Add configuration property for PNG/JPG thumbnail used in LNURL-pay metadata

README.md

@@ -63,6 +63,9 @@ Instead of the path to the macaroon and cert files you can also provide the hex
 #### Other configuration
 
 - `static-path`: Path to a folder that you want to serve with LnMe (e.g. /home/bitcoin/lnme/website). Use this if you want to customize your ⚡website. default: disabled
+- `lnurlp-min-sendable`: Min sendable amount in sats via LNURL-pay. (default: 1)
+- `lnurlp-max-sendable`: Max sendable amount in sats via LNURL-pay. (default: 1000000)
+- `lnurlp-thumbnail-dir`: Path to a PNG thumbnail directory for LNURL-pay metadata. 
 - `lnurlp-comment-allowed`: Allowed length of LNURL-pay comments, maximum around [~2000 characters](https://stackoverflow.com/a/417184). (default: 210)
 - `disable-website`: Disable the default LnMe website. Disable the website if you only want to embed the LnMe widget on your existing website.
 - `disable-cors`: Disable CORS headers. (default: false)

ln/lnd.go

@@ -47,14 +47,14 @@ type LNDclient struct {
 }
 
 // AddInvoice generates an invoice with the given price and memo.
-func (c LNDclient) AddInvoice(value int64, memo string, descriptionHash []byte) (Invoice, error) {
+func (c LNDclient) AddInvoice(msats int64, memo string, descriptionHash []byte) (Invoice, error) {
 	result := Invoice{}
 
-	stdOutLogger.Printf("Adding invoice: memo=%s value=%v", memo, value)
+	stdOutLogger.Printf("Adding invoice: memo=%s msats=%v", memo, msats)
 	invoice := lnrpc.Invoice{
 		Memo:            memo,
 		DescriptionHash: descriptionHash,
-		Value:           value,
+		ValueMsat:       msats,
 	}
 	res, err := c.lndClient.AddInvoice(c.ctx, &invoice)
 	if err != nil {

lnme.go

@@ -117,7 +117,7 @@ func main() {
 			return c.JSON(http.StatusBadRequest, "Bad request")
 		}
 
-		invoice, err := lnClient.AddInvoice(i.Value, i.Memo, nil)
+		invoice, err := lnClient.AddInvoice(msats(i.Value), i.Memo, nil)
 		if err != nil {
 			stdOutLogger.Printf("Error creating invoice: %s", err)
 			return c.JSON(http.StatusInternalServerError, "Error adding invoice")
@@ -162,15 +162,26 @@ func main() {
 			}
 			name := c.Param("name")
 			lightningAddress := name + "@" + host
-			lnurlMetadata := "[[\"text/identifier\", \"" + lightningAddress + "\"], [\"text/plain\", \"Sats for " + lightningAddress + "\"]]"
+			lnurlpMinSendable := msats(cfg.Int64("lnurlp-min-sendable"))
+			lnurlpMaxSendable := msats(cfg.Int64("lnurlp-max-sendable"))
+			lnurlpThumbnailPath := cfg.String("lnurlp-thumbnail-dir") + "/" + name + ".png"
+			lnurlpThumbnailData, err := os.ReadFile(lnurlpThumbnailPath)
+			if lnurlpThumbnailPath != "" && err != nil {
+				stdOutLogger.Println("Error reading thumbnail:", err)
+			}
+			lnurlMetadata := lnurl.Metadata{}.
+				Identifier(lightningAddress).
+				Description("Sats for " + lightningAddress).
+				Thumbnail(lnurlpThumbnailData).
+				String()
 			lnurlpCommentAllowed := cfg.Int64("lnurlp-comment-allowed")
 
