ntex/ntex/src/http/encoding/encoder.rs

//! Stream encoder
use std::{fmt, future::Future, io, io::Write, pin::Pin, task::Context, task::Poll};

#[cfg(feature = "brotli")]
use brotli2::write::BrotliEncoder;
use flate2::write::{GzEncoder, ZlibEncoder};

use crate::http::body::{Body, BodySize, MessageBody, ResponseBody};
use crate::http::header::{ContentEncoding, HeaderValue, CONTENT_ENCODING};
use crate::http::{ResponseHead, StatusCode};
use crate::rt::{spawn_blocking, JoinHandle};
use crate::util::Bytes;

use super::Writer;

const INPLACE: usize = 1024;

pub struct Encoder<B> {
    eof: bool,
    body: EncoderBody<B>,
    encoder: Option<ContentEncoder>,
    fut: Option<JoinHandle<Result<ContentEncoder, io::Error>>>,
}

impl<B: MessageBody> Encoder<B> {
    pub fn response(
        encoding: ContentEncoding,
        head: &mut ResponseHead,
        body: ResponseBody<B>,
    ) -> ResponseBody<B> {
        let can_encode = ContentEncoder::can_encode(encoding)
            && !(head.headers().contains_key(&CONTENT_ENCODING)
                || head.status == StatusCode::SWITCHING_PROTOCOLS
                || head.status == StatusCode::NO_CONTENT
                || encoding == ContentEncoding::Identity
                || encoding == ContentEncoding::Auto);

        if !can_encode {
            body
        } else {
            let body = match body {
                ResponseBody::Other(b) => match b {
                    Body::None => return ResponseBody::Other(Body::None),
                    Body::Empty => return ResponseBody::Other(Body::Empty),
                    Body::Bytes(buf) => EncoderBody::Bytes(buf),
                    Body::Message(stream) => EncoderBody::BoxedStream(stream),
                },
                ResponseBody::Body(stream) => EncoderBody::Stream(stream),
            };

            // Modify response body only if encoder is not None
            let encoder = ContentEncoder::encoder(encoding).unwrap();
            update_head(encoding, head);
            head.no_chunking(false);
            ResponseBody::Other(Body::from_message(Encoder {
                body,
                eof: false,
                fut: None,
                encoder: Some(encoder),
            }))
        }
    }
}

impl<B: fmt::Debug> fmt::Debug for Encoder<B> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Encoder")
            .field("eof", &self.eof)
            .field("body", &self.body)
            .field("encoder", &self.encoder)
            .field("fut", &self.fut.as_ref().map(|_| "JoinHandle(_)"))
            .finish()
    }
}

enum EncoderBody<B> {
    Bytes(Bytes),
    Stream(B),
    BoxedStream(Box<dyn MessageBody>),
}

impl<B> fmt::Debug for EncoderBody<B> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            EncoderBody::Bytes(ref b) => write!(f, "EncoderBody::Bytes({:?})", b),
            EncoderBody::Stream(_) => write!(f, "EncoderBody::Stream(_)"),
            EncoderBody::BoxedStream(_) => write!(f, "EncoderBody::BoxedStream(_)"),
        }
    }
}

impl<B: MessageBody> MessageBody for Encoder<B> {
    fn size(&self) -> BodySize {
        if self.encoder.is_none() {
            match self.body {
                EncoderBody::Bytes(ref b) => b.size(),
                EncoderBody::Stream(ref b) => b.size(),
                EncoderBody::BoxedStream(ref b) => b.size(),
            }
        } else {
            BodySize::Stream
        }
    }

    fn poll_next_chunk(
        &mut self,
        cx: &mut Context<'_>,
    ) -> Poll<Option<Result<Bytes, Box<dyn std::error::Error>>>> {
        loop {
            if self.eof {
                return Poll::Ready(None);
            }

            if let Some(ref mut fut) = self.fut {
                let mut encoder = match Pin::new(fut).poll(cx) {
                    Poll::Ready(Ok(Ok(item))) => item,
                    Poll::Ready(Ok(Err(e))) => return Poll::Ready(Some(Err(Box::new(e)))),
                    Poll::Ready(Err(_)) => {
                        return Poll::Ready(Some(Err(Box::new(io::Error::new(
                            io::ErrorKind::Interrupted,
                            "Canceled",
                        )))));
                    }
                    Poll::Pending => return Poll::Pending,
                };
                let chunk = encoder.take();
                self.encoder = Some(encoder);
                self.fut.take();
                if !chunk.is_empty() {
                    return Poll::Ready(Some(Ok(chunk)));
                }
            }

