/// <summary>BER encode class value.</summary>
/// <param name="buffer">Target buffer. Value is appended to the end of it.</param>
public override void encode(MutableByte buffer)
{
MutableByte tmp = new MutableByte();
byte[] b = BitConverter.GetBytes(_value);
for (int i = 3; i >= 0; i--)
{
if (b[i] != 0 || tmp.Length > 0)
{
tmp.Append(b[i]);
}
}
// if (tmp.Length > 1 && tmp[0] == 0xff && (tmp[1] & 0x80) != 0)
if (tmp.Length > 0 && (tmp[0] & 0x80) != 0)
{
tmp.Prepend(0);
}
else if (tmp.Length == 0)
{
tmp.Append(0);
}
BuildHeader(buffer, Type, tmp.Length);
buffer.Append(tmp);
}
/// <summary>
/// Append BER encoded length to the <see cref="MutableByte"/>
/// </summary>
/// <param name="mb">MutableArray to append BER encoded length to</param>
/// <param name="asnLength">Length value to encode.</param>
/// <exception cref="ArgumentOutOfRangeException">Thrown when length value to encode is less then 0</exception>
internal static void BuildLength(MutableByte mb, int asnLength)
{
if (asnLength < 0)
{
throw new ArgumentOutOfRangeException("Length cannot be less then 0.");
}
byte[] len = BitConverter.GetBytes(asnLength);
MutableByte buf = new MutableByte();
for (int i = 3; i >= 0; i--)
{
if (len[i] != 0 || buf.Length > 0)
{
buf.Append(len[i]);
}
}
if (buf.Length == 0)
{
// we are encoding a 0 value. Can't have a 0 byte length encoding
buf.Append(0);
}
// check for short form encoding
if (buf.Length == 1 && (buf[0] & HIGH_BIT) == 0)
{
mb.Append(buf); // done
}
else
{
// long form encoding
byte encHeader = (byte)buf.Length;
encHeader = (byte)(encHeader | HIGH_BIT);
mb.Append(encHeader);
mb.Append(buf);
}
}
/// <summary>
/// Convert user password to acceptable authentication key.
/// </summary>
/// <param name="userPassword">Authentication password</param>
/// <param name="engineID">Authoritative engine id</param>
/// <returns>Localized authentication key</returns>
/// <exception cref="SnmpAuthenticationException">Thrown when key length is less then 8 bytes</exception>
public byte[] PasswordToKey(byte[] userPassword, byte[] engineID)
{
// key length has to be at least 8 bytes long (RFC3414)
if (userPassword == null || userPassword.Length < 8)
{
throw new SnmpAuthenticationException("Secret key is too short.");
}
int password_index = 0;
int count = 0;
MD5 md5 = new MD5CryptoServiceProvider();
byte[] sourceBuffer = new byte[1048576];
byte[] buf = new byte[64];
while (count < 1048576)
{
for (int i = 0; i < 64; ++i)
{
buf[i] = userPassword[password_index++ % userPassword.Length];
}
Buffer.BlockCopy(buf, 0, sourceBuffer, count, buf.Length);
count += 64;
}
byte[] digest = md5.ComputeHash(sourceBuffer);
MutableByte tmpbuf = new MutableByte();
tmpbuf.Append(digest);
tmpbuf.Append(engineID);
tmpbuf.Append(digest);
byte[] key = md5.ComputeHash(tmpbuf);
return(key);
}
/// <summary>Encode Pdu class to BER byte buffer</summary>
/// <remarks>
/// Encodes the protocol data unit using the passed encoder and stores
/// the results in the passed buffer. An exception is thrown if an
/// error occurs with the encoding of the information.
