sunrpc: Improvements for UDP client timeout handling [BZ #20257]

This commit fixes various aspects in the UDP client timeout handling.
Timeouts are now applied in a more consistent fashion.  Discarded UDP
packets no longer prevent the timeout from happening at all.

1 files changed, 104 insertions, 0 deletions

diff --git a/sunrpc/tst-udp-garbage.c b/sunrpc/tst-udp-garbage.c
new file mode 100644
index 0000000000..4abda93f08
--- /dev/null
+++ b/sunrpc/tst-udp-garbage.c
@@ -0,0 +1,104 @@
+/* Test that garbage packets do not affect timeout handling.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <netinet/in.h>
+#include <rpc/clnt.h>
+#include <rpc/svc.h>
+#include <stdbool.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/xsocket.h>
+#include <support/xthread.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+/* Descriptor for the server UDP socket.  */
+static int server_fd;
+
+static void *
+garbage_sender_thread (void *unused)
+{
+  while (true)
+    {
+      struct sockaddr_storage sa;
+      socklen_t salen = sizeof (sa);
+      char buf[1];
+      if (recvfrom (server_fd, buf, sizeof (buf), 0,
+                    (struct sockaddr *) &sa, &salen) < 0)
+        FAIL_EXIT1 ("recvfrom: %m");
+
+      /* Send garbage packets indefinitely.  */
+      buf[0] = 0;
+      while (true)
+        {
+          /* sendto can fail if the client closed the socket.  */
+          if (sendto (server_fd, buf, sizeof (buf), 0,
+                      (struct sockaddr *) &sa, salen) < 0)
+            break;
+
+          /* Wait a bit, to avoid burning too many CPU cycles in a
+             tight loop.  The wait period must be much shorter than
+             the client timeouts configured below.  */
+          usleep (50 * 1000);
+        }
+    }
+}
+
+static int
+do_test (void)
+{
+  support_become_root ();
+  support_enter_network_namespace ();
+
+  server_fd = xsocket (AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
+  struct sockaddr_in server_address =
+    {
+      .sin_family = AF_INET,
+      .sin_addr.s_addr = htonl (INADDR_LOOPBACK),
+    };
+  xbind (server_fd,
+         (struct sockaddr *) &server_address, sizeof (server_address));
+  {
+    socklen_t sinlen = sizeof (server_address);
+    xgetsockname (server_fd, (struct sockaddr *) &server_address, &sinlen);
+    TEST_VERIFY (sizeof (server_address) == sinlen);
+  }
+
+  /* Garbage packet source.  */
+  xpthread_detach (xpthread_create (NULL, garbage_sender_thread, NULL));
+
+  /* Test client.  Use an arbitrary timeout of one second, which is
+     much longer than the garbage packet interval, but still
+     reasonably short, so that the test completes quickly.  */
+  int client_fd = RPC_ANYSOCK;
+  CLIENT *clnt = clntudp_create (&server_address,
+                                 1, 2, /* Arbitrary RPC endpoint numbers.  */
+                                 (struct timeval) { 1, 0 },
+                                 &client_fd);
+  if (clnt == NULL)
+    FAIL_EXIT1 ("clntudp_create: %m");
+
+  TEST_VERIFY (clnt_call (clnt, 3, /* Arbitrary RPC procedure number.  */
+                          (xdrproc_t) xdr_void, NULL,
+                          (xdrproc_t) xdr_void, NULL,
+                          ((struct timeval) { 1, 0 })));
+
+  return 0;
+}
+
+#include <support/test-driver.c>