github.com/decred/dcrd/wire (go): Package wire implements the Decred wire protocol.  For the complete details of the Decred protocol, see the official wiki entry at https://en.bitcoin.it/wiki/Protocol_specification.  The following only serves as a quick overview to provide information on how to use the package.  At a high level, this package provides support for marshalling and unmarshalling supported Decred messages to and from the wire.  This package does not deal with the specifics of message handling such as what to do when a message is received.  This provides the caller with a high level of flexibility.  The Decred protocol consists of exchanging messages between peers.  Each message is preceded by a header which identifies information about it such as which Decred network it is a part of, its type, how big it is, and a checksum to verify validity.  All encoding and decoding of message headers is handled by this package.  To accomplish this, there is a generic interface for Decred messages named Message which allows messages of any type to be read, written, or passed around through channels, functions, etc.  In addition, concrete implementations of most of the currently supported Decred messages are provided.  For these supported messages, all of the details of marshalling and unmarshalling to and from the wire using Decred encoding are handled so the caller doesn't have to concern themselves with the specifics.  The following provides a quick summary of how the Decred messages are intended to interact with one another.  As stated above, these interactions are not directly handled by this package.  For more in-depth details about the appropriate interactions, see the official Decred protocol wiki entry at https://en.bitcoin.it/wiki/Protocol_specification.  The initial handshake consists of two peers sending each other a version message (MsgVersion) followed by responding with a verack message (MsgVerAck).  Both peers use the information in the version message (MsgVersion) to negotiate things such as protocol version and supported services with each other.  Once the initial handshake is complete, the following chart indicates message interactions in no particular order.  There are several common parameters that arise when using this package to read and write Decred messages.  The following sections provide a quick overview of these parameters so the next sections can build on them.  The protocol version should be negotiated with the remote peer at a higher level than this package via the version (MsgVersion) message exchange, however, this package provides the wire.ProtocolVersion constant which indicates the latest protocol version this package supports and is typically the value to use for all outbound connections before a potentially lower protocol version is negotiated.  The Decred network is a magic number which is used to identify the start of a message and which Decred network the message applies to.  This package provides the following constants:  As discussed in the Decred message overview section, this package reads and writes Decred messages using a generic interface named Message.  In order to determine the actual concrete type of the message, use a type switch or type assertion.  An example of a type switch follows:  In order to unmarshall Decred messages from the wire, use the ReadMessage function.  It accepts any io.Reader, but typically this will be a net.Conn to a remote node running a Decred peer.  Example syntax is:  In order to marshall Decred messages to the wire, use the WriteMessage function.  It accepts any io.Writer, but typically this will be a net.Conn to a remote node running a Decred peer.  Example syntax to request addresses from a remote peer is:  Errors returned by this package are either the raw errors provided by underlying calls to read/write from streams such as io.EOF, io.ErrUnexpectedEOF, and io.ErrShortWrite, or of type wire.MessageError.  This allows the caller to differentiate between general IO errors and malformed messages through type assertions.  This package includes spec changes outlined by the following BIPs:
Keywords: blockchain|cryptocurrency|dcrd|decred|decred-daemon|decred-nodes|go|golang|p2p|peer-to-peer