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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
use std::{
    cmp,
    error::Error as StdError,
    future::Future,
    marker::PhantomData,
    net,
    pin::{pin, Pin},
    rc::Rc,
    task::{Context, Poll},
};

use actix_codec::{AsyncRead, AsyncWrite};
use actix_rt::time::{sleep, Sleep};
use actix_service::Service;
use actix_utils::future::poll_fn;
use bytes::{Bytes, BytesMut};
use futures_core::ready;
use h2::{
    server::{Connection, SendResponse},
    Ping, PingPong,
};
use pin_project_lite::pin_project;

use crate::{
    body::{BodySize, BoxBody, MessageBody},
    config::ServiceConfig,
    header::{
        HeaderName, HeaderValue, CONNECTION, CONTENT_LENGTH, DATE, TRANSFER_ENCODING, UPGRADE,
    },
    service::HttpFlow,
    Extensions, Method, OnConnectData, Payload, Request, Response, ResponseHead,
};

const CHUNK_SIZE: usize = 16_384;

pin_project! {
    /// Dispatcher for HTTP/2 protocol.
    pub struct Dispatcher<T, S, B, X, U> {
        flow: Rc<HttpFlow<S, X, U>>,
        connection: Connection<T, Bytes>,
        conn_data: Option<Rc<Extensions>>,
        config: ServiceConfig,
        peer_addr: Option<net::SocketAddr>,
        ping_pong: Option<H2PingPong>,
        _phantom: PhantomData<B>
    }
}

impl<T, S, B, X, U> Dispatcher<T, S, B, X, U>
where
    T: AsyncRead + AsyncWrite + Unpin,
{
    pub(crate) fn new(
        mut conn: Connection<T, Bytes>,
        flow: Rc<HttpFlow<S, X, U>>,
        config: ServiceConfig,
        peer_addr: Option<net::SocketAddr>,
        conn_data: OnConnectData,
        timer: Option<Pin<Box<Sleep>>>,
    ) -> Self {
        let ping_pong = config.keep_alive().duration().map(|dur| H2PingPong {
            timer: timer
                .map(|mut timer| {
                    // reuse timer slot if it was initialized for handshake
                    timer.as_mut().reset((config.now() + dur).into());
                    timer
                })
                .unwrap_or_else(|| Box::pin(sleep(dur))),
            in_flight: false,
            ping_pong: conn.ping_pong().unwrap(),
        });

        Self {
            flow,
            config,
            peer_addr,
            connection: conn,
            conn_data: conn_data.0.map(Rc::new),
            ping_pong,
            _phantom: PhantomData,
        }
    }
}

struct H2PingPong {
    /// Handle to send ping frames from the peer.
    ping_pong: PingPong,

    /// True when a ping has been sent and is waiting for a reply.
    in_flight: bool,

    /// Timeout for pong response.
    timer: Pin<Box<Sleep>>,
}

impl<T, S, B, X, U> Future for Dispatcher<T, S, B, X, U>
where
    T: AsyncRead + AsyncWrite + Unpin,

    S: Service<Request>,
    S::Error: Into<Response<BoxBody>>,
    S::Future: 'static,
    S::Response: Into<Response<B>>,

    B: MessageBody,
{
    type Output = Result<(), crate::error::DispatchError>;

    #[inline]
    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let this = self.get_mut();

        loop {
            match Pin::new(&mut this.connection).poll_accept(cx)? {
                Poll::Ready(Some((req, tx))) => {
                    let (parts, body) = req.into_parts();
                    let payload = crate::h2::Payload::new(body);
                    let pl = Payload::H2 { payload };
                    let mut req = Request::with_payload(pl);
                    let head_req = parts.method == Method::HEAD;

                    let head = req.head_mut();
                    head.uri = parts.uri;
                    head.method = parts.method;
                    head.version = parts.version;
                    head.headers = parts.headers.into();
                    head.peer_addr = this.peer_addr;

                    req.conn_data.clone_from(&this.conn_data);

                    let fut = this.flow.service.call(req);
                    let config = this.config.clone();

                    // multiplex request handling with spawn task
                    actix_rt::spawn(async move {
                        // resolve service call and send response.
                        let res = match fut.await {
                            Ok(res) => handle_response(res.into(), tx, config, head_req).await,
                            Err(err) => {
                                let res: Response<BoxBody> = err.into();
                                handle_response(res, tx, config, head_req).await
                            }
                        };

                        // log error.
                        if let Err(err) = res {
                            match err {
                                DispatchError::SendResponse(err) => {
                                    tracing::trace!("Error sending response: {err:?}");
                                }
                                DispatchError::SendData(err) => {
                                    tracing::warn!("Send data error: {err:?}");
                                }
                                DispatchError::ResponseBody(err) => {
                                    tracing::error!("Response payload stream error: {err:?}");
                                }
                            }
                        }
                    });
                }
                Poll::Ready(None) => return Poll::Ready(Ok(())),

                Poll::Pending => match this.ping_pong.as_mut() {
                    Some(ping_pong) => loop {
                        if ping_pong.in_flight {
                            // When there is an in-flight ping-pong, poll pong and and keep-alive
                            // timer. On successful pong received, update keep-alive timer to
                            // determine the next timing of ping pong.
                            match ping_pong.ping_pong.poll_pong(cx)? {
                                Poll::Ready(_) => {
                                    ping_pong.in_flight = false;

