Port getheaders JSON-RPC command from dcrd

btcjson/btcdextcmds.go

@@ -90,6 +90,27 @@ func NewGetCurrentNetCmd() *GetCurrentNetCmd {
 	return &GetCurrentNetCmd{}
 }
 
+// GetHeadersCmd defines the getheaders JSON-RPC command.
+//
+// NOTE: This is a btcsuite extension ported from
+// github.com/decred/dcrd/dcrjson.
+type GetHeadersCmd struct {
+	BlockLocators []string `json:"blocklocators"`
+	HashStop      string   `json:"hashstop"`
+}
+
+// NewGetHeadersCmd returns a new instance which can be used to issue a
+// getheaders JSON-RPC command.
+//
+// NOTE: This is a btcsuite extension ported from
+// github.com/decred/dcrd/dcrjson.
+func NewGetHeadersCmd(blockLocators []string, hashStop string) *GetHeadersCmd {
+	return &GetHeadersCmd{
+		BlockLocators: blockLocators,
+		HashStop:      hashStop,
+	}
+}
+
 // VersionCmd defines the version JSON-RPC command.
 //
 // NOTE: This is a btcsuite extension ported from
@@ -112,5 +133,6 @@ func init() {
 	MustRegisterCmd("generate", (*GenerateCmd)(nil), flags)
 	MustRegisterCmd("getbestblock", (*GetBestBlockCmd)(nil), flags)
 	MustRegisterCmd("getcurrentnet", (*GetCurrentNetCmd)(nil), flags)
+	MustRegisterCmd("getheaders", (*GetHeadersCmd)(nil), flags)
 	MustRegisterCmd("version", (*VersionCmd)(nil), flags)
 }

btcjson/btcdextcmds_test.go

@@ -136,6 +136,46 @@ func TestBtcdExtCmds(t *testing.T) {
 			marshalled:   `{"jsonrpc":"1.0","method":"getcurrentnet","params":[],"id":1}`,
 			unmarshalled: &btcjson.GetCurrentNetCmd{},
 		},
+		{
+			name: "getheaders",
+			newCmd: func() (interface{}, error) {
+				return btcjson.NewCmd("getheaders", []string{}, "")
+			},
+			staticCmd: func() interface{} {
+				return btcjson.NewGetHeadersCmd(
+					[]string{},
+					"",
+				)
+			},
+			marshalled: `{"jsonrpc":"1.0","method":"getheaders","params":[[],""],"id":1}`,
+			unmarshalled: &btcjson.GetHeadersCmd{
+				BlockLocators: []string{},
+				HashStop:      "",
+			},
+		},
+		{
+			name: "getheaders - with arguments",
+			newCmd: func() (interface{}, error) {
+				return btcjson.NewCmd("getheaders", []string{"000000000000000001f1739002418e2f9a84c47a4fd2a0eb7a787a6b7dc12f16", "0000000000000000026f4b7f56eef057b32167eb5ad9ff62006f1807b7336d10"}, "000000000000000000ba33b33e1fad70b69e234fc24414dd47113bff38f523f7")
+			},
+			staticCmd: func() interface{} {
+				return btcjson.NewGetHeadersCmd(
+					[]string{
+						"000000000000000001f1739002418e2f9a84c47a4fd2a0eb7a787a6b7dc12f16",
+						"0000000000000000026f4b7f56eef057b32167eb5ad9ff62006f1807b7336d10",
+					},
+					"000000000000000000ba33b33e1fad70b69e234fc24414dd47113bff38f523f7",
+				)
+			},
+			marshalled: `{"jsonrpc":"1.0","method":"getheaders","params":[["000000000000000001f1739002418e2f9a84c47a4fd2a0eb7a787a6b7dc12f16","0000000000000000026f4b7f56eef057b32167eb5ad9ff62006f1807b7336d10"],"000000000000000000ba33b33e1fad70b69e234fc24414dd47113bff38f523f7"],"id":1}`,
+			unmarshalled: &btcjson.GetHeadersCmd{
+				BlockLocators: []string{
+					"000000000000000001f1739002418e2f9a84c47a4fd2a0eb7a787a6b7dc12f16",
+					"0000000000000000026f4b7f56eef057b32167eb5ad9ff62006f1807b7336d10",
+				},
+				HashStop: "000000000000000000ba33b33e1fad70b69e234fc24414dd47113bff38f523f7",
+			},
+		},
 		{
 			name: "version",
 			newCmd: func() (interface{}, error) {

btcjson/btcdextresults.go

@@ -1,5 +1,5 @@
-// Copyright (c) 2016 The btcsuite developers
+// Copyright (c) 2016-2017 The btcsuite developers
-// Copyright (c) 2015-2016 The Decred developers
+// Copyright (c) 2015-2017 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 

btcjson/btcdextresults_test.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2016 The btcsuite developers
+// Copyright (c) 2016-2017 The btcsuite developers
 // Copyright (c) 2015-2016 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.

