staking: Add revocations

pydecred/account.py

@@ -6,6 +6,8 @@
 support.
 """
 
+from tinydecred.crypto.bytearray import decodeBA
+from tinydecred.crypto import opcode, crypto
 from tinydecred.wallet.accounts import Account
 from tinydecred.util import tinyjson, helpers
 from tinydecred.crypto.crypto import AddressSecpPubKey, CrazyKeyError
@@ -422,6 +424,41 @@ def purchaseTickets(self, qty, price):
         self.tickets.extend([tx.txid() for tx in txs[1]])
         return txs[1]
 
+    def revokeTickets(self):
+        """
+        Iterate through missed and expired tickets and revoke them.
+
+        Returns:
+            bool: whether or not an error occured.
+        """
+        revocableTickets = (
+            utxo.txid for utxo in self.utxos.values() if utxo.isRevocableTicket()
+        )
+        txs = (self.blockchain.tx(txid) for txid in revocableTickets)
+        for tx in txs:
+            redeemHash = crypto.AddressScriptHash(
+                self.net.ScriptHashAddrID,
+                txscript.extractStakeScriptHash(tx.txOut[0].pkScript, opcode.OP_SSTX),
+            )
+            redeemScript = next(
+                (
+                    decodeBA(p.purchaseInfo.script)
+                    for p in self.stakePools
+                    if p.purchaseInfo.ticketAddress == redeemHash.string()
+                ),
+                None,
+            )
+            if not redeemScript:
+                raise Exception("did not find redeem script for hash %s" % redeemHash)
+
+            keysource = KeySource(
+                # This will need to change when we start using different
+                # addresses for voting.
+                priv=lambda _: self._votingKey,
+                internal=lambda: "",
+            )
+            self.blockchain.revokeTicket(tx, keysource, redeemScript)
+
     def sync(self, blockchain, signals):
         """
         Synchronize the UTXO set with the server. This should be the first

pydecred/dcrdata.py

@@ -16,7 +16,7 @@
 import atexit
 import websocket
 from tinydecred.util import tinyjson, helpers, database, tinyhttp
-from tinydecred.crypto import crypto
+from tinydecred.crypto import crypto, opcode
 from tinydecred.crypto.bytearray import ByteArray
 from tinydecred.wallet.api import InsufficientFundsError
 from tinydecred.pydecred import txscript, calc
@@ -704,10 +704,19 @@ def isLiveTicket(self):
         isLiveTicket will return True if this is a live ticket.
 
         Returns:
-            bool. True if this is a live ticket.
+            bool: True if this is a live ticket.
         """
         return self.tinfo and self.tinfo.status in ("immature", "live")
 
+    def isRevocableTicket(self):
+        """
+        Returns True if this is an expired or missed ticket.
+
+        Returns:
+            bool: True if this is expired or missed ticket.
+        """
+        return self.tinfo and self.tinfo.status in ("expired", "missed")
+
 
 tinyjson.register(UTXO, "dcr.UTXO")
 
@@ -1626,3 +1635,38 @@ def purchaseTickets(self, keysource, utxosource, req):
                 )
             )
         return (splitTx, tickets), splitSpent, internalOutputs
+
+    def revokeTicket(self, tx, keysource, redeemScript):
+        """
+        Revoke a ticket by signing the supplied redeem script and broadcasting the raw transaction.
+
+        Args:
+            tx (object): the msgTx of the ticket purchase.
+            keysource (object): a KeySource object that holds a function to get the private key used for signing.
+            redeemScript (byte-like): the 1-of-2 multisig script that delegates voting rights for the ticket.
+
+        Returns:
+            MsgTx: the signed revocation.
+        """
+
+        revocation = txscript.makeRevocation(tx, self.relayFee())
+
+        signedScript = txscript.signTxOutput(
+            self.params,
+            revocation,
+            0,
+            redeemScript,
+            txscript.SigHashAll,
+            keysource,
+            revocation.txIn[0].signatureScript,
+            crypto.STEcdsaSecp256k1,
+        )
+
+        # Append the redeem script to the signature
+        signedScript += txscript.addData(redeemScript)
+        revocation.txIn[0].signatureScript = signedScript
+
+        self.broadcast(revocation.txHex())
+
+        log.info("published revocation %s" % revocation.txid())
+        return revocation