From 31141aa12fb8ec85087a11f5cbd623ec71e7e3bb Mon Sep 17 00:00:00 2001
From: Guillem Jover <gjover@sipwise.com>
Date: Wed, 13 Dec 2017 11:30:06 +0100
Subject: [PATCH] TT#26513 Delete the kernel forwarding table on startup

If we are creating the kernel forwarding table, we have to make sure it
has been deleted already, otherwise we can get into collisions with the
already setup forwardings, and the subsequent add will fail anyway.

Change-Id: I2601c602543ff3e3493bae296d263dde545ff352
(cherry picked from commit fd3c1d2519f2e55483725b40e4a06b14b63d828f)
---
 daemon/kernel.c                   | 19 +++++++++++++++++--
 debian/ngcp-rtpengine-daemon.init |  3 ---
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/daemon/kernel.c b/daemon/kernel.c
index 0b17700ee..269e757b9 100644
--- a/daemon/kernel.c
+++ b/daemon/kernel.c
@@ -28,7 +28,7 @@ struct kernel_interface kernel;
 
 
 
-static int kernel_create_table(unsigned int id) {
+static int kernel_action_table(const char *action, unsigned int id) {
 	char str[64];
 	int fd;
 	int i;
@@ -36,7 +36,9 @@ static int kernel_create_table(unsigned int id) {
 	fd = open(PREFIX "/control", O_WRONLY | O_TRUNC);
 	if (fd == -1)
 		return -1;
-	sprintf(str, "add %u\n", id);
+	i = snprintf(str, sizeof(str), "%s %u\n", action, id);
+	if (i >= sizeof(str))
+		goto fail;
 	i = write(fd, str, strlen(str));
 	if (i == -1)
 		goto fail;
@@ -49,6 +51,14 @@ fail:
 	return -1;
 }
 
+static int kernel_create_table(unsigned int id) {
+	return kernel_action_table("add", id);
+}
+
+static int kernel_delete_table(unsigned int id) {
+	return kernel_action_table("del", id);
+}
+
 static int kernel_open_table(unsigned int id) {
 	char str[64];
 	int fd;
@@ -79,6 +89,11 @@ int kernel_setup_table(unsigned int id) {
 
 	kernel.is_wanted = 1;
 
+	if (kernel_delete_table(id) && errno != ENOENT) {
+		ilog(LOG_ERR, "FAILED TO DELETE KERNEL TABLE %i (%s), KERNEL FORWARDING DISABLED",
+				id, strerror(errno));
+		return -1;
+	}
 	if (kernel_create_table(id)) {
 		ilog(LOG_ERR, "FAILED TO CREATE KERNEL TABLE %i (%s), KERNEL FORWARDING DISABLED",
 				id, strerror(errno));
diff --git a/debian/ngcp-rtpengine-daemon.init b/debian/ngcp-rtpengine-daemon.init
index 249316555..f3a1cdb3e 100755
--- a/debian/ngcp-rtpengine-daemon.init
+++ b/debian/ngcp-rtpengine-daemon.init
@@ -182,9 +182,6 @@ case "$1" in
 			ip6tables -D rtpengine -p udp -j RTPENGINE --id "$TABLE" 2>/dev/null
 			ip6tables -I rtpengine -p udp -j RTPENGINE --id "$TABLE"
 		fi
-		if [ -e /proc/rtpengine/control ]; then
-			echo "del $TABLE" > /proc/rtpengine/control 2>/dev/null
-		fi
 	fi
 	set -e
 	log_daemon_msg "Starting $DESC" "$NAME"