Fix darksidewallet for missing transaction IDs (txids)

This commit extends The darkside's stub zcashd rpc handler to handle the
verbose form of `getblock` (that returns the txids of all transactions
in the block) and the rest of the darkside code has to set the txids in
the blocks and individual transactions it returns. Since lightwalletd
doesn't yet support V5 txid calculation, we use the old one, so it's not
accurate for V5 but that doesn't matter (during darkside wallet testing,
the code under test can't detect incorrect txids).

common/darkside.go

@@ -62,6 +62,22 @@ type stagedTx struct {
 // the command line.
 var DarksideEnabled bool
 
+func darksideSetTxID(tx *parser.Transaction) {
+	// SHA256d
+	// This is correct for V4 transactions, but not for V5, but in this test
+	// environment, it's harmless (the incorrect txid calculation can't be
+	// detected). This will be fixed when lightwalletd calculates txids correctly .
+	digest := sha256.Sum256(tx.Bytes())
+	digest = sha256.Sum256(digest[:])
+	tx.SetTxID(digest[:])
+}
+
+func darksideSetBlockTxID(block *parser.Block) {
+	for _, tx := range block.Transactions() {
+		darksideSetTxID(tx)
+	}
+}
+
 // DarksideInit should be called once at startup in darksidewalletd mode.
 func DarksideInit(c *BlockCache, timeout int) {
 	Log.Info("Darkside mode running")
@@ -415,6 +431,20 @@ func darksideRawRequest(method string, params []json.RawMessage) (json.RawMessag
 		if index >= len(state.activeBlocks) {
 			return nil, errors.New(notFoundErr)
 		}
+		if len(params) > 1 && string(params[1]) == "1" {
+			// verbose mode, all that's currently needed is txid
+			block := parser.NewBlock()
+			block.ParseFromSlice(state.activeBlocks[index])
+			darksideSetBlockTxID((block))
+			var r struct {
+				Tx []string `json:"tx"`
+			}
+			r.Tx = make([]string, 0)
+			for _, tx := range block.Transactions() {
+				r.Tx = append(r.Tx, hex.EncodeToString(tx.GetDisplayHash()))
+			}
+			return json.Marshal(r)
+		}
 		return json.Marshal(hex.EncodeToString(state.activeBlocks[index]))
 
 	case "getbestblockhash":
@@ -455,6 +485,7 @@ func darksideRawRequest(method string, params []json.RawMessage) (json.RawMessag
 		if len(rest) != 0 {
 			return nil, errors.New("transaction serialization is too long")
 		}
+		darksideSetTxID(tx)
 		state.incomingTransactions = append(state.incomingTransactions, txBytes)
 
 		return []byte(hex.EncodeToString(tx.GetDisplayHash())), nil
@@ -464,6 +495,7 @@ func darksideRawRequest(method string, params []json.RawMessage) (json.RawMessag
 		addTxToReply := func(txBytes []byte) {
 			ctx := parser.NewTransaction()
 			ctx.ParseFromSlice(txBytes)
+			darksideSetTxID(ctx)
 			reply = append(reply, hex.EncodeToString(ctx.GetDisplayHash()))
 		}
 		for _, blockBytes := range state.stagedBlocks {
@@ -538,6 +570,7 @@ func darksideGetRawTransaction(params []json.RawMessage) (json.RawMessage, error
 		for _, b := range blocks {
 			block := parser.NewBlock()
 			_, _ = block.ParseFromSlice(b)
+			darksideSetBlockTxID(block)
 			for _, tx := range block.Transactions() {
 				if bytes.Equal(tx.GetDisplayHash(), txid) {
 					return marshalReply(tx, block.GetHeight())
@@ -558,6 +591,7 @@ func darksideGetRawTransaction(params []json.RawMessage) (json.RawMessage, error
 	for _, stx := range state.stagedTransactions {
 		tx := parser.NewTransaction()
 		_, _ = tx.ParseFromSlice(stx.bytes)
+		darksideSetTxID(tx)
 		if bytes.Equal(tx.GetDisplayHash(), txid) {
 			return marshalReply(tx, 0), nil
 		}