An SNMP Library for .NET Framework

Hello, The Author: Malcolm Crowe of this code used the UdpClient - Class and this class dosn´t support Timeouts. So I have Implemented a new Class with the name: UDPClient ( instead of UdpClient), where you can define Receive- & Send- Timeouts. greetings from Erwin Herzog P.S.: Sorry, the linebreaks and TAB´s are lost at paste operation. Here is the Code of the new proto.cs - File: =================================== using System; using System.Threading; using System.Net.Sockets; using System.IO; using System.Collections; using System.Text; using System.Net; using X690; // SNMP library for .NET by Malcolm Crowe at University of Paisley // http://cis.paisley.ac.uk/crow-ci0/ // This is version 0 of the library. Email bugs to // mailto:[email protected] // Getting Started // The simplest way to get an SNMP value from a host is // ManagerItem mi = new ManagerItem( // new ManagerSession(hostname,"public"), // "1.3.6.1.2.1.1.4.0"); // Then the actual OID is mi.Name and the value is in mi.Value.ToString(). // TODO: Tables, lists of bindings // Friendly strings derived from MIBs namespace Snmp { public class SnmpTag : BERtag { public SnmpTag(SnmpType s) : base((byte)s) {} public SnmpTag() : base() {} public SnmpTag(byte t) : base(t) {} public override string ToString() { if (atp==BERtype.Universal) return base.ToString(); return ((SnmpType)ToByte()).ToString().ToUpper(); } } public enum SnmpType // RFC1213 subset of ASN.1 { EndMarker = 0x00, Boolean = 0x01, Integer=0x02, UInt32=0x47, BitString=0x03, // internally BitSet OctetString=0x04, // internally string ObjectIdentifier=0x06, // internally uint[] Null=0x05, Sequence=0x30, // Array Counter32=0x41, Counter64=0x46, Gauge=0x42, TimeTicks=0x43, IPAddress=0x40, // byte[] Opaque=0x44, NetAddress=0x45, GetRequestPDU=0xA0, GetNextRequestPDU=0xA1, GetResponsePDU=0xA2, SetRequestPDU=0xA3, TrapPDUv1=0xA4, TrapPDUv2=0xA7, GetBulkRequest=0xA5, InformRequest=0xA6 } public class SnmpBER : Universal { // These 3 declarations are needed to make the Universal machinery for SEQUENCEs work correctly protected override Universal Creator(Stream s) { return new SnmpBER(s); } protected override Universal[] Creators(int n) { return new SnmpBER[n]; } protected override bool ValueOf(uint n) { switch ((SnmpType)(type.ToByte())) { case SnmpType.UInt32: val = GetUInt(); break; case SnmpType.Counter32: val = (uint)GetUInt(); break; case SnmpType.Counter64: val = GetULong(); break; case SnmpType.Gauge: val = GetUInt(); break; case SnmpType.TimeTicks: val = GetUInt(); break; case SnmpType.IPAddress: val = b; break; default: return base.ValueOf(n); // handle Universal types } return true; } public override string ToString() { if (val==null) ValueOf(len); if (val is byte[]) { string r = ""; for (int j=0;j<len;j++) { r += b[j]; if (j<len-1) r += "."; } return r; } else return base.ToString(); } public SnmpBER(Stream s) : base(s) {} public SnmpBER(SnmpType t) { b = new byte[0]; e = true; type = new SnmpTag(t); } public SnmpBER(ulong c,SnmpType t) { type = new SnmpTag(t); e = true; b = new byte[ULongLength(c)]; int n=0; PutULong(ref n,c); } public SnmpBER(uint c) : this((ulong)c,SnmpType.Counter32) {} public SnmpBER(byte[] a) // IPAddress { type = new SnmpTag(SnmpType.IPAddress); e = true; b = a; } public SnmpBER(SnmpType t,params Universal[] obs) : base(new SnmpTag(t),obs) {} void PutULong(ref int ln,ulong a) { if (a==0) { b[ln++] = 0; return; } byte[] c = new byte[16]; int j = 0; while (a>0) { c[j++] = (byte)(a&0xff); a = a>>8; } while (j>0) b[ln++] = c[--j]; } uint ULongLength(ulong a) { uint j=0; while (a>0) { j++; a = a>>8; } return j; } ulong GetULong() { ulong r = 0; int p = 0; byte x; do { x = b[p++]; r = (r<<8) + (ulong)x; } while (p<len); return r; } ulong GetUInt() { uint r = 0; int p = 0; byte x; do { x = b[p++]; r = (r<<8) + (uint)x; } while (p<len); return r; } } public class ManagerSession { public string agentAddress; public string agentCommunity; IPEndPoint agent; int seq = 0; UDPClient udp = new UDPClient(); //AsynchUdpClient AsynchUDP = new AsynchUdpClient(); public ManagerSession(string a, string c) { agentAddress = a; agentCommunity = c; IPAddress host = Dns.GetHostByName(a).AddressList[0]; agent = new IPEndPoint(host, 161); udp.ReceiveTimeout = 5000; udp.SendTimeout = 5000; } public void Close() { udp.Close(); /* AsynchUDP.Close();*/ } public Universal VarBind(uint[] oid) { return VarBind(oid, Universal.Null); } public Universal VarBind(uint[] oid, Universal val) { return new Universal(new Universal(oid),val); } public Universal PDU(SnmpType t,params Universal[] vbinds) { seq += 10; return new SnmpBER(t, new Universal(seq), new Universal(0), // errorStatus new Universal(0), // errorIndex new Universal(vbinds)); } public Universal[] Get(params Universal[] vbinds) { Universal pdu; Universal vbindlist; SnmpBER mess = new SnmpBER(SnmpType.Sequence, new Universal(0), // version-1 new Universal(agentCommunity), PDU(SnmpType.GetRequestPDU,vbinds)); MemoryStream m = new MemoryStream(); mess.Send(m); byte[] bytes = m.ToArray(); udp.Send(bytes,bytes.Length,agent); IPEndPoint from = new IPEndPoint(IPAddress.Any,0); //bytes = AsynchUDP.Receive(ref from); bytes = udp.Receive(ref from); if(bytes != null) { m = new MemoryStream(bytes,false); mess = new SnmpBER(m); pdu = mess[2]; vbindlist = pdu[3]; } else { /* The Class: UDPClient throws an Error if no Data will be Received. So we will never come in here. */ throw new Exception("SNMP Error: No response from RemoteAgent."); } return (Universal[])vbindlist.Value; } public void Set(params Universal[] vbinds) { SnmpBER mess = new SnmpBER(SnmpType.Sequence, new Universal(0), // version-1 new Universal(agentCommunity), PDU(SnmpType.SetRequestPDU,vbinds)); MemoryStream m = new MemoryStream(); mess.Send(m); byte[] bytes = m.ToArray(); udp.Send(bytes,bytes.Length,agent); } public bool GetNext(ref Universal vbind) { SnmpBER mess = new SnmpBER(SnmpType.Sequence, new Universal(0), // version-1 new Universal(agentCommunity), PDU(SnmpType.GetNextRequestPDU,vbind)); MemoryStream m = new MemoryStream(); mess.Send(m); byte[] bytes = m.ToArray(); IPAddress host = Dns.GetHostByName(agentAddress).AddressList[0]; agent = new IPEndPoint(host,161); udp.Send(bytes,bytes.Length,agent); IPEndPoint from = new IPEndPoint(IPAddress.Any,0); //bytes = AsynchUDP.Receive(ref from); bytes = udp.Receive(ref from); if(bytes == null) return false; m = new MemoryStream(bytes,false); mess = new SnmpBER(m); Universal pdu = mess[2]; if (((int)(X690.Integer)pdu[1].Value)!=0) // errorStatus return false; Universal vbindlist = pdu[3]; vbind = ((Universal[])vbindlist.Value)[0]; return true; } } public class ManagerItem { bool canset=true; protected ManagerSession sess; public Universal Value { get { if (canset) Refresh(); return varbind[1]; } set { if (!canset) throw new Exception("ManagerItem has been already READ from"); varbind[1]=value; sess.Set(varbind); } } public uint[] Oid { get { return (uint[])(varbind[0].Value); } } Universal varbind; public ManagerItem(ManagerSession s,uint[] oid) : this (s,s.VarBind(oid)) {} public ManagerItem(ManagerSession s,Universal v) : this(s,v,true) {} public ManagerItem(ManagerSession s,Universal v, bool cs) { sess = s; varbind = v; canset = cs; } public void Refresh() { varbind = sess.Get(varbind)[0]; canset = false; } } public class ManagerSubTree { protected ManagerSession sess; ArrayList values = new ArrayList(); // of Universal (Variable Binding) 0:OID 1:Value uint[] start = null; public ManagerSubTree(ManagerSession s,uint[] oid) { sess = s; start = oid; Refresh(); } bool Match(uint[] a, uint[] b) // check that b starts with a { if (b.Length<a.Length) return false; for (int j=0;j<a.Length;j++) if (a[j]!