Lnurl (#30)

* dunno * fix user lookup * lnurl port * fix host * add config example * amount error msg * print stack trace * lnurl_public_server * remove public server ! * smaller * smaller * webhooks * add tag to response * add EncodedMetadata and Status * add success action and empty routes * update invoice memo * description hash * dunno * fix user lookup * lnurl port * fix host * amount error msg * add config example * print stack trace * lnurl_public_server * remove public server ! * smaller * smaller * webhooks * add tag to response * add EncodedMetadata and Status * add success action and empty routes * update invoice memo * description hash Co-authored-by: gohumble <[email protected]>
BlackPeter13 · Aug 30, 2021 · 77c3a50 · 77c3a50
1 parent f3b3e34
commit 77c3a50
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Showing 2 changed files with 86 additions and 49 deletions.
diff --git a/internal/lnbits/types.go b/internal/lnbits/types.go
@@ -34,10 +34,11 @@ func (u *User) ResetState() {
 }
 
 type InvoiceParams struct {
-	Out     bool   `json:"out"`
-	Amount  int64  `json:"amount"`
-	Memo    string `json:"memo"` // the invoice description.
-	Webhook string `json:"webhook,omitempty"`
+	Out             bool   `json:"out"`                        // must be True if invoice is payed, False if invoice is received
+	Amount          int64  `json:"amount"`                     // amount in MilliSatoshi
+	Memo            string `json:"memo,omitempty"`             // the invoice memo.
+	Webhook         string `json:"webhook,omitempty"`          // the webhook to fire back to when payment is received.
+	DescriptionHash string `json:"description_hash,omitempty"` // the invoice description hash.
 }
 
 type PaymentParams struct {

diff --git a/internal/lnurl/server.go b/internal/lnurl/server.go
@@ -1,6 +1,8 @@
 package lnurl
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"net"
@@ -61,19 +63,84 @@ func NewServer(lnurlserver string, webhookserver string, bot *tb.Bot, client *ln
 func (w *Server) newRouter() *mux.Router {
 	router := mux.NewRouter()
 	router.HandleFunc(lnurlEndpoint+"/{username}", w.handleLnUrl).Methods(http.MethodGet)
+	router.HandleFunc("/@{username}", w.handleLnUrl).Methods(http.MethodGet)
 	//router.HandleFunc("/.well-know/lnurlp/{username}", w.handleLnUrl).Methods(http.MethodGet)
 	return router
 }
 
 func (w Server) handleLnUrl(writer http.ResponseWriter, request *http.Request) {
 	if request.URL.RawQuery == "" {
-		w.createInitialLNURLPayResponse(writer, request)
+		var err error
+		err = w.serveLNURLpFirst(writer, request)
+		if err != nil {
+			log.Errorln(err)
+			return
+		}
 	} else {
-		w.createLNURLPayResponse(writer, request)
+		w.serveLNURLpSecond(writer, request)
+	}
+}
+
+// descriptionHash is the SHA256 hash of the metadata
+func (w Server) descriptionHash(metadata lnurl.Metadata, writer http.ResponseWriter) string {
+	jsonMeta, err := json.Marshal(metadata)
+	if err != nil {
+		writer.WriteHeader(400)
+		return ""
+	}
+	hash := sha256.Sum256([]byte(string(jsonMeta)))
+	hash_string := hex.EncodeToString(hash[:])
+	return hash_string
+}
+
+// metaData returns the metadata that is sent in the first response
+// and is used again in the second response to verify the description hash
+func (w Server) metaData(request *http.Request) lnurl.Metadata {
+	vars := mux.Vars(request)
+	return lnurl.Metadata{{"text/identifier", fmt.Sprintf("%[email protected]", vars["username"])}, {"text/plain", fmt.Sprintf("Pay to %s@%s", vars["username"], w.callbackUrl)}}
+}
+
+// serveLNURLpFirst serves the first part of the LNURLp protocol with the endpoint
+// to call and the metadata that matches the description hash of the second response
+func (w Server) serveLNURLpFirst(writer http.ResponseWriter, request *http.Request) error {
+	vars := mux.Vars(request)
+
+	callback := fmt.Sprintf("%s%s/%s", w.callbackUrl, lnurlEndpoint, vars["username"])
+	callbackURL, err := url.Parse(callback)
+	if err != nil {
+		log.Errorln("callback is not a valid URL")
+		writer.WriteHeader(400)
+		return err
+	}
+	metadata := w.metaData(request)
+	jsonMeta, err := json.Marshal(metadata)
+	if err != nil {
+		writer.WriteHeader(400)
+		return err
+	}
+
+	resp := lnurl.LNURLPayResponse1{
+		LNURLResponse:   lnurl.LNURLResponse{Status: "OK"},
+		Tag:             "payRequest",
+		Callback:        fmt.Sprintf("https://%s", callback),
+		CallbackURL:     callbackURL,
+		MinSendable:     minSendable,
+		MaxSendable:     MaxSendable,
+		CommentAllowed:  512,
+		EncodedMetadata: string(jsonMeta),
+	}
+	jsonResponse, err := json.Marshal(resp)
+	if err != nil {
+		writer.WriteHeader(400)
+		return err
 	}
+	writer.WriteHeader(200)
+	writer.Write(jsonResponse)
+	return nil
 }
 
