imap client: implement noop.

* include/mailutils/imap.h (mu_imap_noop): New proto.
* include/mailutils/sys/imap.h (mu_imap_client_state)
<MU_IMAP_NOOP_RX>: New state.
* libproto/imap/noop.c: New file.
* libproto/imap/Makefile.am (libmu_imap_la_SOURCES): Add noop.c
* mu/imap.c (report_failure): New function.
(com_login,select_mbox,com_status): Use report_failure for
error reporting.
(com_noop): New function.
(imap_comtab)<noop>: New command.

@@ -56,7 +56,9 @@ int mu_imap_login (mu_imap_t imap, const char *user, const char *pass);
 int mu_imap_logout (mu_imap_t imap);
 
 int mu_imap_id (mu_imap_t imap, char **idenv, mu_assoc_t *passoc);
-  
+
+int mu_imap_noop (mu_imap_t imap);
+
 int mu_imap_set_carrier (mu_imap_t imap, mu_stream_t carrier);
 int mu_imap_get_carrier (mu_imap_t imap, mu_stream_t *pcarrier);
 

@@ -46,6 +46,7 @@ enum mu_imap_client_state
     MU_IMAP_ID_RX,
     MU_IMAP_SELECT_RX,
     MU_IMAP_STATUS_RX,
+    MU_IMAP_NOOP_RX,
     MU_IMAP_CLOSING
   };
 

@@ -40,6 +40,7 @@ libmu_imap_la_SOURCES = \
  id.c\
  login.c\
  logout.c\
+ noop.c\
  resplist.c\
  response.c\
  resproc.c\

+/* GNU Mailutils -- a suite of utilities for electronic mail
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   This 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 3 of the License, or (at your option) any later version.
+
+   This 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 this library.  If not, see
+   <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdlib.h>
+#include <mailutils/errno.h>
+#include <mailutils/imap.h>
+#include <mailutils/sys/imap.h>
+
+int
+mu_imap_noop (mu_imap_t imap)
+{
+  int status;
+  
+  if (imap == NULL)
+    return EINVAL;
+  if (!imap->io)
+    return MU_ERR_NO_TRANSPORT;
+  if (imap->state != MU_IMAP_CONNECTED)
+    return MU_ERR_SEQ;
+
+  switch (imap->state)
+    {
+    case MU_IMAP_CONNECTED:
+      status = _mu_imap_tag_next (imap);
+      MU_IMAP_CHECK_EAGAIN (imap, status);
+      status = mu_imapio_printf (imap->io, "%s NOOP\r\n", imap->tag_str);
+      MU_IMAP_CHECK_ERROR (imap, status);
+      MU_IMAP_FCLR (imap, MU_IMAP_RESP);
+      imap->state = MU_IMAP_NOOP_RX;
+
+    case MU_IMAP_NOOP_RX:
+      status = _mu_imap_response (imap, NULL, NULL);
+      MU_IMAP_CHECK_EAGAIN (imap, status);
+      switch (imap->resp_code)
+	{
+	case MU_IMAP_OK:
+	  status = 0;
+	  break;
+
+	case MU_IMAP_NO:
+	  status = MU_ERR_FAILURE;
+	  break;
+
+	case MU_IMAP_BAD:
+	  status = MU_ERR_BADREPLY;
+	  break;
+	}
+      imap->state = MU_IMAP_CONNECTED;
+      break;
+
+    default:
+      status = EINPROGRESS;
+    }
+  return status;
+}
+      

@@ -112,6 +112,16 @@ com_verbose (int argc, char **argv)
   
 }
 
+static void
+report_failure (const char *what, int status)
+{
+  const char *str;
+      
+  mu_error (_("%s failed: %s"), what, mu_strerror (status));
+  if (mu_imap_strerror (imap, &str) == 0)
+    mu_error (_("server reply: %s"), str);
+}
+
 static int connect_argc;
 static char **connect_argv;
 #define host connect_argv[0]
@@ -425,13 +435,7 @@ com_login (int argc, char **argv)
   if (status == 0)
     imap_prompt_env ();
   else
-    {
-      const char *str;
-      
-      mu_error (_("authentication failed: %s"), mu_strerror (status));
-      if (mu_imap_strerror (imap, &str) == 0)
-	mu_error (_("server reply: %s"), str);
-    }
+    report_failure ("login", status);
   return 0;
 }
 
@@ -532,13 +536,7 @@ select_mbox (int argc, char **argv, int writable)
       imap_prompt_env ();
     }
   else
-    {
-      const char *str;
-      
-      mu_error (_("select failed: %s"), mu_strerror (status));
-      if (mu_imap_strerror (imap, &str) == 0)
-	mu_error (_("server reply: %s"), str);
-    }
+    report_failure ("select", status);
   return 0;
 }
 
@@ -578,13 +576,16 @@ com_status (int argc, char **argv)
       print_imap_stats (&st);
     }
   else
-    {
-      const char *str;
-      
-      mu_error (_("status failed: %s"), mu_strerror (status));
-      if (mu_imap_strerror (imap, &str) == 0)
-	mu_error (_("server reply: %s"), str);
-    }
+    report_failure ("status", status);
+  return 0;
+}
+
+static int
+com_noop (int argc MU_ARG_UNUSED, char **argv MU_ARG_UNUSED)
+{
+  int status = mu_imap_noop (imap);
+  if (status)
+    report_failure ("noop", status);
   return 0;
 }
 
@@ -613,6 +614,9 @@ struct mutool_command imap_comtab[] = {
   { "id",           1, -1, com_id,
     N_("[-test KW] [ARG [ARG...]]"),
     N_("send ID command") },
+  { "noop",         1, 1, com_noop,
+    NULL,
+    N_("no operation (keepalive)") },
   { "select",       1, 2, com_select,
     N_("[MBOX]"),
     N_("select a mailbox") },