/// <summary>Decode BER encoded variable binding.
/// </summary>
/// <param name="buffer">BER encoded buffer
/// </param>
/// <param name="offset">Offset in the data buffer from where to start decoding. Offset is
/// passed by reference and will contain the offset of the byte immediately after the parsed
/// variable binding.
/// </param>
/// <returns>Buffer position after the decoded value</returns>
public override int decode(byte[] buffer, int offset)
{
int headerLength;
byte asnType = ParseHeader(buffer, ref offset, out headerLength);
if (asnType != Type)
throw new SnmpException(string.Format("Invalid ASN.1 type. Expected 0x{0:x2} received 0x{1:x2}", Type, asnType));
// verify the length
if ((buffer.Length - offset) < headerLength)
throw new OverflowException("Buffer underflow error");
_oid = new Oid();
offset = _oid.decode(buffer, offset);
int saveOffset = offset;
// Look ahead in the header to see the data type we need to parse
asnType = ParseHeader(buffer, ref saveOffset, out headerLength);
_value = SnmpConstants.GetSyntaxObject(asnType);
if (_value == null)
throw new SnmpDecodingException(String.Format("Invalid ASN.1 type encountered 0x{0:x2}. Unable to continue decoding.", asnType));
offset = _value.decode(buffer, offset);
return offset;
}
/// <summary>
/// Construct Vb with the OID and value
/// </summary>
/// <param name="oid">OID</param>
/// <param name="value">Value</param>
public Vb(Oid oid, AsnType value)
: this(oid)
{
_value = (AsnType)value.Clone();
}
/// <summary>
/// Decode received SNMP packet.
/// </summary>
/// <param name="buffer">BER encoded packet buffer</param>
/// <param name="length">BER encoded packet buffer length</param>
/// <exception cref="SnmpException">Thrown when invalid encoding has been found in the packet</exception>
/// <exception cref="OverflowException">Thrown when parsed header points to more data then is available in the packet</exception>
/// <exception cref="SnmpInvalidVersionException">Thrown when parsed packet is not SNMP version 1</exception>
/// <exception cref="SnmpInvalidPduTypeException">Thrown when received PDU is of a type not supported by SNMP version 1</exception>
public override int Decode(byte[] buffer, int length)
{
MutableByte buf = new MutableByte(buffer, length);
int offset = 0;
offset = base.Decode(buffer, buffer.Length);
if (Version != SnmpVersion.Ver2)
{
throw new SnmpInvalidVersionException("Invalid protocol version");
}
offset = _snmpCommunity.Decode(buf, offset);
int tmpOffset = offset;
byte asnType = AsnType.ParseHeader(buf, ref tmpOffset, out int headerLength);
// Check packet length
if (headerLength + offset > buf.Length)
{
throw new OverflowException("Insufficient data in packet");
}
if (asnType != (byte)PduType.Get && asnType != (byte)PduType.GetNext && asnType != (byte)PduType.Set &&
asnType != (byte)PduType.GetBulk && asnType != (byte)PduType.Response && asnType != (byte)PduType.V2Trap &&
asnType != (byte)PduType.Inform)
{
throw new SnmpInvalidPduTypeException("Invalid SNMP operation received: " + string.Format("0x{0:x2}", asnType));
}
// Now process the Protocol Data Unit
offset = Pdu.Decode(buf, offset);
return(length);
}
/// <summary>
/// Encode SNMP packet for sending.
/// </summary>
/// <returns>BER encoded SNMP packet.</returns>
public override byte[] Encode()
{
MutableByte buf = new MutableByte();
if (Pdu.Type != PduType.Get && Pdu.Type != PduType.GetNext &&
Pdu.Type != PduType.Set && Pdu.Type != PduType.V2Trap &&
Pdu.Type != PduType.Response && Pdu.Type != PduType.GetBulk &&
Pdu.Type != PduType.Inform)
{
throw new SnmpInvalidPduTypeException("Invalid SNMP PDU type while attempting to encode PDU: " + string.Format("0x{0:x2}", Pdu.Type));
}
// snmp version
_protocolVersion.Encode(buf);
// community string
_snmpCommunity.Encode(buf);
// pdu
_pdu.Encode(buf);
// wrap the packet into a sequence
MutableByte tmpBuf = new MutableByte();
AsnType.BuildHeader(tmpBuf, SnmpConstants.SMI_SEQUENCE, buf.Length);
buf.Prepend(tmpBuf);
return(buf);
}
/// <summary>
/// Copy values from another Pdu class.
