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1.9 KiB
title, order, status
| title | order | status |
|---|---|---|
| S09. Add Pre-Processing to All Routes | 28 | draft |
Sometimes you want the same logic to run before every request — auth checks, logging, rate limiting. Register those with set_pre_routing_handler().
Basic usage
svr.set_pre_routing_handler(
[](const httplib::Request &req, httplib::Response &res) {
std::cout << req.method << " " << req.path << std::endl;
return httplib::Server::HandlerResponse::Unhandled;
});
The pre-routing handler runs before routing. It catches every request — including ones that don't match any handler.
The HandlerResponse return value is key:
- Return
Unhandled→ continue normally (routing and the actual handler run) - Return
Handled→ the response is considered complete, skip the rest
Use it for authentication
Put your shared auth check in one place.
svr.set_pre_routing_handler(
[](const httplib::Request &req, httplib::Response &res) {
if (req.path.rfind("/public", 0) == 0) {
return httplib::Server::HandlerResponse::Unhandled; // no auth needed
}
auto auth = req.get_header_value("Authorization");
if (auth.empty()) {
res.status = 401;
res.set_content("unauthorized", "text/plain");
return httplib::Server::HandlerResponse::Handled;
}
return httplib::Server::HandlerResponse::Unhandled;
});
If auth fails, return Handled to respond with 401 immediately. If it passes, return Unhandled and let routing take over.
For per-route auth
If you want different auth rules per route rather than a single global check, set_pre_request_handler() is a better fit. See S11. Authenticate per route with a pre-request handler.
Note: If all you want is to modify the response,
set_post_routing_handler()is the right tool. See S10. Add response headers with a post-routing handler.