[pbs-devel] [PATCH proxmox 1/2] http: teach the Client how to speak gzip

[Maximiliano Sandoval]

Proxmox VE already supports using gzip to encode and decode the body of
http requests. We teach the proxmox-http how to do the same.

This can be also tested against
http://eu.httpbin.org/#/Response_formats/get_gzip via

```rust
async fn test_client() {
    use crate::client_trait::HttpClient;
    let client = Client::new();
    let response = client.get_string("http://eu.httpbin.org/gzip", None).await.unwrap();
    assert_eq!(response, "..");
}
```

Suggested-by: Lukas Wagner <l.wagner at proxmox.com>
Signed-off-by: Maximiliano Sandoval <m.sandoval at proxmox.com>
---
 proxmox-http/Cargo.toml           |  5 +++
 proxmox-http/src/client/simple.rs | 62 +++++++++++++++++++++++++++++--
 2 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/proxmox-http/Cargo.toml b/proxmox-http/Cargo.toml
index 11c6f0b0..9ec32e7f 100644
--- a/proxmox-http/Cargo.toml
+++ b/proxmox-http/Cargo.toml
@@ -21,12 +21,16 @@ tokio = { workspace = true, features = [], optional = true }
 tokio-openssl = { workspace = true, optional = true }
 ureq = { version = "2.4", features = ["native-certs"], optional = true }
 url = { workspace = true, optional = true }
+flate2 = { workspace = true, optional = true }
 
 proxmox-async = { workspace = true, optional = true }
 proxmox-sys = { workspace = true, optional = true }
 proxmox-io = { workspace = true, optional = true }
 proxmox-lang = { workspace = true, optional = true }
 
+[dev-dependencies]
+tokio = { workspace = true, features = [ "macros" ] }
+
 [features]
 default = []
 
@@ -39,6 +43,7 @@ rate-limited-stream = [
     "tokio?/time",
 ]
 client = [
+    "dep:flate2",
     "dep:futures",
     "dep:hyper",
     "dep:openssl",
diff --git a/proxmox-http/src/client/simple.rs b/proxmox-http/src/client/simple.rs
index e9910802..b33154be 100644
--- a/proxmox-http/src/client/simple.rs
+++ b/proxmox-http/src/client/simple.rs
@@ -1,9 +1,11 @@
 use anyhow::{bail, format_err, Error};
 use std::collections::HashMap;
-
+use std::io::Read;
 #[cfg(all(feature = "client-trait", feature = "proxmox-async"))]
 use std::str::FromStr;
 
+use flate2::read::GzDecoder;
+
 use futures::*;
 #[cfg(all(feature = "client-trait", feature = "proxmox-async"))]
 use http::header::HeaderName;
@@ -72,6 +74,10 @@ impl Client {
             HeaderValue::from_str(Self::DEFAULT_USER_AGENT_STRING)?
         };
 
+        request.headers_mut().insert(
+            hyper::header::ACCEPT_ENCODING,
+            HeaderValue::from_static("gzip"),
+        );
         request
             .headers_mut()
             .insert(hyper::header::USER_AGENT, user_agent);
@@ -142,11 +148,22 @@ impl Client {
     ) -> Result<Response<String>, Error> {
         match response {
             Ok(res) => {
-                let (parts, body) = res.into_parts();
+                let (mut parts, body) = res.into_parts();
+                let is_gzip_encoded = parts
+                    .headers
+                    .remove(&hyper::header::CONTENT_ENCODING)
+                    .is_some_and(|h| h == "gzip");
 
                 let buf = hyper::body::to_bytes(body).await?;
-                let new_body = String::from_utf8(buf.to_vec())
-                    .map_err(|err| format_err!("Error converting HTTP result data: {}", err))?;
+                let new_body = if is_gzip_encoded {
+                    let mut gz = GzDecoder::new(&buf[..]);
+                    let mut s = String::new();
+                    gz.read_to_string(&mut s)?;
+                    s
+                } else {
+                    String::from_utf8(buf.to_vec())
+                        .map_err(|err| format_err!("Error converting HTTP result data: {}", err))?
+                };
 
                 Ok(Response::from_parts(parts, new_body))
             }
@@ -245,3 +262,40 @@ impl crate::HttpClient<String, String> for Client {
         })
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    const BODY: &str = "hello world";
+
+    #[tokio::test]
+    async fn test_parse_response_plain_text() {
+        let body = Body::from(BODY);
+        let response = Response::new(body);
+        assert_eq!(Client::response_body_string(response).await.unwrap(), BODY);
+    }
+
+    #[tokio::test]
+    async fn test_parse_response_gzip() {
+        let encoded = encode_gzip(BODY.as_bytes()).unwrap();
+        let body = Body::from(encoded);
+
+        let response = Response::builder()
+            .header(hyper::header::CONTENT_ENCODING, "gzip")
+            .body(body)
+            .unwrap();
+        assert_eq!(Client::response_body_string(response).await.unwrap(), BODY);
+    }
+
+    fn encode_gzip(bytes: &[u8]) -> Result<Vec<u8>, std::io::Error> {
+        use flate2::write::GzEncoder;
+        use flate2::Compression;
+        use std::io::Write;
+
+        let mut e = GzEncoder::new(Vec::new(), Compression::default());
+        e.write_all(bytes).unwrap();
+
+        e.finish()
+    }
+}
-- 
2.39.2