@hoprnet/hopr-cover-traffic-daemon

Cover traffic node

Cover traffic (CT) node is a daemon built with HOPR's core-protocol (hopr-core), which allows it to join the HOPR network in the same way as other HOPR nodes. What distinguishs a CT node from other default HOPR nodes is that:

• CT node maintains a persisted state locally, which records the topology of the network from its own perspective and the latest status of CT delivery to facilitate the management of CT channels and path-selection for cover traffic.
• CT node adopts CoverTrafficStrategy. At each strategy tick, CT strategy decides which channels to be opened/closed based on the current publicly-available network state. Those channels are referred as cover traffic channels (CT channels). At each tick, destination of all the open CT channels are served as the first hop for CT node to send looped traffic.
• CT node is an application of HOPR core. It does not expose any sendMessage() methods and is not designed to be used by end users.

Persisted state

At run time, network topology and CT traffic status are saved into a data file ./ct.json. Note that it must live in same timeline as the hoprdb, as it relies on the indexer being in the same state.

Open/close CT channels

At each tick, CT strategy decides which channel to open and which to close:

Close channels

Among all the existing open CT channels, a CT channel will be closed on a strategy tick, when

• the destination node has a network quality lower than the CT_NETWORK_QUALITY_THRESHOLD threshold (default, 0.15).
• it does not have enough stake.
• its failed traffic rate reaches the MESSAGE_FAIL_THRESHOLD threshold (default, 10).
• it stalls at WAIT_FOR_COMMITMENT state for too long.

Open channels

While filtering channels to close, CT strategy also selects nodes to which it opens CT channels based on the probability weighted by importance, if the total amount of CT channels does not reach the CHANNELS_PER_COVER_TRAFFIC_NODE limit (default: 10). Nodes must:

• not be the CT node itself.
• not be the destination of CT channels from the lastest update.

For the definition of "importance", please check §6 HOPR yellow paper

Metrics

Some metrics can be extracted from the logs, please check metrics.md

Installation

yarn install
yarn build

Run

$ yarn hopr-cover-traffic-daemon --help
Options:
  --help             Show help  [boolean]
  --version          Show version number  [boolean]
  --environment      Environment id which the node shall run on  [string] [choices: "hardhat-localhost", "hardhat-localhost2", "master-goerli", "debug-goerli", "tuttlingen", "prague", "budapest", "athens", "lisbon", "ouagadougou", "paleochora", "monte_rosa"] [default: ""]
  --privateKey       A private key to be used for the node  [string] [required]
  --provider         A custom RPC provider to be used for your HOPR node to connect to blockchain [string]
  --dbFile           A path to DB file for persistent storage  [string] [default: "./ct.json"]
  --data             manually specify the database directory to use  [default: ""]
  --healthCheck      Run a health check end point on localhost:8080  [boolean] [default: false]
  --healthCheckHost  Host to listen on for health check  [default: "localhost"]
  --healthCheckPort  Port to listen on for health check  [default: 8080]

Example

DEBUG="hopr*" yarn hopr-cover-traffic-daemon --environment hardhat-localhost --privateKey 0xcb1e5d91d46eb54a477a7eefec9c87a1575e3e5384d38f990f19c09aa8ddd332 --healthCheckHost "127.0.0.1" --healthCheckPort 20000