yhirose
9bfd2ddf1c
Bring the READMEs and the docs pages (en and ja) in line with the current header: - Fix the client sample that does not compile, the Transfer-Encoding statement for default headers, the verifier callback comment, the thread pool spawn rule, the sanitize_filename description, and the inverted Accept-Encoding sentence. - Describe recent behaviour: TLS errors behind Read/Write failures, Host validation, Connection: close for a body without length, content_reader rules, refused CONNECT, WebSocketClient proxies, CPPHTTPLIB_INTERIM_RESPONSE_MAX_COUNT, the SSE event size limit, and the payload limit of the Stream API. - Complete the API references of WebSocket, WebSocketClient and the stream:: helpers, and the SSE reconnect rules. - Fix cookbook pages: keychain loading on every backend, received Close status, a multipart sample that trusted the client's file name, an echo sample that sent binary as text, SNI, pre-request handler scope, stop() with WebSocket handlers, and the thread pool notes. - Restore the mutex in the LLM app's Chapter 5 code.
2.9 KiB
title, order, status
| title | order | status |
|---|---|---|
| S11. Authenticate Per Route with a Pre-Request Handler | 30 | draft |
The set_pre_routing_handler() from S09. Add pre-processing to all routes runs before routing, so it has no idea which route matched. When you want per-route behavior, set_pre_request_handler() is what you need.
Pre-routing vs. pre-request
| Hook | When it runs | Route info | Request body |
|---|---|---|---|
set_pre_routing_handler |
Before routing | Not available | Not read yet |
set_pre_request_handler |
After routing, right before the route handler | Available via req.matched_route |
Not read yet |
In a pre-request handler, req.matched_route holds the pattern string that matched. You can vary behavior based on the route definition itself.
Because the body has not been read when the pre-request handler runs, you can reject a request — for example on a failed auth check — without consuming a (potentially large) request body. Note that this also means req.body and form fields parsed from the body are not available here; inspect headers, the path, query parameters, or req.matched_route instead.
The pre-request handler runs only for requests that match a route. Files served by set_mount_point() are answered before route matching, so guard static files in the pre-routing handler.
Switch auth per route
svr.set_pre_request_handler(
[](const httplib::Request &req, httplib::Response &res) {
// require auth for routes starting with /admin
if (req.matched_route.rfind("/admin", 0) == 0) {
auto token = req.get_header_value("Authorization");
if (!is_admin_token(token)) {
res.status = 403;
res.set_content("forbidden", "text/plain");
return httplib::Server::HandlerResponse::Handled;
}
}
return httplib::Server::HandlerResponse::Unhandled;
});
matched_route is the pattern before path parameters are expanded (e.g. /admin/users/:id). You compare against the route definition, not the actual request path, so IDs or names don't throw you off.
The pre-request handler also runs for routes registered with svr.WebSocket(). It is called before the 101 Switching Protocols response, so returning Handled sends your HTTP response (such as a 403) and the connection is never upgraded.
The server accepts a handshake from any Origin. A browser sends its cookies even with a handshake that another site starts, so if cookies authenticate the connection, also check req.get_header_value("Origin") against your own origins here.
Return values
Same as pre-routing — return HandlerResponse.
Unhandled: continue (the route handler runs)Handled: we're done, skip the route handler
Passing auth info to the route handler
To pass decoded user info into the route handler, use res.user_data. See S12. Pass data between handlers with res.user_data.