/// </remarks>
/// <param name="buffer">The buffer to write the encoded information.</param>
public override void Encode(MutableByte buffer)
{
MutableByte tmpBuffer = new MutableByte();
// if request id is 0, get a random value
if (requestId.Value == 0)
{
requestId.SetRandom();
}
requestId.Encode(tmpBuffer);
errorStatus.Encode(tmpBuffer);
errorIndex.Encode(tmpBuffer);
// if V2TRAP PDU type, add sysUpTime and trapObjectID OIDs before encoding VarBind
if (Type == EPduType.V2Trap || Type == EPduType.Inform)
{
if (VbList.Count == 0)
{
// add sysUpTime and trapObjectID to the VbList
VbList.Add(SnmpConstants.SysUpTime, TrapSysUpTime);
VbList.Add(SnmpConstants.TrapObjectId, trapObjectID);
}
else
{
// Make sure user didn't manually add sysUpTime and trapObjectID values
// to the pdu
// if we have more then one item in the VarBinds array check for sysUpTime
if (VbList.Count > 0)
{
// if the first Vb in the VarBinds array is not sysUpTime append it in the
// encoded byte array
if (!VbList[0].Oid.Equals(SnmpConstants.SysUpTime))
{
Vb sysUpTimeVb = new Vb(SnmpConstants.SysUpTime, TrapSysUpTime);
VbList.Insert(0, sysUpTimeVb);
}
}
// if we have 2 or more Vbs in the VarBinds array check for trapObjectID Vb
if (VbList.Count > 1)
{
// if second Vb in the VarBinds array is not trapObjectId encode the value
if (!VbList[1].Oid.Equals(SnmpConstants.TrapObjectId))
{
Vb trapObjectIdVb = new Vb(SnmpConstants.TrapObjectId, trapObjectID);
VbList.Insert(1, trapObjectIdVb);
}
}
}
}
// encode variable bindings
VbList.Encode(tmpBuffer);
// Now encode the header for the PDU
BuildHeader(buffer, (byte)Type, tmpBuffer.Length);
buffer.Append(tmpBuffer);
}
/// <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>
/// Convert user password to acceptable authentication key.
/// </summary>
/// <param name="userPassword">User password</param>
/// <param name="engineID">Authoritative engine id</param>
/// <returns>Localized authentication key</returns>
/// <exception cref="SnmpAuthenticationException">Thrown when key length is less then 8 bytes</exception>
public byte[] PasswordToKey(byte[] userPassword, byte[] engineID)
{
// key length has to be at least 8 bytes long (RFC3414)
if (userPassword == null || userPassword.Length < 8)
{
throw new SnmpAuthenticationException("Secret key is too short.");
}
int password_index = 0;
int count = 0;
#if !NETCOREAPP11 && !NETSTANDARD15
SHA1 sha = new SHA1CryptoServiceProvider();
#else
SHA1 sha = SHA1.Create();
#endif
/* Use while loop until we've done 1 Megabyte */
byte[] sourceBuffer = new byte[1048576];
byte[] buf = new byte[64];
while (count < 1048576)
{
for (int i = 0; i < 64; ++i)
{
// Take the next octet of the password, wrapping
// to the beginning of the password as necessary.
buf[i] = userPassword[password_index++ % userPassword.Length];
}
Buffer.BlockCopy(buf, 0, sourceBuffer, count, buf.Length);
count += 64;
}
byte[] digest = sha.ComputeHash(sourceBuffer);
MutableByte tmpbuf = new MutableByte();
tmpbuf.Append(digest);
tmpbuf.Append(engineID);
tmpbuf.Append(digest);
byte[] res = sha.ComputeHash(tmpbuf);
#if !NETCOREAPP11 && !NETSTANDARD15
sha.Clear();
#else
sha.Dispose();
#endif
return(res);
}
/// <summary>
/// Encodes ASN.1 object identifier and append it to the end of the passed buffer.
/// </summary>
/// <param name="buffer">
/// Buffer to append the encoded information to.
/// </param>
public override void encode(MutableByte buffer)
{
MutableByte tmpBuffer = new MutableByte();
UInt32[] values = _data;
if (values == null || values.Length < 2)
{
values = new UInt32[2];
values[0] = values[1] = 0;
}
// silently create an oid = ".0.0" for arrays
// less than 2 in length
if (_data.Length < 2)
{
values = new UInt32[2];
values[0] = 0;
values[1] = 0;
}
// verify that it is a valid object id!
if (values[0] < 0 || values[0] > 2)
{
throw new SnmpException("Invalid Object Identifier");
}
if (values[1] < 0 || values[1] > 40)
{
throw new SnmpException("Invalid Object Identifier");
}
// add the first oid!
