// Receive waits for the response promised by the future and returns the
// blockheader requested from the server given its hash.
func (r FutureGetBlockHeaderResult) Receive() (*wire.BlockHeader, error) {
res, err := receiveFuture(r)
if err != nil {
return nil, err
}
// Unmarshal result as a string.
var bhHex string
err = json.Unmarshal(res, &bhHex)
if err != nil {
return nil, err
}
serializedBH, err := hex.DecodeString(bhHex)
if err != nil {
return nil, err
}
// Deserialize the blockheader and return it.
var bh wire.BlockHeader
err = bh.Deserialize(bytes.NewReader(serializedBH))
if err != nil {
return nil, err
}
return &bh, err
}
func (s *SPVCon) AskForMerkBlocks(current, last uint32) error {
var hdr wire.BlockHeader
_, err := s.headerFile.Seek(int64(current*80), os.SEEK_SET)
if err != nil {
return err
}
for current < last {
err = hdr.Deserialize(s.headerFile)
if err != nil {
return err
}
current++
bHash := hdr.BlockSha()
iv1 := wire.NewInvVect(wire.InvTypeFilteredBlock, &bHash)
gdataMsg := wire.NewMsgGetData()
err = gdataMsg.AddInvVect(iv1)
if err != nil {
return err
}
s.outMsgQueue <- gdataMsg
}
return nil
}
// dbFetchHeaderByHash uses an existing database transaction to retrieve the
// block header for the provided hash.
func dbFetchHeaderByHash(dbTx database.Tx, hash *chainhash.Hash) (*wire.BlockHeader, error) {
headerBytes, err := dbTx.FetchBlockHeader(hash)
if err != nil {
return nil, err
}
var header wire.BlockHeader
err = header.Deserialize(bytes.NewReader(headerBytes))
if err != nil {
return nil, err
}
return &header, nil
}
func (s *SPVCon) AskForHeaders() error {
var hdr wire.BlockHeader
ghdr := wire.NewMsgGetHeaders()
ghdr.ProtocolVersion = s.localVersion
s.headerMutex.Lock() // start header file ops
info, err := s.headerFile.Stat()
if err != nil {
return err
}
headerFileSize := info.Size()
if headerFileSize == 0 || headerFileSize%80 != 0 { // header file broken
return fmt.Errorf("Header file not a multiple of 80 bytes")
}
// seek to 80 bytes from end of file
ns, err := s.headerFile.Seek(-80, os.SEEK_END)
if err != nil {
log.Printf("can't seek\n")
return err
}
log.Printf("suk to offset %d (should be near the end\n", ns)
// get header from last 80 bytes of file
err = hdr.Deserialize(s.headerFile)
if err != nil {
log.Printf("can't Deserialize")
return err
}
s.headerMutex.Unlock() // done with header file
cHash := hdr.BlockSha()
err = ghdr.AddBlockLocatorHash(&cHash)
if err != nil {
return err
}
fmt.Printf("get headers message has %d header hashes, first one is %s\n",
len(ghdr.BlockLocatorHashes), ghdr.BlockLocatorHashes[0].String())
s.outMsgQueue <- ghdr
return nil
}
// FetchBlockHeaderBySha - return a ShaHash
func (db *LevelDb) FetchBlockHeaderBySha(sha *wire.ShaHash) (bh *wire.BlockHeader, err error) {
db.dbLock.Lock()
defer db.dbLock.Unlock()
// Read the raw block from the database.
buf, _, err := db.fetchSha(sha)
if err != nil {
return nil, err
}
// Only deserialize the header portion and ensure the transaction count
// is zero since this is a standalone header.
var blockHeader wire.BlockHeader
err = blockHeader.Deserialize(bytes.NewReader(buf))
if err != nil {
return nil, err
}
bh = &blockHeader
return bh, err
}
// TestBlockHeaderSerialize tests BlockHeader serialize and deserialize.
func TestBlockHeaderSerialize(t *testing.T) {
nonce := uint32(123123) // 0x1e0f3
// baseBlockHdr is used in the various tests as a baseline BlockHeader.
bits := uint32(0x1d00ffff)
baseBlockHdr := &wire.BlockHeader{
Version: 1,
PrevBlock: mainNetGenesisHash,
MerkleRoot: mainNetGenesisMerkleRoot,
Timestamp: time.Unix(0x495fab29, 0), // 2009-01-03 12:15:05 -0600 CST
Bits: bits,
Nonce: nonce,
}
// baseBlockHdrEncoded is the wire encoded bytes of baseBlockHdr.