/// </summary>
/// <param name="value"><see cref="Pdu"/> cast as AsnType</param>
/// <exception cref="ArgumentNullException">Thrown when received argument is null</exception>
public void Set(AsnType value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
Pdu pdu = value as Pdu;
if (pdu != null)
{
this.Type = pdu.Type;
this._requestId.Value = pdu.RequestId;
if (this.Type == PduType.GetBulk)
{
this.NonRepeaters = pdu.NonRepeaters;
this.MaxRepetitions = pdu.MaxRepetitions;
}
else
{
this.ErrorStatus = pdu.ErrorStatus;
this.ErrorIndex = pdu.ErrorIndex;
}
this._vbs.Clear();
foreach (Vb v in pdu.VbList)
{
this._vbs.Add((Vb)v.Clone());
}
}
else
{
throw new ArgumentNullException("value", "Argument is not an Oid class");
}
}
/// <summary>Copy values from another Pdu class.</summary>
/// <param name="value"><see cref="Pdu"/> cast as AsnType</param>
/// <exception cref="ArgumentNullException">Thrown when received argument is null</exception>
public void Set(AsnType value)
{
if (value == null)
{
throw new ArgumentNullException(nameof(value));
}
if (value is Pdu pdu)
{
Type = pdu.Type;
requestId.Value = pdu.RequestId;
if (Type == EPduType.GetBulk)
{
NonRepeaters = pdu.NonRepeaters;
MaxRepetitions = pdu.MaxRepetitions;
}
else
{
ErrorStatus = pdu.ErrorStatus;
ErrorIndex = pdu.ErrorIndex;
}
VbList.Clear();
foreach (Vb v in pdu.VbList)
{
VbList.Add((Vb)v.Clone());
}
}
else
{
throw new ArgumentNullException(nameof(value), "Argument is not an Oid class");
}
}
/// <summary>
/// Encode SNMP packet for sending.
/// </summary>
/// <returns>BER encoded SNMP packet.</returns>
/// <exception cref="SnmpInvalidPduTypeException">Thrown when PDU being encoded is not a valid SNMP version 1 PDU. Acceptable
/// protocol version 1 operations are GET, GET-NEXT, SET and RESPONSE.</exception>
public override byte[] encode()
{
if (this.Pdu.Type != PduType.Get && this.Pdu.Type != PduType.GetNext &&
this.Pdu.Type != PduType.Set && this.Pdu.Type != PduType.Response)
{
throw new SnmpInvalidVersionException("Invalid SNMP PDU type while attempting to encode PDU: " + string.Format("0x{0:x2}", this.Pdu.Type));
}
if (this.Pdu.RequestId == 0)
{
System.Random rand = new System.Random((System.Int32)DateTime.Now.Ticks);
this.Pdu.RequestId = rand.Next();
}
MutableByte tmpBuffer = new MutableByte();
// snmp version
_protocolVersion.encode(tmpBuffer);
// community string
_snmpCommunity.encode(tmpBuffer);
// pdu
this.Pdu.encode(tmpBuffer);
MutableByte buf = new MutableByte();
// wrap the packet into a sequence
AsnType.BuildHeader(buf, SnmpConstants.SMI_SEQUENCE, tmpBuffer.Length);
buf.Append(tmpBuffer);
return(buf);
}
/// <summary>Decode BER encoded variable binding.
/// </summary>
/// <param name="buffer">BER encoded buffer
/// </param>
/// <param name="offset">Offset in the data buffer from where to start decoding. Offset is
/// passed by reference and will contain the offset of the byte immediately after the parsed
/// variable binding.
/// </param>
/// <returns>Buffer position after the decoded value</returns>
public override int decode(byte[] buffer, int offset)
{
int headerLength;
byte asnType = ParseHeader(buffer, ref offset, out headerLength);
if (asnType != Type)
{
throw new SnmpException(string.Format("Invalid ASN.1 type. Expected 0x{0:x2} received 0x{1:x2}", Type, asnType));
}
// verify the length
if ((buffer.Length - offset) < headerLength)
{
throw new OverflowException("Buffer underflow error");
}
_oid = new Oid();
offset = _oid.decode(buffer, offset);
int saveOffset = offset;
// Look ahead in the header to see the data type we need to parse
asnType = ParseHeader(buffer, ref saveOffset, out headerLength);
_value = SnmpConstants.GetSyntaxObject(asnType);
if (_value == null)
{
throw new SnmpDecodingException(String.Format("Invalid ASN.1 type encountered 0x{0:x2}. Unable to continue decoding.", asnType));
}
offset = _value.decode(buffer, offset);
return(offset);
}
/// <summary>
/// "Look-ahead" decode of SNMP packet header including USM information
/// </summary>
/// <remarks>
/// Decode first component of the SNMP version 3 packet allowing the caller to retrieve USM SecureName needed to retrieve
/// client security parameters that will allow authentication and privacy decryption to take place.
///
/// This method is used to support Agent like behavior or to handle unsolicited packets like TRAP and INFORMs. In all of
/// these cases, sender of packets will forward a packet without a request being sent by you. In turn, you will need
/// to parse enough of the packet to retrieve SecureName which you can use to retrieve security parameters associated with
/// that user and attempt to authorize and privacy decrypt the received packet.
///
/// Only use this method when your application is acting as an Agent or if you need to process TRAP and INFORM packets.