tmpBuffer.Append((byte)(values[0] * 40 + values[1]));
// encode remaining instance values
for (int i = 2; i < values.Length; i++)
{
tmpBuffer.Append(encodeInstance(values[i]));
}
// build value header
BuildHeader(buffer, Type, tmpBuffer.Length);
// Append encoded value to the result buffer
buffer.Append(tmpBuffer);
}
/// <summary>BER encode security model field.</summary>
/// <remarks>
/// USM security model is a SEQUENCE encoded inside a OCTETSTRING. To encode it, first encode the sequence
/// of class values then "wrap" it inside a OCTETSTRING field
/// </remarks>
/// <param name="buffer">Buffer to store encoded USM security model header</param>
public override void encode(MutableByte buffer)
{
MutableByte tmp = new MutableByte();
// First encode all the values that will form the sequence
_engineId.encode(tmp);
// Encode engine boots
_engineBoots.encode(tmp);
// encode engine time
_engineTime.encode(tmp);
_securityName.encode(tmp);
if (_authentication != AuthenticationDigests.None)
{
if (_authenticationParameters.Length <= 0)
{
// If authentication is used, set authentication parameters field to 12 bytes set to 0x00
_authenticationParameters.Set(new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 });
}
}
else
{
_authenticationParameters.Reset();
}
_authenticationParameters.encode(tmp);
if (_privacy != PrivacyProtocols.None)
{
if (_privacyParameters.Length <= 0)
{
IPrivacyProtocol privProto = PrivacyProtocol.GetInstance(_privacy);
if (privProto != null)
{
byte[] parameter = new byte[privProto.PrivacyParametersLength];
for (int i = 0; i < privProto.PrivacyParametersLength; i++)
{
parameter[i] = 0x00; // This is not necessary since all array members are, by default, initialized to 0
}
_privacyParameters.Set(parameter);
}
else
{
throw new SnmpException(SnmpException.UnsupportedPrivacyProtocol, "Unrecognized privacy protocol specified.");
}
}
}
else
{
_privacyParameters.Reset();
}
_privacyParameters.encode(tmp);
MutableByte tmp1 = new MutableByte();
BuildHeader(tmp1, SnmpConstants.SMI_SEQUENCE, tmp.Length);
tmp1.Append(tmp);
BuildHeader(buffer, OCTETSTRING, tmp1.Length);
buffer.Append(tmp1);
}
/// <summary>BER encode class value</summary>
/// <param name="buffer">MutableByte to append BER encoded value to.
/// </param>
public override void encode(MutableByte buffer)
{
byte[] b = BitConverter.GetBytes(_value);
MutableByte tmp = new MutableByte();
for (int i = b.Length - 1; i >= 0; i--)
{
if (b[i] != 0 || tmp.Length > 0)
{
tmp.Append(b[i]);
}
}
if (tmp.Length == 0)
{
tmp.Append(0); // value is 0. can't have an empty encoding
}
BuildHeader(buffer, Type, tmp.Length);
buffer.Append(tmp);
}
/// <summary>
/// Convert <see cref="ScopedPdu" /> into a BER encoded byte array. Resulting byte array is appended
/// to the argument specified <see cref="MutableByte" /> class.
/// Privacy operations are not performed by this method. Value encoded and returned by this method is
/// suitable for sending in NoAuthNoPriv or AuthNoPriv security configurations. If privacy is required,
/// caller will have to perform encryption and decryption operations after BER encoding is performed.
/// In privacy protected SNMP version 3 packets, ScopedPdu is 1) encrypted using configured encryption
/// method, 2) added to a <see cref="OctetString" /> field, and 3) appended to the data buffer.
/// Because privacy operation is intrusive, it is recommended that BER encoding of the ScopedPdu packet
/// is stored in a temporary <see cref="MutableByte" /> class, where it can be privacy protected and
/// added to the <see cref="OctetString" /> class for final encoding into the target SNMP v3 packet.
/// </summary>
/// <param name="buffer">
/// <see cref="MutableByte" /> class passed by reference that encoded ScopedPdu
/// value is appended to.
/// </param>
public override void encode(MutableByte buffer)
{
var tmp = new MutableByte();
_contextEngineId.encode(tmp);
_contextName.encode(tmp);
// Encode base
base.encode(tmp);
BuildHeader(buffer, SnmpConstants.SMI_SEQUENCE, tmp.Length);
buffer.Append(tmp);
}
/// <summary>
/// Encode VarBind collection sequence
/// </summary>
/// <param name="buffer">Target buffer. Encoded VarBind collection is appended.</param>
public override void Encode(MutableByte buffer)
{
MutableByte tmp = new MutableByte();
foreach (Vb v in _vbs)
{
v.Encode(tmp);
}
BuildHeader(buffer, Type, tmp.Length);
buffer.Append(tmp);
}
/// <summary>BER encode the variable binding
/// </summary>
/// <param name="buffer"><see cref="MutableByte"/> class to the end of which encoded variable
/// binding values will be added.
