Exemplo n.º 1
0
			mut = Defaults{}
		})
		It("sets the fee", func() { Expect(subject.TX.Fee).To(BeEquivalentTo(100)) })
		It("sets the network id", func() { Expect(subject.NetworkID).To(Equal(DefaultNetwork.ID())) })

		Context("on a transaction with 2 operations", func() {
			BeforeEach(func() { subject.Mutate(Payment()) })
			It("sets the fee to 200", func() { Expect(subject.TX.Fee).To(BeEquivalentTo(200)) })
		})
	})

	Describe("MemoHash", func() {
		BeforeEach(func() { mut = MemoHash{[32]byte{0x01}} })
		It("sets a Hash memo on the transaction", func() {
			Expect(subject.TX.Memo.Type).To(Equal(xdr.MemoTypeMemoHash))
			Expect(subject.TX.Memo.MustHash()).To(Equal(xdr.Hash([32]byte{0x01})))
		})
	})

	Describe("MemoID", func() {
		BeforeEach(func() { mut = MemoID{123} })
		It("sets an ID memo on the transaction", func() {
			Expect(subject.TX.Memo.Type).To(Equal(xdr.MemoTypeMemoId))
			Expect(subject.TX.Memo.MustId()).To(Equal(xdr.Uint64(123)))
		})
	})

	Describe("MemoReturn", func() {
		BeforeEach(func() { mut = MemoReturn{[32]byte{0x01}} })
		It("sets a Hash memo on the transaction", func() {
			Expect(subject.TX.Memo.Type).To(Equal(xdr.MemoTypeMemoReturn))
Exemplo n.º 2
0
// HandlerSend implements /send endpoint
func (rh *RequestHandler) HandlerSend(c web.C, w http.ResponseWriter, r *http.Request) {
	request := &compliance.SendRequest{}
	request.FromRequest(r)

	err := request.Validate()
	if err != nil {
		errorResponse := err.(*protocols.ErrorResponse)
		log.WithFields(errorResponse.LogData).Error(errorResponse.Error())
		server.Write(w, errorResponse)
		return
	}

	destinationObject, stellarToml, err := rh.FederationResolver.Resolve(request.Destination)
	if err != nil {
		log.WithFields(log.Fields{
			"destination": request.Destination,
			"err":         err,
		}).Print("Cannot resolve address")
		server.Write(w, compliance.CannotResolveDestination)
		return
	}

	if stellarToml.AuthServer == "" {
		log.Print("No AUTH_SERVER in stellar.toml")
		server.Write(w, compliance.AuthServerNotDefined)
		return
	}

	var payWithMutator *b.PayWithPath

	if request.SendMax != "" {
		// Path payment
		var sendAsset b.Asset
		if request.SendAssetCode != "" && request.SendAssetIssuer != "" {
			sendAsset = b.CreditAsset(request.SendAssetCode, request.SendAssetIssuer)
		} else if request.SendAssetCode == "" && request.SendAssetIssuer == "" {
			sendAsset = b.NativeAsset()
		} else {
			log.Print("Missing send asset param.")
			server.Write(w, protocols.MissingParameterError)
			return
		}

		payWith := b.PayWith(sendAsset, request.SendMax)

		for _, asset := range request.Path {
			if asset.Code == "" && asset.Issuer == "" {
				payWith = payWith.Through(b.NativeAsset())
			} else {
				payWith = payWith.Through(b.CreditAsset(asset.Code, asset.Issuer))
			}
		}

		payWithMutator = &payWith
	}

	mutators := []interface{}{
		b.Destination{destinationObject.AccountID},
		b.CreditAmount{
			request.AssetCode,
			request.AssetIssuer,
			request.Amount,
		},
	}

	if payWithMutator != nil {
		mutators = append(mutators, *payWithMutator)
	}

	operationMutator := b.Payment(mutators...)
	if operationMutator.Err != nil {
		log.WithFields(log.Fields{
			"err": operationMutator.Err,
		}).Error("Error creating operation")
		server.Write(w, protocols.InternalServerError)
		return
	}

