From a1af5f4f726f8878a403577abf067709b8357db3 Mon Sep 17 00:00:00 2001
From: Mark Michelson <mmichelson@digium.com>
Date: Thu, 25 Feb 2010 22:41:48 +0000
Subject: [PATCH] Fix incorrect ACL behavior when CIDR notation of "/0" is
 used.

AST-2010-003



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@248946 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 main/acl.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/main/acl.c b/main/acl.c
index 3c01fb65b6..67c05b03ca 100644
--- a/main/acl.c
+++ b/main/acl.c
@@ -298,7 +298,14 @@ struct ast_ha *ast_append_ha(const char *sense, const char *stuff, struct ast_ha
 
 		if (!strchr(nm, '.')) {
 			if ((sscanf(nm, "%30d", &x) == 1) && (x >= 0) && (x <= 32)) {
-				ha->netmask.s_addr = htonl(0xFFFFFFFF << (32 - x));
+				if (x == 0) {
+					/* This is special-cased to prevent unpredictable
+					 * behavior of shifting left 32 bits
+					 */
+					ha->netmask.s_addr = 0;
+				} else {
+					ha->netmask.s_addr = htonl(0xFFFFFFFF << (32 - x));
+				}
 			} else {
 				ast_log(LOG_WARNING, "Invalid CIDR in %s\n", stuff);
 				ast_free(ha);