Adds Carrier to take care of sending/getting transactions

pisa/carrier.py

@@ -0,0 +1,77 @@
+from pisa.utils.auth_proxy import JSONRPCException
+from pisa.errors import UNKNOWN_JSON_RPC_EXCEPTION
+from pisa import logging, bitcoin_cli
+from pisa.rpc_errors import *
+
+
+class Carrier:
+    class Receipt:
+        def __init__(self, delivered, confirmations=0, reason=None):
+            self.delivered = delivered
+            self.confirmations = confirmations
+            self.reason = reason
+
+    def send_transaction(self, rawtx, txid):
+        try:
+            logging.info("[Carrier] pushing transaction to the network (txid: {})".format(rawtx))
+            bitcoin_cli.sendrawtransaction(rawtx)
+
+            receipt = self.Receipt(delivered=True)
+
+        except JSONRPCException as e:
+            errno = e.error.get('code')
+            # Since we're pushing a raw transaction to the network we can get two kind of rejections:
+            # RPC_VERIFY_REJECTED and RPC_VERIFY_ALREADY_IN_CHAIN. The former implies that the transaction is rejected
+            # due to network rules, whereas the later implies that the transaction is already in the blockchain.
+            if errno == RPC_VERIFY_REJECTED:
+                # DISCUSS: what to do in this case
+                # DISCUSS: invalid transactions (properly formatted but invalid, like unsigned) fit here too.
+                # DISCUSS: RPC_VERIFY_ERROR could also be a possible case.
+                # DISCUSS: check errors -9 and -10
+                # TODO: UNKNOWN_JSON_RPC_EXCEPTION is not the proper exception here. This is long due.
+                receipt = self.Receipt(delivered=False, reason=UNKNOWN_JSON_RPC_EXCEPTION)
+
+            elif errno == RPC_VERIFY_ALREADY_IN_CHAIN:
+                logging.info("[Carrier] {} is already in the blockchain. Getting confirmation count".format(txid))
+
+                # If the transaction is already in the chain, we get the number of confirmations and watch the job
+                # until the end of the appointment
+                tx_info = self.get_transaction(txid)
+
+                if tx_info is not None:
+                    confirmations = int(tx_info.get("confirmations"))
+                    receipt = self.Receipt(delivered=True, confirmations=confirmations)
+
+                else:
+                    # There's a really unlike edge case where a transaction can be reorged between receiving the
+                    # notification and querying the data. In such a case we just resend
+                    self.send_transaction(rawtx, txid)
+
+            else:
+                # If something else happens (unlikely but possible) log it so we can treat it in future releases
+                logging.error("[Responder] JSONRPCException. Error {}".format(e))
+                receipt = self.Receipt(delivered=False, reason=UNKNOWN_JSON_RPC_EXCEPTION)
+
+        return receipt
+
+    @staticmethod
+    def get_transaction(txid):
+        tx_info = None
+
+        try:
+            tx_info = bitcoin_cli.getrawtransaction(txid, 1)
+
+        except JSONRPCException as e:
+            # While it's quite unlikely, the transaction that was already in the blockchain could have been
+            # reorged while we were querying bitcoind to get the confirmation count. In such a case we just
+            # restart the job
+            if e.error.get('code') == RPC_INVALID_ADDRESS_OR_KEY:
+                logging.info("[Carrier] transaction {} got reorged before obtaining information".format(txid))
+
+            # TODO: Check RPC methods to see possible returns and avoid general else
+            # else:
+            #     # If something else happens (unlikely but possible) log it so we can treat it in future releases
+            #     logging.error("[Responder] JSONRPCException. Error {}".format(e))
+
+        return tx_info
+