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