	// Fetch Sender Info
	senderInfo := ""

	if rh.Config.Callbacks.FetchInfo != "" {
		fetchInfoRequest := compliance.FetchInfoRequest{Address: request.Sender}
		resp, err := rh.Client.PostForm(
			rh.Config.Callbacks.FetchInfo,
			fetchInfoRequest.ToValues(),
		)
		if err != nil {
			log.WithFields(log.Fields{
				"fetch_info": rh.Config.Callbacks.FetchInfo,
				"err":        err,
			}).Error("Error sending request to fetch_info server")
			server.Write(w, protocols.InternalServerError)
			return
		}

		defer resp.Body.Close()
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			log.WithFields(log.Fields{
				"fetch_info": rh.Config.Callbacks.FetchInfo,
				"err":        err,
			}).Error("Error reading fetch_info server response")
			server.Write(w, protocols.InternalServerError)
			return
		}

		if resp.StatusCode != http.StatusOK {
			log.WithFields(log.Fields{
				"fetch_info": rh.Config.Callbacks.FetchInfo,
				"status":     resp.StatusCode,
				"body":       string(body),
			}).Error("Error response from fetch_info server")
			server.Write(w, protocols.InternalServerError)
			return
		}

		senderInfo = string(body)
	}

	memoPreimage := &memo.Memo{
		Transaction: memo.Transaction{
			SenderInfo: senderInfo,
			Route:      destinationObject.Memo,
			Extra:      request.ExtraMemo,
		},
	}

	memoJSON := memoPreimage.Marshal()
	memoHashBytes := sha256.Sum256(memoJSON)
	memoMutator := &b.MemoHash{xdr.Hash(memoHashBytes)}

	transaction, err := submitter.BuildTransaction(
		request.Source,
		rh.Config.NetworkPassphrase,
		operationMutator,
		memoMutator,
	)

	var txBytes bytes.Buffer
	_, err = xdr.Marshal(&txBytes, transaction)
	if err != nil {
		log.Error("Error mashaling transaction")
		server.Write(w, protocols.InternalServerError)
		return
	}

	txBase64 := base64.StdEncoding.EncodeToString(txBytes.Bytes())

	authData := compliance.AuthData{
		Sender:   request.Sender,
		NeedInfo: rh.Config.NeedsAuth,
		Tx:       txBase64,
		Memo:     string(memoJSON),
	}

	data, err := json.Marshal(authData)
	if err != nil {
		log.Error("Error mashaling authData")
		server.Write(w, protocols.InternalServerError)
		return
	}
	sig, err := rh.SignatureSignerVerifier.Sign(rh.Config.Keys.SigningSeed, data)
	if err != nil {
		log.Error("Error signing authData")
		server.Write(w, protocols.InternalServerError)
		return
	}

	authRequest := compliance.AuthRequest{
		Data:      string(data),
		Signature: sig,
	}
	resp, err := rh.Client.PostForm(
		stellarToml.AuthServer,
		authRequest.ToValues(),
	)
	if err != nil {
		log.WithFields(log.Fields{
			"auth_server": stellarToml.AuthServer,
			"err":         err,
		}).Error("Error sending request to auth server")
		server.Write(w, protocols.InternalServerError)
		return
	}

	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Error("Error reading auth server response")
		server.Write(w, protocols.InternalServerError)
		return
	}

	if resp.StatusCode != 200 {
		log.WithFields(log.Fields{
			"status": resp.StatusCode,
			"body":   string(body),
		}).Error("Error response from auth server")
		server.Write(w, protocols.InternalServerError)
		return
	}

	var authResponse compliance.AuthResponse
	err = json.Unmarshal(body, &authResponse)
	if err != nil {
		log.WithFields(log.Fields{
			"status": resp.StatusCode,
			"body":   string(body),
		}).Error("Error unmarshalling auth response")
		server.Write(w, protocols.InternalServerError)
		return
	}

	response := compliance.SendResponse{
		AuthResponse:   authResponse,
		TransactionXdr: txBase64,
	}
	server.Write(w, &response)
}
Exemplo n.º 3
0
// HandlerAuth implements authorize endpoint
func (rh *RequestHandler) HandlerAuth(c web.C, w http.ResponseWriter, r *http.Request) {
	authreq := &compliance.AuthRequest{}
	authreq.FromRequest(r)

	err := authreq.Validate()
	if err != nil {
		errorResponse := err.(*protocols.ErrorResponse)
		log.WithFields(errorResponse.LogData).Error(errorResponse.Error())
		server.Write(w, errorResponse)
		return
	}

	var authData compliance.AuthData
	err = json.Unmarshal([]byte(authreq.Data), &authData)
	if err != nil {
		errorResponse := protocols.NewInvalidParameterError("data", authreq.Data)
		log.WithFields(errorResponse.LogData).Warn(errorResponse.Error())
		server.Write(w, errorResponse)
		return
	}