 			if amount := c.QueryParam("amount"); amount == "" {
 				lnurlPayResponse1 := lnurl.LNURLPayResponse1{
 					LNURLResponse:   lnurl.LNURLResponse{Status: "OK"},
 					Callback:        fmt.Sprintf("%s://%s%s", proto, host, c.Request().URL.Path),
-					MinSendable:     1000,
-					MaxSendable:     100000000,
+					MinSendable:     lnurlpMinSendable,
+					MaxSendable:     lnurlpMaxSendable,
 					EncodedMetadata: lnurlMetadata,
 					CommentAllowed:  lnurlpCommentAllowed,
 					Tag:             "payRequest",
@@ -179,18 +190,17 @@ func main() {
 			} else {
 				stdOutLogger.Printf("New LightningAddress request amount: %s", amount)
 				msats, err := strconv.ParseInt(amount, 10, 64)
-				if err != nil || msats < 1000 {
+				if err != nil || msats < lnurlpMinSendable || msats > lnurlpMaxSendable {
 					stdOutLogger.Printf("Invalid amount: %s", amount)
 					return c.JSON(http.StatusOK, lnurl.LNURLErrorResponse{Status: "ERROR", Reason: "Invalid Amount"})
 				}
-				sats := msats / 1000 // we need sats
 				comment := c.QueryParam("comment")
 				if commentLength := int64(len(comment)); commentLength > lnurlpCommentAllowed {
 					stdOutLogger.Printf("Invalid comment length: %d", commentLength)
 					return c.JSON(http.StatusOK, lnurl.LNURLErrorResponse{Status: "ERROR", Reason: "Invalid comment length"})
 				}
 				metadataHash := sha256.Sum256([]byte(lnurlMetadata))
-				invoice, err := lnClient.AddInvoice(sats, comment, metadataHash[:])
+				invoice, err := lnClient.AddInvoice(msats, comment, metadataHash[:])
 				if err != nil {
 					stdOutLogger.Printf("Error creating invoice: %s", err)
 					return c.JSON(http.StatusOK, lnurl.LNURLErrorResponse{Status: "ERROR", Reason: "Server Error"})
@@ -235,6 +245,10 @@ func main() {
 	e.Logger.Fatal(e.Start(listen))
 }
 
+func msats(sats int64) int64 {
+	return sats * 1000
+}
+
 func LoadConfig() *koanf.Koanf {
 	k := koanf.New(".")
 
@@ -244,6 +258,9 @@ func LoadConfig() *koanf.Koanf {
 	f.String("lnd-macaroon", "", "HEX string of LND macaroon file.")
 	f.String("lnd-cert-path", "~/.lnd/tls.cert", "Path to the LND tls.cert file.")
 	f.String("lnd-cert", "", "HEX string of LND tls cert file.")
+	f.Int64("lnurlp-min-sendable", 1, "Min sendable amount in sats via LNURL-pay.")
+	f.Int64("lnurlp-max-sendable", 1000000, "Max sendable amount in sats via LNURL-pay.")
+	f.String("lnurlp-thumbnail-dir", "", "Path to a PNG thumbnail directory for LNURL-pay metadata.")
 	f.Int64("lnurlp-comment-allowed", 210, "Allowed length of LNURL-pay comments.")
 	f.Bool("disable-website", false, "Disable default embedded website.")
 	f.Bool("disable-ln-address", false, "Disable Lightning Address handling")

lnurl/types.go

@@ -2,7 +2,12 @@
 // only using the LNURL types here
 package lnurl
 
-import "net/url"
+import (
+	"encoding/base64"
+	"encoding/json"
+	"net/http"
+	"net/url"
+)
 
 type LNURLResponse struct {
 	Status string `json:"status,omitempty"`
@@ -50,3 +55,28 @@ type LNURLErrorResponse struct {
 }
 
 type Metadata [][]string
+
+func (metadata Metadata) Identifier(identifier string) Metadata {
+	return append(metadata, []string{"text/identifier", identifier})
+}
+
+func (metadata Metadata) Description(description string) Metadata {
+	return append(metadata, []string{"text/plain", description})
+}
+
+func (metadata Metadata) Thumbnail(imageData []byte) Metadata {
+	if len(imageData) == 0 {
+		return metadata
+	}
+
+	mimeType := http.DetectContentType(imageData)
+	imageDataBase64 := base64.StdEncoding.EncodeToString(imageData)
+
+	return append(metadata, []string{mimeType + ";base64", imageDataBase64})
+}
+
+func (metadata Metadata) String() string {
+	bytes, _ := json.Marshal(metadata)
+
+	return string(bytes)
+}