// blockExists determines whether a block with the given hash exists either in
// the main chain or any side chains.
func (b *BlockChain) blockExists(hash *wire.ShaHash) (bool, error) {
// Check memory chain first (could be main chain or side chain blocks).
if _, ok := b.index[*hash]; ok {
return true, nil
}
// Check if it's the latest checkpoint block
if hash.IsEqual(b.chainParams.Checkpoints[len(b.chainParams.Checkpoints)-1].Hash) {
return true, nil
}
// Check in database (rest of main chain not in memory).
return b.db.ExistsSha(hash)
}
func (db *LevelDb) getBlkLoc(sha *wire.ShaHash) (int32, error) {
key := shaBlkToKey(sha)
checkpointSha, _ := wire.NewShaHashFromStr("00000000000000000a8dc6ed5b133d0eb2fd6af56203e4159789b092defd8ab2")
if sha.IsEqual(checkpointSha) {
return 382320, nil
}
data, err := db.lDb.Get(key, db.ro)
if err != nil {
if err == leveldb.ErrNotFound {
err = database.ErrBlockShaMissing
}
return 0, err
}
// deserialize
blkHeight := binary.LittleEndian.Uint64(data)
return int32(blkHeight), nil
}
func MakeMerkleParent(left *wire.ShaHash, right *wire.ShaHash) *wire.ShaHash {
// dupes can screw things up; CVE-2012-2459. check for them
if left != nil && right != nil && left.IsEqual(right) {
fmt.Printf("DUP HASH CRASH")
return nil
}
// if left child is nil, output nil. Need this for hard mode.
if left == nil {
return nil
}
// if right is nil, hash left with itself
if right == nil {
right = left
}
// Concatenate the left and right nodes
var sha [64]byte
copy(sha[:32], left[:])
copy(sha[32:], right[:])
newSha := wire.DoubleSha256SH(sha[:])
return &newSha
}
// MakeMerkleParent ...
func MakeMerkleParent(left *wire.ShaHash, right *wire.ShaHash) *wire.ShaHash {
// this can screw things up; CVE-2012-2459
if left != nil && right != nil && left.IsEqual(right) {
fmt.Printf("DUP HASH CRASH")
return nil
}
// if left chils is nil, output nil. Shouldn't need this?
if left == nil {
fmt.Printf("L CRASH")
return nil
}
// if right is nil, has left with itself
if right == nil {
right = left
}
// Concatenate the left and right nodes
var sha [wire.HashSize * 2]byte
copy(sha[:wire.HashSize], left[:])
copy(sha[wire.HashSize:], right[:])
newSha := wire.DoubleSha256SH(sha[:])
return &newSha
}
// blockLocatorFromHash returns a block locator for the passed block hash.
// See BlockLocator for details on the algotirhm used to create a block locator.
//
// In addition to the general algorithm referenced above, there are a couple of
// special cases which are handled:
//
// - If the genesis hash is passed, there are no previous hashes to add and
// therefore the block locator will only consist of the genesis hash
// - If the passed hash is not currently known, the block locator will only
// consist of the passed hash
//
// This function MUST be called with the chain state lock held (for reads).
func (b *BlockChain) blockLocatorFromHash(hash *wire.ShaHash) BlockLocator {
// The locator contains the requested hash at the very least.
locator := make(BlockLocator, 0, wire.MaxBlockLocatorsPerMsg)
locator = append(locator, hash)
// Nothing more to do if a locator for the genesis hash was requested.
if hash.IsEqual(b.chainParams.GenesisHash) {
return locator
}
// Attempt to find the height of the block that corresponds to the
// passed hash, and if it's on a side chain, also find the height at
// which it forks from the main chain.
blockHeight := int32(-1)
forkHeight := int32(-1)
node, exists := b.index[*hash]
if !exists {
// Try to look up the height for passed block hash. Assume an
// error means it doesn't exist and just return the locator for
// the block itself.
var height int32
err := b.db.View(func(dbTx database.Tx) error {
var err error
height, err = dbFetchHeightByHash(dbTx, hash)
return err
})
if err != nil {
return locator
}
blockHeight = height
} else {
blockHeight = node.height
// Find the height at which this node forks from the main chain
// if the node is on a side chain.
if !node.inMainChain {
for n := node; n.parent != nil; n = n.parent {
if n.inMainChain {
forkHeight = n.height
break
}
}
}
}
// Generate the block locators according to the algorithm described in
// in the BlockLocator comment and make sure to leave room for the final
// genesis hash.
//
// The error is intentionally ignored here since the only way the code
// could fail is if there is something wrong with the database which
// will be caught in short order anyways and it's also safe to ignore
// block locators.