chaincfg/chainhash/hash.go

@@ -84,35 +84,45 @@ func NewHash(newHash []byte) (*Hash, error) {
 // the hexadecimal string of a byte-reversed hash, but any missing characters
 // result in zero padding at the end of the Hash.
 func NewHashFromStr(hash string) (*Hash, error) {
-	// Return error if hash string is too long.
+	ret := new(Hash)
-	if len(hash) > MaxHashStringSize {
+	err := Decode(ret, hash)
-		return nil, ErrHashStrSize
-	}
-
-	// Hex decoder expects the hash to be a multiple of two.
-	if len(hash)%2 != 0 {
-		hash = "0" + hash
-	}
-
-	// Convert string hash to bytes.
-	buf, err := hex.DecodeString(hash)
 	if err != nil {
 		return nil, err
 	}
-
+	return ret, nil
-	// Un-reverse the decoded bytes, copying into in leading bytes of a
+}
-	// Hash.  There is no need to explicitly pad the result as any
+
-	// missing (when len(buf) < HashSize) bytes from the decoded hex string
+// Decode decodes the byte-reversed hexadecimal string encoding of a Hash to a
-	// will remain zeros at the end of the Hash.
+// destination.
-	var ret Hash
+func Decode(dst *Hash, src string) error {
-	blen := len(buf)
+	// Return error if hash string is too long.
-	mid := blen / 2
+	if len(src) > MaxHashStringSize {
-	if blen%2 != 0 {
+		return ErrHashStrSize
-		mid++
+	}
-	}
+
-	blen--
+	// Hex decoder expects the hash to be a multiple of two.  When not, pad
-	for i, b := range buf[:mid] {
+	// with a leading zero.
-		ret[i], ret[blen-i] = buf[blen-i], b
+	var srcBytes []byte
-	}
+	if len(src)%2 == 0 {
-	return &ret, nil
+		srcBytes = []byte(src)
+	} else {
+		srcBytes = make([]byte, 1+len(src))
+		srcBytes[0] = '0'
+		copy(srcBytes[1:], src)
+	}
+
+	// Hex decode the source bytes to a temporary destination.
+	var reversedHash Hash
+	_, err := hex.Decode(reversedHash[HashSize-hex.DecodedLen(len(srcBytes)):], srcBytes)
+	if err != nil {
+		return err
+	}
+
+	// Reverse copy from the temporary hash to destination.  Because the
+	// temporary was zeroed, the written result will be correctly padded.
+	for i, b := range reversedHash[:HashSize/2] {
+		dst[i], dst[HashSize-1-i] = reversedHash[HashSize-1-i], b
+	}
+
+	return nil
 }

docs/json_rpc_api.md

@@ -584,6 +584,7 @@ The following is an overview of the RPC methods which are implemented by btcd, b
 |5|[node](#node)|N|Attempts to add or remove a peer. |None|
 |6|[generate](#generate)|N|When in simnet or regtest mode, generate a set number of blocks. |None|
 |7|[version](#version)|Y|Returns the JSON-RPC API version.|
+|8|[getheaders](#getheaders)|Y|Returns block headers starting with the first known block hash from the request.|
 
 
 <a name="ExtMethodDetails" />
@@ -678,6 +679,19 @@ The following is an overview of the RPC methods which are implemented by btcd, b
 
 ***
 
+<a name="getheaders"/>
+
+|   |   |
+|---|---|
+|Method|getheaders|
+|Parameters|1. Block Locators (JSON array, required)<br />&nbsp;`[ (json array of strings)`<br />&nbsp;&nbsp;`"blocklocator", (string) the known block hash`<br />&nbsp;&nbsp;`...`<br />&nbsp;`]`<br />2. hashstop (string) - last desired block's hash|
+|Description|Returns block headers starting with the first known block hash from the request.|
+|Returns|`[ (json array of strings)`<br />&nbsp;&nbsp;`"blockheader",`<br />&nbsp;&nbsp;`...`<br />`]`|
+|Example Return|`[`<br />&nbsp;&nbsp;`"0000002099417930b2ae09feda10e38b58c0f6bb44b4d60fa33f0e000000000000000000d53...",`<br />&nbsp;&nbsp;`"000000203ba25a173bfd24d09e0c76002a910b685ca297bd09a17b020000000000000000702..."`<br />`]`|
+[Return to Overview](#MethodOverview)<br />
+
+***
+
 <a name="WSExtMethods" />
 ### 7. Websocket Extension Methods (Websocket-specific)
 

