From 2f88fc93cf944f555b4fc6b9d9fb5f08635bd608 Mon Sep 17 00:00:00 2001
From: nom3ad <19239479+nom3ad@users.noreply.github.com>
Date: Wed, 7 Sep 2022 12:26:21 +0530
Subject: [PATCH] add some comments

---
 sshuttle/client.py   |  6 ++++--
 sshuttle/firewall.py |  4 ++--
 sshuttle/helpers.py  |  2 +-
 sshuttle/ssh.py      | 16 +++++++++++-----
 4 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/sshuttle/client.py b/sshuttle/client.py
index a1578df..875f1f5 100644
--- a/sshuttle/client.py
+++ b/sshuttle/client.py
@@ -226,7 +226,10 @@ class FirewallClient:
                 argv_tries.append(argvbase)
                 # runas_path = which("runas")
                 # if runas_path:
-                # argv_tries.append(['runas' , '/noprofile', '/user:Administrator',  'python'])
+                #   argv_tries.append([runas_path , '/noprofile', '/user:Administrator',  'python'])
+                # XXX:attempt to elevate privilege using 'runas' in windows seems not working.
+                # This is due to underlying ShellExecute() Windows api does not allow child process to inherit stdio.
+                # TODO(nom3ad): try to implement another way to achieve this.
             else:
                 # Linux typically uses sudo; OpenBSD uses doas. However, some
                 # Linux distributions are starting to use doas.
@@ -303,7 +306,6 @@ class FirewallClient:
                     socket_share_data = s1.share(self.p.pid)
                     s1.close()
                     socket_share_data_b64 = base64.b64encode(socket_share_data)
-                    # debug3(f"{socket_share_data_b64=}")
                     self.p.stdin.write(socket_share_data_b64 + b'\n')
                     self.p.stdin.flush()
                     return s2.makefile('rwb')
diff --git a/sshuttle/firewall.py b/sshuttle/firewall.py
index 5193b15..4134e3d 100644
--- a/sshuttle/firewall.py
+++ b/sshuttle/firewall.py
@@ -328,6 +328,8 @@ def main(method_name, syslog):
                 user, group, tmark)
 
         try:
+            # For some methods (eg: windivert) firewall setup will be differed / will run asynchronously.
+            # Such method implements wait_for_firewall_ready() to wait until firewall is up and running.
             method.wait_for_firewall_ready()
         except NotImplementedError:
             pass
@@ -347,9 +349,7 @@ def main(method_name, syslog):
         # authentication at shutdown time - that cleanup is important!
         while 1:
             try:
-                debug3("===================================================")
                 line = stdin.readline(128)
-                debug3("===================================================" + str(line))
             except IOError as e:
                 debug3('read from stdin failed: %s' % (e,))
                 return
diff --git a/sshuttle/helpers.py b/sshuttle/helpers.py
index 4dca60e..979c131 100644
--- a/sshuttle/helpers.py
+++ b/sshuttle/helpers.py
@@ -227,8 +227,8 @@ def which(file, mode=os.F_OK | os.X_OK):
 
 def is_admin_user():
     if sys.platform == 'win32':
-        import ctypes
         # https://stackoverflow.com/questions/130763/request-uac-elevation-from-within-a-python-script/41930586#41930586
+        import ctypes
         try:
             return ctypes.windll.shell32.IsUserAnAdmin()
         except Exception:
diff --git a/sshuttle/ssh.py b/sshuttle/ssh.py
index bede68a..3ffb045 100644
--- a/sshuttle/ssh.py
+++ b/sshuttle/ssh.py
@@ -206,11 +206,11 @@ def connect(ssh_cmd, rhostport, python, stderr, add_cmd_delimiter, options):
 
     if sys.platform != 'win32':
         (s1, s2) = socket.socketpair()
+        pstdin, pstdout = os.dup(s1.fileno()), os.dup(s1.fileno())
 
         def preexec_fn():
             # runs in the child process
             s2.close()
-        pstdin, pstdout = os.dup(s1.fileno()), os.dup(s1.fileno())
         s1.close()
 
         def get_serversock():
@@ -218,11 +218,18 @@ def connect(ssh_cmd, rhostport, python, stderr, add_cmd_delimiter, options):
             os.close(pstdout)
             return s2
     else:
+        # In Windows python implementation it seems not possible to use sockets as subprocess stdio
+        # Also select.select() won't work on pipes.
+        # So we have to use both socketpair and pipes together along with reader/writer threads to
+        # stream data between them
+        # NOTE: Their can be a way to use sockets as stdio with some hacks.
+        #   https://stackoverflow.com/questions/4993119/redirect-io-of-process-to-windows-socket
         (s1, s2) = socket.socketpair()
-        preexec_fn = None
         pstdin = ssubprocess.PIPE
         pstdout = ssubprocess.PIPE
 
+        preexec_fn = None
+
         def get_serversock():
             import threading
 
@@ -231,7 +238,7 @@ def connect(ssh_cmd, rhostport, python, stderr, add_cmd_delimiter, options):
                     fd = p.stdout.fileno()
                     for data in iter(lambda: os.read(fd, 16384), b''):
                         s1.sendall(data)
-                        debug3(f"<<<<< p.stdout.read() {len(data)} {data[:min(32,len(data))]}...")
+                        # debug3(f"<<<<< p.stdout.read() {len(data)} {data[:min(32,len(data))]}...")
                 finally:
                     debug2("Thread 'stream_stdout_to_sock' exiting")
                     s1.close()
@@ -240,7 +247,7 @@ def connect(ssh_cmd, rhostport, python, stderr, add_cmd_delimiter, options):
             def stream_sock_to_stdin():
                 try:
                     for data in iter(lambda: s1.recv(16384), b''):
-                        debug3(f">>>>> p.stdout.write() {len(data)} {data[:min(32,len(data))]}...")
+                        # debug3(f">>>>> p.stdout.write() {len(data)} {data[:min(32,len(data))]}...")
                         while data:
                             n = p.stdin.write(data)
                             data = data[n:]
@@ -251,7 +258,6 @@ def connect(ssh_cmd, rhostport, python, stderr, add_cmd_delimiter, options):
 
             threading.Thread(target=stream_stdout_to_sock,  name='stream_stdout_to_sock', daemon=True).start()
             threading.Thread(target=stream_sock_to_stdin, name='stream_sock_to_stdin',  daemon=True).start()
-            # s2.setblocking(False)
             return s2
 
     # https://stackoverflow.com/questions/48671215/howto-workaround-of-close-fds-true-and-redirect-stdout-stderr-on-windows