forked from DecentralizedClimateFoundation/DCIPs
86 lines
2.5 KiB
Markdown
86 lines
2.5 KiB
Markdown
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---
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eip: 868
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title: Node Discovery v4 ENR Extension
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author: Felix Lange <fjl@ethereum.org>
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type: Standards Track
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category: Networking
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status: Final
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created: 2018-02-02
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requires: 8, 778
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discussions-to: https://github.com/ethereum/devp2p/issues/44
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---
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# Abstract
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This EIP defines an extension to Node Discovery Protocol v4 to enable authoritative
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resolution of [Ethereum Node Records (ENR)](./eip-778.md).
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# Motivation
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To bridge current and future discovery networks and to aid the implementation of other
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relay mechanisms for ENR such as DNS, we need a way to request the most up-to-date version
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of a node record. This EIP provides a way to request it using the existing discovery
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protocol.
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# Specification
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Implementations of Node Discovery Protocol v4 should support two new packet types, a
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request and reply of the node record. The existing ping and pong packets are extended with
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a new field containing the sequence number of the ENR.
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### Ping Packet (0x01)
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```text
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packet-data = [version, from, to, expiration, enr-seq]
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```
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`enr-seq` is the current sequence number of the sending node's record. All other fields
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retain their existing meaning.
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### Pong Packet (0x02)
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```text
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packet-data = [to, ping-hash, expiration, enr-seq]
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```
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`enr-seq` is the current sequence number of the sending node's record. All other fields
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retain their existing meaning.
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### ENRRequest Packet (0x05)
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```text
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packet-data = [ expiration ]
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```
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When a packet of this type is received, the node should reply with an ENRResponse packet
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containing the current version of its record.
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To guard against amplification attacks, the sender of ENRRequest should have replied to a
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ping packet recently (just like for FindNode). The `expiration` field, a UNIX timestamp,
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should be handled as for all other existing packets i.e. no reply should be sent if it
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refers to a time in the past.
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### ENRResponse Packet (0x06)
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```text
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packet-data = [ request-hash, ENR ]
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```
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This packet is the response to ENRRequest.
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- `request-hash` is the hash of the entire ENRRequest packet being replied to.
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- `ENR` is the node record.
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The recipient of the packet should verify that the node record is signed by node who sent
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ENRResponse.
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## Resolving Records
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To resolve the current record of a node public key, perform a recursive Kademlia lookup
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using the FindNode, Neighbors packets. When the node is found, send ENRRequest to it and
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return the record from the response.
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# Copyright
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Copyright and related rights waived via [CC0](../LICENSE.md).
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