/// <summary> /// Answers the message. /// </summary> /// <param name='messageStream'>Message stream.</param> /// <param name="process">The calling process or <c>null</c> if the process /// could not be obtained.</param> /// <remarks>code based on winpgnt.c from PuTTY source code</remarks> public void AnswerMessage(Stream messageStream, Process process = null) { if (messageStream.CanTimeout) { messageStream.ReadTimeout = 5000; } var messageParser = new BlobParser(messageStream); var responseBuilder = new BlobBuilder(); BlobHeader header; try { header = messageParser.ReadHeader(); if (MessageReceived != null) { var eventArgs = new MessageReceivedEventArgs(header); MessageReceived(this, eventArgs); if (eventArgs.Fail) { throw new Exception(); } } } catch (Exception) { header = new BlobHeader(); header.Message = Message.UNKNOWN; // this will cause the switch statement below to use the default case // which returns an error to the stream. } switch (header.Message) { case Message.SSH1_AGENTC_REQUEST_RSA_IDENTITIES: /* * Reply with SSH1_AGENT_RSA_IDENTITIES_ANSWER. */ try { if (header.BlobLength > 1) { // ruby net-ssh tries to send a SSH2_AGENT_REQUEST_VERSION message // which has the same id number as SSH1_AGENTC_REQUEST_RSA_IDENTITIES // with a string tacked on. We need to read the string from the // stream, but it is not used for anything. messageParser.ReadString(); } var keyList = ListKeys(SshVersion.SSH1); if (FilterKeyListCallback != null) { keyList = FilterKeyListCallback(keyList); } foreach (SshKey key in keyList) { responseBuilder.AddBytes(key.GetPublicKeyBlob()); responseBuilder.AddStringBlob(key.Comment); } responseBuilder.InsertHeader(Message.SSH1_AGENT_RSA_IDENTITIES_ANSWER, keyList.Count); // TODO may want to check that there is enough room in the message stream break; // succeeded } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH2_AGENTC_REQUEST_IDENTITIES: /* * Reply with SSH2_AGENT_IDENTITIES_ANSWER. */ try { var keyList = ListKeys(SshVersion.SSH2); if (FilterKeyListCallback != null) { keyList = FilterKeyListCallback(keyList); } foreach (SshKey key in keyList) { responseBuilder.AddBlob(key.GetPublicKeyBlob()); responseBuilder.AddStringBlob(key.Comment); } responseBuilder.InsertHeader(Message.SSH2_AGENT_IDENTITIES_ANSWER, keyList.Count); // TODO may want to check that there is enough room in the message stream break; // succeeded } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH1_AGENTC_RSA_CHALLENGE: /* * Reply with either SSH1_AGENT_RSA_RESPONSE or * SSH_AGENT_FAILURE, depending on whether we have that key * or not. */ try { //Reading publicKey information var publicKeyParams = messageParser.ReadSsh1PublicKeyData(true); //Searching for Key here var matchingKey = mKeyList.Where(key => key.Version == SshVersion.SSH1 && (key.GetPublicKeyParameters().Equals(publicKeyParams))).Single(); //Reading challenge var encryptedChallenge = messageParser.ReadSsh1BigIntBlob(); var sessionId = messageParser.ReadBytes(16); //Checking responseType field if (messageParser.ReadUInt32() != 1) { goto default; //responseType !=1 is not longer supported } //Answering to the challenge var engine = new Pkcs1Encoding(new RsaEngine()); engine.Init(false /* decrypt */, matchingKey.GetPrivateKeyParameters()); var decryptedChallenge = engine.ProcessBlock(encryptedChallenge, 0, encryptedChallenge.Length); using (MD5 md5 = MD5.Create()) { var md5Buffer = new byte[48]; decryptedChallenge.CopyTo(md5Buffer, 0); sessionId.CopyTo(md5Buffer, 32); responseBuilder.AddBytes(md5.ComputeHash(md5Buffer)); responseBuilder.InsertHeader(Message.SSH1_AGENT_RSA_RESPONSE); break; } } catch (InvalidOperationException) { // this is expected if there is not a matching key } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH2_AGENTC_SIGN_REQUEST: /* * Reply with either SSH2_AGENT_SIGN_RESPONSE or SSH_AGENT_FAILURE, * depending on whether we have that key or not. */ try { var keyBlob = messageParser.ReadBlob(); var reqData = messageParser.ReadBlob(); var flags = new SignRequestFlags(); try { // usually, there are no flags, so parser will throw flags = (SignRequestFlags)messageParser.ReadUInt32(); } catch { } var matchingKey = mKeyList.Where(key => key.Version == SshVersion.SSH2 && key.GetPublicKeyBlob().SequenceEqual(keyBlob)).First(); var confirmConstraints = matchingKey.Constraints .Where(constraint => constraint.Type == KeyConstraintType.SSH_AGENT_CONSTRAIN_CONFIRM); if (confirmConstraints.Count() > 0) { if (!ConfirmUserPermissionCallback.Invoke(matchingKey, process)) { goto default; } } /* create signature */ var signKey = matchingKey; var signer = signKey.GetSigner(); var algName = signKey.Algorithm.GetIdentifierString(); signer.Init(true, signKey.GetPrivateKeyParameters()); signer.BlockUpdate(reqData, 0, reqData.Length); byte[] signature = signer.GenerateSignature(); signature = signKey.FormatSignature(signature); BlobBuilder signatureBuilder = new BlobBuilder(); if (!flags.HasFlag(SignRequestFlags.SSH_AGENT_OLD_SIGNATURE)) { signatureBuilder.AddStringBlob(algName); } signatureBuilder.AddBlob(signature); responseBuilder.AddBlob(signatureBuilder.GetBlob()); responseBuilder.InsertHeader(Message.SSH2_AGENT_SIGN_RESPONSE); try { KeyUsed(this, new KeyUsedEventArgs(signKey, process)); } catch { } break; // succeeded } catch (InvalidOperationException) { // this is expected if there is not a matching key } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failure case Message.SSH1_AGENTC_ADD_RSA_IDENTITY: case Message.SSH1_AGENTC_ADD_RSA_ID_CONSTRAINED: /* * Add to the list and return SSH_AGENT_SUCCESS, or * SSH_AGENT_FAILURE if the key was malformed. */ if (IsLocked) { goto default; } bool ssh1constrained = (header.Message == Message.SSH1_AGENTC_ADD_RSA_ID_CONSTRAINED); try { var publicKeyParams = messageParser.ReadSsh1PublicKeyData(false); var keyPair = messageParser.ReadSsh1KeyData(publicKeyParams); SshKey key = new SshKey(SshVersion.SSH1, keyPair); key.Comment = messageParser.ReadString(); key.Source = "External client"; if (ssh1constrained) { while (messageStream.Position < header.BlobLength + 4) { KeyConstraint constraint = new KeyConstraint(); constraint.Type = (KeyConstraintType)messageParser.ReadUInt8(); if (constraint.Type == KeyConstraintType.SSH_AGENT_CONSTRAIN_LIFETIME) { constraint.Data = messageParser.ReadUInt32(); } key.AddConstraint(constraint); } } AddKey(key); responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; } catch (CallbackNullException) { // this is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH2_AGENTC_ADD_IDENTITY: case Message.SSH2_AGENTC_ADD_ID_CONSTRAINED: /* * Add to the list and return SSH_AGENT_SUCCESS, or * SSH_AGENT_FAILURE if the key was malformed. */ if (IsLocked) { goto default; } bool constrained = (header.Message == Message.SSH2_AGENTC_ADD_ID_CONSTRAINED); try { OpensshCertificate cert; var publicKeyParams = messageParser.ReadSsh2PublicKeyData(out cert); var keyPair = messageParser.ReadSsh2KeyData(publicKeyParams); SshKey key = new SshKey(SshVersion.SSH2, keyPair, null, cert); key.Comment = messageParser.ReadString(); key.Source = "External client"; if (constrained) { while (messageStream.Position < header.BlobLength + 4) { KeyConstraint constraint = new KeyConstraint(); constraint.Type = (KeyConstraintType)messageParser.ReadUInt8(); if (constraint.Type == KeyConstraintType.SSH_AGENT_CONSTRAIN_LIFETIME) { constraint.Data = messageParser.ReadUInt32(); } key.AddConstraint(constraint); } } AddKey(key); responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; // success! } catch (CallbackNullException) { // this is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH1_AGENTC_REMOVE_RSA_IDENTITY: case Message.SSH2_AGENTC_REMOVE_IDENTITY: /* * Remove from the list and return SSH_AGENT_SUCCESS, or * perhaps SSH_AGENT_FAILURE if it wasn't in the list to * start with. */ if (IsLocked) { goto default; } SshVersion removeVersion; byte[] rKeyBlob; if (header.Message == Message.SSH1_AGENTC_REMOVE_RSA_IDENTITY) { removeVersion = SshVersion.SSH1; rKeyBlob = messageParser.ReadBytes(header.BlobLength - 1); } else if (header.Message == Message.SSH2_AGENTC_REMOVE_IDENTITY) { removeVersion = SshVersion.SSH2; rKeyBlob = messageParser.ReadBlob(); } else { Debug.Fail("Should not get here."); goto default; } try { var matchingKey = mKeyList.Get(removeVersion, rKeyBlob); var startKeyListLength = mKeyList.Count; RemoveKey(matchingKey); // only succeed if key was removed if (mKeyList.Count == startKeyListLength - 1) { responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; //success! } } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH1_AGENTC_REMOVE_ALL_RSA_IDENTITIES: case Message.SSH2_AGENTC_REMOVE_ALL_IDENTITIES: /* * Remove all SSH-1 or SSH-2 keys. */ if (IsLocked) { goto default; } SshVersion removeAllVersion; if (header.Message == Message.SSH1_AGENTC_REMOVE_ALL_RSA_IDENTITIES) { removeAllVersion = SshVersion.SSH1; } else if (header.Message == Message.SSH2_AGENTC_REMOVE_ALL_IDENTITIES) { removeAllVersion = SshVersion.SSH2; } else { Debug.Fail("Should not get here."); goto default; } try { RemoveAllKeys(removeAllVersion); responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; //success! } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH_AGENTC_LOCK: try { var passphrase = new PinnedArray <byte>(messageParser.ReadBlob()); try { Lock(passphrase.Data); } finally { passphrase.Clear(); } if (IsLocked) { responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; } } catch (AgentLockedException) { // This is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; case Message.SSH_AGENTC_UNLOCK: try { var passphrase = new PinnedArray <byte>(messageParser.ReadBlob()); try { Unlock(passphrase.Data); } finally { passphrase.Clear(); } if (!IsLocked) { responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; } } catch (AgentLockedException) { // This is expected } catch (PassphraseException) { // This is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; default: responseBuilder.Clear(); responseBuilder.InsertHeader(Message.SSH_AGENT_FAILURE); break; } /* write response to stream */ if (messageStream.CanSeek) { messageStream.Position = 0; } messageStream.Write(responseBuilder.GetBlob(), 0, responseBuilder.Length); messageStream.Flush(); }
/// <summary> /// Answers the message. /// </summary> /// <param name='messageStream'>Message stream.</param> /// <param name="process">The calling process or <c>null</c> if the process /// could not be obtained.</param> /// <remarks>code based on winpgnt.c from PuTTY source code</remarks> public void AnswerMessage(Stream messageStream, Process process = null) { if (messageStream.CanTimeout) { messageStream.ReadTimeout = 5000; } var messageParser = new BlobParser(messageStream); var responseBuilder = new BlobBuilder(); BlobHeader header; try { header = messageParser.ReadHeader(); if (MessageReceived != null) { var eventArgs = new MessageReceivedEventArgs(header); MessageReceived(this, eventArgs); if (eventArgs.Fail) { throw new Exception (); } } } catch (Exception) { header = new BlobHeader(); header.Message = Message.UNKNOWN; // this will cause the switch statement below to use the default case // which returns an error to the stream. } switch (header.Message) { case Message.SSH1_AGENTC_REQUEST_RSA_IDENTITIES: /* * Reply with SSH1_AGENT_RSA_IDENTITIES_ANSWER. */ try { if (header.BlobLength > 1) { // ruby net-ssh tries to send a SSH2_AGENT_REQUEST_VERSION message // which has the same id number as SSH1_AGENTC_REQUEST_RSA_IDENTITIES // with a string tacked on. We need to read the string from the // stream, but it is not used for anything. messageParser.ReadString (); } var keyList = ListKeys(SshVersion.SSH1); if (FilterKeyListCallback != null) { keyList = FilterKeyListCallback(keyList); } foreach (SshKey key in keyList) { responseBuilder.AddBytes(key.GetPublicKeyBlob()); responseBuilder.AddStringBlob(key.Comment); } responseBuilder.InsertHeader(Message.SSH1_AGENT_RSA_IDENTITIES_ANSWER, keyList.Count); // TODO may want to check that there is enough room in the message stream break; // succeeded } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH2_AGENTC_REQUEST_IDENTITIES: /* * Reply with SSH2_AGENT_IDENTITIES_ANSWER. */ try { var keyList = ListKeys(SshVersion.SSH2); if (FilterKeyListCallback != null) { keyList = FilterKeyListCallback(keyList); } foreach (SshKey key in keyList) { responseBuilder.AddBlob(key.GetPublicKeyBlob()); responseBuilder.AddStringBlob(key.Comment); } responseBuilder.InsertHeader(Message.SSH2_AGENT_IDENTITIES_ANSWER, keyList.Count); // TODO may want to check that there is enough room in the message stream break; // succeeded } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH1_AGENTC_RSA_CHALLENGE: /* * Reply with either SSH1_AGENT_RSA_RESPONSE or * SSH_AGENT_FAILURE, depending on whether we have that key * or not. */ try { //Reading publicKey information var publicKeyParams = messageParser.ReadSsh1PublicKeyData(true); //Searching for Key here var matchingKey = mKeyList.Where(key => key.Version == SshVersion.SSH1 && (key.GetPublicKeyParameters().Equals(publicKeyParams))).Single(); //Reading challenge var encryptedChallenge = messageParser.ReadSsh1BigIntBlob(); var sessionId = messageParser.ReadBytes(16); //Checking responseType field if (messageParser.ReadInt() != 1) { goto default; //responseType !=1 is not longer supported } //Answering to the challenge var engine = new Pkcs1Encoding(new RsaEngine()); engine.Init(false /* decrypt */, matchingKey.GetPrivateKeyParameters()); var decryptedChallenge = engine.ProcessBlock(encryptedChallenge, 0, encryptedChallenge.Length); using (MD5 md5 = MD5.Create()) { var md5Buffer = new byte[48]; decryptedChallenge.CopyTo(md5Buffer, 0); sessionId.CopyTo(md5Buffer, 32); responseBuilder.AddBytes(md5.ComputeHash(md5Buffer)); responseBuilder.InsertHeader(Message.SSH1_AGENT_RSA_RESPONSE); break; } } catch (InvalidOperationException) { // this is expected if there is not a matching key } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH2_AGENTC_SIGN_REQUEST: /* * Reply with either SSH2_AGENT_SIGN_RESPONSE or SSH_AGENT_FAILURE, * depending on whether we have that key or not. */ try { var keyBlob = messageParser.ReadBlob(); var reqData = messageParser.ReadBlob(); var flags = new SignRequestFlags(); try { // usually, there are no flags, so parser will throw flags = (SignRequestFlags)messageParser.ReadInt(); } catch { } var matchingKey = mKeyList.Where(key => key.Version == SshVersion.SSH2 && key.GetPublicKeyBlob().SequenceEqual(keyBlob)).First(); var confirmConstraints = matchingKey.Constraints .Where(constraint => constraint.Type == KeyConstraintType.SSH_AGENT_CONSTRAIN_CONFIRM); if (confirmConstraints.Count() > 0) { if (!ConfirmUserPermissionCallback.Invoke(matchingKey, process)) { goto default; } } /* create signature */ var signKey = matchingKey; var signer = signKey.GetSigner(); var algName = signKey.Algorithm.GetIdentifierString(); signer.Init(true, signKey.GetPrivateKeyParameters()); signer.BlockUpdate(reqData, 0, reqData.Length); byte[] signature = signer.GenerateSignature(); signature = signKey.FormatSignature(signature); BlobBuilder signatureBuilder = new BlobBuilder(); if (!flags.HasFlag(SignRequestFlags.SSH_AGENT_OLD_SIGNATURE)) { signatureBuilder.AddStringBlob(algName); } signatureBuilder.AddBlob(signature); responseBuilder.AddBlob(signatureBuilder.GetBlob()); responseBuilder.InsertHeader(Message.SSH2_AGENT_SIGN_RESPONSE); try { KeyUsed(this, new KeyUsedEventArgs(signKey, process)); } catch { } break; // succeeded } catch (InvalidOperationException) { // this is expected if there is not a matching key } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failure case Message.SSH1_AGENTC_ADD_RSA_IDENTITY: case Message.SSH1_AGENTC_ADD_RSA_ID_CONSTRAINED: /* * Add to the list and return SSH_AGENT_SUCCESS, or * SSH_AGENT_FAILURE if the key was malformed. */ if (IsLocked) { goto default; } bool ssh1constrained = (header.Message == Message.SSH1_AGENTC_ADD_RSA_ID_CONSTRAINED); try { var publicKeyParams = messageParser.ReadSsh1PublicKeyData(false); var keyPair = messageParser.ReadSsh1KeyData(publicKeyParams); SshKey key = new SshKey(SshVersion.SSH1, keyPair); key.Comment = messageParser.ReadString(); key.Source = "External client"; if (ssh1constrained) { while (messageStream.Position < header.BlobLength + 4) { KeyConstraint constraint = new KeyConstraint(); constraint.Type = (KeyConstraintType)messageParser.ReadByte(); if (constraint.Type == KeyConstraintType.SSH_AGENT_CONSTRAIN_LIFETIME) { constraint.Data = messageParser.ReadInt(); } key.AddConstraint(constraint); } } AddKey(key); responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; } catch (CallbackNullException) { // this is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH2_AGENTC_ADD_IDENTITY: case Message.SSH2_AGENTC_ADD_ID_CONSTRAINED: /* * Add to the list and return SSH_AGENT_SUCCESS, or * SSH_AGENT_FAILURE if the key was malformed. */ if (IsLocked) { goto default; } bool constrained = (header.Message == Message.SSH2_AGENTC_ADD_ID_CONSTRAINED); try { var publicKeyParams = messageParser.ReadSsh2PublicKeyData(); var keyPair = messageParser.ReadSsh2KeyData(publicKeyParams); SshKey key = new SshKey(SshVersion.SSH2, keyPair); key.Comment = messageParser.ReadString(); key.Source = "External client"; if (constrained) { while (messageStream.Position < header.BlobLength + 4) { KeyConstraint constraint = new KeyConstraint(); constraint.Type = (KeyConstraintType)messageParser.ReadByte(); if (constraint.Type == KeyConstraintType.SSH_AGENT_CONSTRAIN_LIFETIME) { constraint.Data = messageParser.ReadInt(); } key.AddConstraint(constraint); } } AddKey(key); responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; // success! } catch (CallbackNullException) { // this is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH1_AGENTC_REMOVE_RSA_IDENTITY: case Message.SSH2_AGENTC_REMOVE_IDENTITY: /* * Remove from the list and return SSH_AGENT_SUCCESS, or * perhaps SSH_AGENT_FAILURE if it wasn't in the list to * start with. */ if (IsLocked) { goto default; } SshVersion removeVersion; byte[] rKeyBlob; if (header.Message == Message.SSH1_AGENTC_REMOVE_RSA_IDENTITY) { removeVersion = SshVersion.SSH1; rKeyBlob = messageParser.ReadBytes(header.BlobLength - 1); } else if (header.Message == Message.SSH2_AGENTC_REMOVE_IDENTITY) { removeVersion = SshVersion.SSH2; rKeyBlob = messageParser.ReadBlob(); } else { Debug.Fail("Should not get here."); goto default; } try { var matchingKey = mKeyList.Get(removeVersion, rKeyBlob); var startKeyListLength = mKeyList.Count; RemoveKey(matchingKey); // only succeed if key was removed if (mKeyList.Count == startKeyListLength - 1) { responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; //success! } } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH1_AGENTC_REMOVE_ALL_RSA_IDENTITIES: case Message.SSH2_AGENTC_REMOVE_ALL_IDENTITIES: /* * Remove all SSH-1 or SSH-2 keys. */ if (IsLocked) { goto default; } SshVersion removeAllVersion; if (header.Message == Message.SSH1_AGENTC_REMOVE_ALL_RSA_IDENTITIES) { removeAllVersion = SshVersion.SSH1; } else if (header.Message == Message.SSH2_AGENTC_REMOVE_ALL_IDENTITIES) { removeAllVersion = SshVersion.SSH2; } else { Debug.Fail("Should not get here."); goto default; } try { RemoveAllKeys(removeAllVersion); responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; //success! } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; // failed case Message.SSH_AGENTC_LOCK: try { var passphrase = new PinnedArray<byte>(messageParser.ReadBlob()); try { Lock(passphrase.Data); } finally { passphrase.Clear(); } if (IsLocked) { responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; } } catch (AgentLockedException) { // This is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; case Message.SSH_AGENTC_UNLOCK: try { var passphrase = new PinnedArray<byte>(messageParser.ReadBlob()); try { Unlock(passphrase.Data); } finally { passphrase.Clear(); } if (!IsLocked) { responseBuilder.InsertHeader(Message.SSH_AGENT_SUCCESS); break; } } catch (AgentLockedException) { // This is expected } catch (PassphraseException) { // This is expected } catch (Exception ex) { Debug.Fail(ex.ToString()); } goto default; default: responseBuilder.Clear(); responseBuilder.InsertHeader(Message.SSH_AGENT_FAILURE); break; } /* write response to stream */ if (messageStream.CanSeek) messageStream.Position = 0; messageStream.Write(responseBuilder.GetBlob(), 0, responseBuilder.Length); messageStream.Flush(); }