rpcserver.go

@@ -1,5 +1,5 @@
-// Copyright (c) 2013-2016 The btcsuite developers
+// Copyright (c) 2013-2017 The btcsuite developers
-// Copyright (c) 2015-2016 The Decred developers
+// Copyright (c) 2015-2017 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -45,9 +45,9 @@ import (
 
 // API version constants
 const (
-	jsonrpcSemverString = "1.0.0"
+	jsonrpcSemverString = "1.1.0"
 	jsonrpcSemverMajor  = 1
-	jsonrpcSemverMinor  = 0
+	jsonrpcSemverMinor  = 1
 	jsonrpcSemverPatch  = 0
 )
 
@@ -163,6 +163,7 @@ var rpcHandlersBeforeInit = map[string]commandHandler{
 	"getdifficulty":         handleGetDifficulty,
 	"getgenerate":           handleGetGenerate,
 	"gethashespersec":       handleGetHashesPerSec,
+	"getheaders":            handleGetHeaders,
 	"getinfo":               handleGetInfo,
 	"getmempoolinfo":        handleGetMempoolInfo,
 	"getmininginfo":         handleGetMiningInfo,
@@ -270,6 +271,7 @@ var rpcLimited = map[string]struct{}{
 	"getblockhash":          {},
 	"getcurrentnet":         {},
 	"getdifficulty":         {},
+	"getheaders":            {},
 	"getinfo":               {},
 	"getnettotals":          {},
 	"getnetworkhashps":      {},
@@ -2148,6 +2150,65 @@ func handleGetHashesPerSec(s *rpcServer, cmd interface{}, closeChan <-chan struc
 	return int64(s.server.cpuMiner.HashesPerSecond()), nil
 }
 
+// handleGetHeaders implements the getheaders command.
+//
+// NOTE: This is a btcsuite extension ported from
+// github.com/decred/dcrd.
+func handleGetHeaders(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (interface{}, error) {
+	c := cmd.(*btcjson.GetHeadersCmd)
+	blockLocators := make([]*chainhash.Hash, len(c.BlockLocators))
+	for i := range c.BlockLocators {
+		blockLocator, err := chainhash.NewHashFromStr(c.BlockLocators[i])
+		if err != nil {
+			return nil, &btcjson.RPCError{
+				Code: btcjson.ErrRPCInvalidParameter,
+				Message: "Failed to decode block locator: " +
+					err.Error(),
+			}
+		}
+		blockLocators[i] = blockLocator
+	}
+	var hashStop chainhash.Hash
+	if c.HashStop != "" {
+		err := chainhash.Decode(&hashStop, c.HashStop)
+		if err != nil {
+			return nil, &btcjson.RPCError{
+				Code:    btcjson.ErrRPCInvalidParameter,
+				Message: "Failed to decode hashstop: " + err.Error(),
+			}
+		}
+	}
+	blockHashes, err := s.server.locateBlocks(blockLocators, &hashStop)
+	if err != nil {
+		return nil, &btcjson.RPCError{
+			Code: btcjson.ErrRPCDatabase,
+			Message: "Failed to fetch hashes of block " +
+				"headers: " + err.Error(),
+		}
+	}
+	blockHeaders, err := fetchHeaders(s.server.db, blockHashes)
+	if err != nil {
+		return nil, &btcjson.RPCError{
+			Code: btcjson.ErrRPCDatabase,
+			Message: "Failed to fetch headers of located blocks: " +
+				err.Error(),
+		}
+	}
+
+	hexBlockHeaders := make([]string, len(blockHeaders))
+	var buf bytes.Buffer
+	for i, h := range blockHeaders {
+		err := h.Serialize(&buf)
+		if err != nil {
+			return nil, internalRPCError(err.Error(),
+				"Failed to serialize block header")
+		}
+		hexBlockHeaders[i] = hex.EncodeToString(buf.Bytes())
+		buf.Reset()
+	}
+	return hexBlockHeaders, nil
+}
+
 // handleGetInfo implements the getinfo command. We only return the fields
 // that are not related to wallet functionality.
 func handleGetInfo(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (interface{}, error) {

rpcserverhelp.go

@@ -1,5 +1,5 @@
-// Copyright (c) 2015-2016 The btcsuite developers
+// Copyright (c) 2015-2017 The btcsuite developers
-// Copyright (c) 2015-2016 The Decred developers
+// Copyright (c) 2015-2017 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -360,6 +360,12 @@ var helpDescsEnUS = map[string]string{
 	"infowalletresult-relayfee":        "The minimum relay fee for non-free transactions in BTC/KB",
 	"infowalletresult-errors":          "Any current errors",
 
