[pbs-devel] [PATCH proxmox v5 5/5] http: teach the Client how to decode deflate content

Fri Jul 5 15:04:32 CEST 2024

The Backup Server can compress the content using deflate so we teach the
client how to decode it.

If a request is sent with the `Accept-Encoding` [2] header set to
`deflate`, and the response's `Content-Encoding` [1] header is equal to
`deflate` we wrap the Body stream with a stream that can decode `zlib`
on the run.

Note that from the `Accept-Encoding` docs [2], the `deflate` encoding is
actually `zlib`.

This can be also tested against
http://eu.httpbin.org/#/Response_formats/get_deflate by adding the
following test:

```rust
    #[tokio::test]
    async fn test_client() {
        let client = Client::new();
        let headers = HashMap::from([(
            hyper::header::ACCEPT_ENCODING.to_string(),
            "deflate".to_string(),
        )]);
        let response = client
            .get_string("https://eu.httpbin.org/deflate", Some(&headers))
            .await;
        assert!(response.is_ok());
    }
```

at `proxmox-http/src/client/simple.rs` and running

```
cargo test --features=client,client-trait
```

[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding
[2] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding

Suggested-by: Lukas Wagner <l.wagner at proxmox.com>
Signed-off-by: Maximiliano Sandoval <m.sandoval at proxmox.com>
---
 proxmox-http/Cargo.toml           |  7 ++++
 proxmox-http/src/client/simple.rs | 65 ++++++++++++++++++++++++++++++-
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/proxmox-http/Cargo.toml b/proxmox-http/Cargo.toml
index 9ece24eb..4455ba85 100644
--- a/proxmox-http/Cargo.toml
+++ b/proxmox-http/Cargo.toml
@@ -26,6 +26,11 @@ proxmox-async = { workspace = true, optional = true }
 proxmox-sys = { workspace = true, optional = true }
 proxmox-io = { workspace = true, optional = true }
 proxmox-lang = { workspace = true, optional = true }
+proxmox-compression = { workspace = true, optional = true }
+
+[dev-dependencies]
+tokio = { workspace = true, features = [ "macros" ] }
+flate2 = { workspace = true }
 
 [features]
 default = []
@@ -42,12 +47,14 @@ client = [
     "dep:futures",
     "dep:hyper",
     "dep:openssl",
+    "dep:proxmox-compression",
     "dep:tokio",
     "dep:tokio-openssl",
     "http-helpers",
     "hyper?/client",
     "hyper?/http1",
     "hyper?/http2",
+    "hyper?/stream",
     "hyper?/tcp",
     "rate-limited-stream",
     "tokio?/io-util",
diff --git a/proxmox-http/src/client/simple.rs b/proxmox-http/src/client/simple.rs
index e9910802..062889ac 100644
--- a/proxmox-http/src/client/simple.rs
+++ b/proxmox-http/src/client/simple.rs
@@ -78,7 +78,8 @@ impl Client {
 
         self.add_proxy_headers(&mut request)?;
 
-        self.client.request(request).map_err(Error::from).await
+        let encoded_response = self.client.request(request).map_err(Error::from).await?;
+        decode_response(encoded_response).await
     }
 
     pub async fn post(
@@ -245,3 +246,65 @@ impl crate::HttpClient<String, String> for Client {
         })
     }
 }
+
+/// Wraps the `Body` stream in a DeflateDecoder stream if the `Content-Encoding`
+/// header of the response is `deflate`, otherwise returns the original
+/// response.
+async fn decode_response(mut res: Response<Body>) -> Result<Response<Body>, Error> {
+    let Some(content_encoding) = res.headers_mut().remove(&hyper::header::CONTENT_ENCODING) else {
+        return Ok(res);
+    };
+
+    let encodings = content_encoding.to_str()?;
+    if encodings == "deflate" {
+        let (parts, body) = res.into_parts();
+        let decoder = proxmox_compression::DeflateDecoder::builder(body)
+            .zlib(true)
+            .build();
+        let decoded_body = Body::wrap_stream(decoder);
+        Ok(Response::from_parts(parts, decoded_body))
+    } else {
+        bail!("Unknown encoding format: {encodings}");
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    use std::io::Write;
+
+    const BODY: &str = r#"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do
+eiusmod tempor incididunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut
+enim aeque doleamus animo, cum corpore dolemus, fieri tamen permagna accessio potest,
+si aliquod aeternum et infinitum impendere."#;
+
+    #[tokio::test]
+    async fn test_parse_response_deflate() {
+        let encoded = encode_deflate(BODY.as_bytes()).unwrap();
+        let encoded_body = Body::from(encoded);
+        let encoded_response = Response::builder()
+            .header(hyper::header::CONTENT_ENCODING, "deflate")
+            .body(encoded_body)
+            .unwrap();
+
+        let decoded_response = decode_response(encoded_response).await.unwrap();
+
+        assert_eq!(
+            Client::response_body_string(decoded_response)
+                .await
+                .unwrap(),
+            BODY
+        );
+    }
+
+    fn encode_deflate(bytes: &[u8]) -> Result<Vec<u8>, std::io::Error> {
+        use flate2::write::ZlibEncoder;
+        use flate2::Compression;
+
+        let mut e = ZlibEncoder::new(Vec::new(), Compression::default());
+        e.write_all(bytes).unwrap();
+
+        e.finish()
+    }
+}
-- 
2.39.2



