basic event and relaypool.

event/event.go

@@ -0,0 +1,150 @@
+package event
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"math/big"
+
+	"github.com/fiatjaf/bip340"
+)
+
+const (
+	KindSetMetadata     uint8 = 0
+	KindTextNote        uint8 = 1
+	KindRecommendServer uint8 = 2
+	KindContactList     uint8 = 3
+)
+
+type Event struct {
+	ID string `json:"id"` // it's the hash of the serialized event
+
+	PubKey    string `json:"pubkey"`
+	CreatedAt uint32 `json:"created_at"`
+
+	Kind uint8 `json:"kind"`
+
+	Tags    Tags   `json:"tags"`
+	Content string `json:"content"`
+	Sig     string `json:"sig"`
+}
+
+type Tags []Tag
+
+func (t Tags) Scan(src interface{}) error {
+	var jtags []byte = make([]byte, 0)
+
+	switch v := src.(type) {
+	case []byte:
+		jtags = v
+	case string:
+		jtags = []byte(v)
+	default:
+		return errors.New("couldn't scan tags, it's not a json string")
+	}
+
+	json.Unmarshal(jtags, t)
+	return nil
+}
+
+type Tag []interface{}
+
+// Serialize outputs a byte array that can be hashed/signed to identify/authenticate
+func (evt *Event) Serialize() []byte {
+	// the serialization process is just putting everything into a JSON array
+	// so the order is kept
+	arr := make([]interface{}, 6)
+
+	// version: 0
+	arr[0] = 0
+
+	// pubkey
+	arr[1] = evt.PubKey
+
+	// created_at
+	arr[2] = int64(evt.CreatedAt)
+
+	// kind
+	arr[3] = int64(evt.Kind)
+
+	// tags
+	if evt.Tags != nil {
+		arr[4] = evt.Tags
+	} else {
+		arr[4] = make([]bool, 0)
+	}
+
+	// content
+	arr[5] = evt.Content
+
+	serialized, _ := json.Marshal(arr)
+	return serialized
+}
+
+// CheckSignature checks if the signature is valid for the id
+// (which is a hash of the serialized event content).
+// returns an error if the signature itself is invalid.
+func (evt Event) CheckSignature() (bool, error) {
+	// read and check pubkey
+	pubkeyb, err := hex.DecodeString(evt.PubKey)
+	if err != nil {
+		return false, err
+	}
+	if len(pubkeyb) != 32 {
+		return false, fmt.Errorf("pubkey must be 32 bytes, not %d", len(pubkeyb))
+	}
+
+	// check tags
+	for _, tag := range evt.Tags {
+		for _, item := range tag {
+			switch item.(type) {
+			case string, int64, float64, int, bool:
+				// fine
+			default:
+				// not fine
+				return false, fmt.Errorf("tag contains an invalid value %v", item)
+			}
+		}
+	}
+
+	sig, err := hex.DecodeString(evt.Sig)
+	if err != nil {
+		return false, fmt.Errorf("signature is invalid hex: %w", err)
+	}
+	if len(sig) != 64 {
+		return false, fmt.Errorf("signature must be 64 bytes, not %d", len(sig))
+	}
+
+	var p [32]byte
+	copy(p[:], pubkeyb)
+
+	var s [64]byte
+	copy(s[:], sig)
+
+	h := sha256.Sum256(evt.Serialize())
+
+	return bip340.Verify(p, h, s)
+}
+
+// Sign signs an event with a given privateKey
+func (evt Event) Sign(privateKey string) error {
+	h := sha256.Sum256(evt.Serialize())
+	s, _ := new(big.Int).SetString(privateKey, 16)
+
+	if s == nil {
+		return errors.New("invalid private key " + privateKey)
+	}
+
+	aux := make([]byte, 32)
+	rand.Read(aux)
+	sig, err := bip340.Sign(s, h, aux)
+	if err != nil {
+		return err
+	}
+
+	evt.Sig = hex.EncodeToString(sig[:])
+	return nil
+}

go.mod

@@ -0,0 +1,8 @@
+module github.com/fiatjaf/go-nostr
+
+go 1.15
+
+require (
+	github.com/fiatjaf/bip340 v1.0.0
+	github.com/gorilla/websocket v1.4.2
+)

