Files
rea/bridge/mitmproxy/capture.py
T
Kaoru0822andClaude Opus 5.5 e1fb40460d fix(capture): skip special-scheme leading slashes before userinfo
Ending the authority at a backslash exposed a credential: for
`https://\user:pass@host/path`, WHATWG parsing skips every leading "/"
or "\" after a special scheme (and in scheme-relative references), so
`user:pass` is userinfo, but the new boundary stopped at the first
backslash and found no "@". The same applied to `https:\\user:pass@host`
and `https:user:pass@host`.

Start the authority after that whole slash run for non-file special
schemes and scheme-relative references. File URLs keep their "//"
boundary because they carry no userinfo. Load the adapter in tests with
fresh mitmproxy stand-ins scoped to its import instead of leaving them
in sys.modules.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-13 11:25:05 +00:00

259 lines
12 KiB
Python

"""REA offline adapter using mitmproxy's unchanged native tnetstring decoder.
No FlowReader migrations, HAR conversion, proxy listener, or target requests.
The containing mitmdump process and its configuration directory are REA-owned.
"""
import base64
import hashlib
import json
import math
import re
import resource
from pathlib import Path
from mitmproxy import ctx, version
from mitmproxy.io import tnetstring
PROFILE = "12.2.3"
OUTPUT_BYTES = 96 * 1024 * 1024
CREDENTIALS = {b"authorization", b"proxy-authorization", b"cookie", b"set-cookie"}
class CaptureFailure(Exception):
def __init__(self, reason, message, pointer=""):
self.reason, self.pointer = reason, pointer
super().__init__(message)
def pointer(parent, key):
return parent + "/" + str(key).replace("~", "~0").replace("/", "~1")
class BoundedReader:
"""Refuse malicious declared lengths before the upstream parser allocates."""
def __init__(self, handle, size):
self.handle, self.size = handle, size
def read(self, count):
if count < 0 or count > self.size - self.handle.tell():
raise CaptureFailure("format", "Native record declares bytes beyond the retained capture.")
return self.handle.read(count)
SPECIAL_SCHEMES = {"ftp", "file", "http", "https", "ws", "wss"}
SCHEME_PREFIX = r"^[\x00-\x20]*([a-z][a-z0-9+.-]*):"
URL_PREFIX = r"^([\x00-\x20]*(?:([a-z][a-z0-9+.-]*):)?//)"
def authority_start(text):
"""Return where an authority begins and whether it is special, or None.
Follows WHATWG URL parsing as src/domain/recordedTransportUrl.ts does:
special schemes (and scheme-relative references) skip every leading "/"
or "\\" before the authority, so `https://\\user:pass@host` still has
userinfo. File URLs carry no userinfo and keep their "//" boundary.
"""
scheme = re.match(SCHEME_PREFIX, text, flags=re.I)
name = scheme.group(1).lower() if scheme is not None else None
if name is not None and name in SPECIAL_SCHEMES and name != "file":
start = scheme.end()
else:
prefix = re.match(URL_PREFIX, text, flags=re.I)
if prefix is None:
return None
if prefix.group(2) is not None:
return prefix.end(), prefix.group(2).lower() in SPECIAL_SCHEMES
start = prefix.end()
while start < len(text) and text[start] in "/\\":
start += 1
return start, True
def without_userinfo(value):
"""Remove an authority's userinfo using the WHATWG authority boundary.
Special schemes and scheme-relative references also end the authority
at a backslash, so later path text containing "@" is not userinfo.
