mock up DisputePayout

src/Makefile.am

@@ -252,6 +252,7 @@ libbitcoin_server_a_SOURCES = \
   bloom.cpp \
   cc/eval.cpp \
   cc/importpayout.cpp \
+  cc/disputepayout.cpp \
   chain.cpp \
   checkpoints.cpp \
   deprecation.cpp \

src/cc/disputepayout.cpp

@@ -0,0 +1,102 @@
+#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;
+}

src/cc/eval.cpp

@@ -18,6 +18,39 @@ bool EvalConditionValidity(const CC *cond, const CTransaction *txTo, int nIn)
         return CheckImportPayout(cond, txTo, nIn);
     }
 
+    /* Example of how you might call DisputePayout
+
+    if (strcmp(ASSETCHAINS_SYMBOL, "PANGEA") == 0) {
+        if (strcmp(cond->method, "DisputePoker") == 0) {
+            return DisputePayout(PokerVM(), cond, txTo, nIn);
+        }
+    }
+
+    */
+
     fprintf(stderr, "no defined behaviour for method: %s\n", cond->method);
     return 0;
 }
+
+
+
+bool GetPushData(const CScript &sig, std::vector<unsigned char> &data)
+{
+    opcodetype opcode;
+    auto pc = sig.begin();
+    if (sig.GetOp(pc, opcode, data)) return opcode > OP_0 && opcode <= OP_PUSHDATA4;
+    return false;
+}
+
+
+bool GetOpReturnData(const CScript &sig, std::vector<unsigned char> &data)
+{
+    auto pc = sig.begin();
+    opcodetype opcode;
+    if (sig.GetOp2(pc, opcode, NULL))
+        if (opcode == OP_RETURN)
+            if (sig.GetOp(pc, opcode, data))
+                return opcode > OP_0 && opcode <= OP_PUSHDATA4;
+    return false;
+}
+

src/cc/eval.h

@@ -14,5 +14,36 @@ bool EvalConditionValidity(const CC *cond, const CTransaction *tx, int nIn);
  */
 bool CheckImportPayout(const CC *cond, const CTransaction *payoutTx, int nIn);
 
+/*
+ * Virtual machine to use in the case of on-chain app evaluation
+ */
+class AppVM
+{ 
+public:
+    /*
+     * in:  header   - paramters agreed upon by all players
+     * in:  body     - gamestate
+     * out: length   - length of game (longest wins)
+     * out: payments - vector of CTxOut, always deterministically sorted.
+     */
+    virtual std::pair<int,std::vector<CTxOut>>
+        evaluate(std::vector<unsigned char> header, std::vector<unsigned char> body) = 0;
+};
+
+/*
+ * Test a DisputePayout CC Eval condition, using a provided AppVM
+ */
+bool DisputePayout(AppVM &vm, const CC *cond, const CTransaction *disputeTx, int nIn);
+
+/*
+ * Get PUSHDATA from a script
+ */
+bool GetPushData(const CScript &sig, std::vector<unsigned char> &data);
+
+/*
+ * Get OP_RETURN data from a script
+ */
+bool GetOpReturnData(const CScript &sig, std::vector<unsigned char> &data);
+
 
 #endif /* CC_EVAL_H */

src/cc/importpayout.cpp

@@ -2,30 +2,10 @@
 #include "streams.h"
 #include "chain.h"
 #include "main.h"
+#include "cc/eval.h"
 #include "cryptoconditions/include/cryptoconditions.h"
 
 
-bool GetPushData(const CScript &sig, std::vector<unsigned char> &data)
-{
-    opcodetype opcode;
-    auto pc = sig.begin();
-    if (sig.GetOp(pc, opcode, data)) return opcode > OP_0 && opcode <= OP_PUSHDATA4;
-    return false;
-}
-
-
-bool GetOpReturnData(const CScript &sig, std::vector<unsigned char> &data)
-{
-    auto pc = sig.begin();
-    opcodetype opcode;
-    if (sig.GetOp2(pc, opcode, NULL))
-        if (opcode == OP_RETURN)
-            if (sig.GetOp(pc, opcode, data))
-                return opcode > OP_0 && opcode <= OP_PUSHDATA4;
-    return false;
-}
-
-
 class MomProof
 {
 public:
@@ -128,10 +108,10 @@ uint256 ExecMerkle(uint256 hash, const std::vector<uint256>& vMerkleBranch, int
  *
  *   in  0:      Spends Stake TX and contains ImportPayout CC
  *   out 0:      OP_RETURN MomProof
- *   out 1:      OP_RETURN serialized exportTx from other chain
+ *   out 1:      OP_RETURN serialized disputeTx from other chain
  *   out 2-:     arbitrary payouts
  *
- * exportTx: Spends sessionTx.0 (opener on asset chain)
+ * disputeTx: Spends sessionTx.0 (opener on asset chain)
  *
  *   in 0:       spends sessionTx.0
  *   in 1-:      anything
@@ -149,30 +129,30 @@ bool CheckImportPayout(const CC *cond, const CTransaction *payoutTx, int nIn)
     uint256 payoutsHash = SerializeHash(payouts);
     std::vector<unsigned char> vPayoutsHash(payoutsHash.begin(), payoutsHash.end());
 
-    // load exportTx from vout[1]
+    // load disputeTx from vout[1]
-    CTransaction exportTx;
+    CTransaction disputeTx;
     {
         std::vector<unsigned char> exportData;
         if (!GetOpReturnData(payoutTx->vout[1].scriptPubKey, exportData)) return 0;
-        CDataStream(exportData, SER_DISK, PROTOCOL_VERSION) >> exportTx;
+        CDataStream(exportData, SER_DISK, PROTOCOL_VERSION) >> disputeTx;
         // TODO: end of stream? exception?
     }
 
-    // Check exportTx.0 is vPayoutsHash
+    // Check disputeTx.0 is vPayoutsHash
     std::vector<unsigned char> exportPayoutsHash;
-    if (!GetOpReturnData(exportTx.vout[0].scriptPubKey, exportPayoutsHash)) return 0;
+    if (!GetOpReturnData(disputeTx.vout[0].scriptPubKey, exportPayoutsHash)) return 0;
     if (exportPayoutsHash != vPayoutsHash) return 0; 
 
-    // Check exportTx spends sessionTx.0
+    // Check disputeTx spends sessionTx.0
     // condition ImportPayout params is session ID from other chain
     {
         if (cond->paramsBinLength != 32) return 0;
-        COutPoint prevout = exportTx.vin[0].prevout;
+        COutPoint prevout = disputeTx.vin[0].prevout;
         if (memcmp(prevout.hash.begin(), cond->paramsBin, 32) != 0 ||
                    prevout.n != 0) return 0;
     }
 
-    // Check exportTx solves momproof from vout[0]
+    // Check disputeTx solves momproof from vout[0]
     {
         std::vector<unsigned char> vchMomProof;
         if (!GetOpReturnData(payoutTx->vout[0].scriptPubKey, vchMomProof)) return 0;
@@ -183,7 +163,7 @@ bool CheckImportPayout(const CC *cond, const CTransaction *payoutTx, int nIn)
         uint256 mom;
         if (!GetMoM(momProof.notaryHash, mom)) return 0;
 
-        uint256 proofResult = ExecMerkle(exportTx.GetHash(), momProof.branch, momProof.nPos);
+        uint256 proofResult = ExecMerkle(disputeTx.GetHash(), momProof.branch, momProof.nPos);
         if (proofResult != mom) return 0;
     }