path: root/whisper/main.go

// +build none

// Contains a simple whisper peer setup and self messaging to allow playing
// around with the protocol and API without a fancy client implementation.

package main

import (
    "fmt"
    "log"
    "os"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/nat"
    "github.com/ethereum/go-ethereum/whisper"
)

func main() {
    logger.AddLogSystem(logger.NewStdLogSystem(os.Stdout, log.LstdFlags, logger.InfoLevel))

    // Generate the peer identity
    key, err := crypto.GenerateKey()
    if err != nil {
        fmt.Printf("Failed to generate peer key: %v.\n", err)
        os.Exit(-1)
    }
    name := common.MakeName("whisper-go", "1.0")
    shh := whisper.New()

    // Create an Ethereum peer to communicate through
    server := p2p.Server{
        PrivateKey: key,
        MaxPeers:   10,
        Name:       name,
        Protocols:  []p2p.Protocol{shh.Protocol()},
        ListenAddr: ":30300",
        NAT:        nat.Any(),
    }
    fmt.Println("Starting Ethereum peer...")
    if err := server.Start(); err != nil {
        fmt.Printf("Failed to start Ethereum peer: %v.\n", err)
        os.Exit(1)
    }

    // Send a message to self to check that something works
    payload := fmt.Sprintf("Hello world, this is %v. In case you're wondering, the time is %v", name, time.Now())
    if err := selfSend(shh, []byte(payload)); err != nil {
        fmt.Printf("Failed to self message: %v.\n", err)
        os.Exit(-1)
    }
}

// SendSelf wraps a payload into a Whisper envelope and forwards it to itself.
func selfSend(shh *whisper.Whisper, payload []byte) error {
    ok := make(chan struct{})

    // Start watching for self messages, output any arrivals
    id := shh.NewIdentity()
    shh.Watch(whisper.Filter{
        To: &id.PublicKey,
        Fn: func(msg *whisper.Message) {
            fmt.Printf("Message received: %s, signed with 0x%x.\n", string(msg.Payload), msg.Signature)
            close(ok)
        },
    })
    // Wrap the payload and encrypt it
    msg := whisper.NewMessage(payload)
    envelope, err := msg.Wrap(whisper.DefaultPoW, whisper.Options{
        From: id,
        To:   &id.PublicKey,
        TTL:  whisper.DefaultTTL,
    })
    if err != nil {
        return fmt.Errorf("failed to seal message: %v", err)
    }
    // Dump the message into the system and wait for it to pop back out
    if err := shh.Send(envelope); err != nil {
        return fmt.Errorf("failed to send self-message: %v", err)
    }
    select {
    case <-ok:
    case <-time.After(time.Second):
        return fmt.Errorf("failed to receive message in time")
    }
    return nil
}