SharpPcap.Packets.IPProtocol.extractProtocol C# (CSharp) Method

        public static int extractProtocol(int lLen, byte[] packetBytes)
        {
            IPPacket.IPVersions ipVer = ExtractVersion(lLen, packetBytes);
            int protoOffset;

            switch (ipVer)
            {
                case IPPacket.IPVersions.IPv4:
                    protoOffset = IPv4Fields_Fields.IP_CODE_POS;
                    break;
                case IPPacket.IPVersions.IPv6:
                    protoOffset = IPv6Fields_Fields.NEXT_HEADER_POS;
                    break;
                default:
                    return -1;//unknown ip version
            }
            return packetBytes[lLen + protoOffset];
        }

        /// <summary> Convert captured packet data into an object.</summary>
        public static Packet dataToPacket(int linkType, byte[] bytes, Timeval tv)
        {
            int ethProtocol;

            // retrieve the length of the headers associated with this link layer type.
            // this length is the offset to the header embedded in the packet.
            int lLen = LinkLayer.getLinkLayerLength(linkType);

            // extract the protocol code for the type of header embedded in the
            // link-layer of the packet
            int offset = LinkLayer.getProtoOffset(linkType);

            if (offset == -1)
            {
                // if there is no embedded protocol, assume IP?
                ethProtocol = EthernetPacket.EtherType.IP;
            }
            else
            {
                ethProtocol = ArrayHelper.extractInteger(bytes, offset, EthernetFields_Fields.ETH_CODE_LEN);
            }

            // try to recognize the ethernet type..
            switch (ethProtocol)
            {
            // arp
            case EthernetPacket.EtherType.ARP:
                return(new ARPPacket(lLen, bytes, tv));

            case EthernetPacket.EtherType.IPV6:
            case EthernetPacket.EtherType.IP:
                // ethernet level code is recognized as IP, figure out what kind..
                int ipProtocol = IPProtocol.extractProtocol(lLen, bytes);
                switch (ipProtocol)
                {
                case (int)IPProtocol.IPProtocolType.ICMP: return(new ICMPPacket(lLen, bytes, tv));

                case (int)IPProtocol.IPProtocolType.IGMP: return(new IGMPPacket(lLen, bytes, tv));

                case (int)IPProtocol.IPProtocolType.TCP:  return(new TCPPacket(lLen, bytes, tv));

                case (int)IPProtocol.IPProtocolType.UDP:  return(new UDPPacket(lLen, bytes, tv));

                // unidentified ip..
                default:
                    return(new IPPacket(lLen, bytes, tv));
                }

            // ethernet level code not recognized, default to anonymous packet..
            default:
                return(new EthernetPacket(lLen, bytes, tv));
            }
        }