path: root/swarm/pss/ping.go

// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library 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.
//
// The go-ethereum library 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 the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// +build !nopssprotocol,!nopssping

package pss

import (
    "errors"
    "time"

    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/protocols"
    "github.com/ethereum/go-ethereum/swarm/log"
)

// Generic ping protocol implementation for
// pss devp2p protocol emulation
type PingMsg struct {
    Created time.Time
    Pong    bool // set if message is pong reply
}

type Ping struct {
    Pong bool      // toggle pong reply upon ping receive
    OutC chan bool // trigger ping
    InC  chan bool // optional, report back to calling code
}

func (p *Ping) pingHandler(msg interface{}) error {
    var pingmsg *PingMsg
    var ok bool
    if pingmsg, ok = msg.(*PingMsg); !ok {
        return errors.New("invalid msg")
    }
    log.Debug("ping handler", "msg", pingmsg, "outc", p.OutC)
    if p.InC != nil {
        p.InC <- pingmsg.Pong
    }
    if p.Pong && !pingmsg.Pong {
        p.OutC <- true
    }
    return nil
}

var PingProtocol = &protocols.Spec{
    Name:       "psstest",
    Version:    1,
    MaxMsgSize: 1024,
    Messages: []interface{}{
        PingMsg{},
    },
}

var PingTopic = ProtocolTopic(PingProtocol)

func NewPingProtocol(ping *Ping) *p2p.Protocol {
    return &p2p.Protocol{
        Name:    PingProtocol.Name,
        Version: PingProtocol.Version,
        Length:  uint64(PingProtocol.MaxMsgSize),
        Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
            quitC := make(chan struct{})
            pp := protocols.NewPeer(p, rw, PingProtocol)
            log.Trace("running pss vprotocol", "peer", p, "outc", ping.OutC)
            go func() {
                for {
                    select {
                    case ispong := <-ping.OutC:
                        pp.Send(&PingMsg{
                            Created: time.Now(),
                            Pong:    ispong,
                        })
                    case <-quitC:
                    }
                }
            }()
            err := pp.Run(ping.pingHandler)
            quitC <- struct{}{}
            return err
        },
    }
}