feat: add dlp: false passthrough option for egress routes

Routes with `dlp: false` skip all DLP scanning (including CRLF injection,
which cannot be disabled via `dlp.outbound_detectors: false`) and tunnel
HTTPS connections without TLS interception so the client sees the server's
real certificate. Fixes Docker image pulls, which fail when the proxy MITM's
the TLS handshake and the container doesn't trust the per-bottle CA.

Closes #462

bot_bottle/egress_addon.py

@@ -97,10 +97,11 @@ class EgressAddon:
     # comes from the orchestrator's /resolve (PRD 0070); there is no static
     # per-bottle routes file, SIGHUP reload, or single-tenant fallback.
     _resolver: "PolicyResolver"
-    # Class default so __new__-built addons have it (real runs get a fresh
-    # per-instance dict in __init__; only http_connect mutates it, which the
-    # request-flow tests don't exercise).
+    # Class defaults so __new__-built addons have them (real runs get fresh
+    # per-instance collections in __init__; only http_connect mutates them,
+    # which request-flow tests don't exercise unless they call http_connect).
     _conn_tokens: "dict[str, str]" = {}
+    _passthrough_conns: "set[str]" = set()
 
     def __init__(self) -> None:
         # Resolver-only: the gateway is always multi-tenant, resolving each
@@ -125,6 +126,10 @@ class EgressAddon:
         # `Proxy-Authorization` (HTTPS tunnels don't repeat it on the bumped
         # inner requests). Keyed by client_conn.id; cleared on disconnect.
         self._conn_tokens: dict[str, str] = {}
+        # Connections whose route carries `dlp: false` — mitmproxy tunnels
+        # these without TLS interception so the client sees the server's real
+        # cert. Keyed by client_conn.id; cleared on disconnect.
+        self._passthrough_conns: set[str] = set()
         self._token_allow_timeout = _token_allow_timeout_from_env(os.environ)
 
     @staticmethod
@@ -305,17 +310,53 @@ class EgressAddon:
     def http_connect(self, flow: http.HTTPFlow) -> None:
         """Capture the identity token from an HTTPS tunnel's CONNECT (the inner
         bumped requests won't carry `Proxy-Authorization`), keyed by client
-        connection, and strip it so it never reaches upstream."""
+        connection, and strip it so it never reaches upstream.
+
+        For `dlp: false` routes, also resolve the policy here to make the
+        allowlist decision before the TLS handshake: the tunnel is either
+        blocked immediately or marked for passthrough in `_passthrough_conns`
+        so `tls_clienthello` skips interception."""
         token = _token_from_proxy_auth(
             flow.request.headers.get("Proxy-Authorization", ""))
         flow.request.headers.pop("Proxy-Authorization", None)
         conn = flow.client_conn
-        if conn is not None and getattr(conn, "id", ""):
-            self._conn_tokens[conn.id] = token
+        conn_id = getattr(conn, "id", "") if conn is not None else ""
+        if conn_id:
+            self._conn_tokens[conn_id] = token
+
+        # Resolve once to check if this host is a dlp: false route. For
+        # non-passthrough hosts nothing changes — the allowlist check happens
+        # in request() as normal. For passthrough hosts we must decide here
+        # because the inner requests never reach request() after the bypass.
+        client_ip = conn.peername[0] if conn is not None and conn.peername else ""
+        config, _slug, env = resolve_client_context(self._resolver, client_ip, token)
+        host = flow.request.pretty_host
+        route = match_route(config.routes, host)
+        if route is not None and route.dlp_passthrough:
+            decision = decide(config.routes, host, "/", env, deny_reason=config.deny_reason)
+            if decision.action == "block":
+                flow.response = http.Response.make(
+                    403,
+                    decision.reason.encode("utf-8"),
+                    {"Content-Type": "text/plain; charset=utf-8"},
+                )
+                return
+            if conn_id:
+                self._passthrough_conns.add(conn_id)
+
+    def tls_clienthello(self, client_hello: typing.Any) -> None:
+        """Skip TLS interception for `dlp: false` routes so the client sees
+        the server's real certificate rather than the MITM CA's leaf."""
+        conn_id = getattr(client_hello.context.client, "id", "")
+        if conn_id in self._passthrough_conns:
+            client_hello.ignore_connection = True
 
     def client_disconnected(self, client: typing.Any) -> None:
-        """Drop the per-connection token when the client goes away."""
-        self._conn_tokens.pop(getattr(client, "id", ""), None)
+        """Drop the per-connection token and passthrough flag when the client
+        goes away."""
+        conn_id = getattr(client, "id", "")
+        self._conn_tokens.pop(conn_id, None)
+        self._passthrough_conns.discard(conn_id)
 
     async def request(self, flow: http.HTTPFlow) -> None:
         request_path, _, query = flow.request.path.partition("?")
@@ -335,8 +376,10 @@ class EgressAddon:
         # DLP outbound scan BEFORE stripping auth — catches tokens the
         # agent tried to smuggle in any header, path, query param, or body.
         # Hostname is included to catch DNS-tunnelling exfiltration attempts.
+        # `dlp: false` routes skip scanning entirely (TLS is also not
+        # intercepted for HTTPS, so this branch only fires for plain HTTP).
         route = match_route(config.routes, flow.request.pretty_host)
-        if route is not None:
+        if route is not None and not route.dlp_passthrough:
             if not await self._handle_outbound_dlp(flow, route, slug, env):
                 return
             # The redact policy may have rewritten the request line; recompute
@@ -606,7 +649,7 @@ class EgressAddon:
         bottle's resolved config (`request()` stashed it — see `_flow_ctx`)."""
         config, _slug, env = self._flow_ctx(flow)
         route = match_route(config.routes, flow.request.pretty_host)
-        if route is None:
+        if route is None or route.dlp_passthrough:
             return
         if flow.response is None:
             return
@@ -652,7 +695,7 @@ class EgressAddon:
             return
         config, slug, env = self._flow_ctx(flow)
         route = match_route(config.routes, flow.request.pretty_host)
-        if route is None:
+        if route is None or route.dlp_passthrough:
             return
         message = flow.websocket.messages[-1]  # type: ignore[union-attr]
         content = message.content.decode("utf-8", errors="replace")