baseBlockHdrEncoded := []byte{
0x01, 0x00, 0x00, 0x00, // Version 1
0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2,
0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a, // MerkleRoot
0x29, 0xab, 0x5f, 0x49, // Timestamp
0xff, 0xff, 0x00, 0x1d, // Bits
0xf3, 0xe0, 0x01, 0x00, // Nonce
}
tests := []struct {
in *wire.BlockHeader // Data to encode
out *wire.BlockHeader // Expected decoded data
buf []byte // Serialized data
}{
{
baseBlockHdr,
baseBlockHdr,
baseBlockHdrEncoded,
},
}
t.Logf("Running %d tests", len(tests))
for i, test := range tests {
// Serialize the block header.
var buf bytes.Buffer
err := test.in.Serialize(&buf)
if err != nil {
t.Errorf("Serialize #%d error %v", i, err)
continue
}
if !bytes.Equal(buf.Bytes(), test.buf) {
t.Errorf("Serialize #%d\n got: %s want: %s", i,
spew.Sdump(buf.Bytes()), spew.Sdump(test.buf))
continue
}
// Deserialize the block header.
var bh wire.BlockHeader
rbuf := bytes.NewReader(test.buf)
err = bh.Deserialize(rbuf)
if err != nil {
t.Errorf("Deserialize #%d error %v", i, err)
continue
}
if !reflect.DeepEqual(&bh, test.out) {
t.Errorf("Deserialize #%d\n got: %s want: %s", i,
spew.Sdump(&bh), spew.Sdump(test.out))
continue
}
}
}
func CheckHeader(r io.ReadSeeker, height int64, p *chaincfg.Params) bool {
var err error
var cur, prev, epochStart wire.BlockHeader
// don't try to verfy the genesis block. That way madness lies.
if height == 0 {
return true
}
// initial load of headers
// load epochstart, previous and current.
// get the header from the epoch start, up to 2016 blocks ago
_, err = r.Seek(80*(height-(height%epochLength)), os.SEEK_SET)
if err != nil {
log.Printf(err.Error())
return false
}
err = epochStart.Deserialize(r)
if err != nil {
log.Printf(err.Error())
return false
}
// log.Printf("start epoch at height %d ", height-(height%epochLength))
// seek to n-1 header
_, err = r.Seek(80*(height-1), os.SEEK_SET)
if err != nil {
log.Printf(err.Error())
return false
}
// read in n-1
err = prev.Deserialize(r)
if err != nil {
log.Printf(err.Error())
return false
}
// seek to curHeight header and read in
_, err = r.Seek(80*(height), os.SEEK_SET)
if err != nil {
log.Printf(err.Error())
return false
}
err = cur.Deserialize(r)
if err != nil {
log.Printf(err.Error())
return false
}
// get hash of n-1 header
prevHash := prev.BlockSha()
// check if headers link together. That whole 'blockchain' thing.
if prevHash.IsEqual(&cur.PrevBlock) == false {
log.Printf("Headers %d and %d don't link.\n",
height-1, height)
log.Printf("%s - %s",
prev.BlockSha().String(), cur.BlockSha().String())
return false
}
rightBits := epochStart.Bits // normal, no adjustment; Dn = Dn-1
// see if we're on a difficulty adjustment block
if (height)%epochLength == 0 {
// if so, check if difficulty adjustment is valid.
// That whole "controlled supply" thing.
// calculate diff n based on n-2016 ... n-1
rightBits = calcDiffAdjust(epochStart, prev, p)
// done with adjustment, save new ephochStart header
epochStart = cur
log.Printf("Update epoch at height %d", height)
} else { // not a new epoch
// if on testnet, check for difficulty nerfing
if p.ResetMinDifficulty && cur.Timestamp.After(
prev.Timestamp.Add(targetSpacing*2)) {
// fmt.Printf("nerf %d ", curHeight)
rightBits = p.PowLimitBits // difficulty 1
}
if cur.Bits != rightBits {
log.Printf("Block %d %s incorrect difficuly. Read %x, expect %x\n",
height, cur.BlockSha().String(), cur.Bits, rightBits)
return false
}
}
// check if there's a valid proof of work. That whole "Bitcoin" thing.
if !checkProofOfWork(cur, p) {
log.Printf("Block %d Bad proof of work.\n", height)
return false
}
return true // it must have worked if there's no errors and got to the end.
