Firedancer

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Bundle Client ​

Firedancer can optionally receive bundles containing additional transactions from a bundle server.

BUNDLES

A bundle contains up to 5 transactions that are packed "atomically" into a block without interleaving with other transactions.

Bundles pay "tips" to the block producer in addition to regular transaction fees.

Bundle protocol ​

WARNING

Only connect to trusted bundle servers.

A malicious bundle server can cause as Firedancer block producer to create empty or skipped blocks.

Firedancer subscribes to the following feeds provided by a bundle server:

  • bundles (groups of transactions)
  • raw transactions
  • block builder fee info (configures the bundle tip commission to be paid back to the bundle server operator)

The bundle tile within Firedancer runs the bundle client. It reconnects with backoff on failure.

It also periodically requests "block builder fee" information, which instructs Firedancer of the bundle tip commission charged by the bundle server.

Transport ​

The bundle protocol uses gRPC over HTTP/2.

The bundle tile uses regular TCP sockets (does not use Firedancer XDP).

HTTPS (TLS 1.3) is supported using OpenSSL.

TLS CA certificates ​

When using to secure gRPC (HTTPS), the bundle tile verifies the server certificate against CA certificates in /etc/ssl/certs. The CA cert path is hardcoded.

Packet capture ​

Bundle gRPC connections are encrypted.

By default, the bundle tile does not log or otherwise export encryption keys.

To decrypt bundle flows captured in a .pcap file, an external file created by [development.bundle.ssl_key_log_file] is required.

The Wireshark gRPC dissector, combined with solana_dissector helps view and extract transactions in bundle flows.