didericis
6c886200d9
The apex-vs-subdomain question, the cert/SNI mismatch when pipelock-passthrough hosts have wildcard certs, and the mirror-divergence corner cases stacked up faster than the feature earned its keep. Going back to exact-host match only. Addon (`match_route`): single pass, case-insensitive exact match. `*.foo.com` in a route table is now a literal string that won't match anything — operators that want subdomains declare them individually. Pipelock mirror (`_pipelock_safe_hosts`): silently drops hosts that don't fit pipelock's `[A-Za-z0-9_.-]+` charset (wildcards, IPv6 literals, stray chars). Previously normalised wildcards to their suffix; now just drops them, which matches egress-proxy's behavior of not matching them either. 8 wildcard test cases removed; 2 lightweight "wildcards are not supported" assertions retained as documentation. 386 unit pass. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
258 lines
8.9 KiB
Python
258 lines
8.9 KiB
Python
"""Pure logic for the egress-proxy mitmproxy addon (PRD 0017).
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Split out of `egress_proxy_addon.py` so the host's unit tests can
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exercise the parse + decision functions without depending on the
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`mitmproxy` package. The companion module wraps these with the
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`mitmproxy.http.HTTPFlow` API and is loaded inside the sidecar
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container.
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Stdlib only: this file ships into the egress-proxy image, where the
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container's Python is whatever mitmproxy itself runs on.
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"""
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from __future__ import annotations
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import json
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import typing
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from dataclasses import dataclass
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@dataclass(frozen=True)
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class Route:
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"""One row of the egress-proxy route table.
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`host` is the request's `Host` header (or SNI hostname) to match
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against. `path_allowlist` is an optional tuple of absolute path
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prefixes the request path must start with; empty tuple means no
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path constraint. `auth_scheme` and `token_env` together form the
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credential-injection pair (both set or both empty); a non-empty
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pair tells the addon to overwrite the inbound Authorization with
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`<auth_scheme> <value-of-environ[token_env]>`.
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"""
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host: str
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path_allowlist: tuple[str, ...] = ()
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auth_scheme: str = ""
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token_env: str = ""
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@dataclass(frozen=True)
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class Decision:
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"""The result of `decide()`. Either forward (with optional
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`inject_authorization` header) or block (with a `reason` to surface
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to the agent)."""
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action: str # "forward" or "block"
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reason: str = ""
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inject_authorization: str | None = None
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def parse_routes(payload: object) -> tuple[Route, ...]:
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"""Parse the routes-file payload (already JSON-decoded) into a
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tuple of `Route`s. Raises `ValueError` on any malformed entry —
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the caller decides whether to keep the old table or refuse to
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start.
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Schema:
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{
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"routes": [
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{
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"host": "api.github.com",
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"path_allowlist": ["/repos/x/", "/users/x"], # optional
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"auth_scheme": "Bearer", # optional
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"token_env": "EGRESS_PROXY_TOKEN_0" # optional
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},
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...
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]
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}
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"""
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if not isinstance(payload, dict):
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raise ValueError("routes payload: top-level must be an object")
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raw = payload.get("routes")
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if not isinstance(raw, list):
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raise ValueError("routes payload: 'routes' must be a list")
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out: list[Route] = []
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for i, r in enumerate(raw):
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out.append(_parse_one(i, r))
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return tuple(out)
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def _parse_one(idx: int, raw: object) -> Route:
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label = f"route[{idx}]"
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if not isinstance(raw, dict):
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raise ValueError(f"{label}: must be an object (got {type(raw).__name__})")
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host = raw.get("host")
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if not isinstance(host, str) or not host:
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raise ValueError(f"{label}: 'host' must be a non-empty string")
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path_allow_raw = raw.get("path_allowlist", [])
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if not isinstance(path_allow_raw, list):
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raise ValueError(f"{label} ({host}): 'path_allowlist' must be a list")
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prefixes: list[str] = []
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for j, p in enumerate(path_allow_raw):
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if not isinstance(p, str):
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raise ValueError(
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f"{label} ({host}): path_allowlist[{j}] must be a string"
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)
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if not p.startswith("/"):
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raise ValueError(
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f"{label} ({host}): path_allowlist[{j}] {p!r} must be an "
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f"absolute path prefix starting with '/'"
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)
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prefixes.append(p)
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auth_scheme = raw.get("auth_scheme", "")
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token_env = raw.get("token_env", "")
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if not isinstance(auth_scheme, str):
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raise ValueError(f"{label} ({host}): 'auth_scheme' must be a string")
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if not isinstance(token_env, str):
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raise ValueError(f"{label} ({host}): 'token_env' must be a string")
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# Both-or-neither: 'auth' on the manifest side renders to this
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# pair atomically. A partial pair here means the renderer or a
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# hand-edited file is broken.