/// </remarks>
/// <param name="berBuffer">Raw SNMP version 3 packet</param>
/// <param name="length">SNMP version 3 packet length</param>
/// <returns>UserSecurityModel class parsed from the parameter SNMP version 3 packet</returns>
/// <exception cref="SnmpInvalidVersionException">Thrown when attempting to parse an SNMP packet that is not version 3</exception>
/// <exception cref="OverflowException">Thrown when header specifies packet length that is longer then the amount of data received.</exception>
/// <exception cref="SnmpDecodingException">Thrown when invalid sequence is enountered while decoding global message data sequence</exception>
/// <exception cref="SnmpException">Thrown with SnmpException.UnsupportedNoAuthPriv when packet is using privacy without authentication (not allowed)</exception>
/// <exception cref="SnmpException">Thrown with SnmpException.UnsupportedSecurityModel when packet is sent with security model other then USM (only USM is defined in SNMPv3 standard)</exception>
public UserSecurityModel GetUSM(byte[] berBuffer, int length)
{
MutableByte buffer = new MutableByte(berBuffer, length);
int offset = 0;
// let base class parse first sequence and SNMP version number
offset = base.Decode(buffer, length);
// check for correct SNMP protocol version
if (_protocolVersion != (int)SnmpVersion.Ver3)
{
throw new SnmpInvalidVersionException("Expecting SNMP version 3.");
}
// now grab the global message data sequence header information
byte asnType = AsnType.ParseHeader(buffer, ref offset, out int len);
if (asnType != SnmpConstants.SMI_SEQUENCE)
{
throw new SnmpDecodingException("Invalid sequence type when decoding global message data sequence.");
}
// check that packet size can accommodate the length specified in the header
if (len > (buffer.Length - offset))
{
throw new OverflowException("Packet is too small to contain the data described in the header.");
}
// retrieve message id
offset = _messageId.Decode(buffer, offset);
// max message size
offset = _maxMessageSize.Decode(buffer, offset);
// message flags
offset = MsgFlags.Decode(buffer, offset);
// verify that a valid authentication/privacy configuration is present in the packet
if (MsgFlags.Authentication == false && MsgFlags.Privacy == true)
{
throw new SnmpException(SnmpException.UnsupportedNoAuthPriv,
"SNMP version 3 noAuthPriv security combination is not supported.");
}
// security model code
offset = _securityModel.Decode(buffer, offset);
// we only support USM. code = 0x03
if (_securityModel.Value != USM.Type)
{
throw new SnmpException(SnmpException.UnsupportedSecurityModel,
"Class only support SNMP Version 3 User Security Model.");
}
// parse user security model
offset = USM.Decode(buffer, offset);
return(USM);
}
/// <summary>
/// Wrap BER encoded SNMP information contained in the parameter <see cref="MutableByte"/> class.
///
/// Information in the parameter is prepended by the SNMP version field and wrapped in a sequence header.
///
/// Derived classes call this method to finalize SNMP packet encoding.
/// </summary>
/// <param name="buffer">Buffer containing BER encoded SNMP information</param>
public virtual void Encode(MutableByte buffer)
{
// Encode SNMP protocol version
MutableByte temp = new MutableByte();
_protocolVersion.Encode(temp);
buffer.Prepend(temp);
temp.Reset();
AsnType.BuildHeader(temp, SnmpConstants.SMI_SEQUENCE, buffer.Length);
buffer.Prepend(temp);
}
/// <summary>
/// SET class value from another Counter64 class cast as <seealso cref="AsnType"/>.
/// </summary>
/// <param name="value">Counter64 class cast as <seealso cref="AsnType"/></param>
/// <exception cref="ArgumentException">Argument is not Counter64 type.</exception>
public void Set(AsnType value)
{
Counter64 val = value as Counter64;
if (val != null)
{
_value = val.Value;
}
else
{
throw new ArgumentException("Invalid argument type.");
}
}
/// <summary>
/// SET class value from another Integer32 class cast as <see cref="AsnType"/>.
/// </summary>
/// <param name="value">Integer32 class cast as <see cref="AsnType"/></param>
/// <exception cref="ArgumentException">Argument is not Integer32 type.</exception>
public void Set(AsnType value)
{
Integer32 val = value as Integer32;
if (val != null)
{
_value = val.Value;
}
else
{
throw new ArgumentException("Invalid argument type.");
}
}
/// <summary>
/// SET class value from another UInteger32 or Integer32 class cast as <seealso cref="AsnType"/>.
/// </summary>
/// <param name="value">UInteger32 class cast as <seealso cref="AsnType"/></param>
/// <exception cref="ArgumentNullException">Parameter is null.</exception>
public void Set(AsnType value)
{
if (value == null)
{
throw new ArgumentNullException("value", "Parameter is null");
}
if (value is UInteger32)
{
_value = ((UInteger32)value).Value;
}
else if (value is Integer32)
{
_value = (UInt32)((Integer32)value).Value;
}
}
/// <summary>
/// Get SNMP protocol version from the packet. This routine does not verify if version number is valid. Caller
/// should verify that returned value represents a valid SNMP protocol version number.
