sign url

backend/internal/service/presignedurl.go

@@ -0,0 +1,41 @@
+package service
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"time"
+)
+
+const secret = "thisismyrandomstring"
+
+func sign(fileID string, expires int64, secret string) string {
+	data := fmt.Sprintf("%s:%d", fileID, expires)
+	mac := hmac.New(sha256.New, []byte(secret))
+	mac.Write([]byte(data))
+	return hex.EncodeToString(mac.Sum(nil))
+}
+
+func GenerateFileDownloadUrl(fileID string) string {
+	expires := time.Now().Add(10 * time.Minute).Unix()
+	sig := sign(fileID, expires, secret)
+
+	url := fmt.Sprintf(
+		"http://192.168.1.142:8080/api/v1/files/%s?expires=%d&sig=%s",
+		fileID,
+		expires,
+		sig,
+	)
+
+	return url
+}
+
+func Validate(fileID, sig string, expires int64) bool {
+	if time.Now().Unix() > expires {
+		return false
+	}
+
+	expected := sign(fileID, expires, secret)
+	return hmac.Equal([]byte(sig), []byte(expected))
+}