manually read tls clienthello [wip]

1 files changed, 52 insertions, 0 deletions

diff --git a/libmproxy/contrib/tls/utils.py b/libmproxy/contrib/tls/utils.py
new file mode 100644
index 00000000..a971af49
--- /dev/null
+++ b/libmproxy/contrib/tls/utils.py
@@ -0,0 +1,52 @@
+# This file is dual licensed under the terms of the Apache License, Version
+# 2.0, and the BSD License. See the LICENSE file in the root of this repository
+# for complete details.
+
+from __future__ import absolute_import, division, print_function
+
+import construct
+
+import six
+
+
+class _UBInt24(construct.Adapter):
+    def _encode(self, obj, context):
+        return (
+            six.int2byte((obj & 0xFF0000) >> 16) +
+            six.int2byte((obj & 0x00FF00) >> 8) +
+            six.int2byte(obj & 0x0000FF)
+        )
+
+    def _decode(self, obj, context):
+        obj = bytearray(obj)
+        return (obj[0] << 16 | obj[1] << 8 | obj[2])
+
+
+def UBInt24(name):  # noqa
+    return _UBInt24(construct.Bytes(name, 3))
+
+
+def LengthPrefixedArray(subcon, length_field=construct.UBInt8("length")):
+    """
+    An array prefixed by a byte length field.
+
+    In contrast to construct.macros.PrefixedArray,
+    the length field signifies the number of bytes, not the number of elements.
+    """
+    subcon_with_pos = construct.Struct(
+        subcon.name,
+        construct.Embed(subcon),
+        construct.Anchor("__current_pos")
+    )
+
+    return construct.Embed(
+        construct.Struct(
+            "",
+            length_field,
+            construct.Anchor("__start_pos"),
+            construct.RepeatUntil(
+                lambda obj, ctx: obj.__current_pos == ctx.__start_pos + getattr(ctx, length_field.name),
+                subcon_with_pos
+            ),
+        )
+    )
\ No newline at end of file