btcjson: Add optional locktime to createrawtransaction

rpcserver:
If the locktime is given, the transaction inputs will be set to a
non-max value, activating the locktime.  The locktime for the
new transaction will be set to the given value.

This mimics Bitcoin Core commit 212bcca92089f406d9313dbe6d0e1d25143d61ff

btcjson/chainsvrcmds.go

@@ -53,18 +53,22 @@ type TransactionInput struct {
 
 // CreateRawTransactionCmd defines the createrawtransaction JSON-RPC command.
 type CreateRawTransactionCmd struct {
-	Inputs  []TransactionInput
-	Amounts map[string]float64 `jsonrpcusage:"{\"address\":amount,...}"` // In BTC
+	Inputs   []TransactionInput
+	Amounts  map[string]float64 `jsonrpcusage:"{\"address\":amount,...}"` // In BTC
+	LockTime *int64
 }
 
 // NewCreateRawTransactionCmd returns a new instance which can be used to issue
 // a createrawtransaction JSON-RPC command.
 //
 // Amounts are in BTC.
-func NewCreateRawTransactionCmd(inputs []TransactionInput, amounts map[string]float64) *CreateRawTransactionCmd {
+func NewCreateRawTransactionCmd(inputs []TransactionInput, amounts map[string]float64,
+	lockTime *int64) *CreateRawTransactionCmd {
+
 	return &CreateRawTransactionCmd{
-		Inputs:  inputs,
-		Amounts: amounts,
+		Inputs:   inputs,
+		Amounts:  amounts,
+		LockTime: lockTime,
 	}
 }
 

btcjson/chainsvrcmds_test.go

@@ -51,7 +51,7 @@ func TestChainSvrCmds(t *testing.T) {
 					{Txid: "123", Vout: 1},
 				}
 				amounts := map[string]float64{"456": .0123}
-				return btcjson.NewCreateRawTransactionCmd(txInputs, amounts)
+				return btcjson.NewCreateRawTransactionCmd(txInputs, amounts, nil)
 			},
 			marshalled: `{"jsonrpc":"1.0","method":"createrawtransaction","params":[[{"txid":"123","vout":1}],{"456":0.0123}],"id":1}`,
 			unmarshalled: &btcjson.CreateRawTransactionCmd{
@@ -59,6 +59,27 @@ func TestChainSvrCmds(t *testing.T) {
 				Amounts: map[string]float64{"456": .0123},
 			},
 		},
+		{
+			name: "createrawtransaction optional",
+			newCmd: func() (interface{}, error) {
+				return btcjson.NewCmd("createrawtransaction", `[{"txid":"123","vout":1}]`,
+					`{"456":0.0123}`, 12312333333)
+			},
+			staticCmd: func() interface{} {
+				txInputs := []btcjson.TransactionInput{
+					{Txid: "123", Vout: 1},
+				}
+				amounts := map[string]float64{"456": .0123}
+				return btcjson.NewCreateRawTransactionCmd(txInputs, amounts, btcjson.Int64(12312333333))
+			},
+			marshalled: `{"jsonrpc":"1.0","method":"createrawtransaction","params":[[{"txid":"123","vout":1}],{"456":0.0123},12312333333],"id":1}`,
+			unmarshalled: &btcjson.CreateRawTransactionCmd{
+				Inputs:   []btcjson.TransactionInput{{Txid: "123", Vout: 1}},
+				Amounts:  map[string]float64{"456": .0123},
+				LockTime: btcjson.Int64(12312333333),
+			},
+		},
+
 		{
 			name: "decoderawtransaction",
 			newCmd: func() (interface{}, error) {