/// </param>
public override void encode(MutableByte buffer)
{
// encode oid to the temporary buffer
MutableByte oidbuf = new MutableByte();
_oid.encode(oidbuf);
// encode value to a temporary buffer
MutableByte valbuf = new MutableByte();
_value.encode(valbuf);
// calculate data content length of the vb
int vblen = oidbuf.Length + valbuf.Length;
// encode vb header at the end of the result
BuildHeader(buffer, Type, vblen);
// add values to the encoded arrays to the end of the result
buffer.Append(oidbuf);
buffer.Append(valbuf);
}
/// <summary>BER encode OctetString variable.</summary>
/// <param name="buffer"><see cref="MutableByte"/> encoding destination.</param>
public override void encode(MutableByte buffer)
{
if (_data == null || _data.Length == 0)
{
BuildHeader(buffer, Type, 0);
}
else
{
BuildHeader(buffer, Type, _data.Length);
buffer.Append(_data);
}
}
/// <summary>
/// Convert user password to acceptable authentication key.
/// </summary>
/// <param name="userPassword">User password</param>
/// <param name="engineID">Authoritative engine id</param>
/// <returns>Localized authentication key</returns>
/// <exception cref="SnmpAuthenticationException">Thrown when key length is less then 8 bytes</exception>
public byte[] PasswordToKey(byte[] userPassword, byte[] engineID)
{
// key length has to be at least 8 bytes long (RFC3414)
if (userPassword == null || userPassword.Length < 8)
{
throw new SnmpAuthenticationException("Secret key is too short.");
}
var password_index = 0;
var count = 0;
SHA1 sha = new SHA1CryptoServiceProvider();
/* Use while loop until we've done 1 Megabyte */
var sourceBuffer = new byte[1048576];
var buf = new byte[64];
while (count < 1048576)
{
for (var i = 0; i < 64; ++i)
{
// Take the next octet of the password, wrapping
// to the beginning of the password as necessary.
buf[i] = userPassword[password_index++ % userPassword.Length];
}
Buffer.BlockCopy(buf, 0, sourceBuffer, count, buf.Length);
count += 64;
}
var digest = sha.ComputeHash(sourceBuffer);
var tmpbuf = new MutableByte();
tmpbuf.Append(digest);
tmpbuf.Append(engineID);
tmpbuf.Append(digest);
var res = sha.ComputeHash(tmpbuf);
sha.Clear(); // release resources
return(res);
}
/// <summary>
/// Encode single OID instance value
/// </summary>
/// <param name="number">Instance value</param>
/// <returns>Encoded instance value</returns>
protected byte[] encodeInstance(uint number)
{
var result = new MutableByte();
if (number <= 127)
{
result.Set((byte)number);
}
else
{
var val = number;
var tmp = new MutableByte();
while (val != 0)
{
var b = BitConverter.GetBytes(val);
var bval = b[0];
if ((bval & 0x80) != 0)
{
bval = (byte)(bval & ~HIGH_BIT); // clear high bit
}
val >>= 7; // shift original value by 7 bits
tmp.Append(bval);
}
// now we need to reverse the bytes for the final encoding
for (var i = tmp.Length - 1; i >= 0; i--)
{
if (i > 0)
{
result.Append((byte)(tmp[i] | HIGH_BIT));
}
else
{
result.Append(tmp[i]);
}
}
}
return(result);
}
/// <summary>
/// BER encode sequence
/// </summary>
/// <param name="buffer">Target buffer</param>
public override void encode(MutableByte buffer)
{
int dataLen = 0;
if (_data != null && _data.Length > 0)
{
dataLen = _data.Length;
}
BuildHeader(buffer, Type, dataLen);
if (dataLen > 0)
{
buffer.Append(_data);
}
}
/// <summary>
/// Encode VarBind collection sequence
/// </summary>
/// <param name="buffer">Target buffer. Encoded VarBind collection is appended.</param>
public override void encode(MutableByte buffer)
{
var tmp = new MutableByte();
//foreach (Vb v in _vbs)
//{
// v.encode(tmp);
//}
//Awais this optimization needs review.
Parallel.ForEach(_vbs, v => { v.encode(tmp); });
BuildHeader(buffer, Type, tmp.Length);
buffer.Append(tmp);
}
/// <summary>
/// Encodes ASN.1 object identifier and append it to the end of the passed buffer.
/// </summary>
/// <param name="buffer">
/// Buffer to append the encoded information to.
