PeerInfo UnMarshal Error

[Harrywang55666]

package main

import (
	"github.com/libp2p/go-libp2p-peerstore"
	"github.com/libp2p/go-libp2p"
	"encoding/json"
	"context"
	"github.com/whyrusleeping/go-logging"
	"os"
)

func main() {
	log := logging.MustGetLogger("main")
	logging.SetBackend(logging.NewLogBackend(os.Stderr, "", 0))
	ctx := context.Background()
	host, err := libp2p.New(ctx, libp2p.ListenAddrStrings("/ip4/0.0.0.0/tcp/0"))
	if err != nil {
		log.Fatal("new host err:", err)
	}
	data, err := json.Marshal(host.Peerstore().PeerInfo(host.ID()))
	if err != nil {
		log.Fatal("marshal json err:", err)
	}

	log.Debugf("data: %s", data)

	var info peerstore.PeerInfo
	if err := json.Unmarshal(data, &info); err != nil {
		log.Fatal("unmarshal json err:", err)
	}

	log.Debug("info:", info)
	return
}

after running result:

17:07:16.353 DEBUG       main: data: {"ID":"\u0012 \ufffdr\ufffd\ufffd\ufffdpz\ufffd\ufffdS\u0016\u0007 `|\no\u000e\ufffd\ufffd\ufffd\ufffd4\ufffd\ufffd\ufffd\ufffd\u0016O\ufffd\u0011\ufffd","Addrs":null} main.go:25
17:07:16.353 CRITI       main: unmarshal json err:input isn't valid multihash main.go:29

[Stebalien]

We haven't defined a way to marshal/unmarshal peer IDs to/from JSON (although we probably should).

[hsanjuan]

This is just adding MarshalJSON and UnmarshalJSON to the type.

[zhizouxiao]

I think it's time to close this issue, MarshalJSON and UnmarshalJSON have been added.

func (pi *PeerInfo) MarshalJSON() ([]byte, error) {
        out := make(map[string]interface{})
        out["ID"] = pi.ID.Pretty()
        var addrs []string
        for _, a := range pi.Addrs {
                addrs = append(addrs, a.String())
        }
        out["Addrs"] = addrs
        return json.Marshal(out)
}

func (pi *PeerInfo) UnmarshalJSON(b []byte) error {
        var data map[string]interface{}
        err := json.Unmarshal(b, &data)
        if err != nil {
                return err
        }
        pid, err := peer.IDB58Decode(data["ID"].(string))
        if err != nil {
                return err
        }
        pi.ID = pid
        addrs, ok := data["Addrs"].([]interface{})
        if ok {
                for _, a := range addrs {
                        pi.Addrs = append(pi.Addrs, ma.StringCast(a.(string)))
                }
        }
        return nil
}

[Stebalien]

Hm. Actually, I was wrong. The code in the top post should work.

[zhizouxiao]

@Stebalien I figure it out. The reason is (pi *PeerInfo) MarshalJSON() ([]byte, error) with a pointer receiver, so when a pointer is needed in json.Marshal. The code below has been tested.

pi := host.Peerstore().PeerInfo(host.ID())
data, err := json.Marshal(&pi)

[Stebalien]

I see. We should just change it to take a value. Also, we should change it to not panic on bad values. The current code is buggy as hell.

[zhizouxiao]

@Stebalien I made a pull request. Now json.Marshal can take value or pointer, either is okay. But I can't pass the travis CI.

[zhizouxiao]

@Harrywang55666 I think it's time to close this issue.