rpc: add (*Client).GetDesignatedByRole method

pkg/rpc/client/native.go

@@ -3,9 +3,14 @@ package client
 // Various non-policy things from native contracts.
 
 import (
+	"crypto/elliptic"
 	"fmt"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
+	"github.com/nspcc-dev/neo-go/pkg/core/native/noderoles"
+	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 )
 
 // GetOraclePrice invokes `getPrice` method on a native Oracle contract.
@@ -34,3 +39,54 @@ func (c *Client) GetGasPerBlock() (int64, error) {
 	}
 	return c.invokeNativeGetMethod(neoHash, "getGasPerBlock")
 }
+
+// GetDesignatedByRole invokes `getDesignatedByRole` method on a native RoleManagement contract.
+func (c *Client) GetDesignatedByRole(role noderoles.Role, index uint32) (keys.PublicKeys, error) {
+	rmHash, err := c.GetNativeContractHash(nativenames.Designation)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get native RoleManagement hash: %w", err)
+	}
+	result, err := c.InvokeFunction(rmHash, "getDesignatedByRole", []smartcontract.Parameter{
+		{
+			Type:  smartcontract.IntegerType,
+			Value: int64(role),
+		},
+		{
+			Type:  smartcontract.IntegerType,
+			Value: int64(index),
+		},
+	}, nil)
+	if err != nil {
+		return nil, err
+	}
+	err = getInvocationError(result)
+	if err != nil {
+		return nil, fmt.Errorf("`getDesignatedByRole`: %w", err)
+	}
+	return topPublicKeysFromStack(result.Stack)
+}
+
+// topPublicKeysFromStack returns the top array of public keys from stack.
+func topPublicKeysFromStack(st []stackitem.Item) (keys.PublicKeys, error) {
+	index := len(st) - 1 // top stack element is last in the array
+	var (
+		pks keys.PublicKeys
+		err error
+	)
+	items, ok := st[index].Value().([]stackitem.Item)
+	if !ok {
+		return nil, fmt.Errorf("invalid stack item type: %s", st[index].Type())
+	}
+	pks = make(keys.PublicKeys, len(items))
+	for i, item := range items {
+		val, ok := item.Value().([]byte)
+		if !ok {
+			return nil, fmt.Errorf("invalid array element #%d: %s", i, item.Type())
+		}
+		pks[i], err = keys.NewPublicKeyFromBytes(val, elliptic.P256())
+		if err != nil {
+			return nil, err
+		}
+	}
+	return pks, nil
+}

pkg/rpc/client/rpc_test.go

@@ -2,6 +2,7 @@ package client
 
 import (
 	"context"
+	"crypto/elliptic"
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
@@ -17,6 +18,7 @@ import (
 	"github.com/nspcc-dev/neo-go/internal/testserdes"
 	"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/noderoles"
 	"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"
@@ -476,6 +478,28 @@ var rpcClientTestCases = map[string][]rpcClientTestCase{
 			},
 		},
 	},
+	"getDesignatedByRole": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetDesignatedByRole(noderoles.P2PNotary, 10)
+			},
+			serverResponse: `{"id" : 1,"result" : {"stack" : [{"value" : [{"type":"ByteString","value":"Aw0WkQoDc8WqpG18xPMTEgfHO6gRTVtMN0Mw6zw06fzl"},{"type":"ByteString","value":"A+bmJ9wIaj96Ygr+uQQvQ0AaUrQmj2b3AGnztAOkU3/L"}],"type" : "Array"}],"exception" : null,"script" : "ERQSwB8ME2dldERlc2lnbmF0ZWRCeVJvbGUMFOKV45FUTBeK2U8D7E3N/3hTTs9JQWJ9W1I=","gasconsumed" : "2028150","state" : "HALT"}, "jsonrpc" : "2.0"}`,
+			result: func(c *Client) interface{} {
+				pk1Bytes, _ := base64.StdEncoding.DecodeString("Aw0WkQoDc8WqpG18xPMTEgfHO6gRTVtMN0Mw6zw06fzl")
+				pk1, err := keys.NewPublicKeyFromBytes(pk1Bytes, elliptic.P256())
+				if err != nil {
+					panic("invalid pub key #1 bytes")
+				}
+				pk2Bytes, _ := base64.StdEncoding.DecodeString("A+bmJ9wIaj96Ygr+uQQvQ0AaUrQmj2b3AGnztAOkU3/L")
+				pk2, err := keys.NewPublicKeyFromBytes(pk2Bytes, elliptic.P256())
+				if err != nil {
+					panic("invalid pub key #2 bytes")
+				}
+				return keys.PublicKeys{pk1, pk2}
+			},
+		},
+	},
 	"getMaxNotValidBeforeDelta": {
 		{
 			name: "positive",