///
/// <code>
/// int protocolVersion = Packet.GetProtocolVersion(inPacket, inLength);
/// if( protocolVersion != -1 )
/// {
/// if( protocolVersion == SnmpConstants.SNMPV1 || protocolVersion == SnmpConstants.SNMPV2 || protocolVersion == SnmpConstants.SNMPV3 )
/// {
/// // do something
/// }
/// else
/// {
/// Console.WriteLine("Invalid SNMP protocol version.");
/// }
/// }
/// else
/// {
/// Console.WriteLine("Invalid SNMP packet.");
/// }
/// </code>
/// </summary>
/// <param name="buffer">BER encoded SNMP packet</param>
/// <param name="bufferLength">Length of the BER encoded packet</param>
/// <returns>Returns SNMP protocol version, if packet is not valid returned value is -1.</returns>
public static int GetProtocolVersion(byte[] buffer, int bufferLength)
{
int offset = 0;
int length = 0;
byte asnType = AsnType.ParseHeader(buffer, ref offset, out length);
if ((offset + length) > bufferLength)
{
return(-1); // This is not a valid packet
}
Integer32 version = new Integer32();
offset = version.decode(buffer, offset);
return(version.Value);
}
/// <summary>
/// Return SNMP type object of the type specified by name. Supported variable types are:
/// <see cref="Integer32"/>, <see cref="Counter32"/>, <see cref="Gauge32"/>, <see cref="Counter64"/>,
/// <see cref="TimeTicks"/>, <see cref="OctetString"/>, <see cref="IpAddress"/>, <see cref="Oid"/>, and
/// <see cref="Null"/>.
///
/// Type names are the same as support class names compared without case sensitivity (e.g. Integer == INTEGER).
/// </summary>
/// <param name="name">Name of the object type (not case sensitive)</param>
/// <returns>New <see cref="AsnType"/> object.</returns>
public static AsnType GetSyntaxObject(string name)
{
AsnType obj = null;
if (name.ToUpper().Equals("INTEGER32") || name.ToUpper().Equals("INTEGER"))
{
obj = new Integer32();
}
else if (name.ToUpper().Equals("COUNTER32"))
{
obj = new Counter32();
}
else if (name.ToUpper().Equals("GAUGE32"))
{
obj = new Gauge32();
}
else if (name.ToUpper().Equals("COUNTER64"))
{
obj = new Counter64();
}
else if (name.ToUpper().Equals("TIMETICKS"))
{
obj = new TimeTicks();
}
else if (name.ToUpper().Equals("OCTETSTRING"))
{
obj = new OctetString();
}
else if (name.ToUpper().Equals("IPADDRESS"))
{
obj = new IpAddress();
}
else if (name.ToUpper().Equals("OID"))
{
obj = new Oid();
}
else if (name.ToUpper().Equals("NULL"))
{
obj = new Null();
}
else
{
throw new ArgumentException("Invalid value type name");
}
return(obj);
}
/// <summary>
/// Return SNMP type object of the type specified by name. Supported variable types are:
/// * <see cref="Integer32"/>
/// * <see cref="Counter32"/>
/// * <see cref="Gauge32"/>
/// * <see cref="Counter64"/>
/// * <see cref="TimeTicks"/>
/// * <see cref="OctetString"/>
/// * <see cref="IpAddress"/>
/// * <see cref="Oid"/>
/// * <see cref="Null"/>
/// </summary>
/// <param name="name">Name of the object type</param>
/// <returns>New <see cref="AsnType"/> object.</returns>
public static AsnType GetSyntaxObject(string name)
{
AsnType obj = null;
if (name == "Integer32")
{
obj = new Integer32();
}
else if (name == "Counter32")
{
obj = new Counter32();
}
else if (name == "Gauge32")
{
obj = new Gauge32();
}
else if (name == "Counter64")
{
obj = new Counter64();
}
else if (name == "TimeTicks")
{
obj = new TimeTicks();
}
else if (name == "OctetString")
{
obj = new OctetString();
}
else if (name == "IpAddress")
{
obj = new IpAddress();
}
else if (name == "Oid")
{
obj = new Oid();
}
else if (name == "Null")
{
obj = new Null();
}
else
{
throw new ArgumentException("Invalid value type name");
}
return(obj);
}
/// <summary>
/// Get SNMP protocol version from the packet. This routine does not verify if version number is valid. Caller
/// should verify that returned value represents a valid SNMP protocol version number.
///
/// <code>
/// int protocolVersion = Packet.GetProtocolVersion(inPacket, inLength);
/// if( protocolVersion != -1 )
/// {
/// if( protocolVersion == SnmpConstants.SNMPV1 || protocolVersion == SnmpConstants.SNMPV2 || protocolVersion == SnmpConstants.SNMPV3 )
/// {
/// // do something
/// }
/// else
/// {
/// Console.WriteLine("Invalid SNMP protocol version.");
/// }
/// }
/// else
/// {
/// Console.WriteLine("Invalid SNMP packet.");
/// }
/// </code>
/// </summary>
/// <param name="buffer">BER encoded SNMP packet</param>
/// <param name="bufferLength">Length of the BER encoded packet</param>
/// <returns>Returns SNMP protocol version, if packet is not valid returned value is -1.</returns>
/// <exception cref="SnmpDecodingException">Thrown when invalid sequence type is found at the start of the SNMP packet being decoded</exception>
public static int GetProtocolVersion(byte[] buffer, int bufferLength)
{
int offset = 0;
byte asnType = AsnType.ParseHeader(buffer, ref offset, out int length);
if ((offset + length) > bufferLength)
{
return(-1); // This is not a valid packet
}
if (asnType != SnmpConstants.SMI_SEQUENCE)
{
throw new SnmpDecodingException("Invalid sequence type at the start of the SNMP packet.");
}
Integer32 version = new Integer32();
_ = version.decode(buffer, offset);
return(version.Value);
}
/// <summary>
/// Get SNMP protocol version from the packet. This routine does not verify if version number is valid. Caller
/// should verify that returned value represents a valid SNMP protocol version number.
