fix(client): detect valid eof after reading a body

If a connection closes immediately after reading the end of the body,
the next call to `conn.poll()` should not error, but just indicate
that the connection is done.

Closes #1396

src/proto/conn.rs

@@ -88,6 +88,9 @@ where I: AsyncRead + AsyncWrite,
                 trace!("poll when on keep-alive");
                 if !T::should_read_first() {
                     self.try_empty_read()?;
+                    if self.is_read_closed() {
+                        return Ok(Async::Ready(None));
+                    }
                 }
                 self.maybe_park_read();
                 return Ok(Async::NotReady);
@@ -134,6 +137,11 @@ where I: AsyncRead + AsyncWrite,
         }
     }
 
+    fn should_error_on_eof(&self) -> bool {
+        // If we're idle, it's probably just the connection closing gracefully.
+        T::should_error_on_parse_eof() && !self.state.is_idle()
+    }
+
     pub fn read_head(&mut self) -> Poll<Option<(super::MessageHead<T::Incoming>, bool)>, ::Error> {
         debug_assert!(self.can_read_head());
         trace!("Conn::read_head");
@@ -145,7 +153,7 @@ where I: AsyncRead + AsyncWrite,
                 // If we are currently waiting on a message, then an empty
                 // message should be reported as an error. If not, it is just
                 // the connection closing gracefully.
-                let must_error = !self.state.is_idle() && T::should_error_on_parse_eof();
+                let must_error = self.should_error_on_eof();
                 self.state.close_read();
                 self.io.consume_leading_lines();
                 let was_mid_parse = !self.io.read_buf().is_empty();
@@ -185,6 +193,9 @@ where I: AsyncRead + AsyncWrite,
                     (true, Reading::Body(decoder))
                 };
                 self.state.reading = reading;
+                if !body {
+                    self.try_keep_alive();
+                }
                 Ok(Async::Ready(Some((head, body))))
             },
             _ => {
@@ -219,6 +230,7 @@ where I: AsyncRead + AsyncWrite,
         };
 
         self.state.reading = reading;
+        self.try_keep_alive();
         ret
     }
 
@@ -251,11 +263,12 @@ where I: AsyncRead + AsyncWrite,
         } else {
              match self.io.read_from_io() {
                 Ok(Async::Ready(0)) => {
-                    trace!("try_empty_read; found EOF on connection");
+                    trace!("try_empty_read; found EOF on connection: {:?}", self.state);
+                    let must_error = self.should_error_on_eof();
+                    // order is important: must_error needs state BEFORE close_read
                     self.state.close_read();
-                    let must_error = !self.state.is_idle() && T::should_error_on_parse_eof();
                     if must_error {
-                        Err(io::ErrorKind::UnexpectedEof.into())
+                        Err(io::Error::new(io::ErrorKind::UnexpectedEof, "unexpected EOF waiting for response"))
                     } else {
                         Ok(())
                     }
@@ -860,7 +873,7 @@ mod tests {
     use super::super::h1::Encoder;
     use mock::AsyncIo;
 
-    use super::{Conn, Reading, Writing};
+    use super::{Conn, Decoder, Reading, Writing};
     use ::uri::Uri;
 
     use std::str::FromStr;
@@ -960,6 +973,55 @@ mod tests {
         }).wait();
     }
 
+    #[test]
+    fn test_conn_body_finish_read_eof() {
+        let _: Result<(), ()> = future::lazy(|| {
+            let io = AsyncIo::new_eof();
+            let mut conn = Conn::<_, proto::Chunk, ClientTransaction>::new(io, Default::default());
+            conn.state.busy();
+            conn.state.writing = Writing::KeepAlive;
+            conn.state.reading = Reading::Body(Decoder::length(0));
+
+            match conn.poll() {
+                Ok(Async::Ready(Some(Frame::Body { chunk: None }))) => (),
+                other => panic!("unexpected frame: {:?}", other)
+            }
+
+            // conn eofs, but tokio-proto will call poll() again, before calling flush()
+            // the conn eof in this case is perfectly fine
+
+            match conn.poll() {
+                Ok(Async::Ready(None)) => (),
+                other => panic!("unexpected frame: {:?}", other)
+            }
+            Ok(())
+        }).wait();
+    }
+
+    #[test]
+    fn test_conn_message_empty_body_read_eof() {
+        let _: Result<(), ()> = future::lazy(|| {
+            let io = AsyncIo::new_buf(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n".to_vec(), 1024);
+            let mut conn = Conn::<_, proto::Chunk, ClientTransaction>::new(io, Default::default());
+            conn.state.busy();
+            conn.state.writing = Writing::KeepAlive;
+
+            match conn.poll() {
+                Ok(Async::Ready(Some(Frame::Message { body: false, .. }))) => (),
+                other => panic!("unexpected frame: {:?}", other)
+            }
+
+            // conn eofs, but tokio-proto will call poll() again, before calling flush()
+            // the conn eof in this case is perfectly fine
+
+            match conn.poll() {
+                Ok(Async::Ready(None)) => (),
+                other => panic!("unexpected frame: {:?}", other)
+            }
+            Ok(())
+        }).wait();
+    }
+
     #[test]
     fn test_conn_closed_read() {
         let io = AsyncIo::new_buf(vec![], 0);