From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Wed, 6 Oct 2021 12:43:09 +0000 (+0300)
Subject: imap-login: proxy: Don't forward untagged BYE responses to the client
X-Git-Tag: 2.3.17~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6f664bd5a47717bbe8c2168b1010d3367841d877;p=thirdparty%2Fdovecot%2Fcore.git

imap-login: proxy: Don't forward untagged BYE responses to the client

It will just cause confusion, especially when connections are retried.
It could end up looking like:

x login user pass
* BYE Internal error occurred. Refer to server log for more information.
* BYE Internal error occurred. Refer to server log for more information.
* BYE Internal error occurred. Refer to server log for more information.
* BYE Internal error occurred. Refer to server log for more information.
x NO [UNAVAILABLE] Account is temporarily unavailable.
---

diff --git a/src/imap-login/imap-proxy.c b/src/imap-login/imap-proxy.c
index e06996083a..aa5a5aaf54 100644
--- a/src/imap-login/imap-proxy.c
+++ b/src/imap-login/imap-proxy.c
@@ -438,6 +438,13 @@ int imap_proxy_parse_line(struct client *client, const char *line)
 	} else if (strncasecmp(line, "* ID ", 5) == 0) {
 		/* Reply to ID command we sent, ignore it */
 		return 0;
+	} else if (str_begins(line, "* BYE ")) {
+		/* Login unexpectedly failed (due to some internal error).
+		   Don't forward the BYE to the client, since we're not going
+		   to disconnect it. It could be a possibility to convert these
+		   to NO replies, but they're likely not going to provide
+		   anything useful. */
+		return 0;
 	} else if (str_begins(line, "* ")) {
 		/* untagged reply. just forward it. */
 		client_send_raw(client, t_strconcat(line, "\r\n", NULL));