go.sum

@@ -0,0 +1,48 @@
+github.com/aead/siphash v1.0.1/go.mod h1:Nywa3cDsYNNK3gaciGTWPwHt0wlpNV15vwmswBAUSII=
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+github.com/btcsuite/btcd v0.0.0-20190109040709-5bda5314ca95/go.mod h1:d3C0AkH6BRcvO8T0UEPu53cnw4IbV63x1bEjildYhO0=
+github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f/go.mod h1:TdznJufoqS23FtqVCzL0ZqgP5MqXbb4fg/WgDys70nA=
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+github.com/fiatjaf/bip340 v1.0.0/go.mod h1:MxAz+5FQUTW4OT2gnCBC6Our486wmqf72ykZIrh7+is=
+github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
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relaypool/relaypool.go

@@ -0,0 +1,243 @@
+package relaypool
+
+import (
+	"encoding/json"
+	"errors"
+	"log"
+
+	"github.com/fiatjaf/go-nostr/event"
+	nostrutils "github.com/fiatjaf/go-nostr/utils"
+	"github.com/gorilla/websocket"
+)
+
+type RelayPool struct {
+	SecretKey *string
+
+	Relays     map[string]Policy
+	websockets map[string]*websocket.Conn
+
+	Events  chan *EventMessage
+	Notices chan *NoticeMessage
+
+	SubscribedKeys   []string
+	SubscribedEvents []string
+}
+
+type Policy struct {
+	SimplePolicy
+	ReadSpecific map[string]SimplePolicy
+}
+
+type SimplePolicy struct {
+	Read  bool
+	Write bool
+}
+
+type EventMessage struct {
+	Event   event.Event
+	Context byte
+	Relay   string
+}
+
+func (em *EventMessage) UnmarshalJSON(b []byte) error {
+	var temp []json.RawMessage
+	if err := json.Unmarshal(b, temp); err != nil {
+		return err
+	}
+	if len(temp) < 2 {
+		return errors.New("message is not an array of 2 or more")
+	}
+	if err := json.Unmarshal(temp[0], em.Event); err != nil {
+		return err
+	}
+	var context string
+	if err := json.Unmarshal(temp[1], &context); err != nil {
+		return err
+	}
+	em.Context = context[0]
+	return nil
+}
+
+type NoticeMessage struct {
+	Message string
+	Relay   string
+}
+
+func (nm *NoticeMessage) UnmarshalJSON(b []byte) error {
+	var temp []json.RawMessage
+	if err := json.Unmarshal(b, temp); err != nil {
+		return err
+	}
+	if len(temp) < 2 {
+		return errors.New("message is not an array of 2 or more")
+	}
+	var tag string
+	if err := json.Unmarshal(temp[0], &tag); err != nil {
+		return err
+	}
+	if tag != "notice" {
+		return errors.New("tag is not 'notice'")
+	}
+
+	if err := json.Unmarshal(temp[1], &nm.Message); err != nil {
+		return err
+	}
+	return nil
+}
+
+// New creates a new RelayPool with no relays in it
+func New() *RelayPool {
+	return &RelayPool{
+		Relays:     make(map[string]Policy),
+		websockets: make(map[string]*websocket.Conn),
+
+		Events:  make(chan *EventMessage),
+		Notices: make(chan *NoticeMessage),
+	}
+}
+
+// Add adds a new relay to the pool, if policy is nil, it will be a simple
+// read+write policy.
+func (r *RelayPool) Add(url string, policy *Policy) {
+	if policy == nil {
+		policy = &Policy{SimplePolicy: SimplePolicy{Read: true, Write: true}}
+	}
+
+	nm := nostrutils.NormalizeURL(url)
+	if nm == "" {
+		return
+	}
+
+	r.Relays[nm] = *policy
+	conn, _, err := websocket.DefaultDialer.Dial(nostrutils.WebsocketURL(url), nil)
+	if err != nil {
+		return
+	}
+
+	defer r.Remove(nm)
+	done := make(chan struct{})
+
+	r.websockets[nm] = conn
+
+	go func() {
+		defer close(done)
+		for {
+			typ, message, err := conn.ReadMessage()
+			if err != nil {
+				log.Println("read error: ", err)
