Files
dragonx/src/cc/disputepayout.cpp
2018-03-30 17:20:02 -03:00

103 lines
3.4 KiB
C++

#include "primitives/transaction.h"
#include "streams.h"
#include "chain.h"
#include "main.h"
#include "cc/eval.h"
#include "cryptoconditions/include/cryptoconditions.h"
bool GetSpends(uint256 hash, std::vector<boost::optional<CTransaction>> &spends)
{
// NOT IMPLEMENTED
return false;
}
class DisputeHeader
{
public:
int waitBlocks;
std::vector<unsigned char> vmHeader;
ADD_SERIALIZE_METHODS;
template <typename Stream, typename Operation>
inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
READWRITE(VARINT(waitBlocks));
READWRITE(vmHeader);
}
};
/*
* Crypto-Condition EVAL method that resolves a dispute of a session
*
* IN: vm - AppVM virtual machine to verify states
* IN: cond - CC EVAL node
* IN: disputeTx - transaction attempting to resolve dispute
* IN: nIn - index of input of dispute tx
*
* disputeTx: attempt to resolve a dispute
*
* in 0: Spends Session TX first output, reveals DisputeHeader
* out 0: OP_RETURN hash of payouts
*/
bool DisputePayout(AppVM &vm, const CC *cond, const CTransaction *disputeTx, int nIn)
{
// TODO: Error messages!
if (disputeTx->vout.size() < 2) return 0;
// get payouts hash
std::vector<unsigned char> vPayoutHash;
uint256 payoutHash;
if (!GetOpReturnData(disputeTx->vout[0].scriptPubKey, vPayoutHash)) return 0;
memcpy(payoutHash.begin(), vPayoutHash.data(), 32);
// load dispute header
DisputeHeader disputeHeader;
std::vector<unsigned char> headerData(cond->paramsBin,
cond->paramsBin+cond->paramsBinLength);
CDataStream(headerData, SER_DISK, PROTOCOL_VERSION) >> disputeHeader;
// TODO: exception? end of stream?
// ensure that enough time has passed
CTransaction sessionTx;
uint256 sessionBlockHash;
if (!GetTransaction(disputeTx->vin[0].prevout.hash, sessionTx, sessionBlockHash, false))
return false; // wth? TODO: log TODO: MUST be upsteam of disputeTx, how to ensure?
// below does this by looking up block in blockindex
// what if GetTransaction returns from mempool, maybe theres no block?
CBlockIndex* sessionBlockIndex = mapBlockIndex[sessionBlockHash];
if (chainActive.Height() < sessionBlockIndex->nHeight + disputeHeader.waitBlocks)
return false; // Not yet
// get spends
std::vector<boost::optional<CTransaction>> spends;
if (!GetSpends(disputeTx->vin[0].prevout.hash, spends)) return 0;
// verify result from VM
int maxLength = -1;
uint256 bestPayout;
for (int i=1; i<spends.size(); i++)
{
if (!spends[i]) continue;
std::vector<unsigned char> vmBody;
if (!GetOpReturnData(spends[i]->vout[0].scriptPubKey, vmBody)) continue;
auto out = vm.evaluate(disputeHeader.vmHeader, vmBody);
uint256 resultHash = SerializeHash(out.second);
if (out.first > maxLength) {
maxLength = out.first;
bestPayout = resultHash;
}
// The below means that if for any reason there is a draw,
else if (out.first == maxLength) {
if (bestPayout != payoutHash) {
fprintf(stderr, "WARNING: VM has multiple solutions of same length\n");
bestPayout = resultHash;
}
}
}
return bestPayout == payoutHash;
}