}
func (s *SPVCon) IngestHeaders(m *wire.MsgHeaders) (bool, error) {
var err error
_, err = s.headerFile.Seek(-80, os.SEEK_END)
if err != nil {
return false, err
}
var last wire.BlockHeader
err = last.Deserialize(s.headerFile)
if err != nil {
return false, err
}
prevHash := last.BlockSha()
gotNum := int64(len(m.Headers))
if gotNum > 0 {
fmt.Printf("got %d headers. Range:\n%s - %s\n",
gotNum, m.Headers[0].BlockSha().String(),
m.Headers[len(m.Headers)-1].BlockSha().String())
} else {
log.Printf("got 0 headers, we're probably synced up")
return false, nil
}
endPos, err := s.headerFile.Seek(0, os.SEEK_END)
if err != nil {
return false, err
}
// check first header returned to make sure it fits on the end
// of our header file
if !m.Headers[0].PrevBlock.IsEqual(&prevHash) {
// delete 100 headers if this happens! Dumb reorg.
log.Printf("possible reorg; header msg doesn't fit. points to %s, expect %s",
m.Headers[0].PrevBlock.String(), prevHash.String())
if endPos < 8080 {
// jeez I give up, back to genesis
s.headerFile.Truncate(80)
} else {
err = s.headerFile.Truncate(endPos - 8000)
if err != nil {
return false, fmt.Errorf("couldn't truncate header file")
}
}
return false, fmt.Errorf("Truncated header file to try again")
}
tip := endPos / 80
tip-- // move back header length so it can read last header
for _, resphdr := range m.Headers {
// write to end of file
err = resphdr.Serialize(s.headerFile)
if err != nil {
return false, err
}
// advance chain tip
tip++
// check last header
worked := CheckHeader(s.headerFile, tip, params)
if !worked {
if endPos < 8080 {
// jeez I give up, back to genesis
s.headerFile.Truncate(80)
} else {
err = s.headerFile.Truncate(endPos - 8000)
if err != nil {
return false, fmt.Errorf("couldn't truncate header file")
}
}
// probably should disconnect from spv node at this point,
// since they're giving us invalid headers.
return false, fmt.Errorf(
"Header %d - %s doesn't fit, dropping 100 headers.",
resphdr.BlockSha().String(), tip)
}
}
log.Printf("Headers to height %d OK.", tip)
return true, nil
}
// AskForMerkBlocks requests blocks from current to last
// right now this asks for 1 block per getData message.
// Maybe it's faster to ask for many in a each message?
func (s *SPVCon) AskForBlocks() error {
var hdr wire.BlockHeader
s.headerMutex.Lock() // lock just to check filesize
stat, err := os.Stat(headerFileName)
s.headerMutex.Unlock() // checked, unlock
endPos := stat.Size()
headerTip := int32(endPos/80) - 1 // move back 1 header length to read
dbTip, err := s.TS.GetDBSyncHeight()
if err != nil {
return err
}
fmt.Printf("dbTip %d headerTip %d\n", dbTip, headerTip)
if dbTip > headerTip {
return fmt.Errorf("error- db longer than headers! shouldn't happen.")
}
if dbTip == headerTip {
// nothing to ask for; set wait state and return
fmt.Printf("no blocks to request, entering wait state\n")
fmt.Printf("%d bytes received\n", s.RBytes)
s.inWaitState <- true
// also advertise any unconfirmed txs here
s.Rebroadcast()
return nil
}
fmt.Printf("will request merkleblocks %d to %d\n", dbTip, headerTip)
if !s.HardMode { // don't send this in hardmode! that's the whole point
// create initial filter
filt, err := s.TS.GimmeFilter()
if err != nil {
return err
}
// send filter
s.SendFilter(filt)
fmt.Printf("sent filter %x\n", filt.MsgFilterLoad().Filter)
}
// loop through all heights where we want merkleblocks.
for dbTip <= headerTip {
// load header from file
s.headerMutex.Lock() // seek to header we need
_, err = s.headerFile.Seek(int64((dbTip-1)*80), os.SEEK_SET)
if err != nil {
return err
}
err = hdr.Deserialize(s.headerFile) // read header, done w/ file for now
s.headerMutex.Unlock() // unlock after reading 1 header
if err != nil {
log.Printf("header deserialize error!\n")
return err
}
bHash := hdr.BlockSha()
// create inventory we're asking for
iv1 := new(wire.InvVect)
// if hardmode, ask for legit blocks, none of this ralphy stuff
if s.HardMode {
iv1 = wire.NewInvVect(wire.InvTypeBlock, &bHash)
} else { // ah well
iv1 = wire.NewInvVect(wire.InvTypeFilteredBlock, &bHash)
}
gdataMsg := wire.NewMsgGetData()
// add inventory
err = gdataMsg.AddInvVect(iv1)
if err != nil {
return err
}
hah := NewRootAndHeight(hdr.BlockSha(), dbTip)
if dbTip == headerTip { // if this is the last block, indicate finality
hah.final = true
}
s.outMsgQueue <- gdataMsg
// waits here most of the time for the queue to empty out
s.blockQueue <- hah // push height and mroot of requested block on queue
dbTip++
}
return nil
}