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if bool(auth_scheme) != bool(token_env):
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raise ValueError(
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f"{label} ({host}): 'auth_scheme' and 'token_env' must be both "
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f"set or both empty (got auth_scheme={auth_scheme!r}, "
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f"token_env={token_env!r})"
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)
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return Route(
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host=host,
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path_allowlist=tuple(prefixes),
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auth_scheme=auth_scheme,
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token_env=token_env,
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)
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def load_routes(text: str) -> tuple[Route, ...]:
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"""Convenience: parse JSON text → routes. Raises `ValueError` for
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both decode and shape errors so callers handle them uniformly."""
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try:
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payload = json.loads(text)
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except json.JSONDecodeError as e:
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raise ValueError(f"routes payload: invalid JSON: {e}") from e
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return parse_routes(payload)
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def is_git_push_request(path: str, query: str) -> bool:
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"""Return True if the request is a git smart-HTTP push.
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git push over HTTPS hits two endpoints:
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GET <repo>/info/refs?service=git-receive-pack (capabilities)
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POST <repo>/git-receive-pack (the push)
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Fetches use `service=git-upload-pack` / `/git-upload-pack` and
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are unaffected. Egress-proxy refuses HTTPS push because git-gate's
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pre-receive gitleaks scan is the gate for outbound git data;
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routing push through egress-proxy would bypass that. Use the
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bottle.git SSH path if you need to push.
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Universal across routes — the block fires even when no
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egress_proxy route matches the host. A bare-pass route (host with
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no auth, no path_allowlist) would otherwise let push through to
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pipelock + upstream untouched.
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"""
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if path.endswith("/git-receive-pack"):
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return True
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if path.endswith("/info/refs"):
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# Query string is parsed leniently — `service=git-receive-pack`
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# may appear with other params in any order.
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for pair in query.split("&"):
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k, _, v = pair.partition("=")
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if k == "service" and v == "git-receive-pack":
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return True
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return False
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def match_route(
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routes: typing.Sequence[Route],
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request_host: str,
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) -> Route | None:
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"""Return the first route whose `host` matches `request_host`
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exactly (case-insensitive). DNS names are case-insensitive.
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Wildcard hosts (`*.foo.com`) are NOT supported — they caused
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too many edge cases (apex match? cert validation? pipelock
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mirror mismatch?) for too little payoff. Operators that need
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multiple subdomains declare them individually (or one common
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parent host as a bare-pass route)."""
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target = request_host.lower()
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for r in routes:
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if r.host.lower() == target:
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return r
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return None
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def decide(
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routes: typing.Sequence[Route],
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request_host: str,
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request_path: str,
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environ: typing.Mapping[str, str],
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) -> Decision:
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"""Pure decision: given a route table + request host + path + env,
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return what the addon should do with the request.
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- No matching route → BLOCK. The route table is the bottle's
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egress allowlist; defense-in-depth complements pipelock's
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hostname gate on the downstream leg. A bottle that wants a
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host reachable from the agent must declare a route for it
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(bare-pass route — no `auth`, no `path_allowlist` — is fine
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for hosts that just need passthrough).
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- Matching route with `path_allowlist` set, request path doesn't
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start with any of the allowed prefixes → block with a clear
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reason.
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- Matching route with an auth pair → forward + inject
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Authorization. Token comes from `environ[route.token_env]`;
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missing/empty values block (route declared auth but the secret
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isn't here — operator misconfig).
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"""
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route = match_route(routes, request_host)
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if route is None:
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return Decision(
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action="block",
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reason=(
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f"egress-proxy: host {request_host!r} is not in the "
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f"bottle's egress_proxy.routes allowlist. Declare a "
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f"route for it or remove the request."
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),
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)
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if route.path_allowlist:
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if not any(request_path.startswith(p) for p in route.path_allowlist):
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return Decision(
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action="block",
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reason=(
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f"egress-proxy: path {request_path!r} not in "
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f"path_allowlist for {route.host!r}"
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),
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)
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if route.auth_scheme and route.token_env:
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token = environ.get(route.token_env, "")
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if not token:
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return Decision(
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action="block",
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reason=(
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f"egress-proxy: route for {route.host!r} declared auth "
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f"but env var {route.token_env!r} is unset"
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),
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)
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return Decision(
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action="forward",
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inject_authorization=f"{route.auth_scheme} {token}",
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)
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return Decision(action="forward")
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__all__ = [
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"Decision",
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"Route",
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"decide",
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"is_git_push_request",
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"load_routes",
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"match_route",
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"parse_routes",
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]
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