feat: enhance HTTP/2 support by ensuring Host header is set and adding multiplexed request tests

rust/crates/rustproxy-http/src/proxy_service.rs

@@ -244,7 +244,10 @@ impl HttpProxyService {
             .map(|h| {
                 // Strip port from host header
                 h.split(':').next().unwrap_or(h).to_string()
-            });
+            })
+            // HTTP/2 uses :authority pseudo-header instead of Host;
+            // hyper maps it to the URI authority component
+            .or_else(|| req.uri().host().map(|h| h.to_string()));
 
         let path = req.uri().path().to_string();
         let method = req.method().clone();
@@ -397,11 +400,18 @@ impl HttpProxyService {
             }
         }
 
+        // Ensure Host header is set (HTTP/2 requests don't have Host; need it for h1 backends)
+        if !upstream_headers.contains_key("host") {
+            if let Some(ref h) = host {
+                if let Ok(val) = hyper::header::HeaderValue::from_str(h) {
+                    upstream_headers.insert(hyper::header::HOST, val);
+                }
+            }
+        }
+
         // Add standard reverse-proxy headers (X-Forwarded-*)
         {
-            let original_host = parts.headers.get("host")
-                .and_then(|h| h.to_str().ok())
-                .unwrap_or("");
+            let original_host = host.as_deref().unwrap_or("");
             let forwarded_proto = if route_match.route.action.tls.as_ref()
                 .map(|t| matches!(t.mode,
                     rustproxy_config::TlsMode::Terminate
@@ -574,10 +584,11 @@ impl HttpProxyService {
         source_ip: &str,
         pool_key: &crate::connection_pool::PoolKey,
     ) -> Result<Response<BoxBody<Bytes, hyper::Error>>, hyper::Error> {
+        // Always use HTTP/1.1 for h1 backend connections (h2 incoming requests have version HTTP/2.0)
         let mut upstream_req = Request::builder()
             .method(parts.method)
             .uri(upstream_path)
-            .version(parts.version);
+            .version(hyper::Version::HTTP_11);
 
         if let Some(headers) = upstream_req.headers_mut() {
             *headers = upstream_headers;
@@ -848,6 +859,7 @@ impl HttpProxyService {
 
         // Copy all original headers (preserving the client's Host header).
         // Skip X-Forwarded-* since we set them ourselves below.
+        let mut has_host_header = false;
         for (name, value) in parts.headers.iter() {
             let name_str = name.as_str();
             if name_str == "x-forwarded-for"
@@ -856,13 +868,25 @@ impl HttpProxyService {
             {
                 continue;
             }
+            if name_str == "host" {
+                has_host_header = true;
+            }
             raw_request.push_str(&format!("{}: {}\r\n", name, value.to_str().unwrap_or("")));
         }
 
+        // HTTP/2 requests don't have Host header; add one from URI authority for h1 backends
+        let ws_host = parts.uri.host().map(|h| h.to_string());
+        if !has_host_header {
+            if let Some(ref h) = ws_host {
+                raw_request.push_str(&format!("host: {}\r\n", h));
+            }
+        }
+
         // Add standard reverse-proxy headers (X-Forwarded-*)
         {
             let original_host = parts.headers.get("host")
                 .and_then(|h| h.to_str().ok())
+                .or(ws_host.as_deref())
                 .unwrap_or("");
             let forwarded_proto = if route.action.tls.as_ref()
                 .map(|t| matches!(t.mode,

rust/crates/rustproxy-passthrough/src/sni_parser.rs

@@ -196,6 +196,7 @@ pub fn is_http(data: &[u8]) -> bool {
         b"PATC",
         b"OPTI",
         b"CONN",
+        b"PRI ",   // HTTP/2 connection preface
     ];
     starts.iter().any(|s| data.starts_with(s))
 }