ceremonyclient/go-libp2p/examples/multipro/echo.go

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2023-08-21 03:50:38 +00:00
package main
import (
"fmt"
"io"
"log"
"github.com/libp2p/go-libp2p/core/host"
"github.com/libp2p/go-libp2p/core/network"
"github.com/gogo/protobuf/proto"
"github.com/google/uuid"
pb "github.com/libp2p/go-libp2p/examples/multipro/pb"
)
// pattern: /protocol-name/request-or-response-message/version
const echoRequest = "/echo/echoreq/0.0.1"
const echoResponse = "/echo/echoresp/0.0.1"
type EchoProtocol struct {
node *Node // local host
requests map[string]*pb.EchoRequest // used to access request data from response handlers
done chan bool // only for demo purposes to hold main from terminating
}
func NewEchoProtocol(node *Node, done chan bool) *EchoProtocol {
e := EchoProtocol{node: node, requests: make(map[string]*pb.EchoRequest), done: done}
node.SetStreamHandler(echoRequest, e.onEchoRequest)
node.SetStreamHandler(echoResponse, e.onEchoResponse)
// design note: to implement fire-and-forget style messages you may just skip specifying a response callback.
// a fire-and-forget message will just include a request and not specify a response object
return &e
}
// remote peer requests handler
func (e *EchoProtocol) onEchoRequest(s network.Stream) {
// get request data
data := &pb.EchoRequest{}
buf, err := io.ReadAll(s)
if err != nil {
s.Reset()
log.Println(err)
return
}
s.Close()
// unmarshal it
err = proto.Unmarshal(buf, data)
if err != nil {
log.Println(err)
return
}
log.Printf("%s: Received echo request from %s. Message: %s", s.Conn().LocalPeer(), s.Conn().RemotePeer(), data.Message)
valid := e.node.authenticateMessage(data, data.MessageData)
if !valid {
log.Println("Failed to authenticate message")
return
}
log.Printf("%s: Sending echo response to %s. Message id: %s...", s.Conn().LocalPeer(), s.Conn().RemotePeer(), data.MessageData.Id)
// send response to the request using the message string he provided
resp := &pb.EchoResponse{
MessageData: e.node.NewMessageData(data.MessageData.Id, false),
Message: data.Message}
// sign the data
signature, err := e.node.signProtoMessage(resp)
if err != nil {
log.Println("failed to sign response")
return
}
// add the signature to the message
resp.MessageData.Sign = signature
ok := e.node.sendProtoMessage(s.Conn().RemotePeer(), echoResponse, resp)
if ok {
log.Printf("%s: Echo response to %s sent.", s.Conn().LocalPeer().String(), s.Conn().RemotePeer().String())
}
e.done <- true
}
// remote echo response handler
func (e *EchoProtocol) onEchoResponse(s network.Stream) {
data := &pb.EchoResponse{}
buf, err := io.ReadAll(s)
if err != nil {
s.Reset()
log.Println(err)
return
}
s.Close()
// unmarshal it
err = proto.Unmarshal(buf, data)
if err != nil {
log.Println(err)
return
}
// authenticate message content
valid := e.node.authenticateMessage(data, data.MessageData)
if !valid {
log.Println("Failed to authenticate message")
return
}
// locate request data and remove it if found
req, ok := e.requests[data.MessageData.Id]
if ok {
// remove request from map as we have processed it here
delete(e.requests, data.MessageData.Id)
} else {
log.Println("Failed to locate request data boject for response")
return
}
if req.Message != data.Message {
log.Fatalln("Expected echo to respond with request message")
}
log.Printf("%s: Received echo response from %s. Message id:%s. Message: %s.", s.Conn().LocalPeer(), s.Conn().RemotePeer(), data.MessageData.Id, data.Message)
e.done <- true
}
func (e *EchoProtocol) Echo(host host.Host) bool {
log.Printf("%s: Sending echo to: %s....", e.node.ID(), host.ID())
// create message data
req := &pb.EchoRequest{
MessageData: e.node.NewMessageData(uuid.New().String(), false),
Message: fmt.Sprintf("Echo from %s", e.node.ID())}
signature, err := e.node.signProtoMessage(req)
if err != nil {
log.Println("failed to sign message")
return false
}
// add the signature to the message
req.MessageData.Sign = signature
ok := e.node.sendProtoMessage(host.ID(), echoRequest, req)
if !ok {
return false
}
// store request so response handler has access to it
e.requests[req.MessageData.Id] = req
log.Printf("%s: Echo to: %s was sent. Message Id: %s, Message: %s", e.node.ID(), host.ID(), req.MessageData.Id, req.Message)
return true
}