=b[j]) return false; return true; } public void Refresh() { Universal v = sess.VarBind(start); values.Clear(); uint[] next = start; bool fix = false; while (sess.GetNext(ref v)) { uint[] from = (uint[])v[0].Value; if (!Match(start,from)) // outside the start subtree break; // the SNMP standard says that from should be lexicographically greater than next if (from.Length<=next.Length && Match(from,next)) // non-compliance { if (fix||(from.Length<next.Length)) // already tried to fix it or agent really bad throw(new Exception("Non-compliant agent")); fix = true; // try as a fix to add .0 on the end next = new uint[from.Length+1]; for (int j=0;j<from.Length;j++) next[j] = from[j]; next[from.Length] = 0; // and try again } else // compliant: add it to the result set { values.Add(v); next = from; fix = false; } v = sess.VarBind(next); } } public int Length { get { return values.Count; }} public ManagerItem this[int x] { get { return new ManagerItem(sess,(Universal)values[x],false); }} public _Enumerator GetEnumerator() { return new _Enumerator(this); } public class _Enumerator { ManagerSubTree st; int ix = -1; public _Enumerator(ManagerSubTree t) { st=t; } public bool MoveNext() { if (ix==st.Length-1) return false; ix++; return true; } public ManagerItem Current { get { return st[ix]; } } public void Reset() { ix = -1; } } } #region UDPClient with Timeouts public class UDPClient : UdpClient { public UDPClient() : base() { } public UDPClient(int port) : base(port) { } public UDPClient(IPEndPoint localEP) : base(localEP) { } public byte[] SendReceive(byte[] dgram, IPEndPoint destEP, ref IPEndPoint remoteEP) { if ( dgram == null || destEP == null ) return null; byte[] receive; this.Send(dgram, dgram.Length, destEP); //Send using base's Send(); receive = this.Receive(ref remoteEP); return receive; } public bool ReuseAddress { get { object tmpO = this.Client.GetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress); return Convert.ToBoolean(tmpO); } set { Socket s = this.Client; s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, Convert.ToInt32(value)); } } public int ReceiveTimeout { get { Socket s = this.Client; return (int)s.GetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout); } set { if ( value < 0 ) value = 0; Socket s = this.Client; s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, value); } } public int SendTimeout { get { Socket s = this.Client; return (int)s.GetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout); } set { if ( value < 0 ) value = 0; Socket s = this.Client; //Uses the Socket returned by Client to set an option that is not available using UdpClient. s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, value); } } public Socket Socket { get { return this.Client; } set { if ( value == null ) throw new ArgumentNullException("Socket", "Socket is null."); this.Client = value; } } public bool Connected { get { return Socket.Connected; } } public bool IsActive { get { return this.Active; } } public IPEndPoint RemoteIPEndPoint { get { return (IPEndPoint)Socket.RemoteEndPoint; } } public IPEndPoint LocalIPEndPoint { get { return (IPEndPoint)Socket.LocalEndPoint; } } } //End UDPClient Class #endregion UDPClient with Timeouts }

Call the constructor in a Thread. Have a timeout set for the thread. Make the thread die if it doesn't respond by the timeout seconds.

Test to see if the host exists before calling the constructor?