+	// GetHeadersCmd help.
+	"getheaders--synopsis":     "Returns block headers starting with the first known block hash from the request",
+	"getheaders-blocklocators": "JSON array of hex-encoded hashes of blocks.  Headers are returned starting from the first known hash in this list",
+	"getheaders-hashstop":      "Block hash to stop including block headers for; if not found, all headers to the latest known block are returned.",
+	"getheaders--result0":      "Serialized block headers of all located blocks, limited to some arbitrary maximum number of hashes (currently 2000, which matches the wire protocol headers message, but this is not guaranteed)",
+
 	// GetInfoCmd help.
 	"getinfo--synopsis": "Returns a JSON object containing various state info.",
 
@@ -646,6 +652,7 @@ var rpcResultTypes = map[string][]interface{}{
 	"getdifficulty":         {(*float64)(nil)},
 	"getgenerate":           {(*bool)(nil)},
 	"gethashespersec":       {(*float64)(nil)},
+	"getheaders":            {(*[]string)(nil)},
 	"getinfo":               {(*btcjson.InfoChainResult)(nil)},
 	"getmempoolinfo":        {(*btcjson.GetMempoolInfoResult)(nil)},
 	"getmininginfo":         {(*btcjson.GetMiningInfoResult)(nil)},

server.go

@@ -1,4 +1,5 @@
-// Copyright (c) 2013-2016 The btcsuite developers
+// Copyright (c) 2013-2017 The btcsuite developers
+// Copyright (c) 2015-2017 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -640,58 +641,30 @@ func (sp *serverPeer) OnGetBlocks(_ *peer.Peer, msg *wire.MsgGetBlocks) {
 	}
 }
 
-// OnGetHeaders is invoked when a peer receives a getheaders bitcoin
+// locateBlocks returns the hashes of the blocks after the first known block in
-// message.
+// locators, until hashStop is reached, or up to a max of
-func (sp *serverPeer) OnGetHeaders(_ *peer.Peer, msg *wire.MsgGetHeaders) {
+// wire.MaxBlockHeadersPerMsg block hashes.  This implements the search
-	// Ignore getheaders requests if not in sync.
+// algorithm used by getheaders.
-	if !sp.server.blockManager.IsCurrent() {
+func (s *server) locateBlocks(locators []*chainhash.Hash, hashStop *chainhash.Hash) ([]chainhash.Hash, error) {
-		return
-	}
-
 	// Attempt to look up the height of the provided stop hash.
-	chain := sp.server.blockManager.chain
+	chain := s.blockManager.chain
 	endIdx := int32(math.MaxInt32)
-	height, err := chain.BlockHeightByHash(&msg.HashStop)
+	height, err := chain.BlockHeightByHash(hashStop)
 	if err == nil {
 		endIdx = height + 1
 	}
 
 	// There are no block locators so a specific header is being requested
 	// as identified by the stop hash.
-	if len(msg.BlockLocatorHashes) == 0 {
+	if len(locators) == 0 {
 		// No blocks with the stop hash were found so there is nothing
 		// to do.  Just return.  This behavior mirrors the reference
 		// implementation.
 		if endIdx == math.MaxInt32 {
-			return
+			return nil, nil
 		}
 
-		// Fetch the raw block header bytes from the database.
+		return []chainhash.Hash{*hashStop}, nil
-		var headerBytes []byte
-		err := sp.server.db.View(func(dbTx database.Tx) error {
-			var err error
-			headerBytes, err = dbTx.FetchBlockHeader(&msg.HashStop)
-			return err
-		})
-		if err != nil {
-			peerLog.Warnf("Lookup of known block hash failed: %v",
-				err)
-			return
-		}
-
-		// Deserialize the block header.
-		var header wire.BlockHeader
-		err = header.Deserialize(bytes.NewReader(headerBytes))
-		if err != nil {
-			peerLog.Warnf("Block header deserialize failed: %v",
-				err)
-			return
-		}
-
-		headersMsg := wire.NewMsgHeaders()
-		headersMsg.AddBlockHeader(&header)
-		sp.QueueMessage(headersMsg, nil)
-		return
 	}
 