///
/// <code>
/// int protocolVersion = Packet.GetProtocolVersion(inPacket, inLength);
/// if( protocolVersion != -1 )
/// {
/// if( protocolVersion == SnmpConstants.SNMPV1 || protocolVersion == SnmpConstants.SNMPV2 || protocolVersion == SnmpConstants.SNMPV3 )
/// // do something
/// else
/// Console.WriteLine("Invalid SNMP protocol version.");
/// }
/// else
/// Console.WriteLine("Invalid SNMP packet.");
/// </code>
/// </summary>
/// <param name="buffer">BER encoded SNMP packet</param>
/// <param name="bufferLength">Length of the BER encoded packet</param>
/// <returns>Returns SNMP protocol version, if packet is not valid returned value is -1.</returns>
/// <exception cref="SnmpDecodingException">Thrown when invalid sequence type is found at the start of the SNMP packet being decoded</exception>
public static ESnmpVersion GetProtocolVersion(byte[] buffer, int bufferLength)
{
int offset = 0;
byte asnType = AsnType.ParseHeader(buffer, ref offset, out int length);
if ((offset + length) > bufferLength)
{
throw new SnmpDecodingException("Cannot parse SNMP version from packet, input past end");
}
if (asnType != SnmpConstants.SmiSequence)
{
throw new SnmpDecodingException("Invalid sequence type at the start of the SNMP packet.");
}
Integer32 version = new Integer32();
offset = version.Decode(buffer, offset);
return((ESnmpVersion)version.Value);
}
/// <summary>
/// Decode received packet. This method overrides the base implementation that cannot be used with this type of the packet.
/// </summary>
/// <param name="buffer">Packet buffer</param>
/// <param name="length">Buffer length</param>
public override int decode(byte[] buffer, int length)
{
int offset = 0;
MutableByte buf = new MutableByte(buffer, length);
offset = base.decode(buffer, length);
// parse community
offset = _snmpCommunity.decode(buf, offset);
// look ahead to make sure this is a TRAP packet
int tmpOffset = offset;
byte tmpAsnType = AsnType.ParseHeader(buffer, ref tmpOffset, out _);
if (tmpAsnType != (byte)PduType.Trap)
{
throw new SnmpException(string.Format("Invalid SNMP ASN.1 type. Received: {0:x2}", tmpAsnType));
}
// decode protocol data unit
offset = this.Pdu.decode(buf, offset);
return(offset);
}
/// <summary>Encode SNMP packet for sending.</summary>
/// <returns>BER encoded SNMP packet.</returns>
/// <exception cref="SnmpInvalidPduTypeException">
/// Thrown when PDU being encoded is not a valid SNMP version 1 PDU. Acceptable
/// protocol version 1 operations are GET, GET-NEXT, SET and RESPONSE.
/// </exception>
public override byte[] Encode()
{
if (
Pdu.Type != EPduType.Get &&
Pdu.Type != EPduType.GetNext &&
Pdu.Type != EPduType.Set &&
Pdu.Type != EPduType.Response)
{
throw new SnmpInvalidVersionException("Invalid SNMP PDU type while attempting to encode PDU: " + string.Format("0x{0:x2}", Pdu.Type));
}
if (Pdu.RequestId == 0)
{
Random rand = new Random((int)DateTime.Now.Ticks);
Pdu.RequestId = rand.Next();
}
MutableByte tmpBuffer = new MutableByte();
// snmp version
protocolVersion.Encode(tmpBuffer);
// community string
Community.Encode(tmpBuffer);
// pdu
Pdu.Encode(tmpBuffer);
MutableByte buf = new MutableByte();
// wrap the packet into a sequence
AsnType.BuildHeader(buf, SnmpConstants.SmiSequence, tmpBuffer.Length);
buf.Append(tmpBuffer);
return(buf);
}
public static AsnType Get(IPAddress agent, string community, string oid)
{
// Define agent parameters class
AgentParameters agentParameters = new AgentParameters(SnmpVersion.Ver2, new OctetString(community));
// Construct target
UdpTarget target = new UdpTarget(agent, 161, 2000, 1);
// Pdu class used for all requests
Pdu pdu = new Pdu(PduType.Get);
pdu.VbList.Add(oid); //sysDescr
// Make SNMP request
var snmpResponse = target.Request(pdu, agentParameters) as SnmpV2Packet;
AsnType result = null;
// If result is null then agent didn't reply or we couldn't parse the reply.
