[geary/mjog/imap-command-cancellation: 1/6] Geary.Imap: Don't cancel waiting for responses for submitted commands

[Michael Gratton <mjog src gnome org>]

commit 67f0678b1d13f5192f06b03da505a1a8e4029aa7
Author: Michael Gratton <mike vee net>
Date:   Tue Sep 1 22:39:50 2020 +1000

    Geary.Imap: Don't cancel waiting for responses for submitted commands
    
    The IMAP protocol does not allow commands to be cancelled once sent over
    the wire to the server. However `IMAP.Command` objects are currently
    submitted to be send with a cancellable, which may be cancelled before
    the response is received from the server. If this happens, the repsonse
    to the command from the server is not waited for, and untagged data from
    the cancelled command may end up being handled by the subsequent
    command, which is bad.
    
    After submitting a command to the connection, don't supply the given
    cancellable to the command's wait method, so it hangs around to handle
    any tagged and untagged responses as required.

 src/engine/imap/transport/imap-client-session.vala | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/src/engine/imap/transport/imap-client-session.vala 
b/src/engine/imap/transport/imap-client-session.vala
index 27e84837c..6edbacf09 100644
--- a/src/engine/imap/transport/imap-client-session.vala
+++ b/src/engine/imap/transport/imap-client-session.vala
@@ -1785,7 +1785,12 @@ public class Geary.Imap.ClientSession : BaseObject, Logging.Source {
             throw new ImapError.NOT_CONNECTED("Not connected to %s", imap_endpoint.to_string());
 
         this.cx.send_command(cmd);
-        yield cmd.wait_until_complete(cancellable);
+
+        // Once a command has been sent over the wire, it can't be
+        // cancelled until a response is received, because the server
+        // will send a response back anyway and so the command needs
+        // to be around for it.
+        yield cmd.wait_until_complete(null);
 
         // This won't be null since the Command.wait_until_complete
         // will throw an error if it is.