core, rpc: add GetCommittee method

Closes #1414

pkg/core/blockchain.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
+	"sort"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -1403,6 +1404,16 @@ func (bc *Blockchain) GetStandByCommittee() keys.PublicKeys {
 	return bc.sbCommittee.Copy()
 }
 
+// GetCommittee returns the sorted list of public keys of nodes in committee.
+func (bc *Blockchain) GetCommittee() (keys.PublicKeys, error) {
+	pubs, err := bc.contracts.NEO.GetCommitteeMembers(bc, bc.dao)
+	if err != nil {
+		return nil, err
+	}
+	sort.Sort(pubs)
+	return pubs, nil
+}
+
 // GetValidators returns current validators.
 func (bc *Blockchain) GetValidators() ([]*keys.PublicKey, error) {
 	return bc.contracts.NEO.GetValidatorsInternal(bc, bc.dao)

pkg/core/blockchainer/blockchainer.go

@@ -26,6 +26,7 @@ type Blockchainer interface {
 	Close()
 	HeaderHeight() uint32
 	GetBlock(hash util.Uint256) (*block.Block, error)
+	GetCommittee() (keys.PublicKeys, error)
 	GetContractState(hash util.Uint160) *state.Contract
 	GetContractScriptHash(id int32) (util.Uint160, error)
 	GetEnrollments() ([]state.Validator, error)

pkg/network/helper_test.go

@@ -76,6 +76,9 @@ func (chain testChain) GetAppExecResult(hash util.Uint256) (*state.AppExecResult
 func (chain testChain) GetBlock(hash util.Uint256) (*block.Block, error) {
 	panic("TODO")
 }
+func (chain testChain) GetCommittee() (keys.PublicKeys, error) {
+	panic("TODO")
+}
 func (chain testChain) GetContractState(hash util.Uint160) *state.Contract {
 	panic("TODO")
 }

pkg/rpc/client/rpc.go

@@ -9,6 +9,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"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/keys"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/rpc/request"
 	"github.com/nspcc-dev/neo-go/pkg/rpc/response/result"
@@ -179,6 +180,18 @@ func (c *Client) GetConnectionCount() (int, error) {
 	return resp, nil
 }
 
+// GetCommittee returns the current public keys of NEO nodes in committee.
+func (c *Client) GetCommittee() (keys.PublicKeys, error) {
+	var (
+		params = request.NewRawParams()
+		resp   = new(keys.PublicKeys)
+	)
+	if err := c.performRequest("getcommittee", params, resp); err != nil {
+		return nil, err
+	}
+	return *resp, nil
+}
+
 // GetContractState queries contract information, according to the contract script hash.
 func (c *Client) GetContractState(hash util.Uint160) (*state.Contract, error) {
 	var (

pkg/rpc/client/rpc_test.go

@@ -19,6 +19,7 @@ import (
 	"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"
+	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
 	"github.com/nspcc-dev/neo-go/pkg/internal/testserdes"
 	"github.com/nspcc-dev/neo-go/pkg/rpc/request"
@@ -30,6 +31,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	"github.com/pkg/errors"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -284,6 +286,22 @@ var rpcClientTestCases = map[string][]rpcClientTestCase{
 			},
 		},
 	},
+	"getcommittee": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetCommittee()
+			},
+			serverResponse: `{"jsonrpc":"2.0","id":1,"result":["02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e"]}`,
+			result: func(c *Client) interface{} {
+				member, err := keys.NewPublicKeyFromString("02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e")
+				if err != nil {
+					panic(errors.Wrap(err, "failed to decode public key"))
+				}
+				return keys.PublicKeys{member}
+			},
+		},
+	},
 	"getconnectioncount": {
 		{
 			name: "positive",
@@ -1068,6 +1086,12 @@ var rpcClientErrorCases = map[string][]rpcClientErrorCase{
 				return c.GetBlockSysFee(1)
 			},
 		},
+		{
+			name: "getcommittee_unmarshalling_error",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetCommittee()
+			},
+		},
 		{
 			name: "getconnectioncount_unmarshalling_error",
 			invoke: func(c *Client) (interface{}, error) {

pkg/rpc/server/server.go

@@ -87,6 +87,7 @@ var rpcHandlers = map[string]func(*Server, request.Params) (interface{}, *respon
 	"getblockhash":         (*Server).getBlockHash,
 	"getblockheader":       (*Server).getBlockHeader,
 	"getblocksysfee":       (*Server).getBlockSysFee,
+	"getcommittee":         (*Server).getCommittee,
 	"getconnectioncount":   (*Server).getConnectionCount,
 	"getcontractstate":     (*Server).getContractState,
 	"getnep5balances":      (*Server).getNEP5Balances,
@@ -881,6 +882,15 @@ func (s *Server) getValidators(_ request.Params) (interface{}, *response.Error)
 	return res, nil
 }
 
+// getCommittee returns the current list of NEO committee members
+func (s *Server) getCommittee(_ request.Params) (interface{}, *response.Error) {
+	keys, err := s.chain.GetCommittee()
+	if err != nil {
+		return nil, response.NewInternalServerError("can't get committee members", err)
+	}
+	return keys, nil
+}
+
 // invokeFunction implements the `invokeFunction` RPC call.
 func (s *Server) invokeFunction(reqParams request.Params) (interface{}, *response.Error) {
 	scriptHash, err := reqParams.ValueWithType(0, request.StringT).GetUint160FromHex()

pkg/rpc/server/server_test.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"reflect"
+	"sort"
 	"strconv"
 	"strings"
 	"testing"
@@ -353,6 +354,17 @@ var rpcTestCases = map[string][]rpcTestCase{
 			fail:   true,
 		},
 	},
+	"getcommittee": {
+		{
+			params: "[]",
+			result: func(e *executor) interface{} {
+				// it's a test chain, so committee is a sorted standby committee
+				expected := e.chain.GetStandByCommittee()
+				sort.Sort(expected)
+				return &expected
+			},
+		},
+	},
 	"getconnectioncount": {
 		{
 			params: "[]",