todo: add http2-only client for h2c case

rpxy-lib/src/backend/upstream_opts.rs

@@ -4,8 +4,8 @@ use crate::error::*;
 pub enum UpstreamOption {
   OverrideHost,
   UpgradeInsecureRequests,
-  ConvertHttpsTo11,
-  ConvertHttpsTo2,
+  ForceHttp11Upstream,
+  ForceHttp2Upstream,
   // TODO: Adds more options for heder override
 }
 impl TryFrom<&str> for UpstreamOption {
@@ -14,8 +14,8 @@ impl TryFrom<&str> for UpstreamOption {
     match val {
       "override_host" => Ok(Self::OverrideHost),
       "upgrade_insecure_requests" => Ok(Self::UpgradeInsecureRequests),
-      "convert_https_to_11" => Ok(Self::ConvertHttpsTo11),
-      "convert_https_to_2" => Ok(Self::ConvertHttpsTo2),
+      "force_http11_upstream" => Ok(Self::ForceHttp11Upstream),
+      "force_http2_upstream" => Ok(Self::ForceHttp2Upstream),
       _ => Err(RpxyError::Other(anyhow!("Unsupported header option"))),
     }
   }

rpxy-lib/src/globals.rs

@@ -225,7 +225,8 @@ where
     }
 
     if !(upstream.iter().all(|(_, elem)| {
-      !(elem.opts.contains(&UpstreamOption::ConvertHttpsTo11) && elem.opts.contains(&UpstreamOption::ConvertHttpsTo2))
+      !(elem.opts.contains(&UpstreamOption::ForceHttp11Upstream)
+        && elem.opts.contains(&UpstreamOption::ForceHttp2Upstream))
     })) {
       error!("Either one of force_http11 or force_http2 can be enabled");
       return Err(RpxyError::ConfigBuild("Invalid upstream option setting"));

rpxy-lib/src/handler/handler_main.rs

@@ -356,14 +356,20 @@ where
     }
 
     // If not specified (force_httpXX_upstream) and https, version is preserved except for http/3
-    apply_upstream_options_to_request_line(req, upstream_group)?;
-    // Maybe workaround: Change version to http/1.1 when destination scheme is http
-    if req.version() != Version::HTTP_11 && upstream_chosen.uri.scheme() == Some(&Scheme::HTTP) {
-      *req.version_mut() = Version::HTTP_11;
-    } else if req.version() == Version::HTTP_3 {
-      debug!("HTTP/3 is currently unsupported for request to upstream. Use HTTP/2.");
+    match req.version() {
+      Version::HTTP_3 => {
+        debug!("HTTP/3 is currently unsupported for request to upstream.");
         *req.version_mut() = Version::HTTP_2;
       }
+      _ => {
+        if upstream_chosen.uri.scheme() == Some(&Scheme::HTTP) {
+          // Change version to http/1.1 when destination scheme is http
+          debug!("Change version to http/1.1 when destination scheme is http.");
+          *req.version_mut() = Version::HTTP_11;
+        }
+      }
+    }
+    apply_upstream_options_to_request_line(req, upstream_group)?;
 
     Ok(context)
   }

rpxy-lib/src/handler/utils_request.rs

@@ -11,8 +11,12 @@ use hyper::{header, Request};
 pub(super) fn apply_upstream_options_to_request_line<B>(req: &mut Request<B>, upstream: &UpstreamGroup) -> Result<()> {
   for opt in upstream.opts.iter() {
     match opt {
-      UpstreamOption::ConvertHttpsTo11 => *req.version_mut() = hyper::Version::HTTP_11,
-      UpstreamOption::ConvertHttpsTo2 => *req.version_mut() = hyper::Version::HTTP_2,
+      UpstreamOption::ForceHttp11Upstream => *req.version_mut() = hyper::Version::HTTP_11,
+      UpstreamOption::ForceHttp2Upstream => {
+        // case: h2c -> https://www.rfc-editor.org/rfc/rfc9113.txt
+        // Upgrade from HTTP/1.1 to HTTP/2 is deprecated. So, http-2 prior knowledge is required.
+        *req.version_mut() = hyper::Version::HTTP_2;
+      }
       _ => (),
     }
   }

rpxy-lib/src/lib.rs

@@ -70,6 +70,7 @@ where
     .enable_http2()
     .build();
 
+  // TODO: HTTP2 only client is needed for http2 cleartext case
   let msg_handler = HttpMessageHandlerBuilder::default()
     .forwarder(Arc::new(Client::builder().build::<_, hyper::Body>(connector)))
     .globals(globals.clone())