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Ethereum-Wire-Protocol.md

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Ethereum Wire Protocol

Peer-to-peer communications between nodes running Ethereum clients run using the underlying ÐΞVp2p Wire Protocol.

Basic Chain Syncing

  • Two peers connect & say Hello and send their Status message. Status includes the Total Difficulty(TD) & hash of their best block.
  • The client with the worst TD asks peer for full chain of just block hashes.
  • Chain of hashes is stored in space shared by all peer connections, and used as a "work pool".
  • While there are hashes in the chain of hashes that we don't have in our chain:
    • Ask for N blocks from our peer using the hashes. Mark them as on their way so we don't get them from another peer.

Ethereum Sub-protocol

Status [+0x00: P, protocolVersion: P, networkId: P, td: P, bestHash: B_32, genesisHash: B_32] Inform a peer of its current ethereum state. This message should be sent after the initial handshake and prior to any ethereum related messages.

  • protocolVersion is one of:
    • 0x00 for PoC-1;
    • 0x01 for PoC-2;
    • 0x07 for PoC-3;
    • 0x09 for PoC-4.
    • 0x17 for PoC-5.
    • 0x1c for PoC-6.
  • networkId should be 0 for testnet, 1 for mainnet.
  • td: Total Difficulty of the best chain. Integer, as found in block header.
  • bestHash: The hash of the best (i.e. highest TD) known block.
  • genesisHash: The hash of the Genesis block.

NewBlockHashes [+0x01: P, hash1: B_32, hash2: B_32, ...] Specify one or more new blocks which have appeared on the network. The list may contain 256 hashes at most. To be maximally helpful, nodes should inform peers of all blocks that they may not be aware of. Including hashes that the sending peer could reasonably be considered to know (due to the fact they were previously informed of because that node has itself advertised knowledge of the hashes through NewBlockHashes) is considered Bad Form, and may reduce the reputation of the sending node. Including hashes that the sending node later refuses to honour with a proceeding GetBlocks message is considered Bad Form, and may reduce the reputation of the sending node.

Transactions [+0x02: P, [nonce: P, receivingAddress: B_20, value: P, ...], ...] Specify (a) transaction(s) that the peer should make sure is included on its transaction queue. The items in the list (following the first item 0x12) are transactions in the format described in the main Ethereum specification. Nodes must not resend the same transaction to a peer in the same session. This packet must contain at least one (new) transaction.

GetBlockHashes [+0x03: P, hash : B_32, maxBlocks: P] Requests a BlockHashes message of at most maxBlocks entries, of block hashes from the blockchain, starting at the parent of block hash. Does not require the peer to give maxBlocks hashes - they could give somewhat fewer.

BlockHashes [+0x04: P, hash_0: B_32, hash_1: B_32, ...] Gives a series of hashes of blocks (each the child of the next). This implies that the blocks are ordered from youngest to oldest.

GetBlocks [+0x05: P, hash_0: B_32, hash_1: B_32, ...] Requests a Blocks message detailing a number of blocks to be sent, each referred to by a hash. Note: Don't expect that the peer necessarily give you all these blocks in a single message - you might have to re-request them.

Blocks [+0x06, [blockHeader, transactionList, uncleList], ...] Specify (a) block(s) as an answer to GetBlocks. The items in the list (following the message ID) are blocks in the format described in the main Ethereum specification. This may validly contain no blocks if no blocks were able to be returned for the GetBlocks query.

NewBlock [+0x07, [blockHeader, transactionList, uncleList], totalDifficulty] Specify a single block that the peer should know about. The composite item in the list (following the message ID) is a block in the format described in the main Ethereum specification.

  • totalDifficulty is the total difficulty of the block (aka score).

PV61 specific

BlockHashesFromNumber [+0x08: P, number: P, maxBlocks: P] Requires peer to reply with a BlockHashes message. Message should contain block with that of number number on the canonical chain. Should also be followed by subsequent blocks, on the same chain, detailing a number of the first block hash and a total of hashes to be sent. Returned hash list must be ordered by block number in ascending order.

New model syncing (PV62)

NewBlockHashes [+0x01: P, [hash_0: B_32, number_0: P], [hash_1: B_32, number_1: P], ...] Specify one or more new blocks which have appeared on the network. To be maximally helpful, nodes should inform peers of all blocks that they may not be aware of. Including hashes that the sending peer could reasonably be considered to know (due to the fact they were previously informed of because that node has itself advertised knowledge of the hashes through NewBlockHashes) is considered Bad Form, and may reduce the reputation of the sending node. Including hashes that the sending node later refuses to honour with a proceeding GetBlockHeaders message is considered Bad Form, and may reduce the reputation of the sending node.

GetBlockHeaders [+0x03: P, block: { P , B_32 }, maxHeaders: P, skip: P, reverse: P in { 0 , 1 } ] Require peer to return a BlockHeaders message. Reply must contain a number of block headers, of rising number when reverse is 0, falling when 1, skip blocks apart, beginning at block block (denoted by either number or hash) in the canonical chain, and with at most maxHeaders items.

BlockHeaders [+0x04, blockHeader_0, blockHeader_1, ...] Reply to GetBlockHeaders. The items in the list (following the message ID) are block headers in the format described in the main Ethereum specification, previously asked for in a GetBlockHeaders message. This may validly contain no block headers if no block headers were able to be returned for the GetBlockHeaders query.

GetBlockBodies [+0x05, hash_0: B_32, hash_1: B_32, ...] Require peer to return a BlockBodies message. Specify the set of blocks that we're interested in with the hashes.

BlockBodies [+0x06, [transactions_0, uncles_0] , ...] Reply to GetBlockBodies. The items in the list (following the message ID) are some of the blocks, minus the header, in the format described in the main Ethereum specification, previously asked for in a GetBlockBodies message. This may validly contain no items if no blocks were able to be returned for the GetBlockBodies query.

ELIMINATED: GetBlockHashes, BlockHashes, GetBlocks, Blocks, BlockHashesFromNumber

Fast synchronization (PV63)

GetNodeData [+0x0d, hash_0: B_32, hash_1: B_32, ...] Require peer to return a NodeData message. Hint that useful values in it are those which correspond to given hashes.

NodeData [+0x0e, value_0: B, value_1: B, ...] Provide a set of values which correspond to previously asked node data hashes from GetNodeData. Does not need to contain all; best effort is fine. If it contains none, then has no information for previous GetNodeData hashes.

GetReceipts [+0x0f, hash_0: B_32, hash_1: B_32, ...] Require peer to return a Receipts message. Hint that useful values in it are those which correspond to blocks of the given hashes.

Receipts [+0x10, [receipt_0, receipt_1], ...] Provide a set of receipts which correspond to previously asked in GetReceipts.

Session Management

For the Ethereum sub-protocol, upon an active session, a Status message must be sent. Following the reception of the peer's Status message, the Ethereum session is active and any other messages may be sent. All transactions should initially be sent with one or more Transactions messages.

Transactions messages should also be sent periodically as the node has new transactions to disseminate. A node should never send a transaction back to the peer that it can determine already knows of it (either because it was previously sent or because it was informed from this peer originally).

Upcoming changes

Changes (PoC-7)

Changed (PoC-6)