	senderStellarToml, err := rh.StellarTomlResolver.GetStellarTomlByAddress(authData.Sender)
	if err != nil {
		log.WithFields(log.Fields{"err": err, "sender": authData.Sender}).Warn("Cannot get stellar.toml of sender")
		server.Write(w, protocols.InvalidParameterError)
		return
	}

	if senderStellarToml.SigningKey == "" {
		errorResponse := protocols.NewInvalidParameterError("data.sender", authData.Sender)
		log.WithFields(errorResponse.LogData).Warn("No SIGNING_KEY in stellar.toml of sender")
		server.Write(w, errorResponse)
		return
	}

	// Verify signature
	signatureBytes, err := base64.StdEncoding.DecodeString(authreq.Signature)
	if err != nil {
		errorResponse := protocols.NewInvalidParameterError("sig", authreq.Signature)
		log.WithFields(errorResponse.LogData).Warn("Error decoding signature")
		server.Write(w, errorResponse)
		return
	}
	err = rh.SignatureSignerVerifier.Verify(senderStellarToml.SigningKey, []byte(authreq.Data), signatureBytes)
	if err != nil {
		log.WithFields(log.Fields{
			"signing_key": senderStellarToml.SigningKey,
			"data":        authreq.Data,
			"sig":         authreq.Signature,
		}).Warn("Invalid signature")
		errorResponse := protocols.NewInvalidParameterError("sig", authreq.Signature)
		server.Write(w, errorResponse)
		return
	}

	b64r := base64.NewDecoder(base64.StdEncoding, strings.NewReader(authData.Tx))
	var tx xdr.Transaction
	_, err = xdr.Unmarshal(b64r, &tx)
	if err != nil {
		errorResponse := protocols.NewInvalidParameterError("data.tx", authData.Tx)
		log.WithFields(log.Fields{
			"err": err,
			"tx":  authData.Tx,
		}).Warn("Error decoding Transaction XDR")
		server.Write(w, errorResponse)
		return
	}

	if tx.Memo.Hash == nil {
		errorResponse := protocols.NewInvalidParameterError("data.tx", authData.Tx)
		log.WithFields(log.Fields{"tx": authData.Tx}).Warn("Transaction does not contain Memo.Hash")
		server.Write(w, errorResponse)
		return
	}

	// Validate memo preimage hash
	memoPreimageHashBytes := sha256.Sum256([]byte(authData.Memo))
	memoBytes := [32]byte(*tx.Memo.Hash)

	if memoPreimageHashBytes != memoBytes {
		errorResponse := protocols.NewInvalidParameterError("data.tx", authData.Tx)

		h := xdr.Hash(memoPreimageHashBytes)
		tx.Memo.Hash = &h

		var txBytes bytes.Buffer
		_, err = xdr.Marshal(&txBytes, tx)
		if err != nil {
			log.Error("Error mashaling transaction")
			server.Write(w, protocols.InternalServerError)
			return
		}

		expectedTx := base64.StdEncoding.EncodeToString(txBytes.Bytes())

		log.WithFields(log.Fields{"tx": authData.Tx, "expected_tx": expectedTx}).Warn("Memo preimage hash does not equal tx Memo.Hash")
		server.Write(w, errorResponse)
		return
	}

	var memoPreimage memo.Memo
	err = json.Unmarshal([]byte(authData.Memo), &memoPreimage)
	if err != nil {
		errorResponse := protocols.NewInvalidParameterError("data.memo", authData.Memo)
		log.WithFields(log.Fields{
			"err":  err,
			"memo": authData.Memo,
		}).Warn("Cannot unmarshal memo preimage")
		server.Write(w, errorResponse)
		return
	}

	transactionHash, err := submitter.TransactionHash(&tx, rh.Config.NetworkPassphrase)
	if err != nil {
		log.WithFields(log.Fields{"err": err}).Warn("Error calculating tx hash")
		server.Write(w, protocols.InternalServerError)
		return
	}

