fix tight loop on aborted connection

src/server.rs

@@ -140,7 +140,7 @@ use proto::{self, Config, Prioritized};
 use bytes::{Buf, Bytes, IntoBuf};
 use futures::{self, Async, Future, Poll};
 use http::{Request, Response};
-use std::{convert, fmt, mem};
+use std::{convert, fmt, io, mem};
 use std::time::Duration;
 use tokio_io::{AsyncRead, AsyncWrite};
 
@@ -1045,6 +1045,12 @@ where
 
         while rem > 0 {
             let n = try_nb!(self.inner_mut().read(&mut buf[..rem]));
+            if n == 0 {
+                return Err(io::Error::new(
+                    io::ErrorKind::ConnectionReset,
+                    "connection closed unexpectedly",
+                ).into());
+            }
 
             if PREFACE[self.pos..self.pos + n] != buf[..n] {
                 // TODO: Should this just write the GO_AWAY frame directly?

tests/h2-support/src/mock.rs

@@ -329,7 +329,7 @@ impl io::Write for Mock {
         let mut me = self.pipe.inner.lock().unwrap();
 
         if me.closed {
-            return Err(io::Error::new(io::ErrorKind::BrokenPipe, "mock closed"));
+            return Ok(buf.len());
         }
 
         if me.tx_rem == 0 {

tests/h2-tests/tests/server.rs

@@ -589,3 +589,19 @@ fn poll_reset_after_send_response_is_user_error() {
 
     srv.join(client).wait().expect("wait");
 }
+
+#[test]
+fn server_error_on_unclean_shutdown() {
+    use std::io::Write;
+
+    let _ = ::env_logger::try_init();
+    let (io, mut client) = mock::new();
+
+    let srv = server::Builder::new()
+        .handshake::<_, Bytes>(io);
+
+    client.write_all(b"PRI *").expect("write");
+    drop(client);
+
+    srv.wait().expect_err("should error");
+}