+				return
+			}
+			if typ == websocket.PingMessage {
+				conn.WriteMessage(websocket.PongMessage, nil)
+			}
+
+			if typ != websocket.TextMessage || len(message) == 0 || message[0] != '[' {
+				continue
+			}
+
+			var noticeMessage *NoticeMessage
+			var eventMessage *EventMessage
+			err = json.Unmarshal(message, eventMessage)
+			if err == nil {
+				eventMessage.Relay = nm
+				r.Events <- eventMessage
+			} else {
+				err = json.Unmarshal(message, noticeMessage)
+				if err == nil {
+					noticeMessage.Relay = nm
+					r.Notices <- noticeMessage
+				} else {
+					continue
+				}
+			}
+		}
+	}()
+}
+
+// Remove removes a relay from the pool.
+func (r *RelayPool) Remove(url string) {
+	nm := nostrutils.NormalizeURL(url)
+	if conn, ok := r.websockets[nm]; ok {
+		conn.Close()
+	}
+	delete(r.Relays, nm)
+	delete(r.websockets, nm)
+}
+
+func (r *RelayPool) SubKey(key string) {
+	for _, conn := range r.websockets {
+		conn.WriteMessage(websocket.TextMessage, []byte("sub-key:"+key))
+	}
+}
+
+func (r *RelayPool) UnsubKey(key string) {
+	for _, conn := range r.websockets {
+		conn.WriteMessage(websocket.TextMessage, []byte("unsub-key:"+key))
+	}
+}
+
+func (r *RelayPool) SubEvent(id string) {
+	for _, conn := range r.websockets {
+		conn.WriteMessage(websocket.TextMessage, []byte("sub-event:"+id))
+	}
+}
+
+func (r *RelayPool) ReqFeed(opts map[string]interface{}) {
+	var sopts string
+	if opts == nil {
+		sopts = "{}"
+	} else {
+		jopts, _ := json.Marshal(opts)
+		sopts = string(jopts)
+	}
+
+	for _, conn := range r.websockets {
+		conn.WriteMessage(websocket.TextMessage, []byte("req-feed:"+sopts))
+	}
+}
+
+func (r *RelayPool) ReqEvent(id string, opts map[string]interface{}) {
+	if opts == nil {
+		opts = make(map[string]interface{})
+	}
+	opts["id"] = id
+
+	jopts, _ := json.Marshal(opts)
+	sopts := string(jopts)
+
+	for _, conn := range r.websockets {
+		conn.WriteMessage(websocket.TextMessage, []byte("req-event:"+sopts))
+	}
+}
+
+func (r *RelayPool) ReqKey(key string, opts map[string]interface{}) {
+	if opts == nil {
+		opts = make(map[string]interface{})
+	}
+	opts["key"] = key
+
+	jopts, _ := json.Marshal(opts)
+	sopts := string(jopts)
+
+	for _, conn := range r.websockets {
+		conn.WriteMessage(websocket.TextMessage, []byte("req-key:"+sopts))
+	}
+}
+
+func (r *RelayPool) PublishEvent(evt *event.Event) error {
+	if r.SecretKey == nil && evt.Sig == "" {
+		return errors.New("PublishEvent needs either a signed event to publish or to have been configured with a .SecretKey.")
+	}
+
+	if evt.Sig == "" {
+		evt.Sign(*r.SecretKey)
+	}
+
+	jevt, _ := json.Marshal(evt)
+
+	for _, conn := range r.websockets {
+		conn.WriteMessage(websocket.TextMessage, jevt)
+	}
+
+	return nil
+}

utils/utils.go

@@ -0,0 +1,32 @@
+package nostrutils
+
+import (
+	"net/url"
+	"strings"
+)
+
+func NormalizeURL(u string) string {
+	if !strings.HasPrefix(u, "http") && !strings.HasPrefix(u, "ws") {
+		u = "ws://" + u
+	}
+	p, err := url.Parse(u)
+	if err != nil {
+		return ""
+	}
+
+	if strings.HasSuffix(p.RawPath, "/") {
+		p.RawPath = p.RawPath[0 : len(p.RawPath)-1]
+	}
+
+	if strings.HasSuffix(p.RawPath, "/ws") {
+		p.RawPath = p.RawPath[0 : len(p.RawPath)-3]
+	}
+
+	return p.String()
+}
+
+func WebsocketURL(u string) string {
+	p, _ := url.Parse(NormalizeURL(u))
+	p.RawPath += "/ws"
+	return p.String()
+}