docs/json_rpc_api.md

@@ -199,10 +199,10 @@ the method name for further details such as parameter and return information.
 |   |   |
 |---|---|
 |Method|createrawtransaction|
-|Parameters|1. transaction inputs (JSON array, required) - json array of json objects<br />`[`<br />&nbsp;&nbsp;`{`<br />&nbsp;&nbsp;&nbsp;&nbsp;`"txid": "hash", (string, required) the hash of the input transaction`<br />&nbsp;&nbsp;&nbsp;&nbsp;`"vout": n  (numeric, required) the specific output of the input transaction to redeem`<br />&nbsp;&nbsp;`}, ...`<br />`]`<br />2. addresses and amounts (JSON object, required) - json object with addresses as keys and amounts as values<br />`{`<br />&nbsp;&nbsp;`"address": n.nnn (numeric, required) the address to send to as the key and the amount in BTC as the value`<br />&nbsp;&nbsp;`, ...`<br />`}`|
+|Parameters|1. transaction inputs (JSON array, required) - json array of json objects<br />`[`<br />&nbsp;&nbsp;`{`<br />&nbsp;&nbsp;&nbsp;&nbsp;`"txid": "hash", (string, required) the hash of the input transaction`<br />&nbsp;&nbsp;&nbsp;&nbsp;`"vout": n  (numeric, required) the specific output of the input transaction to redeem`<br />&nbsp;&nbsp;`}, ...`<br />`]`<br />2. addresses and amounts (JSON object, required) - json object with addresses as keys and amounts as values<br />`{`<br />&nbsp;&nbsp;`"address": n.nnn (numeric, required) the address to send to as the key and the amount in BTC as the value`<br />&nbsp;&nbsp;`, ...`<br />`}`<br />3. locktime (int64, optional, default=0) - specifies the transaction locktime.  If non-zero, the inputs will also have their locktimes activated. |
 |Description|Returns a new transaction spending the provided inputs and sending to the provided addresses.<br />The transaction inputs are not signed in the created transaction.<br />The `signrawtransaction` RPC command provided by wallet must be used to sign the resulting transaction.|
 |Returns|`"transaction" (string) hex-encoded bytes of the serialized transaction`|
-|Example Parameters|1. transaction inputs `[{"txid":"e6da89de7a6b8508ce8f371a3d0535b04b5e108cb1a6e9284602d3bfd357c018","vout":1}]`<br />2. addresses and amounts `{"13cgrTP7wgbZYWrY9BZ22BV6p82QXQT3nY": 0.49213337}`|
+|Example Parameters|1. transaction inputs `[{"txid":"e6da89de7a6b8508ce8f371a3d0535b04b5e108cb1a6e9284602d3bfd357c018","vout":1}]`<br />2. addresses and amounts `{"13cgrTP7wgbZYWrY9BZ22BV6p82QXQT3nY": 0.49213337}`<br />3. locktime `0`|
 |Example Return|`010000000118c057d3bfd3024628e9a6b18c105e4bb035053d1a378fce08856b7ade89dae6010000`<br />`0000ffffffff0199efee02000000001976a9141cb013db35ecccc156fdfd81d03a11c51998f99388`<br />`ac00000000`<br /><font color="orange">**Newlines added for display purposes.  The actual return does not contain newlines.**</font>|
 [Return to Overview](#MethodOverview)<br />
 

rpcserver.go

@@ -511,6 +511,15 @@ func messageToHex(msg wire.Message) (string, error) {
 func handleCreateRawTransaction(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (interface{}, error) {
 	c := cmd.(*btcjson.CreateRawTransactionCmd)
 
+	// Validate the locktime, if given.
+	if c.LockTime != nil &&
+		(*c.LockTime < 0 || *c.LockTime > int64(wire.MaxTxInSequenceNum)) {
+		return nil, &btcjson.RPCError{
+			Code:    btcjson.ErrRPCInvalidParameter,
+			Message: "Locktime out of range",
+		}
+	}
+
 	// Add all transaction inputs to a new transaction after performing
 	// some validity checks.
 	mtx := wire.NewMsgTx()
@@ -522,6 +531,9 @@ func handleCreateRawTransaction(s *rpcServer, cmd interface{}, closeChan <-chan
 
 		prevOut := wire.NewOutPoint(txHash, uint32(input.Vout))
 		txIn := wire.NewTxIn(prevOut, []byte{})
+		if c.LockTime != nil && *c.LockTime != 0 {
+			txIn.Sequence = wire.MaxTxInSequenceNum - 1
+		}
 		mtx.AddTxIn(txIn)
 	}
 
@@ -584,6 +596,11 @@ func handleCreateRawTransaction(s *rpcServer, cmd interface{}, closeChan <-chan
 		mtx.AddTxOut(txOut)
 	}
 
+	// Set the Locktime, if given.
+	if c.LockTime != nil {
+		mtx.LockTime = uint32(*c.LockTime)
+	}
+
 	// Return the serialized and hex-encoded transaction.  Note that this
 	// is intentionally not directly returning because the first return
 	// value is a string and it would result in returning an empty string to

rpcserverhelp.go

@@ -52,6 +52,7 @@ var helpDescsEnUS = map[string]string{
 	"createrawtransaction-amounts--key":   "address",
 	"createrawtransaction-amounts--value": "n.nnn",
 	"createrawtransaction-amounts--desc":  "The destination address as the key and the amount in BTC as the value",
+	"createrawtransaction-locktime":       "Locktime value; a non-zero value will also locktime-activate the inputs",
 	"createrawtransaction--result0":       "Hex-encoded bytes of the serialized transaction",
 
 	// ScriptSig help.