/// </param>
public override void encode(MutableByte buffer)
{
var tmpBuffer = new MutableByte();
var values = _data;
if (values == null || values.Length < 2)
{
values = new uint[2];
values[0] = values[1] = 0;
}
// verify that it is a valid object id!
if (values[0] < 0 || values[0] > 2)
{
throw new SnmpException("Invalid Object Identifier");
}
if (values[1] < 0 || values[1] > 40)
{
throw new SnmpException("Invalid Object Identifier");
}
// add the first oid!
tmpBuffer.Append((byte)(values[0] * 40 + values[1]));
// encode remaining instance values
for (var i = 2; i < values.Length; i++)
{
tmpBuffer.Append(encodeInstance(values[i]));
}
// build value header
BuildHeader(buffer, Type, tmpBuffer.Length);
// Append encoded value to the result buffer
buffer.Append(tmpBuffer);
}
/// <summary>ASN.1 encode SNMP version 1 trap</summary>
/// <param name="buffer"><see cref="MutableByte"/> buffer to the end of which encoded values are appended.</param>
public override void Encode(MutableByte buffer)
{
MutableByte trapBuffer = new MutableByte();
// encode the enterprise id & address
_enterprise.Encode(trapBuffer);
_agentAddr.Encode(trapBuffer);
_generic.Encode(trapBuffer);
_specific.Encode(trapBuffer);
_timeStamp.Encode(trapBuffer);
VbList.Encode(trapBuffer);
MutableByte tmpBuffer = new MutableByte();
BuildHeader(tmpBuffer, (byte)PduType.Trap, trapBuffer.Length);
trapBuffer.Prepend(tmpBuffer);
buffer.Append(trapBuffer);
}
/// <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);
}
/// <summary>Decode BER encoded Oid value.</summary>
/// <param name="buffer">BER encoded buffer</param>
/// <param name="offset">The offset location to begin decoding</param>
/// <returns>Buffer position after the decoded value</returns>
public override int decode(byte[] buffer, int offset)
{
int headerLength;
var asnType = ParseHeader(buffer, ref offset, out headerLength);
if (asnType != Type)
{
throw new SnmpException("Invalid ASN.1 type.");
}
// check for sufficient data
if (buffer.Length - offset < headerLength)
{
throw new OverflowException("Buffer underflow error");
}
if (headerLength == 0)
{
_data = null;
return(offset);
}
var list = new List <uint>();
// decode the first byte
--headerLength;
var oid = Convert.ToUInt32(buffer[offset++]);
list.Add(oid / 40);
list.Add(oid % 40);
//
// decode the rest of the identifiers
//
while (headerLength > 0)
{
uint result = 0;
// this is where we decode individual values
{
if ((buffer[offset] & HIGH_BIT) == 0)
{
// short encoding
result = buffer[offset];
offset += 1;
--headerLength;
}
else
{
// long encoding
var tmp = new MutableByte();
var completed = false;
do
{
tmp.Append((byte)(buffer[offset] & ~HIGH_BIT));
if ((buffer[offset] & HIGH_BIT) == 0)
{
completed = true;
}
offset += 1; // advance offset
--headerLength; // take out the processed byte from the header length
} while (!completed);
// convert byte array to integer
for (var i = 0; i < tmp.Length; i++)
{
result <<= 7;
result |= tmp[i];
}
}
}
list.Add(result);
}
_data = list.ToArray();
if (_data.Length == 2 && _data[0] == 0 && _data[1] == 0)
{
_data = null;
}
return(offset);
}
/// <summary>
/// Build ASN.1 header in the MutableByte array.
/// </summary>
/// <remarks>
/// Header is the TL part of the TLV (type, length, value) BER encoded data representation.
///
/// Each value is encoded as a Type byte, length of the data field and the actual, encoded
/// data. This method will encode the type and length fields.
