91 lines
2.7 KiB
Go
91 lines
2.7 KiB
Go
package chain
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import (
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"errors"
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"github.com/CityOfZion/neo-go/pkg/wire/payload/transaction"
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"github.com/CityOfZion/neo-go/pkg/database"
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"github.com/CityOfZion/neo-go/pkg/wire/payload"
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)
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var (
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// ErrBlockAlreadyExists happens when you try to save the same block twice
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ErrBlockAlreadyExists = errors.New("this block has already been saved in the database")
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)
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// Chain represents a blockchain instance
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type Chain struct {
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db *Chaindb
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}
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//New returns a new chain instance
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func New(db database.Database) *Chain {
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return &Chain{
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db: &Chaindb{db},
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}
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}
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// SaveBlock verifies and saves the block in the database
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// XXX: for now we will just save without verifying the block
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// This function is called by the server and if an error is returned then
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// the server informs the sync manager to redownload the block
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// XXX:We should also check if the header is already saved in the database
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// If not, then we need to validate the header with the rest of the chain
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// For now we re-save the header
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func (c *Chain) SaveBlock(msg payload.BlockMessage) error {
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err := c.VerifyBlock(msg.Block)
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if err != nil {
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return err
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}
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//XXX(Issue): We can either check the hash here for genesisblock.
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//We most likely will have it anyways after validation/ We can return it from VerifyBlock
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// Or we can do it somewhere in startup, performance benefits
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// won't be that big since it's just a bytes.Equal.
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// so it's more about which is more readable and where it makes sense to put
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return c.db.saveBlock(msg.Block, false)
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}
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// VerifyBlock verifies whether a block is valid according
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// to the rules of consensus
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func (c *Chain) VerifyBlock(block payload.Block) error {
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// Check if we already have this block
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// XXX: We can optimise by implementing a Has method
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// caching the last block in memory
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lastBlock, err := c.db.GetLastBlock()
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if err != nil {
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return err
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}
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// Check if we have already saved this block
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// by looking if the latest block height is more than
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// incoming block height
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if lastBlock.Index > block.Index {
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return ErrBlockAlreadyExists
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}
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return nil
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}
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// VerifyTx verifies whether a transaction is valid according
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// to the rules of consensus
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func (c *Chain) VerifyTx(tx transaction.Transactioner) error {
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return nil
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}
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// SaveHeaders will save the set of headers without validating
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func (c *Chain) SaveHeaders(msg payload.HeadersMessage) error {
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err := c.verifyHeaders(msg.Headers)
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if err != nil {
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return err
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}
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return c.db.saveHeaders(msg.Headers)
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}
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// verifyHeaders will be used to verify a batch of headers
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// should only ever be called during the initial block download
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// or when the node receives a HeadersMessage
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func (c *Chain) verifyHeaders(hdrs []*payload.BlockBase) error {
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return nil
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}
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