Add ability to see this nodes public address (that is used for signing) (#856)

Add block sealing information to IBFT API .

consensus/istanbul/backend/api.go

@@ -29,6 +29,66 @@ type API struct {
 	istanbul *backend
 }
 
+// BlockSigners is contains who created and who signed a particular block, denoted by its number and hash
+type BlockSigners struct {
+	Number     uint64
+	Hash       common.Hash
+	Author     common.Address
+	Committers []common.Address
+}
+
+// NodeAddress returns the public address that is used to sign block headers in IBFT
+func (api *API) NodeAddress() common.Address {
+	return api.istanbul.Address()
+}
+
+// GetSignersFromBlock returns the signers and minter for a given block number, or the
+// latest block available if none is specified
+func (api *API) GetSignersFromBlock(number *rpc.BlockNumber) (*BlockSigners, error) {
+	// Retrieve the requested block number (or current if none requested)
+	var header *types.Header
+	if number == nil || *number == rpc.LatestBlockNumber {
+		header = api.chain.CurrentHeader()
+	} else {
+		header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
+	}
+
+	if header == nil {
+		return nil, errUnknownBlock
+	}
+
+	return api.signers(header)
+}
+
+// GetSignersFromBlockByHash returns the signers and minter for a given block hash
+func (api *API) GetSignersFromBlockByHash(hash common.Hash) (*BlockSigners, error) {
+	header := api.chain.GetHeaderByHash(hash)
+	if header == nil {
+		return nil, errUnknownBlock
+	}
+
+	return api.signers(header)
+}
+
+func (api *API) signers(header *types.Header) (*BlockSigners, error) {
+	author, err := api.istanbul.Author(header)
+	if err != nil {
+		return nil, err
+	}
+
+	committers, err := api.istanbul.Signers(header)
+	if err != nil {
+		return nil, err
+	}
+
+	return &BlockSigners{
+		Number:     header.Number.Uint64(),
+		Hash:       header.Hash(),
+		Author:     author,
+		Committers: committers,
+	}, nil
+}
+
 // GetSnapshot retrieves the state snapshot at a given block.
 func (api *API) GetSnapshot(number *rpc.BlockNumber) (*Snapshot, error) {
 	// Retrieve the requested block number (or current if none requested)

consensus/istanbul/backend/engine.go

@@ -103,6 +103,31 @@ func (sb *backend) Author(header *types.Header) (common.Address, error) {
 	return ecrecover(header)
 }
 
+// Signers extracts all the addresses who have signed the given header
+// It will extract for each seal who signed it, regardless of if the seal is
+// repeated
+func (sb *backend) Signers(header *types.Header) ([]common.Address, error) {
+	extra, err := types.ExtractIstanbulExtra(header)
+	if err != nil {
+		return []common.Address{}, err
+	}
+
+	var addrs []common.Address
+	proposalSeal := istanbulCore.PrepareCommittedSeal(header.Hash())
+
+	// 1. Get committed seals from current header
+	for _, seal := range extra.CommittedSeal {
+		// 2. Get the original address by seal and parent block hash
+		addr, err := istanbul.GetSignatureAddress(proposalSeal, seal)
+		if err != nil {
+			sb.logger.Error("not a valid address", "err", err)
+			return nil, errInvalidSignature
+		}
+		addrs = append(addrs, addr)
+	}
+	return addrs, nil
+}
+
 // VerifyHeader checks whether a header conforms to the consensus rules of a
 // given engine. Verifying the seal may be done optionally here, or explicitly
 // via the VerifySeal method.
@@ -271,22 +296,16 @@ func (sb *backend) verifyCommittedSeals(chain consensus.ChainReader, header *typ
 	validators := snap.ValSet.Copy()
 	// Check whether the committed seals are generated by parent's validators
 	validSeal := 0
-	proposalSeal := istanbulCore.PrepareCommittedSeal(header.Hash())
-	// 1. Get committed seals from current header
-	for _, seal := range extra.CommittedSeal {
-		// 2. Get the original address by seal and parent block hash
-		addr, err := istanbul.GetSignatureAddress(proposalSeal, seal)
-		if err != nil {
-			sb.logger.Error("not a valid address", "err", err)
-			return errInvalidSignature
-		}
-		// Every validator can have only one seal. If more than one seals are signed by a
-		// validator, the validator cannot be found and errInvalidCommittedSeals is returned.
+	committers, err := sb.Signers(header)
+	if err != nil {
+		return err
+	}
+	for _, addr := range committers {
 		if validators.RemoveValidator(addr) {
-			validSeal += 1
-		} else {
-			return errInvalidCommittedSeals
+			validSeal++
+			continue
 		}
+		return errInvalidCommittedSeals
 	}
 
 	// The length of validSeal should be larger than number of faulty node + 1  

docs/Consensus/ibft/istanbul-rpc-api.md

@@ -84,3 +84,48 @@ istanbul.propose(address, auth)
 #### Parameters
 `String` - The address of candidate
 `bool` - `true` votes in and `false` votes out
+
+### istanbul.nodeAddress
+Retrieves the public address that is used to sign proposals, which is derived from the nodes `nodekey`.
+```
+istanbul.nodeAddress()
+```
+
+#### Returns
+`string` - The nodes public signing address
+
+### istanbul.getSignersFromBlock
+Retrieves the public addresses for whose seals are included in the block. This means that they participated in the
+consensus for this block and attested to its validity.
+A block number may be optionally given, or else the current block is assumed.
+```
+istanbul.getSignersFromBlock(blockNumber)
+```
+
+#### Parameters
+`Number` - The block number to retrieve
+
+#### Returns
+`Object` -
+    - `number`: `Number` - The retrieved block's number
+    - `hash`: `String` - The retrieved block's hash
+    - `author`: `String` - The address of the block proposer
+    - `committers`: `[]String` - The list of all addresses whose seal appears in this block
+
+### istanbul.getSignersFromBlockByHash
+Retrieves the public addresses for whose seals are included in the block. This means that they participated in the
+consensus for this block and attested to its validity. A block hash must be given, and does NOT default to the current
+latest block.
+```
+istanbul.getSignersFromBlockByHash(blockHash)
+```
+
+#### Parameters
+`String` - The hash of the block to retrieve
+
+#### Returns
+`Object` -
+    - `number`: `Number` - The retrieved block's number
+    - `hash`: `String` - The retrieved block's hash
+    - `author`: `String` - The address of the block proposer
+    - `committers`: `[]String` - The list of all addresses whose seal appears in this block

internal/web3ext/web3ext.go

@@ -921,7 +921,19 @@ web3._extend({
 			name: 'discard',
 			call: 'istanbul_discard',
 			params: 1
-		})
+		}),
+
+		new web3._extend.Method({
+			name: 'getSignersFromBlock',
+			call: 'istanbul_getSignersFromBlock',
+			params: 1,
+			inputFormatter: [web3._extend.formatters.inputBlockNumberFormatter]
+		}),
+		new web3._extend.Method({
+			name: 'getSignersFromBlockByHash',
+			call: 'istanbul_getSignersFromBlockByHash',
+			params: 1
+		}),
 	],
 	properties:
 	[
@@ -929,6 +941,10 @@ web3._extend({
 			name: 'candidates',
 			getter: 'istanbul_candidates'
 		}),
+		new web3._extend.Property({
+			name: 'nodeAddress',
+			getter: 'istanbul_nodeAddress'
+		}),
 	]
 });
 `