if (snmpResponse != null)
{
// ErrorStatus other then 0 is an error returned by
// the Agent - see SnmpConstants for error definitions
if (snmpResponse.Pdu.ErrorStatus != 0)
{
// agent reported an error with the request
throw new Exception($"Error in SNMP reply. Error {snmpResponse.Pdu.ErrorStatus} index {snmpResponse.Pdu.ErrorIndex}");
}
else
{
result = snmpResponse.Pdu.VbList[0].Value;
}
}
target.Close();
return(result);
}
/// <summary>Used to create correct variable type object for the specified encoded type</summary>
/// <param name="asnType">ASN.1 type code</param>
/// <returns>A new object matching type supplied or null if type was not recognized.</returns>
public static AsnType GetSyntaxObject(byte asnType)
{
AsnType obj = null;
if (asnType == SnmpConstants.SMI_INTEGER)
{
obj = new Integer32();
}
else if (asnType == SnmpConstants.SMI_COUNTER32)
{
obj = new Counter32();
}
else if (asnType == SnmpConstants.SMI_GAUGE32)
{
obj = new Gauge32();
}
else if (asnType == SnmpConstants.SMI_COUNTER64)
{
obj = new Counter64();
}
else if (asnType == SnmpConstants.SMI_TIMETICKS)
{
obj = new TimeTicks();
}
else if (asnType == SnmpConstants.SMI_STRING)
{
obj = new OctetString();
}
else if (asnType == SnmpConstants.SMI_OPAQUE)
{
obj = new Opaque();
}
else if (asnType == SnmpConstants.SMI_IPADDRESS)
{
obj = new IpAddress();
}
else if (asnType == SnmpConstants.SMI_OBJECTID)
{
obj = new Oid();
}
else if (asnType == SnmpConstants.SMI_PARTY_CLOCK)
{
obj = new V2PartyClock();
}
else if (asnType == SnmpConstants.SMI_NOSUCHINSTANCE)
{
obj = new NoSuchInstance();
}
else if (asnType == SnmpConstants.SMI_NOSUCHOBJECT)
{
obj = new NoSuchObject();
}
else if (asnType == SnmpConstants.SMI_ENDOFMIBVIEW)
{
obj = new EndOfMibView();
}
else if (asnType == SnmpConstants.SMI_NULL)
{
obj = new Null();
}
return(obj);
}
/// <summary>Encode SNMP version 3 packet</summary>
/// <param name="authKey">Authentication key (not password)</param>
/// <param name="privKey">Privacy key (not password)</param>
/// <remarks>
/// Before encoding the packet into a byte array you need to ensure all required information is
/// set. Examples of required information is request type, Vbs (Oid + values pairs), USM settings including
/// SecretName, authentication method and secret (if needed), privacy method and secret (if needed), etc.
/// </remarks>
/// <returns>Byte array BER encoded SNMP packet.</returns>
public byte[] Encode(byte[] authKey, byte[] privKey)
{
MutableByte buffer = new MutableByte();
// encode the global message data sequence header information
MutableByte globalMessageData = new MutableByte();
// if message id is 0 then generate a new, random message id
if (messageId.Value == 0)
{
Random rand = new Random();
messageId.Value = rand.Next(1, int.MaxValue);
}
// encode message id
messageId.Encode(globalMessageData);
// encode max message size
maxMessageSize.Encode(globalMessageData);
// message flags
messageFlags.Encode(globalMessageData);
// security model code
securityModel.Value = userSecurityModel.Type;
securityModel.Encode(globalMessageData);
// add global message data to the main buffer
// encode sequence header and add data
AsnType.BuildHeader(buffer, SnmpConstants.SmiSequence, globalMessageData.Length);
buffer.Append(globalMessageData);
MutableByte packetHeader = new MutableByte(buffer);
// before going down this road, check if this is a discovery packet
OctetString savedUserName = new OctetString();
bool privacy = messageFlags.Privacy;
bool authentication = messageFlags.Authentication;
bool reportable = messageFlags.Reportable;
if (userSecurityModel.EngineId.Length <= 0)
{
// save USM settings prior to encoding a Discovery packet
savedUserName.Set(userSecurityModel.SecurityName);
userSecurityModel.SecurityName.Reset(); // delete security name for discovery packets
messageFlags.Authentication = false;
messageFlags.Privacy = false;
messageFlags.Reportable = true;
}
userSecurityModel.Encode(buffer);
if (userSecurityModel.EngineId.Length <= 0)
{
// restore saved USM values
userSecurityModel.SecurityName.Set(savedUserName);
messageFlags.Authentication = authentication;
messageFlags.Privacy = privacy;
messageFlags.Reportable = reportable;
}
// Check if privacy encryption is required
MutableByte encodedPdu = new MutableByte();
if (messageFlags.Privacy && userSecurityModel.EngineId.Length > 0)
{
IPrivacyProtocol privacyProtocol = PrivacyProtocol.GetInstance(userSecurityModel.Privacy);
if (privacyProtocol == null)
{
throw new SnmpException(SnmpException.EErrorCode.UnsupportedPrivacyProtocol, "Specified privacy protocol is not supported.");
}
// Get BER encoded ScopedPdu
MutableByte unencryptedPdu = new MutableByte();
scopedPdu.Encode(unencryptedPdu);
