Upgrading to Splinter v0.3.13 from Splinter v0.3.12

Breaking changes and significant changes in this release:

Socket-based transports now require a version handshake

Socket-based transport connections now require a version handshake in order to connect successfully. (This includes the TCP and TLS transports.) The connections use this handshake to agree on the header format that describes the data being sent over the socket.

All members of a Splinter network must upgrade, because only the Splinter daemons for Splinter 0.3.13 and above can successfully connect.

Version handshake in detail

In Splinter 0.3.12 and earlier, data was sent over these connections with a frame that looked like this (where data-length describes the length of the data that follows):


Splinter 0.3.13 adds a header that specifies a version, so that future changes will be backward compatible. With the new headers, the connections exchange a version handshake to establish the header version that can be understood by both sides.

First, the outgoing connection sends the versions it supports:


The receiving connection replies with either a version in that range or 0 if none is supported.

Once the version has been established, data will be transmitted with the appropriate header for the version. For version 1, the header has the following format:


In this format, data-length describes the length of the data that follows and header-checksum specifies a checksum.

TlsConnection::new has been deprecated

The constructor for TlsConnection has been deprecated in favor of creating connections via TlsTransport. The transport now manages the negotiation of the data header version, as described in the previous section. The current constructor sets the connection’s header version to version 1.

See this commit for an example of how to migrate from constructor to the transport implementation.

RestApiServerError has an additional variant, BindError

A new error variant has been added to the RestApiServerError to indicate errors when binding to an address. This is useful for notifying the caller of RestApi::run that the REST API server could not be bound to the given address.

When starting the server and reacting to specific events, a new match arm is required:

let rest_api = RestApiBuilder::new()

match rest_api.run() {
    // ...
    RestApiServerError::BindError => error!("Unable to bind to localhost:8080"),