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progress on a streaming interface
This commit is contained in:
parent
949cec0dce
commit
fd362c6aa5
3 changed files with 74 additions and 18 deletions
22
node.go
22
node.go
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@ -1,23 +1,22 @@
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package merkle
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import (
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"crypto"
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_ "crypto/sha1" // to satisfy our DefaultHash
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"crypto/sha1"
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"fmt"
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"hash"
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)
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var (
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// DefaultHash is for checksum of blocks and nodes
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DefaultHash = crypto.SHA1
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// DefaultHashMaker is for checksum of blocks and nodes
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DefaultHashMaker = func() hash.Hash { return sha1.New() }
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)
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// HashMaker produces a new has for use in making checksums
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type HashMaker func() hash.Hash
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// NewNode returns a new Node with the DefaultHash for checksums
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// NewNode returns a new Node with the DefaultHashMaker for checksums
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func NewNode() *Node {
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return NewNodeHash(DefaultHash.New)
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return NewNodeHash(DefaultHashMaker)
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}
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// NewNodeHash returns a new Node using the provided crypto.Hash for checksums
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@ -25,13 +24,22 @@ func NewNodeHash(h HashMaker) *Node {
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return &Node{hash: h}
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}
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// NewNodeHashBlock returns a new Node using the provided crypto.Hash, and calculates the block's checksum
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func NewNodeHashBlock(h HashMaker, b []byte) *Node {
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n := &Node{hash: h}
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h1 := n.hash()
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h1.Write(b)
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n.checksum = h1.Sum(nil)
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return n
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}
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// Node is a fundamental part of the tree.
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type Node struct {
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hash HashMaker
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checksum []byte
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Parent, Left, Right *Node
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pos int // XXX maybe keep their order when it is a direct block's hash
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//pos int // XXX maybe keep their order when it is a direct block's hash
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}
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// IsLeaf indicates this node is for specific block (and has no children)
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@ -9,7 +9,7 @@ import (
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func TestNodeSums(t *testing.T) {
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var (
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nodes []*Node
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h = DefaultHash.New()
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h = DefaultHashMaker()
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words = `Who were expelled from the academy for crazy & publishing obscene odes on the windows of the skull`
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expectedChecksum = "819fe8fed7a46900bd0613344c5ba2be336c74db"
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)
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@ -19,7 +19,7 @@ func TestNodeSums(t *testing.T) {
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t.Errorf("on word %q, encountered %s", word, err)
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}
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sum := h.Sum(nil)
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nodes = append(nodes, &Node{checksum: sum, hash: DefaultHash.New})
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nodes = append(nodes, &Node{checksum: sum, hash: DefaultHashMaker})
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}
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newNodes := nodes
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66
stream.go
66
stream.go
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@ -1,14 +1,18 @@
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package merkle
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import "hash"
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import (
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"hash"
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"log"
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)
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// NewHash provides a hash.Hash to generate a merkle.Tree checksum, given a
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// HashMaker for the checksums of the blocks written and the blockSize of each
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// block per node in the tree.
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func NewHash(hm HashMaker, merkleBlockSize int) hash.Hash {
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func NewHash(hm HashMaker, merkleBlockLength int) hash.Hash {
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mh := new(merkleHash)
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mh.blockSize = merkleBlockSize
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mh.blockSize = merkleBlockLength
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mh.hm = hm
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mh.tree = &Tree{Nodes: []*Node{}, BlockLength: merkleBlockLength}
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return mh
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}
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@ -18,9 +22,11 @@ func NewHash(hm HashMaker, merkleBlockSize int) hash.Hash {
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// TODO satisfy the hash.Hash interface
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type merkleHash struct {
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blockSize int
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tree Tree
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hm HashMaker
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blockSize int
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tree *Tree
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hm HashMaker
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lastBlock []byte // as needed, for Sum()
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partialLastBlock bool
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}
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// XXX this will be tricky, as the last block can be less than the BlockSize.
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@ -32,15 +38,57 @@ type merkleHash struct {
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//
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// if that last block was complete, then no worries. start the next node.
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func (mh *merkleHash) Sum(b []byte) []byte {
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return nil
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// TODO check if len(mh.lastBlock) < blockSize
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sum, err := mh.tree.Root().Checksum()
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if err != nil {
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log.Println(err)
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}
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return sum
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}
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func (mh *merkleHash) Write(b []byte) (int, error) {
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return 0, nil
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// basically we need to:
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// * chunk these writes into blockSize
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// * create Node of the sum
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// * add the Node to the tree
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// * stash remainder in the mh.lastBlock
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var (
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curBlock = make([]byte, mh.blockSize)
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numBytes int = 0
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numWritten int
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)
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if mh.lastBlock != nil && len(mh.lastBlock) > 0 {
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numBytes = copy(curBlock, mh.lastBlock)
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// not adding to numWritten, since these blocks were accounted for in a
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// prior Write()
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}
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if numBytes > 0 {
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copy(curBlock, b[:(mh.blockSize-numBytes)])
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numWritten += (mh.blockSize - numBytes)
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// TODO Node for curBlock
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n := NewNodeHashBlock(mh.hm, curBlock)
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_ = n
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}
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numBytes = len(b) - numBytes
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for i := 0; i < numBytes/mh.blockSize; i++ {
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// TODO Node for curBlock
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}
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// TODO stash (numBytes % mh.blockSize) in mh.lastBlock
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// TODO if len(mh.lastBlock) < blockSize, then set that before returning
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return numWritten, nil
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}
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func (mh *merkleHash) Reset() {
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mh.Tree = Tree{}
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mh.tree = &Tree{}
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mh.lastBlock = nil
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}
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// likely not the best to pass this through and not use our own node block
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// size, but let's revisit this.
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func (mh *merkleHash) BlockSize() int { return mh.hm().BlockSize() }
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func (mh *merkleHash) Size() int { return mh.hm().Size() }
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