-func (w Server) createLNURLPayResponse(writer http.ResponseWriter, request *http.Request) {
+// serveLNURLpSecond serves the second LNURL response with the payment request with the correct description hash
+func (w Server) serveLNURLpSecond(writer http.ResponseWriter, request *http.Request) {
 	vars := mux.Vars(request)
 	user := &lnbits.User{}
 	tx := w.database.Where("telegram_username = ?", vars["username"]).First(user)
@@ -88,7 +155,7 @@ func (w Server) createLNURLPayResponse(writer http.ResponseWriter, request *http
 	stringAmount := request.FormValue("amount")
 	amount, err := strconv.Atoi(stringAmount)
 	if err != nil {
-		errmsg := fmt.Sprintf("[createLNURLPayResponse] Couldn't cast amount to int")
+		errmsg := fmt.Sprintf("[serveLNURLpSecond] Couldn't cast amount to int")
 		log.Warnln(errmsg)
 		return
 	}
@@ -97,22 +164,26 @@ func (w Server) createLNURLPayResponse(writer http.ResponseWriter, request *http
 
 	if amount < minSendable || amount > MaxSendable {
 		// amount is not ok
-		errmsg := fmt.Sprintf("[createLNURLPayResponse] Amount out of bounds")
+		errmsg := fmt.Sprintf("[serveLNURLpSecond] Amount out of bounds")
 		log.Warnln(errmsg)
 		resp = lnurl.LNURLPayResponse2{
 			LNURLResponse: lnurl.LNURLResponse{Status: "ERROR", Reason: fmt.Sprintf("Amount out of bounds (min: %d mSat, max: %d mSat).", minSendable, MaxSendable)},
 		}
 	} else {
 		// amount is ok
+
+		// the same description_hash needs to be built in the second request
+		metadata := w.metaData(request)
+		hash_string := w.descriptionHash(metadata, writer)
 		invoice, err := user.Wallet.Invoice(
 			lnbits.InvoiceParams{
-				Amount:  int64(amount / 1000),
-				Out:     false,
-				Memo:    fmt.Sprintf("Pay to %s@%s", vars["username"], w.callbackUrl),
-				Webhook: w.WebhookServer},
+				Amount:          int64(amount / 1000),
+				Out:             false,
+				DescriptionHash: hash_string,
+				Webhook:         w.WebhookServer},
 			*user.Wallet)
 		if err != nil {
-			errmsg := fmt.Sprintf("[createLNURLPayResponse] Couldn't create invoice: %s", err.Error())
+			errmsg := fmt.Sprintf("[serveLNURLpSecond] Couldn't create invoice: %s", err.Error())
 			log.Warnln(errmsg)
 			resp = lnurl.LNURLPayResponse2{
 				LNURLResponse: lnurl.LNURLResponse{Status: "ERROR", Reason: "Couldn't create invoice."},
@@ -134,38 +205,3 @@ func (w Server) createLNURLPayResponse(writer http.ResponseWriter, request *http
 	}
 	writer.Write(jsonResponse)
 }
-
-func (w Server) createInitialLNURLPayResponse(writer http.ResponseWriter, request *http.Request) {
-	vars := mux.Vars(request)
-
-	callback := fmt.Sprintf("%s%s/%s", w.callbackUrl, lnurlEndpoint, vars["username"])
-	callbackURL, err := url.Parse(callback)
-	if err != nil {
-		log.Errorln("callback is not a valid URL")
-		writer.WriteHeader(400)
-		return
-	}
-	metadata := lnurl.Metadata{{fmt.Sprintf("Pay to %s@%s", vars["username"], w.callbackUrl)}}
-	jsonMeta, err := json.Marshal(metadata)
-	if err != nil {
-		writer.WriteHeader(400)
-		return
-	}
-	resp := lnurl.LNURLPayResponse1{
-		LNURLResponse:   lnurl.LNURLResponse{Status: "OK"},
-		Tag:             "payRequest",
-		Callback:        fmt.Sprintf("https://%s", callback),
-		CallbackURL:     callbackURL,
-		MinSendable:     minSendable,
-		MaxSendable:     MaxSendable,
-		CommentAllowed:  512,
-		EncodedMetadata: string(jsonMeta),
-	}
-	jsonResponse, err := json.Marshal(resp)
-	if err != nil {
-		writer.WriteHeader(400)
-		return
-	}
-	writer.WriteHeader(200)
-	writer.Write(jsonResponse)
-}