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

use super::{body::BodyInner, DecompressionBody, DecompressionLayer};
use crate::{
    compression_utils::{AcceptEncoding, CompressionLevel, WrapBody},
    content_encoding::SupportedEncodings,
};
use http::{
    header::{self, ACCEPT_ENCODING},
    Request, Response,
};
use http_body::Body;
use tower_async_service::Service;

/// Decompresses response bodies of the underlying service.
///
/// This adds the `Accept-Encoding` header to requests and transparently decompresses response
/// bodies based on the `Content-Encoding` header.
///
/// See the [module docs](crate::decompression) for more details.
#[derive(Debug, Clone)]
pub struct Decompression<S> {
    pub(crate) inner: S,
    pub(crate) accept: AcceptEncoding,
}

impl<S> Decompression<S> {
    /// Creates a new `Decompression` wrapping the `service`.
    pub fn new(service: S) -> Self {
        Self {
            inner: service,
            accept: AcceptEncoding::default(),
        }
    }

    define_inner_service_accessors!();

    /// Returns a new [`Layer`] that wraps services with a `Decompression` middleware.
    ///
    /// [`Layer`]: tower_async_layer::Layer
    pub fn layer() -> DecompressionLayer {
        DecompressionLayer::new()
    }

    /// Sets whether to request the gzip encoding.
    #[cfg(feature = "decompression-gzip")]
    pub fn gzip(mut self, enable: bool) -> Self {
        self.accept.set_gzip(enable);
        self
    }

    /// Sets whether to request the Deflate encoding.
    #[cfg(feature = "decompression-deflate")]
    pub fn deflate(mut self, enable: bool) -> Self {
        self.accept.set_deflate(enable);
        self
    }

    /// Sets whether to request the Brotli encoding.
    #[cfg(feature = "decompression-br")]
    pub fn br(mut self, enable: bool) -> Self {
        self.accept.set_br(enable);
        self
    }

    /// Sets whether to request the Zstd encoding.
    #[cfg(feature = "decompression-zstd")]
    pub fn zstd(mut self, enable: bool) -> Self {
        self.accept.set_zstd(enable);
        self
    }

    /// Disables the gzip encoding.
    ///
    /// This method is available even if the `gzip` crate feature is disabled.
    pub fn no_gzip(mut self) -> Self {
        self.accept.set_gzip(false);
        self
    }

    /// Disables the Deflate encoding.
    ///
    /// This method is available even if the `deflate` crate feature is disabled.
    pub fn no_deflate(mut self) -> Self {
        self.accept.set_deflate(false);
        self
    }

    /// Disables the Brotli encoding.
    ///
    /// This method is available even if the `br` crate feature is disabled.
    pub fn no_br(mut self) -> Self {
        self.accept.set_br(false);
        self
    }

    /// Disables the Zstd encoding.
    ///
    /// This method is available even if the `zstd` crate feature is disabled.
    pub fn no_zstd(mut self) -> Self {
        self.accept.set_zstd(false);
        self
    }
}

impl<S, ReqBody, ResBody> Service<Request<ReqBody>> for Decompression<S>
where
    S: Service<Request<ReqBody>, Response = Response<ResBody>>,
    ResBody: Body,
{
    type Response = Response<DecompressionBody<ResBody>>;
    type Error = S::Error;

    async fn call(&mut self, mut req: Request<ReqBody>) -> Result<Self::Response, Self::Error> {
        if let header::Entry::Vacant(entry) = req.headers_mut().entry(ACCEPT_ENCODING) {
            if let Some(accept) = self.accept.to_header_value() {
                entry.insert(accept);
            }
        }

        let res = self.inner.call(req).await?;

        let (mut parts, body) = res.into_parts();

        let res =
            if let header::Entry::Occupied(entry) = parts.headers.entry(header::CONTENT_ENCODING) {
                let body = match entry.get().as_bytes() {
                    #[cfg(feature = "decompression-gzip")]
                    b"gzip" if self.accept.gzip() => DecompressionBody::new(BodyInner::gzip(
                        WrapBody::new(body, CompressionLevel::default()),
                    )),

                    #[cfg(feature = "decompression-deflate")]
                    b"deflate" if self.accept.deflate() => DecompressionBody::new(
                        BodyInner::deflate(WrapBody::new(body, CompressionLevel::default())),
                    ),

                    #[cfg(feature = "decompression-br")]
                    b"br" if self.accept.br() => DecompressionBody::new(BodyInner::brotli(
                        WrapBody::new(body, CompressionLevel::default()),
                    )),

                    #[cfg(feature = "decompression-zstd")]
                    b"zstd" if self.accept.zstd() => DecompressionBody::new(BodyInner::zstd(
                        WrapBody::new(body, CompressionLevel::default()),
                    )),

                    _ => {
                        return Ok(Response::from_parts(
                            parts,
                            DecompressionBody::new(BodyInner::identity(body)),
                        ))
                    }
                };

                entry.remove();
                parts.headers.remove(header::CONTENT_LENGTH);

                Response::from_parts(parts, body)
            } else {
                Response::from_parts(parts, DecompressionBody::new(BodyInner::identity(body)))
            };

        Ok(res)
    }
}