Refactor to CensorshipCircumvention and Meek classes. Use Meek domain fronting when requesting bridges in frontend

cli/onionshare_cli/meek.py

@@ -0,0 +1,144 @@
+# -*- coding: utf-8 -*-
+"""
+OnionShare | https://onionshare.org/
+
+Copyright (C) 2014-2021 Micah Lee, et al. <micah@micahflee.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+import subprocess
+from queue import Queue, Empty
+from threading import Thread
+
+
+class Meek(object):
+    """
+    The Meek object starts the meek-client as a subprocess.
+    This process is used to do domain-fronting to connect to
+    the Tor APIs for censorship circumvention and retrieving
+    bridges, before connecting to Tor.
+    """
+
+    def __init__(self, common):
+        """
+        Set up the Meek object
+        """
+
+        self.common = common
+        self.common.log("Meek", "__init__")
+
+        get_tor_paths = self.common.get_tor_paths
+        (
+            self.tor_path,
+            self.tor_geo_ip_file_path,
+            self.tor_geo_ipv6_file_path,
+            self.obfs4proxy_file_path,
+            self.snowflake_file_path,
+            self.meek_client_file_path,
+        ) = get_tor_paths()
+
+        self.meek_proxies = {}
+        self.meek_url = "https://moat.torproject.org.global.prod.fastly.net/"
+        self.meek_front = "cdn.sstatic.net"
+        self.meek_env = {
+            "TOR_PT_MANAGED_TRANSPORT_VER": "1",
+            "TOR_PT_CLIENT_TRANSPORTS": "meek",
+        }
+        self.meek_host = "127.0.0.1"
+        self.meek_port = None
+
+    def start(self):
+        """
+        Start the Meek Client and populate the SOCKS proxies dict
+        for use with requests to the Tor Moat API.
+        """
+        # Small method to read stdout from the subprocess.
+        # We use this to obtain the random port that Meek
+        # started on
+        def enqueue_output(out, queue):
+            for line in iter(out.readline, b""):
+                queue.put(line)
+            out.close()
+
+        # Start the Meek Client as a subprocess.
+
+        if self.common.platform == "Windows":
+            # In Windows, hide console window when opening tor.exe subprocess
+            startupinfo = subprocess.STARTUPINFO()
+            startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
+            self.meek_proc = subprocess.Popen(
+                [
+                    self.meek_client_file_path,
+                    "--url",
+                    self.meek_url,
+                    "--front",
+                    self.meek_front,
+                ],
+                stdout=subprocess.PIPE,
+                startupinfo=startupinfo,
+                bufsize=1,
+                env=self.meek_env,
+                text=True,
+            )
+        else:
+            self.meek_proc = subprocess.Popen(
+                [
+                    self.meek_client_file_path,
+                    "--url",
+                    self.meek_url,
+                    "--front",
+                    self.meek_front,
+                ],
+                stdout=subprocess.PIPE,
+                bufsize=1,
+                env=self.meek_env,
+                text=True,
+            )
+
+        # Queue up the stdout from the subprocess for polling later
+        q = Queue()
+        t = Thread(target=enqueue_output, args=(self.meek_proc.stdout, q))
+        t.daemon = True  # thread dies with the program
+        t.start()
+
+        while True:
+            # read stdout without blocking
+            try:
+                line = q.get_nowait()
+            except Empty:
+                # no stdout yet?
+                pass
+            else:  # we got stdout
+                if "CMETHOD meek socks5" in line:
+                    self.meek_host = line.split(" ")[3].split(":")[0]
+                    self.meek_port = line.split(" ")[3].split(":")[1]
+                    self.common.log("Meek", "start", f"Meek host is {self.meek_host}")
+                    self.common.log("Meek", "start", f"Meek port is {self.meek_port}")
+                    break
+
+        if self.meek_port:
+            self.meek_proxies = {
+                "http": f"socks5h://{self.meek_host}:{self.meek_port}",
+                "https": f"socks5h://{self.meek_host}:{self.meek_port}",
+            }
+        else:
+            self.common.log("Meek", "start", "Could not obtain the meek port")
+            raise MeekNotRunning()
+
+
+class MeekNotRunning(Exception):
+    """
+    We were unable to start Meek or obtain the port
+    number it started on, in order to do domain fronting.
+    """