"""
binary = isinstance(value, bytes)
text = value.decode("latin-1") if binary else value
located = authority_start(text)
if located is None:
return value
start, special = located
terminators = "/?#\\" if special else "/?#"
end = start
while end < len(text) and text[end] not in terminators:
end += 1
at = text.rfind("@", start, end)
if at < 0:
return value
safe = text[:start] + text[at + 1 :]
return safe.encode("latin-1") if binary else safe
def project_record(state, secrets):
binaries, numbers, redactions = [], [], []
byte_secrets = []
for secret in secrets:
try:
byte_secrets.append(secret.encode("utf-8", errors="strict"))
except UnicodeEncodeError:
# Non-scalar JSON strings have no UTF-8 byte representation.
# Keep them in secrets for the ordinary string projection.
pass
def redact(text, path, original):
if any(secret in text or secret in original for secret in secrets):
redactions.append({"pointer": path, "reason": "explicit-sensitive-value"})
return None
return text
def transport_value(value, path, transport_url):
if not (transport_url or re.fullmatch(r"/(?:backup/)*request/(?:path|authority)", path)):
return value, False
binary = isinstance(value, bytes)
separator = b"@" if binary else "@"
safe_url = without_userinfo(value)
if path.endswith("/authority") and separator in safe_url:
safe_url = safe_url.rsplit(separator, 1)[1]
changed = safe_url != value
if changed:
redactions.append({"pointer": path, "reason": "transport-credential"})
return safe_url, changed
def validate_omitted(value, path, depth):
before = len(binaries), len(numbers), len(redactions)
visit(value, path, depth)
del binaries[before[0]:]
del numbers[before[1]:]
del redactions[before[2]:]
def visit(value, path, depth=0, credential=False, transport_url=False):
if depth > 64:
raise CaptureFailure("input-limit", "Native capture exceeds the 64-level evidence nesting budget.", path)
if credential:
validate_omitted(value, path, depth)
redactions.append({"pointer": path, "reason": "transport-credential"})
if isinstance(value, bytes):
binaries.append({"pointer": path, "representation": "producer-bytes", "state": "redacted", "content_base64": None, "bytes": None, "sha256": None})
return None
if isinstance(value, bytes):
safe_bytes, credential_url = transport_value(value, path, transport_url)
content_base64 = base64.b64encode(value).decode("ascii")
digest = hashlib.sha256(value).hexdigest()
hidden = any(secret in value or secret in safe_bytes for secret in byte_secrets) or any(secret in content_base64 or secret in digest or secret in str(len(value)) for secret in secrets)
safe_text = None
try:
safe_text = safe_bytes.decode("utf-8", errors="strict")
except UnicodeDecodeError:
pass
if hidden:
redactions.append({"pointer": path, "reason": "explicit-sensitive-value"})
exclude = hidden or credential_url
binaries.append({"pointer": path, "representation": "producer-bytes", "state": "redacted" if exclude else "retained", "content_base64": None if exclude else content_base64, "bytes": None if exclude else len(value), "sha256": None if exclude else digest})
if hidden:
return None
return safe_text
if isinstance(value, str):
safe_text, _ = transport_value(value, path, transport_url)
return redact(safe_text, path, value)
if isinstance(value, bool) or value is None:
return value
if isinstance(value, (int, float)):
literal = repr(value)
if any(secret in literal for secret in secrets):
redactions.append({"pointer": path, "reason": "explicit-sensitive-value"})
return None
numbers.append({"pointer": path, "producer_type": "integer" if isinstance(value, int) else "float", "literal": literal})
return value if (abs(value) <= 9007199254740991 if isinstance(value, int) else math.isfinite(value)) else None
if isinstance(value, (list, tuple)):
fields = re.fullmatch(r"/(?:backup/)*(?:request|response)/(?:headers|trailers)", path)
if fields:
result = []
for index, field in enumerate(value):
if not isinstance(field, (list, tuple)) or len(field) != 2 or not isinstance(field[0], bytes):
raise CaptureFailure("format", "Native header/trailer is not an ordered byte pair.", pointer(path, index))
result.append([visit(field[0], pointer(pointer(path, index), 0), depth + 2), visit(field[1], pointer(pointer(path, index), 1), depth + 2, field[0].lower() in CREDENTIALS, field[0].lower() in {b"location", b"referer", b"origin"})])
return result
return [visit(item, pointer(path, index), depth + 1) for index, item in enumerate(value)]
if isinstance(value, dict):
result = {}
for key, item in value.items():
if not isinstance(key, str):
raise CaptureFailure("format", "Native record has a non-string dictionary key.", path)
if any(secret in key for secret in secrets):
