dropbear: add option to disable reverse DNS lookups

Add option to disable reverse DNS lookups on client connection, as
connections otherwise stall until DNS times out in configurations without
working reverse DNS.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

CHANGES

@@ -5,7 +5,7 @@
 	Kconfig infrastructure rebased against 2.6.36-rc1, bringing
 	misc fixes + nconfig and savedefconfig targets.
 
-	Updated/fixed packages: busybox
+	Updated/fixed packages: busybox, dropbear
 
 2010.08: Released August 31th, 2010:
 

package/dropbear/Config.in

@@ -5,3 +5,11 @@ config BR2_PACKAGE_DROPBEAR
 	  A small SSH 2 server designed for small memory environments.
 
 	  http://matt.ucc.asn.au/dropbear/dropbear.html
+
+config BR2_PACKAGE_DROPBEAR_DISABLE_REVERSEDNS
+	bool "disable reverse DNS lookups"
+	depends on BR2_PACKAGE_DROPBEAR
+	help
+	  Disable reverse DNS lookups on connection. This can be handy
+	  on systems without working DNS, as connections otherwise
+	  stall until DNS times out.

package/dropbear/dropbear.mk

@@ -21,6 +21,10 @@ $(eval $(call AUTOTARGETS,package,dropbear))
 
 $(DROPBEAR_HOOK_POST_EXTRACT):
 	$(SED) 's,^#define XAUTH_COMMAND.*/xauth,#define XAUTH_COMMAND "/usr/bin/xauth,g' $(DROPBEAR_DIR)/options.h
+ifeq ($(BR2_PACKAGE_DROPBEAR_DISABLE_REVERSEDNS),y)
+	$(SED) 's,^#define DO_HOST_LOOKUP.*,/* #define DO_HOST_LOOKUP */,' \
+		$(DROPBEAR_DIR)/options.h
+endif
 	touch $@
 
 $(DROPBEAR_TARGET_INSTALL_TARGET):