From 991578392c53e2cf175f9864e74635f15d209960 Mon Sep 17 00:00:00 2001
From: Varun Chawla <varun_6april@hotmail.com>
Date: Sun, 22 Feb 2026 20:03:05 -0800
Subject: [PATCH] feat(error): preserve InvalidUri details in error source
 chain

When an invalid URI is parsed by the http crate, the InvalidUri error
contains useful details about what part of the URI was invalid. Previously
this information was discarded when converting to hyper::Error.

Now the original InvalidUri/InvalidUriParts error is stored as the
source of the hyper::Error, making it available through the standard
Error::source() chain and downcastable to the concrete type.

Closes #3043
---
 src/error.rs         | 40 +++++++++++++++++++++++++++++++++-------
 src/proto/h1/role.rs |  4 ++--
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index 8b41f9c93d..0d8b78bb9c 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -92,7 +92,7 @@ pub(super) enum Parse {
     Version,
     #[cfg(all(any(feature = "client", feature = "server"), feature = "http1"))]
     VersionH2,
-    Uri,
+    Uri(Option<Cause>),
     #[cfg(all(feature = "http1", feature = "server"))]
     UriTooLong,
     #[cfg(feature = "http1")]
@@ -459,7 +459,7 @@ impl Error {
             Kind::Parse(Parse::Version) => "invalid HTTP version parsed",
             #[cfg(all(any(feature = "client", feature = "server"), feature = "http1"))]
             Kind::Parse(Parse::VersionH2) => "invalid HTTP version parsed (found HTTP2 preface)",
-            Kind::Parse(Parse::Uri) => "invalid URI",
+            Kind::Parse(Parse::Uri(_)) => "invalid URI",
             #[cfg(all(feature = "http1", feature = "server"))]
             Kind::Parse(Parse::UriTooLong) => "URI too long",
             #[cfg(feature = "http1")]
@@ -582,7 +582,10 @@ impl StdError for Error {
 #[doc(hidden)]
 impl From<Parse> for Error {
     fn from(err: Parse) -> Error {
-        Error::new(Kind::Parse(err))
+        match err {
+            Parse::Uri(Some(cause)) => Error::new(Kind::Parse(Parse::Uri(None))).with(cause),
+            other => Error::new(Kind::Parse(other)),
+        }
     }
 }
 
@@ -632,14 +635,14 @@ impl From<http::status::InvalidStatusCode> for Parse {
 }
 
 impl From<http::uri::InvalidUri> for Parse {
-    fn from(_: http::uri::InvalidUri) -> Parse {
-        Parse::Uri
+    fn from(err: http::uri::InvalidUri) -> Parse {
+        Parse::Uri(Some(Box::new(err)))
     }
 }
 
 impl From<http::uri::InvalidUriParts> for Parse {
-    fn from(_: http::uri::InvalidUriParts) -> Parse {
-        Parse::Uri
+    fn from(err: http::uri::InvalidUriParts) -> Parse {
+        Parse::Uri(Some(Box::new(err)))
     }
 }
 
@@ -692,4 +695,27 @@ mod tests {
         let svc_err = Error::new_user_service(recvd);
         assert_eq!(svc_err.h2_reason(), h2::Reason::HTTP_1_1_REQUIRED);
     }
+
+    #[test]
+    fn uri_error_preserves_source() {
+        use std::error::Error as _;
+
+        // Parse an invalid URI through the http crate
+        let invalid: std::result::Result<http::Uri, _> = "dangling whitespace ".parse();
+        let uri_err: http::uri::InvalidUri = invalid.unwrap_err();
+
+        // Convert through the same path hyper uses: InvalidUri -> Parse -> Error
+        let parse: Parse = Parse::from(uri_err);
+        let error: Error = Error::from(parse);
+
+        // The error should have a source
+        assert!(error.source().is_some(), "URI error should preserve source");
+
+        // The source should be the original InvalidUri
+        let source = error.source().unwrap();
+        assert!(
+            source.downcast_ref::<http::uri::InvalidUri>().is_some(),
+            "source should be http::uri::InvalidUri"
+        );
+    }
 }
diff --git a/src/proto/h1/role.rs b/src/proto/h1/role.rs
index f92092e5a9..aae7095443 100644
--- a/src/proto/h1/role.rs
+++ b/src/proto/h1/role.rs
@@ -199,7 +199,7 @@ impl Http1Transaction for Server {
                             Parse::Method
                         } else {
                             debug_assert!(req.path.is_none());
-                            Parse::Uri
+                            Parse::Uri(None)
                         }
                     })
                 }
@@ -467,7 +467,7 @@ impl Http1Transaction for Server {
         let status = match *err.kind() {
             Kind::Parse(Parse::Method)
             | Kind::Parse(Parse::Header(_))
-            | Kind::Parse(Parse::Uri)
+            | Kind::Parse(Parse::Uri(_))
             | Kind::Parse(Parse::Version) => StatusCode::BAD_REQUEST,
             Kind::Parse(Parse::TooLarge) => StatusCode::REQUEST_HEADER_FIELDS_TOO_LARGE,
             Kind::Parse(Parse::UriTooLong) => StatusCode::URI_TOO_LONG,