Merge pull request #1577 from wpaulino/getblock-compat

rpcclient: send legacy GetBlock request for backwards compatibility

rpcclient/chain.go

@@ -52,14 +52,61 @@ func (c *Client) GetBestBlockHash() (*chainhash.Hash, error) {
 	return c.GetBestBlockHashAsync().Receive()
 }
 
+// legacyGetBlockRequest constructs and sends a legacy getblock request which
+// contains two separate bools to denote verbosity, in contract to a single int
+// parameter.
+func (c *Client) legacyGetBlockRequest(hash string, verbose,
+	verboseTx bool) ([]byte, error) {
+
+	hashJSON, err := json.Marshal(hash)
+	if err != nil {
+		return nil, err
+	}
+	verboseJSON, err := json.Marshal(btcjson.Bool(verbose))
+	if err != nil {
+		return nil, err
+	}
+	verboseTxJSON, err := json.Marshal(btcjson.Bool(verboseTx))
+	if err != nil {
+		return nil, err
+	}
+	return c.RawRequest("getblock", []json.RawMessage{
+		hashJSON, verboseJSON, verboseTxJSON,
+	})
+}
+
+// waitForGetBlockRes waits for the response of a getblock request. If the
+// response indicates an invalid parameter was provided, a legacy style of the
+// request is resent and its response is returned instead.
+func (c *Client) waitForGetBlockRes(respChan chan *response, hash string,
+	verbose, verboseTx bool) ([]byte, error) {
+
+	res, err := receiveFuture(respChan)
+
+	// If we receive an invalid parameter error, then we may be
+	// communicating with a btcd node which only understands the legacy
+	// request, so we'll try that.
+	if err, ok := err.(*btcjson.RPCError); ok &&
+		err.Code == btcjson.ErrRPCInvalidParams.Code {
+		return c.legacyGetBlockRequest(hash, verbose, verboseTx)
+	}
+
+	// Otherwise, we can return the response as is.
+	return res, err
+}
+
 // FutureGetBlockResult is a future promise to deliver the result of a
 // GetBlockAsync RPC invocation (or an applicable error).
-type FutureGetBlockResult chan *response
+type FutureGetBlockResult struct {
+	client   *Client
+	hash     string
+	Response chan *response
+}
 
 // Receive waits for the response promised by the future and returns the raw
 // block requested from the server given its hash.
 func (r FutureGetBlockResult) Receive() (*wire.MsgBlock, error) {
-	res, err := receiveFuture(r)
+	res, err := r.client.waitForGetBlockRes(r.Response, r.hash, false, false)
 	if err != nil {
 		return nil, err
 	}
@@ -98,7 +145,11 @@ func (c *Client) GetBlockAsync(blockHash *chainhash.Hash) FutureGetBlockResult {
 	}
 
 	cmd := btcjson.NewGetBlockCmd(hash, btcjson.Int(0))
-	return c.sendCmd(cmd)
+	return FutureGetBlockResult{
+		client:   c,
+		hash:     hash,
+		Response: c.sendCmd(cmd),
+	}
 }
 
 // GetBlock returns a raw block from the server given its hash.
@@ -111,12 +162,16 @@ func (c *Client) GetBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error) {
 
 // FutureGetBlockVerboseResult is a future promise to deliver the result of a
 // GetBlockVerboseAsync RPC invocation (or an applicable error).
-type FutureGetBlockVerboseResult chan *response
+type FutureGetBlockVerboseResult struct {
+	client   *Client
+	hash     string
+	Response chan *response
+}
 
 // Receive waits for the response promised by the future and returns the data
 // structure from the server with information about the requested block.
 func (r FutureGetBlockVerboseResult) Receive() (*btcjson.GetBlockVerboseResult, error) {
-	res, err := receiveFuture(r)
+	res, err := r.client.waitForGetBlockRes(r.Response, r.hash, true, false)
 	if err != nil {
 		return nil, err
 	}
@@ -143,7 +198,11 @@ func (c *Client) GetBlockVerboseAsync(blockHash *chainhash.Hash) FutureGetBlockV
 	// From the bitcoin-cli getblock documentation:
 	// "If verbosity is 1, returns an Object with information about block ."
 	cmd := btcjson.NewGetBlockCmd(hash, btcjson.Int(1))
-	return c.sendCmd(cmd)
+	return FutureGetBlockVerboseResult{
+		client:   c,
+		hash:     hash,
+		Response: c.sendCmd(cmd),
+	}
 }
 
 // GetBlockVerbose returns a data structure from the server with information
@@ -155,10 +214,18 @@ func (c *Client) GetBlockVerbose(blockHash *chainhash.Hash) (*btcjson.GetBlockVe
 	return c.GetBlockVerboseAsync(blockHash).Receive()
 }
 
-type FutureGetBlockVerboseTxResult chan *response
+// FutureGetBlockVerboseTxResult is a future promise to deliver the result of a
+// GetBlockVerboseTxResult RPC invocation (or an applicable error).
+type FutureGetBlockVerboseTxResult struct {
+	client   *Client
+	hash     string
+	Response chan *response
+}
 
+// Receive waits for the response promised by the future and returns a verbose
+// version of the block including detailed information about its transactions.
 func (r FutureGetBlockVerboseTxResult) Receive() (*btcjson.GetBlockVerboseTxResult, error) {
-	res, err := receiveFuture(r)
+	res, err := r.client.waitForGetBlockRes(r.Response, r.hash, true, true)
 	if err != nil {
 		return nil, err
 	}
@@ -182,11 +249,17 @@ func (c *Client) GetBlockVerboseTxAsync(blockHash *chainhash.Hash) FutureGetBloc
 	if blockHash != nil {
 		hash = blockHash.String()
 	}
-	// From the bitcoin-cli getblock documentation:
-	// "If verbosity is 2, returns an Object with information about block  and information about each transaction."
-	cmd := btcjson.NewGetBlockCmd(hash, btcjson.Int(2))
 
-	return c.sendCmd(cmd)
+	// From the bitcoin-cli getblock documentation:
+	//
+	// If verbosity is 2, returns an Object with information about block
+	// and information about each transaction.
+	cmd := btcjson.NewGetBlockCmd(hash, btcjson.Int(2))
+	return FutureGetBlockVerboseTxResult{
+		client:   c,
+		hash:     hash,
+		Response: c.sendCmd(cmd),
+	}
 }
 
 // GetBlockVerboseTx returns a data structure from the server with information