                                    let dead_line = this.config.keep_alive_deadline().unwrap();
                                    ping_pong.timer.as_mut().reset(dead_line.into());
                                }
                                Poll::Pending => {
                                    return ping_pong.timer.as_mut().poll(cx).map(|_| Ok(()));
                                }
                            }
                        } else {
                            // When there is no in-flight ping-pong, keep-alive timer is used to
                            // wait for next timing of ping-pong. Therefore, at this point it serves
                            // as an interval instead.
                            ready!(ping_pong.timer.as_mut().poll(cx));

                            ping_pong.ping_pong.send_ping(Ping::opaque())?;

                            let dead_line = this.config.keep_alive_deadline().unwrap();
                            ping_pong.timer.as_mut().reset(dead_line.into());

                            ping_pong.in_flight = true;
                        }
                    },
                    None => return Poll::Pending,
                },
            }
        }
    }
}

enum DispatchError {
    SendResponse(h2::Error),
    SendData(h2::Error),
    ResponseBody(Box<dyn StdError>),
}

async fn handle_response<B>(
    res: Response<B>,
    mut tx: SendResponse<Bytes>,
    config: ServiceConfig,
    head_req: bool,
) -> Result<(), DispatchError>
where
    B: MessageBody,
{
    let (res, body) = res.replace_body(());

    // prepare response.
    let mut size = body.size();
    let res = prepare_response(config, res.head(), &mut size);
    let eof_or_head = size.is_eof() || head_req;

    // send response head and return on eof.
    let mut stream = tx
        .send_response(res, eof_or_head)
        .map_err(DispatchError::SendResponse)?;

    if eof_or_head {
        return Ok(());
    }

    let mut body = pin!(body);

    // poll response body and send chunks to client
    while let Some(res) = poll_fn(|cx| body.as_mut().poll_next(cx)).await {
        let mut chunk = res.map_err(|err| DispatchError::ResponseBody(err.into()))?;

        'send: loop {
            let chunk_size = cmp::min(chunk.len(), CHUNK_SIZE);

            // reserve enough space and wait for stream ready.
            stream.reserve_capacity(chunk_size);

            match poll_fn(|cx| stream.poll_capacity(cx)).await {
                // No capacity left. drop body and return.
                None => return Ok(()),

                Some(Err(err)) => return Err(DispatchError::SendData(err)),

                Some(Ok(cap)) => {
                    // split chunk to writeable size and send to client
                    let len = chunk.len();
                    let bytes = chunk.split_to(cmp::min(len, cap));

                    stream
                        .send_data(bytes, false)
                        .map_err(DispatchError::SendData)?;

                    // Current chuck completely sent. break send loop and poll next one.
                    if chunk.is_empty() {
                        break 'send;
                    }
                }
            }
        }
    }

    // response body streaming finished. send end of stream and return.
    stream
        .send_data(Bytes::new(), true)
        .map_err(DispatchError::SendData)?;

    Ok(())
}

fn prepare_response(
    config: ServiceConfig,
    head: &ResponseHead,
    size: &mut BodySize,
) -> http::Response<()> {
    let mut has_date = false;
    let mut skip_len = size != &BodySize::Stream;

    let mut res = http::Response::new(());
    *res.status_mut() = head.status;
    *res.version_mut() = http::Version::HTTP_2;

    // Content length
    match head.status {
        http::StatusCode::NO_CONTENT
        | http::StatusCode::CONTINUE
        | http::StatusCode::PROCESSING => *size = BodySize::None,
        http::StatusCode::SWITCHING_PROTOCOLS => {
            skip_len = true;
            *size = BodySize::Stream;
        }
        _ => {}
    }

    match size {
        BodySize::None | BodySize::Stream => {}

        BodySize::Sized(0) => {
            #[allow(clippy::declare_interior_mutable_const)]
            const HV_ZERO: HeaderValue = HeaderValue::from_static("0");
            res.headers_mut().insert(CONTENT_LENGTH, HV_ZERO);
        }

        BodySize::Sized(len) => {
            let mut buf = itoa::Buffer::new();

            res.headers_mut().insert(
                CONTENT_LENGTH,
                HeaderValue::from_str(buf.format(*len)).unwrap(),
            );
        }
    };

    // copy headers
    for (key, value) in head.headers.iter() {
        match key {
            // omit HTTP/1.x only headers according to:
            // https://datatracker.ietf.org/doc/html/rfc7540#section-8.1.2.2
            &CONNECTION | &TRANSFER_ENCODING | &UPGRADE => continue,

            &CONTENT_LENGTH if skip_len => continue,
            &DATE => has_date = true,

            // omit HTTP/1.x only headers according to:
            // https://datatracker.ietf.org/doc/html/rfc7540#section-8.1.2.2
            hdr if hdr == HeaderName::from_static("keep-alive")
                || hdr == HeaderName::from_static("proxy-connection") =>
            {
                continue
            }

            _ => {}
        }

        res.headers_mut().append(key, value.clone());
    }

    // set date header
    if !has_date {
        let mut bytes = BytesMut::with_capacity(29);
        config.write_date_header_value(&mut bytes);
        res.headers_mut().insert(
            DATE,
            // SAFETY: serialized date-times are known ASCII strings
            unsafe { HeaderValue::from_maybe_shared_unchecked(bytes.freeze()) },
        );
    }

    res
}