import grpc, os, hashlib, secrets, json from . import lightning_pb2 as lnrpc, lightning_pb2_grpc as lightningstub from . import invoices_pb2 as invoicesrpc, invoices_pb2_grpc as invoicesstub from . import router_pb2 as routerrpc, router_pb2_grpc as routerstub from decouple import config from base64 import b64decode from datetime import timedelta, datetime from django.utils import timezone from api.models import LNPayment ####### # Should work with LND (c-lightning in the future if there are features that deserve the work) ####### CERT = b64decode(config('LND_CERT_BASE64')) MACAROON = b64decode(config('LND_MACAROON_BASE64')) LND_GRPC_HOST = config('LND_GRPC_HOST') class LNNode(): os.environ["GRPC_SSL_CIPHER_SUITES"] = 'HIGH+ECDSA' creds = grpc.ssl_channel_credentials(CERT) channel = grpc.secure_channel(LND_GRPC_HOST, creds) lightningstub = lightningstub.LightningStub(channel) invoicesstub = invoicesstub.InvoicesStub(channel) routerstub = routerstub.RouterStub(channel) lnrpc = lnrpc invoicesrpc = invoicesrpc routerrpc = routerrpc payment_failure_context = { 0: "Payment isn't failed (yet)", 1: "There are more routes to try, but the payment timeout was exceeded.", 2: "All possible routes were tried and failed permanently. Or were no routes to the destination at all.", 3: "A non-recoverable error has occured.", 4: "Payment details incorrect (unknown hash, invalid amt or invalid final cltv delta)", 5: "Insufficient local balance."} @classmethod def decode_payreq(cls, invoice): '''Decodes a lightning payment request (invoice)''' request = lnrpc.PayReqString(pay_req=invoice) response = cls.lightningstub.DecodePayReq(request, metadata=[('macaroon', MACAROON.hex())]) return response @classmethod def cancel_return_hold_invoice(cls, payment_hash): '''Cancels or returns a hold invoice''' request = invoicesrpc.CancelInvoiceMsg(payment_hash=bytes.fromhex(payment_hash)) response = cls.invoicesstub.CancelInvoice(request, metadata=[('macaroon', MACAROON.hex())]) # Fix this: tricky because canceling sucessfully an invoice has no response. TODO return str(response) == "" # True if no response, false otherwise. @classmethod def settle_hold_invoice(cls, preimage): '''settles a hold invoice''' request = invoicesrpc.SettleInvoiceMsg(preimage=bytes.fromhex(preimage)) response = cls.invoicesstub.SettleInvoice(request, metadata=[('macaroon', MACAROON.hex())]) # Fix this: tricky because settling sucessfully an invoice has None response. TODO return str(response)=="" # True if no response, false otherwise. @classmethod def gen_hold_invoice(cls, num_satoshis, description, invoice_expiry, cltv_expiry_secs): '''Generates hold invoice''' hold_payment = {} # The preimage is a random hash of 256 bits entropy preimage = hashlib.sha256(secrets.token_bytes(nbytes=32)).digest() # Its hash is used to generate the hold invoice r_hash = hashlib.sha256(preimage).digest() # timelock expiry for the last hop, computed based on a 10 minutes block with 30% padding (~7 min block) cltv_expiry_blocks = int(cltv_expiry_secs / (7*60)) request = invoicesrpc.AddHoldInvoiceRequest( memo=description, value=num_satoshis, hash=r_hash, expiry=int(invoice_expiry*1.5), # actual expiry is padded by 50%, if tight, wrong client system clock will say invoice is expired. cltv_expiry=cltv_expiry_blocks, ) response = cls.invoicesstub.AddHoldInvoice(request, metadata=[('macaroon', MACAROON.hex())]) hold_payment['invoice'] = response.payment_request payreq_decoded = cls.decode_payreq(hold_payment['invoice']) hold_payment['preimage'] = preimage.hex() hold_payment['payment_hash'] = payreq_decoded.payment_hash hold_payment['created_at'] = timezone.make_aware(datetime.fromtimestamp(payreq_decoded.timestamp)) hold_payment['expires_at'] = hold_payment['created_at'] + timedelta(seconds=payreq_decoded.expiry) hold_payment['cltv_expiry'] = cltv_expiry_blocks return hold_payment @classmethod def validate_hold_invoice_locked(cls, lnpayment): '''Checks if hold invoice is locked''' request = invoicesrpc.LookupInvoiceMsg(payment_hash=bytes.fromhex(lnpayment.payment_hash)) response = cls.invoicesstub.LookupInvoiceV2(request, metadata=[('macaroon', MACAROON.hex())]) print('status here') print(response.state) # TODO