fix(web): allow space after : in grpc-status

tonic-web/src/call.rs

@@ -418,20 +418,17 @@ fn decode_trailers_frame(mut buf: Bytes) -> Result<Option<HeaderMap>, Status> {
     }
 
     for trailer in trailers {
-        let mut s = trailer.split(|b| b == &b':');
-        let key = s
-            .next()
-            .ok_or_else(|| Status::internal("trailers couldn't parse key"))?;
-        let value = s
-            .next()
-            .ok_or_else(|| Status::internal("trailers couldn't parse value"))?;
-
-        let value = value
-            .split(|b| b == &b'\r')
-            .next()
-            .ok_or_else(|| Status::internal("trailers was not escaped"))?
-            .strip_prefix(b" ")
-            .unwrap_or(value);
+        let Some((key, value)) = trailer
+            .iter()
+            .position(|b| *b == b':')
+            .map(|pos| trailer.split_at(pos))
+        else {
+            return Err(Status::internal("trailers couldn't parse key/value"));
+        };
+
+        // Skip the ':' separator and trim leading OWS (spaces/tabs) from the value
+        let value = &value[1..]; // skip ':'
+        let value = trim_ascii_start(value);
 
         let header_key = HeaderName::try_from(key)
             .map_err(|e| Status::internal(format!("Unable to parse HeaderName: {e}")))?;
@@ -443,6 +440,14 @@ fn decode_trailers_frame(mut buf: Bytes) -> Result<Option<HeaderMap>, Status> {
     Ok(Some(map))
 }
 
+fn trim_ascii_start(bytes: &[u8]) -> &[u8] {
+    let start = bytes
+        .iter()
+        .position(|b| !b.is_ascii_whitespace())
+        .unwrap_or(bytes.len());
+    &bytes[start..]
+}
+
 fn make_trailers_frame(trailers: HeaderMap) -> Bytes {
     let trailers = encode_trailers(trailers);
     let len = trailers.len();
@@ -659,4 +664,46 @@ mod tests {
 
         assert_eq!(trailers, expected);
     }
+
+    #[test]
+    fn decode_trailers_space_after_colon() {
+        // connect-rpc and standard HTTP use "key: value" (space after colon)
+        let trailers_bytes = b"grpc-status: 0\r\ngrpc-message: this is a message\r\n";
+        let len = trailers_bytes.len();
+
+        let mut frame = BytesMut::new();
+        frame.put_u8(GRPC_WEB_TRAILERS_BIT);
+        frame.put_u32(len as u32);
+        frame.put_slice(&trailers_bytes[..]);
+
+        let map = decode_trailers_frame(frame.freeze()).unwrap().unwrap();
+
+        let mut expected = HeaderMap::new();
+        expected.insert(Status::GRPC_STATUS, HeaderValue::from_static("0"));
+        expected.insert(
+            Status::GRPC_MESSAGE,
+            HeaderValue::from_static("this is a message"),
+        );
+
+        assert_eq!(map, expected);
+    }
+
+    #[test]
+    fn decode_trailers_value_with_colons() {
+        let trailers_bytes = b"grpc-status: 0\r\ngrpc-message: error: something: went wrong\r\n";
+        let len = trailers_bytes.len();
+
+        let mut frame = BytesMut::new();
+        frame.put_u8(GRPC_WEB_TRAILERS_BIT);
+        frame.put_u32(len as u32);
+        frame.put_slice(&trailers_bytes[..]);
+
+        let map = decode_trailers_frame(frame.freeze()).unwrap().unwrap();
+
+        assert_eq!(map.get("grpc-status").unwrap(), "0");
+        assert_eq!(
+            map.get("grpc-message").unwrap(),
+            "error: something: went wrong"
+        );
+    }
 }