consume large uncompressed response to avoid illumos hangs

Gemini's theory: When a test case requests the  /large-response
endpoint but compression is disabled (either by config, lack of header,
or rejection), the server attempts to write the full ~5KB JSON body to
the socket. On illumos, the default TCP socket buffer size is likely
smaller than on macOS/Linux, causing the server's write operation to
block because the test client never reads the data to drain the buffer.
When  teardown()  is called, the server hangs trying to finish the write
during graceful shutdown, eventually timing out.

The fix is to consume the response body in these tests.

Author: david-crespo

dropshot/tests/integration-tests/gzip.rs

@@ -413,10 +413,14 @@ async fn test_no_gzip_without_accept_encoding() {
     let uri = client.url("/large-response");
 
     // Request without any Accept-Encoding header should not get compressed response
-    let response = make_plain_request_response(client, &uri).await;
+    let mut response = make_plain_request_response(client, &uri).await;
 
     assert_eq!(response.headers().get(header::CONTENT_ENCODING), None);
 
+    // Consume the response body to avoid blocking teardown on platforms with
+    // small socket buffers (e.g., illumos).
+    get_response_bytes(&mut response).await;
+
     testctx.teardown().await;
 }
 
@@ -547,13 +551,16 @@ async fn test_reject_gzip_with_quality_zero() {
         .body(dropshot::Body::empty())
         .expect("Failed to construct request");
 
-    let response = client
+    let mut response = client
         .make_request_with_request(request, StatusCode::OK)
         .await
         .expect("Request should succeed");
 
     assert_eq!(response.headers().get(header::CONTENT_ENCODING), None);
 
+    // Consume response body (see test_no_gzip_without_accept_encoding).
+    get_response_bytes(&mut response).await;
+
     testctx.teardown().await;
 }
 
@@ -564,7 +571,7 @@ async fn test_vary_header_is_set() {
 
     // Request with Accept-Encoding: gzip
     let uri = client.url("/large-response");
-    let response = get_gzip_response(client, &uri).await;
+    let mut response = get_gzip_response(client, &uri).await;
 
     // Should have Vary: Accept-Encoding header
     assert!(
@@ -580,6 +587,9 @@ async fn test_vary_header_is_set() {
         vary_value
     );
 
+    // Consume response body (see test_no_gzip_without_accept_encoding).
+    get_response_bytes(&mut response).await;
+
     testctx.teardown().await;
 }
 
@@ -673,10 +683,13 @@ async fn test_compression_config_disabled() {
 
     // Request WITH Accept-Encoding: gzip but compression disabled in config
     let uri = client.url("/large-response");
-    let response = get_gzip_response(client, &uri).await;
+    let mut response = get_gzip_response(client, &uri).await;
 
     assert_eq!(response.headers().get(header::CONTENT_ENCODING), None);
 
+    // Consume response body (see test_no_gzip_without_accept_encoding).
+    get_response_bytes(&mut response).await;
+
     testctx.teardown().await;
 }
 
@@ -725,7 +738,7 @@ async fn test_vary_header_on_non_gzip_requests() {
 
     // Request WITHOUT Accept-Encoding: gzip for a compressible resource
     let uri = client.url("/large-response");
-    let response = make_plain_request_response(client, &uri).await;
+    let mut response = make_plain_request_response(client, &uri).await;
 
     // Should NOT be compressed
     assert!(
@@ -747,5 +760,8 @@ async fn test_vary_header_on_non_gzip_requests() {
         vary_value
     );
 
+    // Consume response body (see test_no_gzip_without_accept_encoding).
+    get_response_bytes(&mut response).await;
+
     testctx.teardown().await;
 }