ERROR HANDLING # Will fail if 'unable to locate invoice'. Happens if invoice expiry # time has passed (but these are 15% padded at the moment). Should catch it # and report back that the invoice has expired (better robustness) if response.state == 0: # OPEN print('STATUS: OPEN') pass if response.state == 1: # SETTLED pass if response.state == 2: # CANCELLED pass if response.state == 3: # ACCEPTED (LOCKED) print('STATUS: ACCEPTED') lnpayment.expiry_height = response.htlcs[0].expiry_height lnpayment.status = LNPayment.Status.LOCKED lnpayment.save() return True # @classmethod # def check_until_invoice_locked(cls, payment_hash, expiration): # '''Checks until hold invoice is locked. # When invoice is locked, returns true. # If time expires, return False.''' # # Experimental, might need asyncio. Best if subscribing all invoices and running a background task # # Maybe best to pass LNpayment object and change status live. # request = invoicesrpc.SubscribeSingleInvoiceRequest(r_hash=payment_hash) # for invoice in cls.invoicesstub.SubscribeSingleInvoice(request): # print(invoice) # if timezone.now > expiration: # break # if invoice.state == 3: # True if hold invoice is accepted. # return True # return False @classmethod def validate_ln_invoice(cls, invoice, num_satoshis): '''Checks if the submited LN invoice comforms to expectations''' payout = { 'valid': False, 'context': None, 'description': None, 'payment_hash': None, 'created_at': None, 'expires_at': None, } try: payreq_decoded = cls.decode_payreq(invoice) print(payreq_decoded) except: payout['context'] = {'bad_invoice':'Does not look like a valid lightning invoice'} return payout if payreq_decoded.num_satoshis == 0: payout['context'] = {'bad_invoice':'The invoice provided has no explicit amount'} return payout if not payreq_decoded.num_satoshis == num_satoshis: payout['context'] = {'bad_invoice':'The invoice provided is not for '+'{:,}'.format(num_satoshis)+ ' Sats'} return payout payout['created_at'] = timezone.make_aware(datetime.fromtimestamp(payreq_decoded.timestamp)) payout['expires_at'] = payout['created_at'] + timedelta(seconds=payreq_decoded.expiry) if payout['expires_at'] < timezone.now(): payout['context'] = {'bad_invoice':f'The invoice provided has already expired'} return payout payout['valid'] = True payout['description'] = payreq_decoded.description payout['payment_hash'] = payreq_decoded.payment_hash return payout @classmethod def pay_invoice(cls, invoice, num_satoshis): '''Sends sats to buyer''' fee_limit_sat = int(max(num_satoshis * float(config('PROPORTIONAL_ROUTING_FEE_LIMIT')), float(config('MIN_FLAT_ROUTING_FEE_LIMIT')))) # 200 ppm or 10 sats request = routerrpc.SendPaymentRequest( payment_request=invoice, fee_limit_sat=fee_limit_sat, timeout_seconds=60) for response in cls.routerstub.SendPaymentV2(request, metadata=[('macaroon', MACAROON.hex())]): print(response) print(response.status) # TODO ERROR HANDLING if response.status == 0 : # Status 0 'UNKNOWN' pass if response.status == 1 : # Status 1 'IN_FLIGHT' return True, 'In flight' if response.status == 3 : # 4 'FAILED' ?? '''0 Payment isn't failed (yet). 1 There are more routes to try, but the payment timeout was exceeded. 2 All possible routes were tried and failed permanently. Or were no routes to the destination at all. 3 A non-recoverable error has occured. 4 Payment details incorrect (unknown hash, invalid amt or invalid final cltv delta) 5 Insufficient local balance. ''' context = cls.payment_failure_context[response.failure_reason] return False, context if response.status == 2 : # STATUS 'SUCCEEDED' return True, None # How to catch the errors like:"grpc_message":"invoice is already paid","grpc_status":6} # These are not in the response only printed to commandline return False @classmethod def double_check_htlc_is_settled(cls, payment_hash): ''' Just as it sounds. Better safe than sorry!''' request = invoicesrpc.LookupInvoiceMsg(payment_hash=bytes.fromhex(payment_hash)) response = cls.invoicesstub.LookupInvoiceV2(request, metadata=[('macaroon', MACAROON.hex())]) return response.state == 1 # LND states: 0 OPEN, 1 SETTLED, 3 ACCEPTED, GRPC_ERROR status 5 when cancelled/returned