feat(offline_download): add simple http tool (close #4002)

internal/offline_download/http/util.go

@@ -0,0 +1,21 @@
+package http
+
+import (
+	"fmt"
+	"mime"
+)
+
+func parseFilenameFromContentDisposition(contentDisposition string) (string, error) {
+	if contentDisposition == "" {
+		return "", fmt.Errorf("Content-Disposition is empty")
+	}
+	_, params, err := mime.ParseMediaType(contentDisposition)
+	if err != nil {
+		return "", err
+	}
+	filename := params["filename"]
+	if filename == "" {
+		return "", fmt.Errorf("filename not found in Content-Disposition: [%s]", contentDisposition)
+	}
+	return filename, nil
+}