path: root/p2p/protocol.go

// Copyright 2014 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with go-ethereum.  If not, see <http://www.gnu.org/licenses/>.

package p2p

import "fmt"

// Protocol represents a P2P subprotocol implementation.
type Protocol struct {
    // Name should contain the official protocol name,
    // often a three-letter word.
    Name string

    // Version should contain the version number of the protocol.
    Version uint

    // Length should contain the number of message codes used
    // by the protocol.
    Length uint64

    // Run is called in a new groutine when the protocol has been
    // negotiated with a peer. It should read and write messages from
    // rw. The Payload for each message must be fully consumed.
    //
    // The peer connection is closed when Start returns. It should return
    // any protocol-level error (such as an I/O error) that is
    // encountered.
    Run func(peer *Peer, rw MsgReadWriter) error
}

func (p Protocol) cap() Cap {
    return Cap{p.Name, p.Version}
}

// Cap is the structure of a peer capability.
type Cap struct {
    Name    string
    Version uint
}

func (cap Cap) RlpData() interface{} {
    return []interface{}{cap.Name, cap.Version}
}

func (cap Cap) String() string {
    return fmt.Sprintf("%s/%d", cap.Name, cap.Version)
}

type capsByNameAndVersion []Cap

func (cs capsByNameAndVersion) Len() int      { return len(cs) }
func (cs capsByNameAndVersion) Swap(i, j int) { cs[i], cs[j] = cs[j], cs[i] }
func (cs capsByNameAndVersion) Less(i, j int) bool {
    return cs[i].Name < cs[j].Name || (cs[i].Name == cs[j].Name && cs[i].Version < cs[j].Version)
}