	response := compliance.AuthResponse{}

	// Sanctions check
	if rh.Config.Callbacks.Sanctions == "" {
		response.TxStatus = compliance.AuthStatusOk
	} else {
		resp, err := rh.Client.PostForm(
			rh.Config.Callbacks.Sanctions,
			url.Values{"sender": {memoPreimage.Transaction.SenderInfo}},
		)
		if err != nil {
			log.WithFields(log.Fields{
				"sanctions": rh.Config.Callbacks.Sanctions,
				"err":       err,
			}).Error("Error sending request to sanctions server")
			server.Write(w, protocols.InternalServerError)
			return
		}

		defer resp.Body.Close()
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			log.Error("Error reading sanctions server response")
			server.Write(w, protocols.InternalServerError)
			return
		}

		switch resp.StatusCode {
		case http.StatusOK: // AuthStatusOk
			response.TxStatus = compliance.AuthStatusOk
		case http.StatusAccepted: // AuthStatusPending
			response.TxStatus = compliance.AuthStatusPending

			var pendingResponse compliance.PendingResponse
			err := json.Unmarshal(body, &pendingResponse)
			if err != nil {
				// Set default value
				response.Pending = 600
			} else {
				response.Pending = pendingResponse.Pending
			}
		case http.StatusForbidden: // AuthStatusDenied
			response.TxStatus = compliance.AuthStatusDenied
		default:
			log.WithFields(log.Fields{
				"status": resp.StatusCode,
				"body":   string(body),
			}).Error("Error response from sanctions server")
			server.Write(w, protocols.InternalServerError)
			return
		}
	}

	// User info
	if authData.NeedInfo {
		if rh.Config.Callbacks.AskUser == "" {
			response.InfoStatus = compliance.AuthStatusDenied

			// Check AllowedFi
			tokens := strings.Split(authData.Sender, "*")
			if len(tokens) != 2 {
				log.WithFields(log.Fields{
					"sender": authData.Sender,
				}).Warn("Invalid stellar address")
				server.Write(w, protocols.InternalServerError)
				return
			}

			allowedFi, err := rh.Repository.GetAllowedFiByDomain(tokens[1])
			if err != nil {
				log.WithFields(log.Fields{"err": err}).Error("Error getting AllowedFi from DB")
				server.Write(w, protocols.InternalServerError)
				return
			}

			if allowedFi == nil {
				// FI not found check AllowedUser
				allowedUser, err := rh.Repository.GetAllowedUserByDomainAndUserID(tokens[1], tokens[0])
				if err != nil {
					log.WithFields(log.Fields{"err": err}).Error("Error getting AllowedUser from DB")
					server.Write(w, protocols.InternalServerError)
					return
				}

				if allowedUser != nil {
					response.InfoStatus = compliance.AuthStatusOk
				}
			} else {
				response.InfoStatus = compliance.AuthStatusOk
			}
		} else {
			// Ask user
			var amount, assetType, assetCode, assetIssuer string

			if len(tx.Operations) > 0 {
				operationBody := tx.Operations[0].Body
				if operationBody.Type == xdr.OperationTypePayment {
					amount = baseAmount.String(operationBody.PaymentOp.Amount)
					operationBody.PaymentOp.Asset.Extract(&assetType, &assetCode, &assetIssuer)
				} else if operationBody.Type == xdr.OperationTypePathPayment {
					amount = baseAmount.String(operationBody.PathPaymentOp.DestAmount)
					operationBody.PathPaymentOp.DestAsset.Extract(&assetType, &assetCode, &assetIssuer)
				}
			}

			resp, err := rh.Client.PostForm(
				rh.Config.Callbacks.AskUser,
				url.Values{
					"amount":       {amount},
					"asset_code":   {assetCode},
					"asset_issuer": {assetIssuer},
					"sender":       {memoPreimage.Transaction.SenderInfo},
					"note":         {memoPreimage.Transaction.Note},
				},
			)
			if err != nil {
				log.WithFields(log.Fields{
					"ask_user": rh.Config.Callbacks.AskUser,
					"err":      err,
				}).Error("Error sending request to ask_user server")
				server.Write(w, protocols.InternalServerError)
				return
			}

			defer resp.Body.Close()
			body, err := ioutil.ReadAll(resp.Body)
			if err != nil {
				log.Error("Error reading ask_user server response")
				server.Write(w, protocols.InternalServerError)
				return
			}

			switch resp.StatusCode {
			case http.StatusOK: // AuthStatusOk
				response.InfoStatus = compliance.AuthStatusOk
			case http.StatusAccepted: // AuthStatusPending
				response.InfoStatus = compliance.AuthStatusPending

