bootstrapping

bootstrapping

The main specification is in Bootstrap_pipeline.tla

Assumptions/Simplifications

• all messages are for the same chain_id
• all headers are for the same proto_level
• no timestamps
• only three message types:
  • Get_current_branch/Current_branch
  • Get_block_headers/Block_header
  • Get_operations/Operation
  • i.e. no Current_head or mempool
• bootstrapping nodes have the ability to request a specific history sample, by levels
• bootstrapping nodes only communicate with established nodes
• node's are blacklisted when we timeout while communicating with them
• lengths of all chains are bounded by MAX_LEVEL
• number of operations per block is bounded by MAX_OPS

Bootstrapping node phases

Block structure

block = {
  header : Headers,
  ops    : Seq(Operations)
}

Header structure

header = {
  level       : Levels,
  predecessor : BlockHashes,
  context     : Hashes,
  fitness     : 0..Max_fitness,
  ops_hash    : Hashes
}

Operations structure

ops = {
  block_hash : BlockHashes,
  op         : 0..MAX_OPS
}

Constants

• BAD_NODES - byzantine nodes
• GOOD_NODES - nodes who follow the protocol
• BAD_BOOTSTRAPPING - byzantine bootstrapping nodes
• GOOD_BOOTSTRAPPING - bootstrapping nodes who follow the protocol
• MIN_PEERS - minimum number of peers
• MAX_PEERS - maximum number of peers
• MAX_LEVEL - maximum level of a block
• MAX_OPS - maximum number of operations per block
• CURRENT_HEAD - each good node's current head
• BLOCKS - each good node's blocks
• VALIDATOR - Blocks -> { "known_valid", "known_invalid", "unknown" }
• SAMPLES - GOOD_NODES * Bootstrapping_nodes -> Seq_n(Levels)
• HASH_BLOCK_MAP - BlockHashes -> Headers

Variables

Message and blacklist variables

• b_blacklist - each good bootstrapping node's set of blacklisted peers
• b_messages - each good bootstrapping node's set of messages
• n_blacklist - each good node's set of blacklisted peers
• n_messages - each good node's set of messages

History variables

Bootstrapping

• sent_get_branch - each good bootstrapping node's set of peers to whom they have sent a Get_current_branch message
• sent_get_headers - each good bootstrapping node's function from peers to whom they have sent a Get_block_headers message to the requested headers
• sent_get_ops - each good bootstrapping node's function from peers to whom they have sent a Get_operations message to the requested operations
• recv_branch - each good bootstrapping node's set of peers from whom they have received a Current_branch message
• recv_header - each good bootstrapping node's function from peers from whom they have received a Block_header message to set of headers received
• recv_ops - each good bootstrapping node's function from peers from whom they have received a Operation message to set of operations received

Node

• sent_branch - each good node's set of peers to whom they have sent a Current_branch message
• sent_headers - each good node's function from peers to whom they have sent a Block_header message to the set of headers sent
• sent_ops - each good node's function from peers to whom they have sent a Operation message to the set of operations sent
• recv_get_branch - each good node's set of peers from whom they have received a Get_current_branch message
• recv_get_headers - each good node's set of peers from whom they have received a Get_block_headers message
• recv_get_ops - each good node's set of peers from whom they have received a Get_operations message

Bootstrapping variables

• phase - each good bootstrapping node's phase
• connections - each good and bad bootstrapping node's set of connections
• current_head - each good bootstrapping node's current head
• fittest_head - each good bootstrapping node's peers' current heads
• validated_blocks - each good bootstrapping node's function from level to validated block at that level
• level_to_validate - each good bootstrapping node's lowest common level of fetched headers and operations
• header_pipe - each good bootstrapping node's queue of fetched headers
• operation_pipe - each good bootstrapping node's queue of fetched operations

Node variables

• servicing_headers - each good node's function from peers from whom they have received a Get_block_headers message to the headers they requested
• servicing_ops - each good node's function from peers from whom they have received a Get_operations message to the operations they requested

Actions

TODO