[sans-io] TLS: add handshake fuzzing

mitmproxy/proxy2/layers/tls.py

@@ -85,7 +85,10 @@ def parse_client_hello(data: bytes) -> Optional[net_tls.ClientHello]:
     # Check if ClientHello is complete
     client_hello = get_client_hello(data)
     if client_hello:
+        try:
             return net_tls.ClientHello(client_hello[4:])
+        except EOFError as e:
+            raise ValueError("Invalid ClientHello") from e
     return None
 
 

test/mitmproxy/proxy2/conftest.py

@@ -1,4 +1,7 @@
+import os
+
 import pytest
+from hypothesis import settings
 
 from mitmproxy import options
 from mitmproxy.addons.core import Core
@@ -21,3 +24,8 @@ def tctx() -> context.Context:
         ),
         opts
     )
+
+
+settings.register_profile("fast", max_examples=10)
+settings.register_profile("deep", max_examples=100_000, deadline=None)
+settings.load_profile(os.getenv("HYPOTHESIS_PROFILE", "fast"))

test/mitmproxy/proxy2/layers/http/test_http_fuzz.py

@@ -1,9 +1,8 @@
-import os
 from typing import Tuple, Dict, Any
 
 import pytest
 from h2.settings import SettingCodes
-from hypothesis import example, given, settings
+from hypothesis import example, given
 from hypothesis.strategies import binary, booleans, composite, dictionaries, integers, lists, sampled_from, sets, text, \
     data
 
@@ -21,10 +20,6 @@ from test.mitmproxy.proxy2.layers.http.test_http2 import make_h2, example_respon
     start_h2_client
 from test.mitmproxy.proxy2.tutils import Placeholder, Playbook, reply, _TracebackInPlaybook, _eq
 
-settings.register_profile("fast", max_examples=10)
-settings.register_profile("deep", max_examples=100_000, deadline=None)
-settings.load_profile(os.getenv("HYPOTHESIS_PROFILE", "fast"))
-
 opts = options.Options()
 Proxyserver().load(opts)
 

test/mitmproxy/proxy2/layers/test_tls_fuzz.py

@@ -0,0 +1,26 @@
+from hypothesis import given, example
+from hypothesis.strategies import binary, integers
+
+from mitmproxy.net.tls import ClientHello
+from mitmproxy.proxy2.layers.tls import parse_client_hello
+
+client_hello_with_extensions = bytes.fromhex(
+    "16030300bb"  # record layer
+    "010000b7"  # handshake layer
+    "03033b70638d2523e1cba15f8364868295305e9c52aceabda4b5147210abc783e6e1000022c02bc02fc02cc030"
+    "cca9cca8cc14cc13c009c013c00ac014009c009d002f0035000a0100006cff0100010000000010000e00000b65"
+    "78616d706c652e636f6d0017000000230000000d00120010060106030501050304010403020102030005000501"
+    "00000000001200000010000e000c02683208687474702f312e3175500000000b00020100000a00080006001d00"
+    "170018"
+)
+
+
+@given(i=integers(0, len(client_hello_with_extensions)), data=binary())
+@example(i=183, data=b'\x00\x00\x00\x00\x00\x00\x00\x00\x00')
+def test_fuzz_h2_request_chunks(i, data):
+    try:
+        ch = parse_client_hello(client_hello_with_extensions[:i] + data)
+    except ValueError:
+        pass
+    else:
+        assert ch is None or isinstance(ch, ClientHello)