[geary/mjog/imap-connection-fixes: 28/34] Geary.ImapError: Add new OPERATIONAL_ERROR code

[Michael Gratton <mjog src gnome org>]

commit 31e052987eaf0f79b34b0a4243f05c0f6170d731
Author: Michael Gratton <mike vee net>
Date:   Thu Mar 26 22:12:55 2020 +1100

    Geary.ImapError: Add new OPERATIONAL_ERROR code
    
    Used to indicate a NO response from an IMAP server when there is no
    more appropriate error.
    
    Mark it as being a recoverable failure so that the replay queue will
    re-try the command which is useful for #502, since a NO is followed
    immediately by a BYE, but we don't get any useful indication that the
    NO is because the connection has become unavailable.

 src/engine/imap-engine/imap-engine.vala |  1 +
 src/engine/imap/imap-error.vala         | 19 ++++++++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)
---
diff --git a/src/engine/imap-engine/imap-engine.vala b/src/engine/imap-engine/imap-engine.vala
index 5f5e926c..36279e7d 100644
--- a/src/engine/imap-engine/imap-engine.vala
+++ b/src/engine/imap-engine/imap-engine.vala
@@ -27,6 +27,7 @@ namespace Geary.ImapEngine {
             err is IOError.NOT_CONNECTED ||
             err is IOError.TIMED_OUT ||
             err is ImapError.NOT_CONNECTED ||
+            err is ImapError.OPERATIONAL_ERROR ||
             err is ImapError.TIMED_OUT ||
             err is ImapError.UNAVAILABLE
         );
diff --git a/src/engine/imap/imap-error.vala b/src/engine/imap/imap-error.vala
index 8e467556..d837464c 100644
--- a/src/engine/imap/imap-error.vala
+++ b/src/engine/imap/imap-error.vala
@@ -31,12 +31,22 @@ public errordomain Geary.ImapError {
      */
     ALREADY_CONNECTED,
 
+    /**
+     * A request failed due to an explicit NO response.
+     *
+     * An explicit NO response is defined per RFC 3501 §7.1.2.
+     *
+     * See [[https://tools.ietf.org/html/rfc3501#section-7.1.2]].
+     */
+    OPERATIONAL_ERROR,
+
     /**
      * A request failed due to an explicit or implicit BAD response.
      *
-     * An explicit BAD response is as per RFC 3501 §7.3.1. An implicit
-     * BAD response is when the server returns an unexpected response,
-     * for example, sends a status response for the same command twice.
+     * An explicit BAD response is defined as per RFC 3501 §7.1.3. An
+     * implicit BAD response is when the server returns an unexpected
+     * response, for example, sends a status response for the same
+     * command twice.
      *
      * See [[https://tools.ietf.org/html/rfc3501#section-7.1.3]].
      */
@@ -46,14 +56,17 @@ public errordomain Geary.ImapError {
      * Indicates that an operation could not proceed without prior authentication.
      */
     UNAUTHENTICATED,
+
     /**
      * An operation is not supported by the IMAP stack or by the server.
      */
     NOT_SUPPORTED,
+
     /**
      * Indicates a basic parsing error, semantic in nature.
      */
     INVALID,
+
     /**
      * A network connection of some kind failed due to an expired timer.
      *