# Validate the omitted subtree too, then discard all of its
# coordinates rather than inventing a replacement identity.
validate_omitted(item, pointer(path, key), depth + 1)
redactions.append({"pointer": path, "reason": "explicit-sensitive-value", "scope": "property-name"})
continue
result[key] = visit(item, pointer(path, key), depth + 1)
return result
raise CaptureFailure("decoder", "Native parser returned an unexpected value type: " + type(value).__name__ + ".", path)
return {"reported": visit(state, ""), "binary_fields": binaries, "numeric_literals": numbers, "redactions": redactions}
def decode(request):
if version.VERSION != PROFILE:
raise CaptureFailure("unsupported", "Expected mitmproxy " + PROFILE + "; observed " + version.VERSION + ".")
records = []
capture = Path(request["snapshot_path"])
size = capture.stat().st_size
with capture.open("rb") as handle:
reader = BoundedReader(handle, size)
while handle.tell() < size:
start = handle.tell()
try:
state = tnetstring.load(reader)
except CaptureFailure:
raise
except RecursionError:
raise CaptureFailure("input-limit", "Native parser exceeded its recursion budget at byte offset " + str(start) + ".") from None
except (ValueError, IndexError, UnicodeError, EOFError):
raise CaptureFailure("format", "Malformed native record at byte offset " + str(start) + ".") from None
if not isinstance(state, dict):
raise CaptureFailure("format", "Native flow record must be a dictionary at byte offset " + str(start) + ".")
records.append({"ordinal": len(records), "location": {"kind": "byte-range", "offset": start, "bytes": handle.tell() - start}, **project_record(state, request["sensitive_values"]), "limitations": ["Fields are original native states without FlowReader migration. Binary fields contain exact producer bytes; reported UTF-8 strings for those fields are derived display views. Unknown flow/version extensions are retained without interpretation."]})
return {"decoder": {"id": "mitmproxy-native-tnetstring", "name": "REA offline native mitmproxy adapter", "version": PROFILE}, "container": {"reported": None, "numeric_literals": [], "redactions": [], "records_pointer": None}, "total_records": len(records), "records": records}
def failure_reply(error):
"""Keep producer constraints, resource exhaustion and adapter defects distinct."""
if isinstance(error, CaptureFailure):
return {"ok": False, "reason": error.reason, "message": str(error), "pointer": error.pointer}
if isinstance(error, MemoryError):
return {"ok": False, "reason": "resource-limit", "message": "Native decoder exhausted its 768 MiB address-space budget.", "pointer": ""}
return {"ok": False, "reason": "decoder", "message": "Offline native decoder failed unexpectedly: " + type(error).__name__ + ".", "pointer": ""}
class OfflineCapture:
def load(self, loader):
loader.add_option("rea_request_path", str, "", "REA private offline capture request")
def running(self):
resource.setrlimit(resource.RLIMIT_AS, (768 * 1024 * 1024, 768 * 1024 * 1024))
resource.setrlimit(resource.RLIMIT_CPU, (30, 30))
resource.setrlimit(resource.RLIMIT_FSIZE, (OUTPUT_BYTES, OUTPUT_BYTES))
resource.setrlimit(resource.RLIMIT_CORE, (0, 0))
request = json.loads(Path(ctx.options.rea_request_path).read_text(encoding="utf-8"))
try:
response = {"ok": True, "value": decode(request)}
except Exception as error:
response = failure_reply(error)
try:
try:
output = json.dumps(response, ensure_ascii=True, allow_nan=False, separators=(",", ":")).encode("ascii")
except Exception as error:
output = json.dumps(failure_reply(error), separators=(",", ":")).encode("ascii")
if len(output) > OUTPUT_BYTES:
output = b'{"ok":false,"reason":"limit","message":"Native reply exceeds the complete-evidence output budget.","pointer":""}'
Path(request["reply_path"]).write_bytes(output)
finally:
ctx.master.shutdown()
addons = [OfflineCapture()]