Do compress SVGs (#321)

* Still compress svgs Even though they're images they're really just xml, so should still be compressed. Fixes #320 * changelog
tower-rs · Jan 20, 2023 · e941dee · e941dee
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diff --git a/tower-http/CHANGELOG.md b/tower-http/CHANGELOG.md
@@ -25,10 +25,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Fixed
 
 - Don't include identity in Content-Encoding header ([#317])
+- **compression:** Do compress SVGs ([#321])
 
 [#290]: https://github.com/tower-rs/tower-http/pull/290
 [#283]: https://github.com/tower-rs/tower-http/pull/283
 [#317]: https://github.com/tower-rs/tower-http/pull/317
+[#321]: https://github.com/tower-rs/tower-http/pull/321
 
 # 0.3.5 (December 02, 2022)
 

diff --git a/tower-http/src/compression/mod.rs b/tower-http/src/compression/mod.rs
@@ -83,10 +83,13 @@ pub use self::{
 
 #[cfg(test)]
 mod tests {
+    use crate::compression::predicate::SizeAbove;
+
     use super::*;
     use async_compression::tokio::write::{BrotliDecoder, BrotliEncoder};
     use bytes::BytesMut;
     use flate2::read::GzDecoder;
+    use http::header::{ACCEPT_ENCODING, CONTENT_ENCODING, CONTENT_TYPE};
     use http_body::Body as _;
     use hyper::{Body, Error, Request, Response, Server};
     use std::sync::{Arc, RwLock};
@@ -281,4 +284,54 @@ mod tests {
         }
         assert!(String::from_utf8(data.to_vec()).is_err());
     }
+
+    #[tokio::test]
+    async fn doesnt_compress_images() {
+        async fn handle(_req: Request<Body>) -> Result<Response<Body>, Error> {
+            let mut res = Response::new(Body::from(
+                "a".repeat((SizeAbove::DEFAULT_MIN_SIZE * 2) as usize),
+            ));
+            res.headers_mut()
+                .insert(CONTENT_TYPE, "image/png".parse().unwrap());
+            Ok(res)
+        }
+
+        let svc = Compression::new(service_fn(handle));
+
+        let res = svc
+            .oneshot(
+                Request::builder()
+                    .header(ACCEPT_ENCODING, "gzip")
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert!(res.headers().get(CONTENT_ENCODING).is_none());
+    }
+
+    #[tokio::test]
+    async fn does_compress_svg() {
+        async fn handle(_req: Request<Body>) -> Result<Response<Body>, Error> {
+            let mut res = Response::new(Body::from(
+                "a".repeat((SizeAbove::DEFAULT_MIN_SIZE * 2) as usize),
+            ));
+            res.headers_mut()
+                .insert(CONTENT_TYPE, "image/svg+xml".parse().unwrap());
+            Ok(res)
+        }
+
+        let svc = Compression::new(service_fn(handle));
+
+        let res = svc
+            .oneshot(
+                Request::builder()
+                    .header(ACCEPT_ENCODING, "gzip")
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(res.headers()[CONTENT_ENCODING], "gzip");
+    }
 }
diff --git a/tower-http/src/compression/predicate.rs b/tower-http/src/compression/predicate.rs
@@ -145,7 +145,7 @@ impl Predicate for DefaultPredicate {
 pub struct SizeAbove(u16);
 
 impl SizeAbove {
-    const DEFAULT_MIN_SIZE: u16 = 32;
+    pub(crate) const DEFAULT_MIN_SIZE: u16 = 32;
 
     /// Create a new `SizeAbove` predicate that will only compress responses larger than
     /// `min_size_bytes`.
@@ -185,23 +185,35 @@ impl Predicate for SizeAbove {
 
 /// Predicate that wont allow responses with a specific `content-type` to be compressed.
 #[derive(Clone, Debug)]
-pub struct NotForContentType(Str);
+pub struct NotForContentType {
+    content_type: Str,
+    exception: Option<Str>,
+}
 
 impl NotForContentType {
     /// Predicate that wont compress gRPC responses.
     pub const GRPC: Self = Self::const_new("application/grpc");
 
     /// Predicate that wont compress images.
-    pub const IMAGES: Self = Self::const_new("image/");
+    pub const IMAGES: Self = Self {
+        content_type: Str::Static("image/"),
+        exception: Some(Str::Static("image/svg+xml")),
+    };
 
     /// Create a new `NotForContentType`.
     pub fn new(content_type: &str) -> Self {
-        Self(Str::Shared(content_type.into()))
+        Self {
+            content_type: Str::Shared(content_type.into()),
+            exception: None,
+        }
     }
 
     /// Create a new `NotForContentType` from a static string.
     pub const fn const_new(content_type: &'static str) -> Self {
-        Self(Str::Static(content_type))
+        Self {
+            content_type: Str::Static(content_type),
+            exception: None,
+        }
     }
 }
 
@@ -210,11 +222,13 @@ impl Predicate for NotForContentType {
     where
         B: Body,
     {
-        let str = match &self.0 {
-            Str::Static(str) => *str,
-            Str::Shared(arc) => &*arc,
-        };
-        !content_type(response).starts_with(str)
+        if let Some(except) = &self.exception {
+            if content_type(response) == except.as_str() {
+                return true;
+            }
+        }
+
+        !content_type(response).starts_with(self.content_type.as_str())
     }
 }
 
@@ -224,6 +238,15 @@ enum Str {
     Shared(Arc<str>),
 }
 
+impl Str {
+    fn as_str(&self) -> &str {
+        match self {
+            Str::Static(s) => s,
+            Str::Shared(s) => s,
+        }
+    }
+}
+
 impl fmt::Debug for Str {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {