118 lines
3.8 KiB
Python
118 lines
3.8 KiB
Python
import logging
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import re
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from collections.abc import Sequence
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from pathlib import Path
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from typing import NamedTuple
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from mitmproxy import ctx
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from mitmproxy import exceptions
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from mitmproxy import flowfilter
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from mitmproxy import http
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from mitmproxy.http import Headers
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from mitmproxy.utils import strutils
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from mitmproxy.utils.spec import parse_spec
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class ModifySpec(NamedTuple):
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matches: flowfilter.TFilter
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subject: bytes
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replacement_str: str
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def read_replacement(self) -> bytes:
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"""
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Process the replacement str. This usually just involves converting it to bytes.
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However, if it starts with `@`, we interpret the rest as a file path to read from.
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Raises:
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- IOError if the file cannot be read.
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"""
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if self.replacement_str.startswith("@"):
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return Path(self.replacement_str[1:]).expanduser().read_bytes()
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else:
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# We could cache this at some point, but unlikely to be a problem.
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return strutils.escaped_str_to_bytes(self.replacement_str)
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def parse_modify_spec(option: str, subject_is_regex: bool) -> ModifySpec:
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flow_filter, subject_str, replacement = parse_spec(option)
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subject = strutils.escaped_str_to_bytes(subject_str)
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if subject_is_regex:
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try:
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re.compile(subject)
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except re.error as e:
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raise ValueError(f"Invalid regular expression {subject!r} ({e})")
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spec = ModifySpec(flow_filter, subject, replacement)
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try:
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spec.read_replacement()
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except OSError as e:
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raise ValueError(f"Invalid file path: {replacement[1:]} ({e})")
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return spec
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class ModifyHeaders:
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def __init__(self) -> None:
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self.replacements: list[ModifySpec] = []
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def load(self, loader):
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loader.add_option(
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"modify_headers",
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Sequence[str],
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[],
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"""
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Header modify pattern of the form "[/flow-filter]/header-name/[@]header-value", where the
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separator can be any character. The @ allows to provide a file path that is used to read
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the header value string. An empty header-value removes existing header-name headers.
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""",
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)
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def configure(self, updated):
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if "modify_headers" in updated:
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self.replacements = []
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for option in ctx.options.modify_headers:
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try:
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spec = parse_modify_spec(option, False)
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except ValueError as e:
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raise exceptions.OptionsError(
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f"Cannot parse modify_headers option {option}: {e}"
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) from e
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self.replacements.append(spec)
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def requestheaders(self, flow):
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if flow.response or flow.error or not flow.live:
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return
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self.run(flow, flow.request.headers)
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def responseheaders(self, flow):
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if flow.error or not flow.live:
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return
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self.run(flow, flow.response.headers)
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def run(self, flow: http.HTTPFlow, hdrs: Headers) -> None:
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matches = []
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# first check all the filters against the original, unmodified flow
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for spec in self.replacements:
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matches.append(spec.matches(flow))
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# unset all specified headers
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for i, spec in enumerate(self.replacements):
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if matches[i]:
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hdrs.pop(spec.subject, None)
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# set all specified headers if the replacement string is not empty
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for i, spec in enumerate(self.replacements):
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if matches[i]:
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try:
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replacement = spec.read_replacement()
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except OSError as e:
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logging.warning(f"Could not read replacement file: {e}")
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continue
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else:
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if replacement:
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hdrs.add(spec.subject, replacement)
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