1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165

use futures::{
    future::{self, Future},
    prelude::*,
};
use hyper::{
    client::HttpConnector,
    header::{HeaderMap, HeaderValue},
    Body, Client as HyperClient, Request, Response, StatusCode, Uri,
};
use lazy_static::lazy_static;
use std::{
    net::IpAddr,
    str::{self, FromStr},
    sync::Arc,
};
use unicase::Ascii;

type BoxFut = Box<Future<Item = Response<Body>, Error = hyper::Error> + Send>;

#[derive(Clone)]
pub struct Client {
    pub forward_to: Arc<String>,
    pub max_chunk_size: usize,
    pub ip: IpAddr,
}

impl Client {
    pub fn new(forward_to: Arc<String>, max_chunk_size: usize, ip: IpAddr) -> Self {
        Self {
            forward_to,
            max_chunk_size,
            ip,
        }
    }
}

pub fn proxy_call(
    http_client: Arc<HyperClient<HttpConnector>>,
    client: Arc<Client>,
    request: Request<Body>,
) -> BoxFut {
    let proxied_request = create_proxied_request(&client.forward_to, client.ip, request);
    let max_chunk_size = client.max_chunk_size;
    let response = http_client.request(proxied_request).then(move |response| {
        match response {
            Ok(response) => chunk_proxied_response(response, max_chunk_size),
            Err(error) => {
                println!("Error: {}", error); // TODO: Configurable logging
                Box::new(future::ok(
                    Response::builder()
                        .status(StatusCode::INTERNAL_SERVER_ERROR)
                        .body(Body::empty())
                        .unwrap(),
                ))
            }
        }
    });

    Box::new(response)
}

fn create_proxied_request(
    upstream_url: &str,
    client_ip: IpAddr,
    mut request: Request<Body>,
) -> Request<Body> {
    *request.headers_mut() = remove_hop_headers(request.headers());
    *request.uri_mut() = forward_uri(upstream_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) {
        Ok(header_entry) => match header_entry {
            hyper::header::Entry::Vacant(entry) => {
                let addr = format!("{}", client_ip);
                entry.insert(addr.parse().unwrap());
            }

            hyper::header::Entry::Occupied(mut entry) => {
                let addr = format!("{}, {}", entry.get().to_str().unwrap(), client_ip);
                entry.insert(addr.parse().unwrap());
            }
        },

        // shouldn't happen...
        Err(_) => panic!("Invalid header name: {}", x_forwarded_for_header_name),
    }

    request
}

/// 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 is_hop_header(name: &str) -> bool {
    // 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)
}

fn forward_uri<B>(forward_url: &str, req: &Request<B>) -> Uri {
    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()).unwrap()
}

/// Transforms the upstream response in a chunked response.
fn chunk_proxied_response(original_resp: Response<Body>, max_chunk_size: usize) -> BoxFut {
    lazy_static! {
        static ref CONTENT_LENGTH: Ascii<&'static str> = Ascii::new("content-length");
    }

    let mut chunked_response = Response::builder();
    for (h, v) in remove_hop_headers(original_resp.headers())
        .iter()
        .filter(|(h, _)| CONTENT_LENGTH.as_ref() != h.as_str())
    {
        chunked_response.header(h, v);
    }

    Box::new(
        original_resp
            .into_body()
            .concat2()
            .from_err()
            .and_then(move |entire_body| {
                let chunks = entire_body
                    .into_bytes()
                    .chunks(max_chunk_size)
                    .map(|part| String::from_utf8(part.to_vec()).unwrap())
                    .collect::<Vec<_>>();

                let stream = futures::stream::iter_ok::<_, ::std::io::Error>(chunks);
                Ok(chunked_response.body(Body::wrap_stream(stream)).unwrap())
            }),
    )
}