// we have to expand the key
IAuthenticationDigest auth = Authentication.GetInstance(userSecurityModel.Authentication);
if (auth == null)
{
throw new SnmpException(SnmpException.EErrorCode.UnsupportedNoAuthPriv, "Invalid authentication protocol. noAuthPriv mode not supported.");
}
byte[] encryptedBuffer = privacyProtocol.Encrypt(unencryptedPdu, 0, unencryptedPdu.Length, privKey, userSecurityModel.EngineBoots, userSecurityModel.EngineTime, out byte[] privacyParameters, auth);
userSecurityModel.PrivacyParameters.Set(privacyParameters);
OctetString encryptedOctetString = new OctetString(encryptedBuffer);
encryptedOctetString.Encode(encodedPdu);
// now redo packet encoding
buffer.Reset();
buffer.Set(packetHeader);
userSecurityModel.Encode(buffer);
int preEncodedLength = encodedPdu.Length;
buffer.Append(encodedPdu);
if (maxMessageSize.Value != 0)
{
// verify compliance with maximum message size
if ((encodedPdu.Length - preEncodedLength) > maxMessageSize)
{
throw new SnmpException(SnmpException.EErrorCode.MaximumMessageSizeExceeded, "ScopedPdu exceeds maximum message size.");
}
}
}
else
{
scopedPdu.Encode(encodedPdu);
buffer.Append(encodedPdu);
}
Encode(buffer);
if (messageFlags.Authentication && userSecurityModel.EngineId.Length > 0)
{
userSecurityModel.Authenticate(authKey, ref buffer);
// Now re-encode the packet with the authentication information
userSecurityModel.Encode(packetHeader);
packetHeader.Append(encodedPdu);
Encode(packetHeader);
buffer = packetHeader;
}
return(buffer);
}
/// <summary>
/// Decode SNMP version 3 packet. This method will perform authentication check and decode privacy protected <see cref="ScopedPdu"/>. This method will
/// not check for the timeliness of the packet, correct engine boot value or engine id because it does not have a reference to the engine time prior to this call.
/// </summary>
/// <param name="berBuffer">BER encoded SNMP version 3 packet buffer</param>
/// <param name="length">Buffer length</param>
/// <param name="authKey">Authentication key (not password)</param>
/// <param name="privKey">Privacy key (not password)</param>
/// <returns>The length of the decoded segment</returns>
public int Decode(byte[] berBuffer, int length, byte[] authKey, byte[] privKey)
{
MutableByte buffer = new MutableByte(berBuffer, length);
int offset = 0;
// let base class parse first sequence and SNMP version number
offset = base.Decode(buffer, length);
// check for correct SNMP protocol version
if (protocolVersion != (int)ESnmpVersion.Ver3)
{
throw new SnmpInvalidVersionException("Expecting SNMP version 3.");
}
// now grab the global message data sequence header information
byte asnType = AsnType.ParseHeader(buffer, ref offset, out int len);
if (asnType != SnmpConstants.SmiSequence)
{
throw new SnmpDecodingException("Invalid sequence type in global message data sequence.");
}
// check that packet size can accommodate the length specified in the header
if (len > (buffer.Length - offset))
{
throw new OverflowException("Packet is too small to contain the data described in the header.");
}
// retrieve message id
offset = messageId.Decode(buffer, offset);
// max message size
offset = maxMessageSize.Decode(buffer, offset);
// message flags
offset = messageFlags.Decode(buffer, offset);
// verify that a valid authentication/privacy configuration is present in the packet
if (messageFlags.Authentication == false && messageFlags.Privacy == true)
{
throw new SnmpException(SnmpException.EErrorCode.UnsupportedNoAuthPriv, "SNMP version 3 noAuthPriv security combination is not supported.");
}
// security model code
offset = securityModel.Decode(buffer, offset);
// we only support USM. code = 0x03
if (securityModel.Value != userSecurityModel.Type)
{
throw new SnmpException(SnmpException.EErrorCode.UnsupportedSecurityModel, "Class only support SNMP Version 3 User Security Model.");
}
// parse user security model
offset = userSecurityModel.Decode(buffer, offset);
// Authenticate message if authentication flag is set and packet is not a discovery packet
if (messageFlags.Authentication && userSecurityModel.EngineId.Length > 0)
{
// Authenticate packet
if (userSecurityModel.AuthenticationParameters.Length != 12)
{
throw new SnmpAuthenticationException("Invalid authentication parameter field length.");
}
if (!userSecurityModel.IsAuthentic(authKey, buffer))
{
throw new SnmpAuthenticationException("Authentication of the incoming packet failed.");
}
}
// Decode ScopedPdu if it is privacy protected and packet is not a discovery packet
if (messageFlags.Privacy && userSecurityModel.EngineId.Length > 0)
{
IPrivacyProtocol privacyProtocol = PrivacyProtocol.GetInstance(userSecurityModel.Privacy);
if (privacyProtocol == null)