 	// Find the most recent known block based on the block locator.
@@ -700,8 +673,8 @@ func (sp *serverPeer) OnGetHeaders(_ *peer.Peer, msg *wire.MsgGetHeaders) {
 	// over with the genesis block if unknown block locators are provided.
 	// This mirrors the behavior in the reference implementation.
 	startIdx := int32(1)
-	for _, hash := range msg.BlockLocatorHashes {
+	for _, loc := range locators {
-		height, err := chain.BlockHeightByHash(hash)
+		height, err := chain.BlockHeightByHash(loc)
 		if err == nil {
 			// Start with the next hash since we know this one.
 			startIdx = height + 1
@@ -709,43 +682,67 @@ func (sp *serverPeer) OnGetHeaders(_ *peer.Peer, msg *wire.MsgGetHeaders) {
 		}
 	}
 
-	// Don't attempt to fetch more than we can put into a single message.
+	// Don't attempt to fetch more than we can put into a single wire
+	// message.
 	if endIdx-startIdx > wire.MaxBlockHeadersPerMsg {
 		endIdx = startIdx + wire.MaxBlockHeadersPerMsg
 	}
 
 	// Fetch the inventory from the block database.
-	hashList, err := chain.HeightRange(startIdx, endIdx)
+	return chain.HeightRange(startIdx, endIdx)
-	if err != nil {
+}
-		peerLog.Warnf("Header lookup failed: %v", err)
-		return
-	}
 
-	// Generate headers message and send it.
+// fetchHeaders fetches and decodes headers from the db for each hash in
-	headersMsg := wire.NewMsgHeaders()
+// blockHashes.
-	err = sp.server.db.View(func(dbTx database.Tx) error {
+func fetchHeaders(db database.DB, blockHashes []chainhash.Hash) ([]*wire.BlockHeader, error) {
-		for i := range hashList {
+	headers := make([]*wire.BlockHeader, 0, len(blockHashes))
-			headerBytes, err := dbTx.FetchBlockHeader(&hashList[i])
+	err := db.View(func(dbTx database.Tx) error {
-			if err != nil {
+		rawHeaders, err := dbTx.FetchBlockHeaders(blockHashes)
-				return err
+		if err != nil {
-			}
+			return err
-
+		}
-			var header wire.BlockHeader
+		for _, headerBytes := range rawHeaders {
-			err = header.Deserialize(bytes.NewReader(headerBytes))
+			h := new(wire.BlockHeader)
-			if err != nil {
+			err = h.Deserialize(bytes.NewReader(headerBytes))
-				return err
+			if err != nil {
-			}
+				return err
-			headersMsg.AddBlockHeader(&header)
+			}
+			headers = append(headers, h)
 		}
-
 		return nil
 	})
-	if err != nil {
+	return headers, err
-		peerLog.Warnf("Failed to build headers: %v", err)
+}
+
+// OnGetHeaders is invoked when a peer receives a getheaders bitcoin
+// message.
+func (sp *serverPeer) OnGetHeaders(_ *peer.Peer, msg *wire.MsgGetHeaders) {
+	// Ignore getheaders requests if not in sync.
+	if !sp.server.blockManager.IsCurrent() {
 		return
 	}
 
-	sp.QueueMessage(headersMsg, nil)
+	blockHashes, err := sp.server.locateBlocks(msg.BlockLocatorHashes,
+		&msg.HashStop)
+	if err != nil {
+		peerLog.Errorf("OnGetHeaders: failed to fetch hashes: %v", err)
+		return
+	}
+	blockHeaders, err := fetchHeaders(sp.server.db, blockHashes)
+	if err != nil {
+		peerLog.Errorf("OnGetHeaders: failed to fetch block headers: "+
+			"%v", err)
+		return
+	}
+
+	if len(blockHeaders) > wire.MaxBlockHeadersPerMsg {
+		peerLog.Warnf("OnGetHeaders: fetched more block headers than " +
+			"allowed per message")
+		// Can still recover from this error, just slice off the extra
+		// headers and continue queing the message.
+		blockHeaders = blockHeaders[:wire.MaxBlockHeaderPayload]
+	}
+	sp.QueueMessage(&wire.MsgHeaders{Headers: blockHeaders}, nil)
 }
 
 // enforceNodeBloomFlag disconnects the peer if the server is not configured to