mib, 6, buf, len, null, size_t.ZERO)) {
                    LOG.error("Didn't get buffer for IFLIST2");
                    return data;
                }
                final long now = System.currentTimeMillis();

                // Iterate offset from buf's pointer up to limit of buf
                int lim = (int) (buf.size() - new IFmsgHdr().size());
                int offset = 0;
                while (offset < lim) {
                    // Get pointer to current native part of buf
                    Pointer p = buf.share(offset);
                    // Cast pointer to if_msghdr
                    IFmsgHdr ifm = new IFmsgHdr(p);
                    ifm.read();
                    // Advance next
                    offset += ifm.ifm_msglen;
                    // Skip messages which are not the right format
                    if (ifm.ifm_type == RTM_IFINFO2) {
                        // Cast pointer to if_msghdr2
                        IFmsgHdr2 if2m = new IFmsgHdr2(p);
                        if2m.read();
                        if (index < 0 || index == if2m.ifm_index) {
                            data.put((int) if2m.ifm_index,
                                    new IFdata(0xff & if2m.ifm_data.ifi_type, if2m.ifm_data.ifi_opackets,
                                            if2m.ifm_data.ifi_ipackets, if2m.ifm_data.ifi_obytes,
                                            if2m.ifm_data.ifi_ibytes, if2m.ifm_data.ifi_oerrors,
                                            if2m.ifm_data.ifi_ierrors, if2m.ifm_data.ifi_collisions,
                                            if2m.ifm_data.ifi_iqdrops, if2m.ifm_data.ifi_baudrate, now));
                            if (index >= 0) {
                                return data;
                            }
                        }
                    }
                }
            }
        }
        return data;
    
<no_super_class>