rpc: add native policy API to RPC client

part of #904

pkg/rpc/client/policy.go

@@ -0,0 +1,77 @@
+package client
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neo-go/pkg/core/native"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/pkg/errors"
+)
+
+// PolicyContractHash represents BE hash of native Policy contract.
+var PolicyContractHash = util.Uint160{154, 97, 164, 110, 236, 151, 184, 147, 6, 215, 206, 129, 241, 91, 70, 32, 145, 208, 9, 50}
+
+// GetMaxTransactionsPerBlock invokes `getMaxTransactionsPerBlock` method on a
+// native Policy contract.
+func (c *Client) GetMaxTransactionsPerBlock() (int64, error) {
+	return c.invokeNativePolicyMethod("getMaxTransactionsPerBlock")
+}
+
+// GetMaxBlockSize invokes `getMaxBlockSize` method on a native Policy contract.
+func (c *Client) GetMaxBlockSize() (int64, error) {
+	return c.invokeNativePolicyMethod("getMaxBlockSize")
+}
+
+// GetFeePerByte invokes `getFeePerByte` method on a native Policy contract.
+func (c *Client) GetFeePerByte() (int64, error) {
+	return c.invokeNativePolicyMethod("getFeePerByte")
+}
+
+func (c *Client) invokeNativePolicyMethod(operation string) (int64, error) {
+	result, err := c.InvokeFunction(PolicyContractHash.StringLE(), operation, []smartcontract.Parameter{}, nil)
+	if err != nil {
+		return 0, err
+	} else if result.State != "HALT" || len(result.Stack) == 0 {
+		return 0, errors.New("invalid VM state")
+	}
+
+	return topIntFromStack(result.Stack)
+}
+
+// GetBlockedAccounts invokes `getBlockedAccounts` method on a native Policy contract.
+func (c *Client) GetBlockedAccounts() (native.BlockedAccounts, error) {
+	result, err := c.InvokeFunction(PolicyContractHash.StringLE(), "getBlockedAccounts", []smartcontract.Parameter{}, nil)
+	if err != nil {
+		return nil, err
+	} else if result.State != "HALT" || len(result.Stack) == 0 {
+		return nil, errors.New("invalid VM state")
+	}
+
+	return topBlockedAccountsFromStack(result.Stack)
+}
+
+func topBlockedAccountsFromStack(st []smartcontract.Parameter) (native.BlockedAccounts, error) {
+	index := len(st) - 1 // top stack element is last in the array
+	var (
+		ba  native.BlockedAccounts
+		err error
+	)
+	switch typ := st[index].Type; typ {
+	case smartcontract.ArrayType:
+		data, ok := st[index].Value.([]smartcontract.Parameter)
+		if !ok {
+			return nil, errors.New("invalid Array item")
+		}
+		ba = make(native.BlockedAccounts, len(data))
+		for i, account := range data {
+			ba[i], err = util.Uint160DecodeBytesLE(account.Value.([]byte))
+			if err != nil {
+				return nil, err
+			}
+		}
+	default:
+		return nil, fmt.Errorf("invalid stack item type: %s", typ)
+	}
+	return ba, nil
+}

pkg/rpc/client/rpc.go

@@ -522,12 +522,10 @@ func (c *Client) AddNetworkFee(tx *transaction.Transaction, acc *wallet.Account)
 		tx.NetworkFee += netFee
 		size += sizeDelta
 	}
-	tx.NetworkFee += util.Fixed8(int64(size) * int64(c.GetFeePerByte()))
+	fee, err := c.GetFeePerByte()
+	if err != nil {
+		return err
+	}
+	tx.NetworkFee += util.Fixed8(int64(size) * fee)
 	return nil
 }
-
-// GetFeePerByte returns transaction network fee per byte
-func (c *Client) GetFeePerByte() util.Fixed8 {
-	// TODO: make it a part of policy contract
-	return util.Fixed8(1000)
-}

pkg/rpc/client/rpc_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/gorilla/websocket"
 	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
+	"github.com/nspcc-dev/neo-go/pkg/core/native"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
@@ -318,6 +319,54 @@ var rpcClientTestCases = map[string][]rpcClientTestCase{
 			},
 		},
 	},
+	"getFeePerByte": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetFeePerByte()
+			},
+			serverResponse: `{"id":1,"jsonrpc":"2.0","result":{"state":"HALT","gas_consumed":"0.0200739","script":"10c00c0d676574466565506572427974650c149a61a46eec97b89306d7ce81f15b462091d0093241627d5b52","stack":[{"type":"Integer","value":"1000"}]}}`,
+			result: func(c *Client) interface{} {
+				return int64(1000)
+			},
+		},
+	},
+	"getMaxTransacctionsPerBlock": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetMaxTransactionsPerBlock()
+			},
+			serverResponse: `{"id":1,"jsonrpc":"2.0","result":{"state":"HALT","gas_consumed":"0.0200739","script":"10c00c1a6765744d61785472616e73616374696f6e73506572426c6f636b0c149a61a46eec97b89306d7ce81f15b462091d0093241627d5b52","stack":[{"type":"Integer","value":"512"}]}}`,
+			result: func(c *Client) interface{} {
+				return int64(512)
+			},
+		},
+	},
+	"getMaxBlockSize": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetMaxBlockSize()
+			},
+			serverResponse: `{"id":1,"jsonrpc":"2.0","result":{"state":"HALT","gas_consumed":"0.0200739","script":"10c00c0f6765744d6178426c6f636b53697a650c149a61a46eec97b89306d7ce81f15b462091d0093241627d5b52","stack":[{"type":"Integer","value":"262144"}]}}`,
+			result: func(c *Client) interface{} {
+				return int64(262144)
+			},
+		},
+	},
+	"getBlockedAccounts": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetBlockedAccounts()
+			},
+			serverResponse: `{"id":1,"jsonrpc":"2.0","result":{"state":"HALT","gas_consumed":"0.0200739","script":"10c00c12676574426c6f636b65644163636f756e74730c149a61a46eec97b89306d7ce81f15b462091d0093241627d5b52","stack":[{"type":"Array","value":[]}]}}`,
+			result: func(c *Client) interface{} {
+				return native.BlockedAccounts{}
+			},
+		},
+	},
 	"getnep5balances": {
 		{
 			name: "positive",