[PATCH] param: disable print notify backchannel by default

[David Disseldorp]

In handling RemoteFindFirstPrinterChangeNotifyEx requests, the spoolss
server can establish a "backchannel" connection to the print client, as
a mechanism for sending print notifications. This behaviour is governed
by the "print notify backchannel" smb.conf parameter.

This change sets "print notify backchannel" to "no" by default, which
sees Samba respond to RemoteFindFirstPrinterChangeNotifyEx requests with
WERR_SERVER_UNAVAILABLE. In recieving such a response, print clients can
fall back to polling for print queue changes.

Signed-off-by: David Disseldorp <ddiss at samba.org>
---
 docs-xml/smbdotconf/printing/printnotifybackchannel.xml | 10 ++++------
 source3/param/loadparm.c                                |  2 +-
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/docs-xml/smbdotconf/printing/printnotifybackchannel.xml b/docs-xml/smbdotconf/printing/printnotifybackchannel.xml
index 4046322..ce6a595 100644
--- a/docs-xml/smbdotconf/printing/printnotifybackchannel.xml
+++ b/docs-xml/smbdotconf/printing/printnotifybackchannel.xml
@@ -8,12 +8,10 @@
 	the server to open a backchannel SMB connection to them. Due to
 	client firewall settings this can cause considerable timeouts
 	and will often fail, as there is no guarantee the client is even
-	running an SMB server. By setting this parameter to <constant>no</constant>
-	the Samba print server will not try to connect back to clients
-	and treat corresponding requests as if the connection back to
-	the client failed. The default setting of <constant>yes</constant>
-	causes smbd to attempt this connection.
+	running an SMB server. By default, the Samba print server will
+	not try to connect back to clients, and will treat corresponding
+	requests as if the connection back to the client failed.
 </para>
 </description>
-<value type="default">yes</value>
+<value type="default">no</value>
 </samba:parameter>
diff --git a/source3/param/loadparm.c b/source3/param/loadparm.c
index e702420..3daebdb 100644
--- a/source3/param/loadparm.c
+++ b/source3/param/loadparm.c
@@ -218,7 +218,7 @@ static struct loadparm_service sDefault =
 	.bAdministrative_share = false,
 	.bGuest_ok = false,
 	.bPrint_ok = false,
-	.bPrintNotifyBackchannel = true,
+	.bPrintNotifyBackchannel = false,
 	.bMap_system = false,
 	.bMap_hidden = false,
 	.bMap_archive = true,
-- 
1.8.1.4