Fix image_proxy

import hmac

import hashlib

from urllib.parse import urlencode

from flask_babel import gettext

from searx import settings

name = gettext("Rest API")

description = gettext("Update REST API")

default_on = True

preference_section = "general"

def proxify(url):

    """helper copied from webapp module"""

    if url.startswith("//"):

        url = "https:" + url

    if not settings.get("result_proxy"):

        return url

    if url.startswith("data:image/"):

        # 50 is an arbitrary number to get only the beginning of the image.

        partial_base64 = url[len("data:image/") : 50].split(";")

        if (

            len(partial_base64) == 2

            and partial_base64[0] in ["gif", "png", "jpeg", "pjpeg", "webp", "tiff", "bmp"]

            and partial_base64[1].startswith("base64,")

        ):

            return url

        else:

            return None

    url_params = dict(mortyurl=url.encode("utf-8"))

    if settings["result_proxy"].get("key"):

        url_params["mortyhash"] = hmac.new(

            settings["result_proxy"]["key"], url.encode("utf-8"), hashlib.sha256

        ).hexdigest()

    return "{0}?{1}".format(settings["result_proxy"]["url"], urlencode(url_params))

def on_result(request, search, result):

    if request.form.get("format") != "json":

        return True

    for attr in ["thumbnail", "thumbnail_src"]:

        if attr in result:

            result[attr] = proxify(result[attr])

    return True

    if url.startswith("//"):

        url = "https:" + url

    if not request.preferences.get_value("image_proxy"):

    if not settings["server"].get("image_proxy"):

        return url

    if url.startswith("data:image/"):