/// </remarks>
/// <param name="mb">MurableByte array</param>
/// <param name="asnType">ASN.1 header type</param>
/// <param name="asnLength">Length of the data contained in the header</param>
internal static void BuildHeader(MutableByte mb, byte asnType, int asnLength)
{
mb.Append(asnType);
BuildLength(mb, asnLength);
}
/// <summary>
/// Encode SNMP version 3 packet
/// </summary>
/// <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 override byte[] encode()
{
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, Int32.MaxValue);
}
// encode message id
_messageId.encode(globalMessageData);
// encode max message size
_maxMessageSize.encode(globalMessageData);
// message flags
_msgFlags.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.SMI_SEQUENCE, 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 = _msgFlags.Privacy;
bool authentication = _msgFlags.Authentication;
bool reportable = _msgFlags.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
_msgFlags.Authentication = false;
_msgFlags.Privacy = false;
_msgFlags.Reportable = true;
}
_userSecurityModel.encode(buffer);
if (_userSecurityModel.EngineId.Length <= 0)
{
// restore saved USM values
_userSecurityModel.SecurityName.Set(savedUserName);
_msgFlags.Authentication = authentication;
_msgFlags.Privacy = privacy;
_msgFlags.Reportable = reportable;
}
// Check if privacy encryption is required
MutableByte encodedPdu = new MutableByte();
if (_msgFlags.Privacy && _userSecurityModel.EngineId.Length > 0)
{
IPrivacyProtocol privacyProtocol = PrivacyProtocol.GetInstance(_userSecurityModel.Privacy);
if (privacyProtocol == null)
{
throw new SnmpException(SnmpException.UnsupportedPrivacyProtocol, "Specified privacy protocol is not supported.");
}
// Get BER encoded ScopedPdu
MutableByte unencryptedPdu = new MutableByte();
_scopedPdu.encode(unencryptedPdu);
byte[] privacyParameters = null;
// we have to expand the key
IAuthenticationDigest auth = Authentication.GetInstance(_userSecurityModel.Authentication);
if (auth == null)
{
throw new SnmpException(SnmpException.UnsupportedNoAuthPriv, "Invalid authentication protocol. noAuthPriv mode not supported.");
}
byte[] pkey = privacyProtocol.PasswordToKey(_userSecurityModel.PrivacySecret, _userSecurityModel.EngineId, auth);
byte[] encryptedBuffer = privacyProtocol.Encrypt(unencryptedPdu, 0, unencryptedPdu.Length, pkey, _userSecurityModel.EngineBoots, _userSecurityModel.EngineTime, out 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.MaximumMessageSizeExceeded, "ScopedPdu exceeds maximum message size.");
}
}
}
else
{
_scopedPdu.encode(encodedPdu);
buffer.Append(encodedPdu);
}
int preVersionLength = buffer.Length;
base.encode(buffer);
int versionHeaderLength = buffer.Length - preVersionLength;
if (_msgFlags.Authentication && _userSecurityModel.EngineId.Length > 0)
{
_userSecurityModel.Authenticate(ref buffer);
// Now re-encode the packet with the authentication information
_userSecurityModel.encode(packetHeader);
packetHeader.Append(encodedPdu);
base.encode(packetHeader);
buffer = packetHeader;
}
return(buffer);
}
/// <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> Used to encode the integer value into an ASN.1 buffer.
/// The passed encoder defines the method for encoding the
/// data.
/// </summary>
/// <param name="buffer">Buffer target to write the encoded data</param>
public override void Encode(MutableByte buffer)
{
int val = _value;
byte[] b = BitConverter.GetBytes(_value);
MutableByte tmp = new MutableByte();
// if value is negative
if (val < 0)
{
for (int i = 3; i >= 0; i--)
{
if (tmp.Length > 0 || b[i] != 0xff)
{
tmp.Append(b[i]);
}
}
if (tmp.Length == 0)
{
// if the value is -1 then all bytes in an integer are 0xff and will be skipped above
tmp.Append(0xff);
}
// make sure value is negative
if ((tmp[0] & 0x80) == 0)
{
tmp.Prepend(0xff);
}
}
else if (val == 0)
{
// this is just a shortcut to save processing time
tmp.Append(0);
}
else
{
// byte[] b = BitConverter.GetBytes(val);
for (int i = 3; i >= 0; i--)
{
if (b[i] != 0 || tmp.Length > 0)
{
tmp.Append(b[i]);
}
}
// if buffer length is 0 then value is 0 and we have to add it to the buffer
if (tmp.Length == 0)
{
tmp.Append(0);
}
else
{
if ((tmp[0] & 0x80) != 0)
{
// first bit of the first byte has to be 0 otherwise value is negative.
tmp.Prepend(0);
}
}
}
// check for 9 1s at the beginning of the encoded value
if ((tmp.Length > 1 && tmp[0] == 0xff && (tmp[1] & 0x80) != 0))
{
tmp.Prepend(0);
}
BuildHeader(buffer, Type, tmp.Length);
buffer.Append(tmp);
}