A simple reverse proxy for use with Hyper and Tokio
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hyper-reverse-proxy/src/lib.rs

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6.2 KiB

//!
//! A simple reverse proxy, to be used with [Hyper].
//!
//! The implementation ensures that [Hop-by-hop headers] are stripped correctly in both directions,
//! and adds the client's IP address to a comma-space-separated list of forwarding addresses in the
//! `X-Forwarded-For` header.
//!
//! The implementation is based on Go's [`httputil.ReverseProxy`].
//!
//! [Hyper]: http://hyper.rs/
//! [Hop-by-hop headers]: http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html
//! [`httputil.ReverseProxy`]: https://golang.org/pkg/net/http/httputil/#ReverseProxy
//!
//! # Example
//!
//! Add these dependencies to your `Cargo.toml` file.
//!
//! ```toml
//! [dependencies]
//! hyper-reverse-proxy = "0.5"
//! hyper = "0.13"
//! futures = "0.3"
//! tokio = { version = "0.2", features = ["full"] }
//! ```
//!
//! The following example will set up a reverse proxy listening on `127.0.0.1:13900`,
//! and will proxy these calls:
//!
//! * `"/target/first"` will be proxied to `http://127.0.0.1:13901`
//!
//! * `"/target/second"` will be proxied to `http://127.0.0.1:13902`
//!
//! * All other URLs will be handled by `debug_request` function, that will display request information.
//!
//! ```rust,no_run
//! use hyper::server::conn::AddrStream;
//! use hyper::{Body, Request, Response, Server};
//! use hyper::service::{service_fn, make_service_fn};
//! use futures::future::{self, Future};
//! use std::{convert::Infallible, net::SocketAddr};
//! use hyper::http::uri::InvalidUri;
//! use std::net::IpAddr;
//!
//! fn debug_request(req: Request<Body>) -> Result<Response<Body>, Infallible> {
//! let body_str = format!("{:?}", req);
//! Ok(Response::new(Body::from(body_str)))
//! }
//!
//! async fn handle(client_ip: IpAddr, req: Request<Body>) -> Result<Response<Body>, Infallible> {
//! if req.uri().path().starts_with("/target/first") {
//! // will forward requests to port 13901
//! Ok(hyper_reverse_proxy::call(client_ip, "http://127.0.0.1:13901", req).await.unwrap())
//!
//! } else if req.uri().path().starts_with("/target/second") {
//!
//! // will forward requests to port 13902
//! Ok(hyper_reverse_proxy::call(client_ip, "http://127.0.0.1:13902", req).await.unwrap())
//!
//! } else {
//! debug_request(req)
//! }
//! }
//!
//! #[tokio::main]
//! async fn main() {
//! let bind_addr = "127.0.0.1:8000";
//! let addr:SocketAddr = bind_addr.parse().expect("Could not parse ip:port.");
//!
//! let make_svc = make_service_fn(|conn: &AddrStream| {
//! let remote_addr = conn.remote_addr().ip();
//! async move {
//! Ok::<_, Infallible>(service_fn(move |req| handle(remote_addr, req)))
//! }
//! });
//!
//! let server = Server::bind(&addr).serve(make_svc);
//!
//! if let Err(e) = server.await {
//! eprintln!("server error: {}", e);
//! }
//!
//! println!("Running server on {:?}", addr);
//! }
//! ```
//!
use hyper::header::{HeaderMap, HeaderValue};
use hyper::http::uri::InvalidUri;
use hyper::{Body, Client, Request, Response, StatusCode, Uri};
use lazy_static::lazy_static;
use std::net::IpAddr;
use std::str::FromStr;
fn is_hop_header(name: &str) -> bool {
use unicase::Ascii;
// A list of the headers, using `unicase` to help us compare without
// worrying about the case, and `lazy_static!` to prevent reallocation
// of the vector.
lazy_static! {
static ref HOP_HEADERS: Vec<Ascii<&'static str>> = vec![
Ascii::new("Connection"),
Ascii::new("Keep-Alive"),
Ascii::new("Proxy-Authenticate"),
Ascii::new("Proxy-Authorization"),
Ascii::new("Te"),
Ascii::new("Trailers"),
Ascii::new("Transfer-Encoding"),
Ascii::new("Upgrade"),
];
}
HOP_HEADERS.iter().any(|h| h == &name)
}
/// Returns a clone of the headers without the [hop-by-hop headers].
///
/// [hop-by-hop headers]: http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html
fn remove_hop_headers(headers: &HeaderMap<HeaderValue>) -> HeaderMap<HeaderValue> {
let mut result = HeaderMap::new();
for (k, v) in headers.iter() {
if !is_hop_header(k.as_str()) {
result.insert(k.clone(), v.clone());
}
}
result
}
fn create_proxied_response<B>(mut response: Response<B>) -> Response<B> {
*response.headers_mut() = remove_hop_headers(response.headers());
response
}
fn forward_uri<B>(forward_url: &str, req: &Request<B>) -> Result<Uri, InvalidUri> {
let forward_uri = match req.uri().query() {
Some(query) => format!("{}{}?{}", forward_url, req.uri().path(), query),
None => format!("{}{}", forward_url, req.uri().path()),
};
Uri::from_str(forward_uri.as_str())
}
fn create_proxied_request<B>(
client_ip: IpAddr,
forward_url: &str,
mut request: Request<B>,
) -> Result<Request<B>, InvalidUri> {
*request.headers_mut() = remove_hop_headers(request.headers());
*request.uri_mut() = forward_uri(forward_url, &request)?;
let x_forwarded_for_header_name = "x-forwarded-for";
// Add forwarding information in the headers
match request.headers_mut().entry(x_forwarded_for_header_name) {
hyper::header::Entry::Vacant(entry) => {
entry.insert(client_ip.to_string().parse().unwrap());
}
hyper::header::Entry::Occupied(mut entry) => {
let addr = format!("{}, {}", entry.get().to_str().unwrap(), client_ip);
entry.insert(addr.parse().unwrap());
}
}
Ok(request)
}
pub async fn call(
client_ip: IpAddr,
forward_uri: &str,
request: Request<Body>,
) -> Result<Response<Body>, InvalidUri> {
let proxied_request = create_proxied_request(client_ip, &forward_uri, request)?;
let client = Client::new();
let response = client.request(proxied_request).await;
let proxied_response = match response {
Ok(response) => create_proxied_response(response),
Err(error) => {
println!("Error: {}", error); // TODO: Configurable logging
Response::builder()
.status(StatusCode::SERVICE_UNAVAILABLE)
.body(Body::empty())
.unwrap()
}
};
Ok(proxied_response)
}