_ = b.db.View(func(dbTx database.Tx) error {
iterNode := node
increment := int32(1)
for len(locator) < wire.MaxBlockLocatorsPerMsg-1 {
// Once there are 10 locators, exponentially increase
// the distance between each block locator.
if len(locator) > 10 {
increment *= 2
}
blockHeight -= increment
if blockHeight < 1 {
break
}
// As long as this is still on the side chain, walk
// backwards along the side chain nodes to each block
// height.
if forkHeight != -1 && blockHeight > forkHeight {
// Intentionally use parent field instead of the
// getPrevNodeFromNode function since we don't
// want to dynamically load nodes when building
// block locators. Side chain blocks should
// always be in memory already, and if they
// aren't for some reason it's ok to skip them.
for iterNode != nil && blockHeight > iterNode.height {
iterNode = iterNode.parent
}
if iterNode != nil && iterNode.height == blockHeight {
locator = append(locator, iterNode.hash)
}
continue
}
// The desired block height is in the main chain, so
// look it up from the main chain database.
h, err := dbFetchHashByHeight(dbTx, blockHeight)
if err != nil {
// This shouldn't happen and it's ok to ignore
// block locators, so just continue to the next
// one.
log.Warnf("Lookup of known valid height failed %v",
blockHeight)
continue
}
locator = append(locator, h)
}
return nil
})
// Append the appropriate genesis block.
locator = append(locator, b.chainParams.GenesisHash)
return locator
}
// BlockLocatorFromHash returns a block locator for the passed block hash.
// See BlockLocator for details on the algotirhm used to create a block locator.
//
// In addition to the general algorithm referenced above, there are a couple of
// special cases which are handled:
//
// - If the genesis hash is passed, there are no previous hashes to add and
// therefore the block locator will only consist of the genesis hash
// - If the passed hash is not currently known, the block locator will only
// consist of the passed hash
func (b *BlockChain) BlockLocatorFromHash(hash *wire.ShaHash) BlockLocator {
// The locator contains the requested hash at the very least.
locator := make(BlockLocator, 0, wire.MaxBlockLocatorsPerMsg)
locator = append(locator, hash)
// Nothing more to do if a locator for the genesis hash was requested.
if hash.IsEqual(b.chainParams.GenesisHash) {
return locator
}
// Nothing more to do if a locator for the latest checkpoint hash was requested
if hash.IsEqual(b.chainParams.Checkpoints[len(b.chainParams.Checkpoints)-1].Hash) {
return locator
}
// Attempt to find the height of the block that corresponds to the
// passed hash, and if it's on a side chain, also find the height at
// which it forks from the main chain.
blockHeight := int32(-1)
forkHeight := int32(-1)
node, exists := b.index[*hash]
if !exists {
// Try to look up the height for passed block hash. Assume an
// error means it doesn't exist and just return the locator for
// the block itself.
height, err := b.db.FetchBlockHeightBySha(hash)
if err != nil {
return locator
}
blockHeight = height
} else {
blockHeight = node.height
// Find the height at which this node forks from the main chain
// if the node is on a side chain.
if !node.inMainChain {
for n := node; n.parent != nil; n = n.parent {
if n.inMainChain {
forkHeight = n.height
break
}
}
}
}
// Generate the block locators according to the algorithm described in
// in the BlockLocator comment and make sure to leave room for the
// final genesis hash.
iterNode := node
increment := int32(1)
for len(locator) < wire.MaxBlockLocatorsPerMsg-1 {
// Once there are 10 locators, exponentially increase the
// distance between each block locator.
if len(locator) > 10 {
increment *= 2
}
blockHeight -= increment
if blockHeight < 1 {
break
}
// As long as this is still on the side chain, walk backwards
// along the side chain nodes to each block height.
if forkHeight != -1 && blockHeight > forkHeight {
// Intentionally use parent field instead of the
// getPrevNodeFromNode function since we don't want to
// dynamically load nodes when building block locators.
// Side chain blocks should always be in memory already,
// and if they aren't for some reason it's ok to skip
// them.
for iterNode != nil && blockHeight > iterNode.height {
iterNode = iterNode.parent
}
if iterNode != nil && iterNode.height == blockHeight {
locator = append(locator, iterNode.hash)
}
continue
}
// The desired block height is in the main chain, so look it up
// from the main chain database.
h, err := b.db.FetchBlockShaByHeight(blockHeight)
if err != nil {
// This shouldn't happen and it's ok to ignore block
// locators, so just continue to the next one.
// PRUNING: We've hit the end of the stored nodes, so return what we have
return locator
/*log.Warnf("Lookup of known valid height failed %v",
blockHeight)
continue*/
}
locator = append(locator, h)
}
// Append the appropriate genesis block.
locator = append(locator, b.chainParams.GenesisHash)
return locator
}
