consensus: Split (MidState).storageProof into two methods

consensus/application.go

@@ -495,12 +495,12 @@ func (ms *MidState) ApplyTransaction(txn types.Transaction, ts V1TransactionSupp
 		ms.reviseFileContractElement(fce, fcr.FileContract)
 	}
 	for _, sp := range txn.StorageProofs {
-		sps, ok := ms.storageProof(ts, sp.ParentID)
+		fce, ok := ms.fileContractElement(ts, sp.ParentID)
 		if !ok {
 			panic("missing V1StorageProofSupplement")
 		}
-		ms.resolveFileContractElement(sps.FileContract, true, txid)
-		for i, sco := range sps.FileContract.FileContract.ValidProofOutputs {
+		ms.resolveFileContractElement(fce, true, txid)
+		for i, sco := range fce.FileContract.ValidProofOutputs {
 			ms.addImmatureSiacoinElement(sp.ParentID.ValidOutputID(i), sco)
 		}
 	}

consensus/state.go

@@ -623,18 +623,21 @@ func (ms *MidState) siafundElement(ts V1TransactionSupplement, id types.SiafundO
 func (ms *MidState) fileContractElement(ts V1TransactionSupplement, id types.FileContractID) (types.FileContractElement, bool) {
 	if rev, ok := ms.revs[id]; ok {
 		return *rev, true
-	}
-	if i, ok := ms.created[id]; ok {
+	} else if i, ok := ms.created[id]; ok {
 		return ms.fces[i], true
+	} else if rev, ok := ts.revision(id); ok {
+		return rev, true
 	}
-	return ts.revision(id)
+	sps, ok := ts.storageProof(id)
+	return sps.FileContract, ok
 }
 
-func (ms *MidState) storageProof(ts V1TransactionSupplement, id types.FileContractID) (V1StorageProofSupplement, bool) {
-	if i, ok := ms.created[id]; ok {
-		return V1StorageProofSupplement{FileContract: ms.fces[i], WindowID: ms.base.Index.ID}, true
+func (ms *MidState) storageProofWindowID(ts V1TransactionSupplement, id types.FileContractID) (types.BlockID, bool) {
+	if i, ok := ms.created[id]; ok && ms.fces[i].FileContract.WindowStart == ms.base.childHeight() {
+		return ms.base.Index.ID, true
 	}
-	return ts.storageProof(id)
+	sps, ok := ts.storageProof(id)
+	return sps.WindowID, ok
 }
 
 func (ms *MidState) spent(id types.ElementID) (types.TransactionID, bool) {

consensus/validation.go

@@ -354,15 +354,16 @@ func validateFileContracts(ms *MidState, txn types.Transaction, ts V1Transaction
 		if txid, ok := ms.spent(sp.ParentID); ok {
 			return fmt.Errorf("storage proof %v conflicts with previous proof (in %v)", i, txid)
 		}
-		sps, ok := ms.storageProof(ts, sp.ParentID)
+		fce, ok := ms.fileContractElement(ts, sp.ParentID)
 		if !ok {
 			return fmt.Errorf("storage proof %v references nonexistent file contract", i)
 		}
-		fc := sps.FileContract.FileContract
-		if ms.base.childHeight() < fc.WindowStart {
+		fc := fce.FileContract
+		windowID, ok := ms.storageProofWindowID(ts, sp.ParentID)
+		if !ok {
 			return fmt.Errorf("storage proof %v cannot be submitted until after window start (%v)", i, fc.WindowStart)
 		}
-		leafIndex := ms.base.StorageProofLeafIndex(fc.Filesize, sps.WindowID, sp.ParentID)
+		leafIndex := ms.base.StorageProofLeafIndex(fc.Filesize, windowID, sp.ParentID)
 		leaf := storageProofLeaf(leafIndex, fc.Filesize, sp.Leaf)
 		if leaf == nil {
 			continue

consensus/validation_test.go

@@ -606,6 +606,19 @@ func TestValidateBlock(t *testing.T) {
 					b.Transactions[1].StorageProofs[0].ParentID = b.Transactions[0].FileContractID(0)
 				},
 			},
+			{
+				"file contract revision 0 conflicts with previous proof or revision",
+				func(b *types.Block) {
+					rev := revision
+					rev.RevisionNumber++
+					b.Transactions = append(b.Transactions, types.Transaction{
+						FileContractRevisions: []types.FileContractRevision{{
+							ParentID:     b.Transactions[1].StorageProofs[0].ParentID,
+							FileContract: rev,
+						}},
+					})
+				},
+			},
 			{
 				fmt.Sprintf("storage proof 1 resolves contract (%v) already resolved by storage proof 0", b.Transactions[0].FileContractID(0)),
 				func(b *types.Block) {