            let result = match self.body {
                EncoderBody::Bytes(ref mut b) => {
                    if b.is_empty() {
                        Poll::Ready(None)
                    } else {
                        Poll::Ready(Some(Ok(std::mem::take(b))))
                    }
                }
                EncoderBody::Stream(ref mut b) => b.poll_next_chunk(cx),
                EncoderBody::BoxedStream(ref mut b) => b.poll_next_chunk(cx),
            };
            match result {
                Poll::Ready(Some(Ok(chunk))) => {
                    if let Some(mut encoder) = self.encoder.take() {
                        if chunk.len() < INPLACE {
                            encoder.write(&chunk)?;
                            let chunk = encoder.take();
                            self.encoder = Some(encoder);
                            if !chunk.is_empty() {
                                return Poll::Ready(Some(Ok(chunk)));
                            }
                        } else {
                            self.fut = Some(spawn_blocking(move || {
                                encoder.write(&chunk)?;
                                Ok(encoder)
                            }));
                        }
                    } else {
                        return Poll::Ready(Some(Ok(chunk)));
                    }
                }
                Poll::Ready(None) => {
                    if let Some(encoder) = self.encoder.take() {
                        let chunk = encoder.finish()?;
                        if chunk.is_empty() {
                            return Poll::Ready(None);
                        } else {
                            self.eof = true;
                            return Poll::Ready(Some(Ok(chunk)));
                        }
                    } else {
                        return Poll::Ready(None);
                    }
                }
                val => return val,
            }
        }
    }
}

fn update_head(encoding: ContentEncoding, head: &mut ResponseHead) {
    head.headers_mut().insert(
        CONTENT_ENCODING,
        HeaderValue::from_static(encoding.as_str()),
    );
}

enum ContentEncoder {
    Deflate(ZlibEncoder<Writer>),
    Gzip(GzEncoder<Writer>),
    #[cfg(feature = "brotli")]
    Br(BrotliEncoder<Writer>),
}

impl ContentEncoder {
    fn can_encode(encoding: ContentEncoding) -> bool {
        #[cfg(feature = "brotli")]
        {
            matches!(
                encoding,
                ContentEncoding::Deflate | ContentEncoding::Gzip | ContentEncoding::Br
            )
        }
        #[cfg(not(feature = "brotli"))]
        {
            matches!(encoding, ContentEncoding::Deflate | ContentEncoding::Gzip)
        }
    }

    fn encoder(encoding: ContentEncoding) -> Option<Self> {
        match encoding {
            ContentEncoding::Deflate => Some(ContentEncoder::Deflate(ZlibEncoder::new(
                Writer::new(),
                flate2::Compression::fast(),
            ))),
            ContentEncoding::Gzip => Some(ContentEncoder::Gzip(GzEncoder::new(
                Writer::new(),
                flate2::Compression::fast(),
            ))),
            #[cfg(feature = "brotli")]
            ContentEncoding::Br => {
                Some(ContentEncoder::Br(BrotliEncoder::new(Writer::new(), 3)))
            }
            _ => None,
        }
    }

    fn take(&mut self) -> Bytes {
        match *self {
            #[cfg(feature = "brotli")]
            ContentEncoder::Br(ref mut encoder) => encoder.get_mut().take(),
            ContentEncoder::Deflate(ref mut encoder) => encoder.get_mut().take(),
            ContentEncoder::Gzip(ref mut encoder) => encoder.get_mut().take(),
        }
    }

    fn finish(self) -> Result<Bytes, io::Error> {
        match self {
            #[cfg(feature = "brotli")]
            ContentEncoder::Br(encoder) => match encoder.finish() {
                Ok(writer) => Ok(writer.buf.freeze()),
                Err(err) => Err(err),
            },
            ContentEncoder::Gzip(encoder) => match encoder.finish() {
                Ok(writer) => Ok(writer.buf.freeze()),
                Err(err) => Err(err),
            },
            ContentEncoder::Deflate(encoder) => match encoder.finish() {
                Ok(writer) => Ok(writer.buf.freeze()),
                Err(err) => Err(err),
            },
        }
    }

    fn write(&mut self, data: &[u8]) -> Result<(), io::Error> {
        match *self {
            #[cfg(feature = "brotli")]
            ContentEncoder::Br(ref mut encoder) => match encoder.write_all(data) {
                Ok(_) => Ok(()),
                Err(err) => {
                    log::trace!("Error decoding br encoding: {}", err);
                    Err(err)
                }
            },
            ContentEncoder::Gzip(ref mut encoder) => match encoder.write_all(data) {
                Ok(_) => Ok(()),
                Err(err) => {
                    log::trace!("Error decoding gzip encoding: {}", err);
                    Err(err)
                }
            },
            ContentEncoder::Deflate(ref mut encoder) => match encoder.write_all(data) {
                Ok(_) => Ok(()),
                Err(err) => {
                    log::trace!("Error decoding deflate encoding: {}", err);
                    Err(err)
                }
            },
        }
    }
}

impl fmt::Debug for ContentEncoder {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            ContentEncoder::Deflate(_) => write!(f, "ContentEncoder::Deflate"),
            ContentEncoder::Gzip(_) => write!(f, "ContentEncoder::Gzip"),
            #[cfg(feature = "brotli")]
            ContentEncoder::Br(_) => write!(f, "ContentEncoder::Br"),
        }
    }
}