				var pendingResponse compliance.PendingResponse
				err := json.Unmarshal(body, &pendingResponse)
				if err != nil {
					// Set default value
					response.Pending = 600
				} else {
					response.Pending = pendingResponse.Pending
				}
			case http.StatusForbidden: // AuthStatusDenied
				response.InfoStatus = compliance.AuthStatusDenied
			default:
				log.WithFields(log.Fields{
					"status": resp.StatusCode,
					"body":   string(body),
				}).Error("Error response from ask_user server")
				server.Write(w, protocols.InternalServerError)
				return
			}
		}

		if response.InfoStatus == compliance.AuthStatusOk {
			// Fetch Info
			fetchInfoRequest := compliance.FetchInfoRequest{Address: memoPreimage.Transaction.Route}
			resp, err := rh.Client.PostForm(
				rh.Config.Callbacks.FetchInfo,
				fetchInfoRequest.ToValues(),
			)
			if err != nil {
				log.WithFields(log.Fields{
					"fetch_info": rh.Config.Callbacks.FetchInfo,
					"err":        err,
				}).Error("Error sending request to fetch_info server")
				server.Write(w, protocols.InternalServerError)
				return
			}

			defer resp.Body.Close()
			body, err := ioutil.ReadAll(resp.Body)
			if err != nil {
				log.WithFields(log.Fields{
					"fetch_info": rh.Config.Callbacks.FetchInfo,
					"err":        err,
				}).Error("Error reading fetch_info server response")
				server.Write(w, protocols.InternalServerError)
				return
			}

			if resp.StatusCode != http.StatusOK {
				log.WithFields(log.Fields{
					"fetch_info": rh.Config.Callbacks.FetchInfo,
					"status":     resp.StatusCode,
					"body":       string(body),
				}).Error("Error response from fetch_info server")
				server.Write(w, protocols.InternalServerError)
				return
			}

			response.DestInfo = string(body)
		}
	} else {
		response.InfoStatus = compliance.AuthStatusOk
	}

	if response.TxStatus == compliance.AuthStatusOk && response.InfoStatus == compliance.AuthStatusOk {
		authorizedTransaction := &entities.AuthorizedTransaction{
			TransactionID:  hex.EncodeToString(transactionHash[:]),
			Memo:           base64.StdEncoding.EncodeToString(memoBytes[:]),
			TransactionXdr: authData.Tx,
			AuthorizedAt:   time.Now(),
			Data:           authreq.Data,
		}
		err = rh.EntityManager.Persist(authorizedTransaction)
		if err != nil {
			log.WithFields(log.Fields{"err": err}).Warn("Error persisting AuthorizedTransaction")
			server.Write(w, protocols.InternalServerError)
			return
		}
	}

	server.Write(w, &response)
}
// Payment implements /payment endpoint
func (rh *RequestHandler) Payment(w http.ResponseWriter, r *http.Request) {
	request := &bridge.PaymentRequest{}
	request.FromRequest(r)

	err := request.Validate()
	if err != nil {
		errorResponse := err.(*protocols.ErrorResponse)
		log.WithFields(errorResponse.LogData).Error(errorResponse.Error())
		server.Write(w, errorResponse)
		return
	}

	if request.Source == "" {
		request.Source = rh.Config.Accounts.BaseSeed
	}

	sourceKeypair, _ := keypair.Parse(request.Source)

	var submitResponse horizon.SubmitTransactionResponse
	var submitError error

	if request.ExtraMemo != "" && rh.Config.Compliance != "" {
		// Compliance server part
		sendRequest := request.ToComplianceSendRequest()

		resp, err := rh.Client.PostForm(
			rh.Config.Compliance+"/send",
			sendRequest.ToValues(),
		)
		if err != nil {
			log.WithFields(log.Fields{"err": err}).Error("Error sending request to compliance server")
			server.Write(w, protocols.InternalServerError)
			return
		}

		defer resp.Body.Close()
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			log.Error("Error reading compliance server response")
			server.Write(w, protocols.InternalServerError)
			return
		}

		if resp.StatusCode != 200 {
			log.WithFields(log.Fields{
				"status": resp.StatusCode,
				"body":   string(body),
			}).Error("Error response from compliance server")
			server.Write(w, protocols.InternalServerError)
			return
		}

		var complianceSendResponse compliance.SendResponse
		err = json.Unmarshal(body, &complianceSendResponse)
		if err != nil {
			log.Error("Error unmarshalling from compliance server")
			server.Write(w, protocols.InternalServerError)
			return
		}

