Gavin: Head first mining will prevent DoS attacks

Implement " head first mining first mining": propagate the new 80-byte block header across the network as quickly as possible, giving miners the opportunity to start mining an empty block once they know the block header.

Only valid, proof-of-work block headers connected to the longest chain will be relayed, so denial-of-service attacks will not be feasible.

Once the entire block is accepted and verified, miners will switch to mining regular blocks as quickly as possible.

There is a hard-coded 30 second timeout period; if it takes longer than 30 seconds for the entire block to be verified and propagated to the network, or if it is not sent at all, miners will switch back to the last fully verified block to mine a non-empty block.

detail:

New getblocktemplate behavior: getblocktemplate returns an empty (coinbase transaction only) block template between receiving a new block's 'blockheader' message and receiving and validating this 'block' message. Long getblocktemplate connections are terminated when a new best-header is received and when the block is fully validated.

New command line option, -blockheadernotify . Similar to -blocknotify , except that notification is only done when a new most-work-header is accepted.

New P2P message, 'invalidblock'. Similar to the 'block' message, except that when a valid proof-of-work is accepted for an invalid block, these messages are sent to peers, telling them that they should stop mining on this block header.

Only peers that follow the BIP130 'sendheaders' protocol will relay the block headers immediately, and only they will receive the 'invalid block' message. Light clients (SPV) will not have 'sendheaders', so they should not be affected. Older clients that cannot understand these 'invalid block' messages will just ignore it.

Please review the code and discuss test results on github. Debate whether header-first mining is beneficial to the Bitcoin network and should be implemented in the bitcoin-classic software on the slack channel or the #bitcoin-dev IRC channel.

Original: https://github.com/bitcoinclassic/bitcoinclassic/pull/152
By: Gavin Andresen
Translator: Satuoxi
Source (translation): Babbitt Information (http://www.8btc.com/head-first-mining)