ln.snmp/types/USMMessage.cs

// /**
//  * File: USMMessage.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using ln.snmp.asn1;
using System.Linq;
using ln.snmp.endpoint;
namespace ln.snmp.types
{
    public class USMMessage : SnmpMessage
    {
        public SnmpV3AuthMethod AuthMethod { get; set; }
        public SnmpV3PrivMethod PrivMethod { get; set; }

        public Integer msgVersion { get; } = new Integer(3);
        public MsgGlobalData msgGlobalData { get; set; }
        public UsmSecurityParameters SecurityParameters { get; set; }

        public ScopedPDU ScopedPDU { get; set; }
        public OctetString EncryptedPDU { get; set; }

        public Variable msgData { get; set; }

        public override PDU snmpPDU
        {
            get => ScopedPDU?.PDU;
            set => ScopedPDU.PDU = value;
        }

        public USMMessage()
            : base(SnmpVersion.V3)
        {
            msgGlobalData = new MsgGlobalData();
            SecurityParameters = new UsmSecurityParameters();
            msgData = new NullValue();
        }

        public USMMessage(ASN1Value asn)
            :this()
        {
            Items = asn.Items.Select((x) => (Variable)x).ToArray();
        }

        public override Variable[] Items
        {
            get => new Variable[] {
                        msgVersion,
                        msgGlobalData,
                        new OctetString(((ASN1Value)SecurityParameters).AsByteArray),
                        msgData
                        };
            set
            {
                msgGlobalData = new MsgGlobalData(value[1]);
                SecurityParameters = new UsmSecurityParameters(new ASN1Value(value[2].Bytes));

                if (value[3].Identifier.Is(IdentifierClass.UNIVERSAL,false,0x04))
                {
                    EncryptedPDU = value[3] as OctetString;
                    msgData = EncryptedPDU;
                } else {
                    ScopedPDU = new ScopedPDU(value[3]);
                    msgData = ScopedPDU;
                }
            }
        }

        public override int MessageID
        {
            get => (int)msgGlobalData.msgID.LongValue;
            set => msgGlobalData.msgID.LongValue = value;
        }

        public override void Add(Variable item)
        {
            throw new NotImplementedException();
        }
        public override void Remove(Variable item)
        {
            throw new NotImplementedException();
        }

        public class MsgGlobalData : AbstractSequence
        {
            public Integer msgID { get; set; }
            public Integer msgMaxSize { get; set; }
            public OctetString msgFlags { get; set; }
            public Integer msgSecurityModel { get; set; }

            public MsgGlobalData()
                :base(new Identifier(IdentifierClass.UNIVERSAL,true,0x10))
            {
                msgID = new Integer((int)(DateTimeOffset.Now.ToUnixTimeSeconds()));
                msgMaxSize = new Integer(65000);
                msgFlags = new OctetString(new byte[] { 0x04 });
                msgSecurityModel = new Integer(3);
            }
            public MsgGlobalData(ASN1Value asn)
                :this()
            {
                Items = asn.Items.ToVariableArray();
            }

            public override void Add(Variable item) => throw new NotImplementedException();
            public override void Remove(Variable item) => throw new NotImplementedException();

            public override Variable[] Items
            {
                get => new Variable[] { msgID,msgMaxSize,msgFlags,msgSecurityModel };
                set
                {
                    msgID = value[0] as Integer;
                    msgMaxSize = value[1] as Integer;
                    msgFlags = value[2] as OctetString;
                    msgSecurityModel = value[3] as Integer;
                }
            }
        }

    }
}