		if complianceSendResponse.AuthResponse.InfoStatus == compliance.AuthStatusPending ||
			complianceSendResponse.AuthResponse.TxStatus == compliance.AuthStatusPending {
			log.WithFields(log.Fields{"response": complianceSendResponse}).Info("Compliance response pending")
			server.Write(w, bridge.NewPaymentPendingError(complianceSendResponse.AuthResponse.Pending))
			return
		}

		if complianceSendResponse.AuthResponse.InfoStatus == compliance.AuthStatusDenied ||
			complianceSendResponse.AuthResponse.TxStatus == compliance.AuthStatusDenied {
			log.WithFields(log.Fields{"response": complianceSendResponse}).Info("Compliance response denied")
			server.Write(w, bridge.PaymentDenied)
			return
		}

		var tx xdr.Transaction
		err = xdr.SafeUnmarshalBase64(complianceSendResponse.TransactionXdr, &tx)
		if err != nil {
			log.Error("Error unmarshalling transaction returned by compliance server")
			server.Write(w, protocols.InternalServerError)
			return
		}

		submitResponse, submitError = rh.TransactionSubmitter.SignAndSubmitRawTransaction(request.Source, &tx)
	} else {
		// Payment without compliance server
		destinationObject, _, err := rh.FederationResolver.Resolve(request.Destination)
		if err != nil {
			log.WithFields(log.Fields{"destination": request.Destination, "err": err}).Print("Cannot resolve address")
			server.Write(w, bridge.PaymentCannotResolveDestination)
			return
		}

		_, err = keypair.Parse(destinationObject.AccountID)
		if err != nil {
			log.WithFields(log.Fields{"AccountId": destinationObject.AccountID}).Print("Invalid AccountId in destination")
			server.Write(w, protocols.NewInvalidParameterError("destination", request.Destination))
			return
		}

		var payWithMutator *b.PayWithPath

		if request.SendMax != "" {
			// Path payment
			var sendAsset b.Asset
			if request.SendAssetCode == "" && request.SendAssetIssuer == "" {
				sendAsset = b.NativeAsset()
			} else {
				sendAsset = b.CreditAsset(request.SendAssetCode, request.SendAssetIssuer)
			}

			payWith := b.PayWith(sendAsset, request.SendMax)

			for i := 0; ; i++ {
				codeFieldName := fmt.Sprintf("path[%d][asset_code]", i)
				issuerFieldName := fmt.Sprintf("path[%d][asset_issuer]", i)

				// If the element does not exist in PostForm break the loop
				if _, exists := r.PostForm[codeFieldName]; !exists {
					break
				}

				code := r.PostFormValue(codeFieldName)
				issuer := r.PostFormValue(issuerFieldName)

				if code == "" && issuer == "" {
					payWith = payWith.Through(b.NativeAsset())
				} else {
					payWith = payWith.Through(b.CreditAsset(code, issuer))
				}
			}

			payWithMutator = &payWith
		}

		var operationBuilder interface{}

		if request.AssetCode != "" && request.AssetIssuer != "" {
			mutators := []interface{}{
				b.Destination{destinationObject.AccountID},
				b.CreditAmount{request.AssetCode, request.AssetIssuer, request.Amount},
			}

			if payWithMutator != nil {
				mutators = append(mutators, *payWithMutator)
			}

			operationBuilder = b.Payment(mutators...)
		} else {
			mutators := []interface{}{
				b.Destination{destinationObject.AccountID},
				b.NativeAmount{request.Amount},
			}

			if payWithMutator != nil {
				mutators = append(mutators, *payWithMutator)
			}

			// Check if destination account exist
			_, err = rh.Horizon.LoadAccount(destinationObject.AccountID)
			if err != nil {
				log.WithFields(log.Fields{"error": err}).Error("Error loading account")
				operationBuilder = b.CreateAccount(mutators...)
			} else {
				operationBuilder = b.Payment(mutators...)
			}
		}

		memoType := request.MemoType
		memo := request.Memo

		if destinationObject.MemoType != "" {
			if request.MemoType != "" {
				log.Print("Memo given in request but federation returned memo fields.")
				server.Write(w, bridge.PaymentCannotUseMemo)
				return
			}

