Bug: regular handler under asgi mount path conflicts with routing to asgi app

[peterschutt]

Description

If we have a regular handler mounted under an asgi mounted path, and the path of the regular handler is a non-prefix sub-string of the a request path the request will not get routed to the asgi app.

I.e., if we have an asgi mounted on "/", and a regular handler at "/path", a request to "/some/path" does not get routed to the asgi app.

URL to code causing the issue

No response

MCVE

from __future__ import annotations

from typing import TYPE_CHECKING

from litestar import Litestar, asgi, get
from litestar.testing import TestClient

if TYPE_CHECKING:
    from litestar.types.asgi_types import Receive, Scope, Send


async def asgi_app(scope: Scope, receive: Receive, send: Send) -> None:
    assert scope["type"] == "http"
    await send({
        "type": "http.response.start",
        "status": 200,
        "headers": [
            (b"content-type", b"text/plain"),
            (b"content-length", b"%d" % len(scope["raw_path"])),
        ],
    })
    await send({
        "type": "http.response.body",
        "body": scope["raw_path"],
    })

asgi_handler = asgi("/", is_mount=True)(asgi_app)


@get("/path")
def get_handler() -> str:
    return "Hello, world!"


def test_regular_handler_under_mounted_asgi_app() -> None:
    app = Litestar(
        route_handlers=[asgi("/", is_mount=True)(asgi_app), get_handler],
        openapi_config=None,
        debug=True,
    )

    with TestClient(app) as client:
        resp = client.get("/some/path")  # currently this is a 404
        assert resp.content == b"/some/path"

Steps to reproduce

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Screenshots

"![SCREENSHOT_DESCRIPTION](SCREENSHOT_LINK.png)"

Logs

No response

Litestar Version

main

Platform

• Linux
• Mac
• Windows
• Other (Please specify in the description above)

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[peterschutt]

Issue looks to come from here:

litestar/litestar/_asgi/routing_trie/traversal.py

Lines 145 to 146 in 7814d59

	children = [sub_route for sub_route in mount_node.children or [] if sub_route != mount_path]
	if not children or all(sub_route not in path for sub_route in children): # type: ignore[operator]

Where path == "/some/path" and children == ["/path"], the request isn't directed to the mounted application because the path contains the child path. I think instead of testing whether the sub-route is a substring of the path, we should check path.startswith(f"{sub_route}/").

[github-actions]

This issue has been closed in #3430. The change will be included in the upcoming patch release.

[github-actions]

A fix for this issue has been released in v2.9.0