gateway_runtime/layers/
headers.rs

1//! # Header Processing Layer
2//!
3//! This layer intercepts incoming requests and outgoing responses to filter or transform
4//! HTTP headers using configured [HeaderMatcher](crate::gateway::HeaderMatcher) functions.
5//!
6//! This allows for renaming headers (e.g., `Authorization` -> `x-auth-token`) or stripping
7//! sensitive/unwanted headers before they reach the application logic or the client.
8
9use crate::alloc::boxed::Box;
10use crate::gateway::HeaderMatcher;
11use crate::{GatewayRequest, GatewayResponse};
12use core::task::{Context, Poll};
13use std::future::Future;
14use std::pin::Pin;
15use tower::Service;
16
17/// A Tower middleware that applies header matching logic.
18#[derive(Clone)]
19pub struct HeaderLayer<S> {
20    inner: S,
21    incoming_matcher: Option<HeaderMatcher>,
22    outgoing_matcher: Option<HeaderMatcher>,
23}
24
25impl<S> HeaderLayer<S> {
26    /// Creates a new `HeaderLayer`.
27    ///
28    /// # Parameters
29    /// *   `inner`: The inner service.
30    /// *   `incoming`: Optional matcher for request headers.
31    /// *   `outgoing`: Optional matcher for response headers.
32    pub fn new(inner: S, incoming: Option<HeaderMatcher>, outgoing: Option<HeaderMatcher>) -> Self {
33        Self {
34            inner,
35            incoming_matcher: incoming,
36            outgoing_matcher: outgoing,
37        }
38    }
39}
40
41impl<S> Service<GatewayRequest> for HeaderLayer<S>
42where
43    S: Service<GatewayRequest, Response = GatewayResponse>,
44    S::Future: Send + 'static,
45{
46    type Response = GatewayResponse;
47    type Error = S::Error;
48    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;
49
50    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
51        self.inner.poll_ready(cx)
52    }
53
54    fn call(&mut self, mut req: GatewayRequest) -> Self::Future {
55        // Process Incoming Headers
56        if let Some(matcher) = &self.incoming_matcher {
57            let mut new_headers = http::HeaderMap::new();
58            for (key, value) in req.headers() {
59                if let Some(new_key) = matcher(key.as_str()) {
60                    if let Ok(k) = http::header::HeaderName::from_bytes(new_key.as_bytes()) {
61                        new_headers.insert(k, value.clone());
62                    }
63                }
64            }
65            *req.headers_mut() = new_headers;
66        }
67
68        let outgoing_matcher = self.outgoing_matcher.clone();
69        let fut = self.inner.call(req);
70
71        Box::pin(async move {
72            let mut resp = fut.await?;
73
74            // Process Outgoing Headers
75            if let Some(matcher) = outgoing_matcher {
76                let mut new_headers = http::HeaderMap::new();
77                for (key, value) in resp.headers() {
78                    if let Some(new_key) = matcher(key.as_str()) {
79                        if let Ok(k) = http::header::HeaderName::from_bytes(new_key.as_bytes()) {
80                            new_headers.insert(k, value.clone());
81                        }
82                    }
83                }
84                *resp.headers_mut() = new_headers;
85            }
86
87            Ok(resp)
88        })
89    }
90}
gateway_runtime/layers/headers.rs

gateway_runtime/layers/
headers.rs