			memoType = destinationObject.MemoType
			memo = destinationObject.Memo
		}

		var memoMutator interface{}
		switch {
		case memoType == "":
			break
		case memoType == "id":
			id, err := strconv.ParseUint(memo, 10, 64)
			if err != nil {
				log.WithFields(log.Fields{"memo": memo}).Print("Cannot convert memo_id value to uint64")
				server.Write(w, protocols.NewInvalidParameterError("memo", request.Memo))
				return
			}
			memoMutator = b.MemoID{id}
		case memoType == "text":
			memoMutator = &b.MemoText{memo}
		case memoType == "hash":
			memoBytes, err := hex.DecodeString(memo)
			if err != nil || len(memoBytes) != 32 {
				log.WithFields(log.Fields{"memo": memo}).Print("Cannot decode hash memo value")
				server.Write(w, protocols.NewInvalidParameterError("memo", request.Memo))
				return
			}
			var b32 [32]byte
			copy(b32[:], memoBytes[0:32])
			hash := xdr.Hash(b32)
			memoMutator = &b.MemoHash{hash}
		default:
			log.Print("Not supported memo type: ", memoType)
			server.Write(w, protocols.NewInvalidParameterError("memo", request.Memo))
			return
		}

		accountResponse, err := rh.Horizon.LoadAccount(sourceKeypair.Address())
		if err != nil {
			log.WithFields(log.Fields{"error": err}).Error("Cannot load source account")
			server.Write(w, bridge.PaymentSourceNotExist)
			return
		}

		sequenceNumber, err := strconv.ParseUint(accountResponse.SequenceNumber, 10, 64)
		if err != nil {
			log.WithFields(log.Fields{"error": err}).Error("Cannot convert SequenceNumber")
			server.Write(w, protocols.InternalServerError)
			return
		}

		transactionMutators := []b.TransactionMutator{
			b.SourceAccount{request.Source},
			b.Sequence{sequenceNumber + 1},
			b.Network{rh.Config.NetworkPassphrase},
			operationBuilder.(b.TransactionMutator),
		}

		if memoMutator != nil {
			transactionMutators = append(transactionMutators, memoMutator.(b.TransactionMutator))
		}

		tx := b.Transaction(transactionMutators...)

		if tx.Err != nil {
			log.WithFields(log.Fields{"err": tx.Err}).Print("Transaction builder error")
			// TODO when build.OperationBuilder interface is ready check for
			// create_account and payment errors separately
			switch {
			case tx.Err.Error() == "Asset code length is invalid":
				server.Write(
					w,
					protocols.NewInvalidParameterError("asset_code", request.AssetCode),
				)
			case strings.Contains(tx.Err.Error(), "cannot parse amount"):
				server.Write(
					w,
					protocols.NewInvalidParameterError("amount", request.Amount),
				)
			default:
				log.WithFields(log.Fields{"err": tx.Err}).Print("Transaction builder error")
				server.Write(w, protocols.InternalServerError)
			}
			return
		}

		txe := tx.Sign(request.Source)
		txeB64, err := txe.Base64()

		if err != nil {
			log.WithFields(log.Fields{"error": err}).Error("Cannot encode transaction envelope")
			server.Write(w, protocols.InternalServerError)
			return
		}

		submitResponse, submitError = rh.Horizon.SubmitTransaction(txeB64)
	}

	if submitError != nil {
		log.WithFields(log.Fields{"error": submitError}).Error("Error submitting transaction")
		server.Write(w, protocols.InternalServerError)
		return
	}

	errorResponse := bridge.ErrorFromHorizonResponse(submitResponse)
	if errorResponse != nil {
		log.WithFields(errorResponse.LogData).Error(errorResponse.Error())
		server.Write(w, errorResponse)
		return
	}

	// Path payment send amount
	if submitResponse.ResultXdr != nil {
		var transactionResult xdr.TransactionResult
		reader := strings.NewReader(*submitResponse.ResultXdr)
		b64r := base64.NewDecoder(base64.StdEncoding, reader)
		_, err := xdr.Unmarshal(b64r, &transactionResult)

		if err == nil && transactionResult.Result.Code == xdr.TransactionResultCodeTxSuccess {
			operationResult := (*transactionResult.Result.Results)[0]
			if operationResult.Tr.PathPaymentResult != nil {
				sendAmount := operationResult.Tr.PathPaymentResult.SendAmount()
				submitResponse.SendAmount = amount.String(sendAmount)
			}
		}
	}

	server.Write(w, &submitResponse)
}