{
throw new SnmpException(SnmpException.EErrorCode.UnsupportedPrivacyProtocol, "Privacy protocol requested is not supported.");
}
if (userSecurityModel.PrivacyParameters.Length != privacyProtocol.PrivacyParametersLength)
{
throw new SnmpException(SnmpException.EErrorCode.InvalidPrivacyParameterLength, "Invalid privacy parameters field length.");
}
// Initialize a temporary OctetString class to hold encrypted ScopedPdu
OctetString encryptedScopedPdu = new OctetString();
offset = encryptedScopedPdu.Decode(buffer, offset);
// decode encrypted packet
byte[] decryptedScopedPdu = privacyProtocol.Decrypt(encryptedScopedPdu, 0, encryptedScopedPdu.Length, privKey, userSecurityModel.EngineBoots, userSecurityModel.EngineTime, userSecurityModel.PrivacyParameters);
int tempOffset = 0;
offset = scopedPdu.Decode(decryptedScopedPdu, tempOffset);
}
else
{
offset = scopedPdu.Decode(buffer, offset);
}
return(offset);
}
/// <summary>
/// SET class value from supplied Vb class
/// </summary>
/// <param name="value">Vb class to clone data from</param>
public void Set(Vb value)
{
_oid = (Oid)value.Oid.Clone();
_value = (Oid)value.Value.Clone();
}
/// <summary>Construct Vb with the supplied OID and Null value</summary>
/// <param name="oid">OID</param>
public Vb(Oid oid)
: this()
{
this.oid = (Oid)oid.Clone();
value = new Null();
}
/// <summary>Construct Vb with the oid value and <seealso cref="Null"/> value.</summary>
/// <param name="oid">String representing OID value to set</param>
public Vb(string oid)
: this()
{
this.oid = new Oid(oid);
value = new Null();
}
/// <summary>
/// SET class value from supplied Vb class
/// </summary>
/// <param name="value">Vb class to clone data from</param>
public void Set(Vb value)
{
this._oid = (Oid)value.Oid.Clone();
this._value = (Oid)value.Value.Clone();
}
/// <summary>
/// Construct Vb with the oid value and <seealso cref="Null"/> value.
/// </summary>
/// <param name="oid">String representing OID value to set</param>
public Vb(string oid)
: this()
{
_oid = new Oid(oid);
_value = new Null();
}
/// <summary>
/// Construct Vb with the supplied OID and Null value
/// </summary>
/// <param name="oid">OID</param>
public Vb(Oid oid)
: this()
{
_oid = (Oid)oid.Clone();
_value = new Null();
}
/// <summary>
/// Construct Vb with the OID and value
/// </summary>
/// <param name="oid">OID</param>
/// <param name="value">Value</param>
public Vb(Oid oid, AsnType value)
: this(oid) {
_value = (AsnType)value.Clone();
}
/// <summary>
/// Reset Vb value to Null
/// </summary>
public void ResetValue()
{
_value = new Null();
}
/// <summary>
/// SET class value from supplied Vb class
/// </summary>
/// <param name="value">Vb class to clone data from</param>
public void Set(Vb value)
{
this._oid = (Oid)value.Oid.Clone();
this._value = (Oid)value.Value.Clone();
}
/// <summary>
/// Reset Vb value to Null
/// </summary>
public void ResetValue()
{
_value = new Null();
}
/// <summary>
/// Executa uma requisição do tipo Set
/// </summary>
/// <param name="setValue">Valor a set definido</param>
public void Send(AsnType setValue)
{
using (var target = new UdpTarget(Host.IP, Host.Port, TimeOut, Retries))
{
var agentp = new AgentParameters(SnmpVersion.Ver2, new OctetString(Host.Community));
// Caso necessario, appenda o .0 na requisição
var oid = new Oid(Object.OID);
if (oid[oid.Length - 1] != 0)
oid.Add(0);
// Cria pacote de dados
RequestData = new Pdu(setValue == null ? PduType.Get : PduType.Set);
// Adiciona dados da requisição
switch (RequestData.Type)
{
case PduType.Get:
RequestData.VbList.Add(oid);
break;
case PduType.Set:
RequestData.VbList.Add(oid, setValue);
break;
default:
throw new InvalidOperationException("unsupported");
}
try
{
if (LogRequests) Logger.Self.Log(this);
Timestamp = DateTime.Now;
// Envia requisição
ResponsePacket = target.Request(RequestData, agentp) as SnmpV2Packet;
// Trata resposta
if (ResponsePacket != null && ResponsePacket.Pdu.ErrorStatus == (int)PduErrorStatus.noError)
{
// TODO: suportar mais de um retorno
var item = ResponsePacket.Pdu.VbList[0];
ResponseValue = item.Value;
if (LogRequests) Logger.Self.Log(item);
}
}
catch (Exception ex)
{
if (LogRequests) Logger.Self.Log(ex);
throw new SnmpException("Não foi possível realizar a operação");
}
}
}
/// <summary>
/// Construct Vb with the oid value and <seealso cref="Null"/> value.
/// </summary>
/// <param name="oid">String representing OID value to set</param>
public Vb(string oid)
: this()
{
_oid = new Oid(oid);
_value = new Null();
}
/// <summary>
/// Construct Vb with the supplied OID and Null value
/// </summary>
/// <param name="oid">OID</param>
public Vb(Oid oid)
: this()
{
_oid = (Oid)oid.Clone();
_value = new Null();
}