From 1cf1a23f11668909b8d88561544ccf0f843127f6 Mon Sep 17 00:00:00 2001
From: Antonio Quartulli <a@unstable.cc>
Date: Sat, 9 Jan 2021 15:45:50 +0100
Subject: [PATCH] routing/linux: check IPv6 forwarding status when enabling
 Router capa

Consider also IPv6 when deciding whether to enable the Router capability.
This way, if a host is a router for IPv6 only, it will still be
advertised as Router to its neighbours.

Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 src/daemon/forward-linux.c | 43 ++++++++++++++++++++++++++++++--------
 src/daemon/lldpd.h         |  1 +
 src/daemon/priv-linux.c    |  3 ++-
 3 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/src/daemon/forward-linux.c b/src/daemon/forward-linux.c
index c7d9f735..db563bdc 100644
--- a/src/daemon/forward-linux.c
+++ b/src/daemon/forward-linux.c
@@ -19,18 +19,43 @@
 
 #include <unistd.h>
 
+int
+ip_forwarding_enabled(int af)
+{
+	int fd, rc = -1;
+	char *fname;
+	char status;
+
+	if (af == LLDPD_AF_IPV4)
+		fname = PROCFS_SYS_NET "ipv4/ip_forward";
+	else if (af == LLDPD_AF_IPV6)
+		fname = PROCFS_SYS_NET "ipv6/conf/all/forwarding";
+	else
+		return -1;
+
+	if ((fd = priv_open(fname)) < 0)
+		return -1;
+
+	if (read(fd, &status, 1) == 1)
+		rc = (status == '1');
+
+	close(fd);
+	return rc;
+}
+
 int
 interfaces_routing_enabled(struct lldpd *cfg) {
 	(void)cfg;
-	int f;
-	char status;
 	int rc;
-	if ((f = priv_open("/proc/sys/net/ipv4/ip_forward")) >= 0) {
-		if (read(f, &status, 1) == 1) {
-			rc = (status == '1');
-		} else rc = -1;
-		close(f);
+
+	rc = ip_forwarding_enabled(LLDPD_AF_IPV4);
+	/*
+	 * Report being a router if IPv4 forwarding is enabled.
+	 * In case of error also stop the execution right away.
+	 * If IPv4 forwarding is disabled we'll check the IPv6 status.
+	 */
+	if (rc != 0)
 		return rc;
-	}
-	return -1;
+
+	return ip_forwarding_enabled(LLDPD_AF_IPV6);
 }
diff --git a/src/daemon/lldpd.h b/src/daemon/lldpd.h
index 0d67d7c9..32581e59 100644
--- a/src/daemon/lldpd.h
+++ b/src/daemon/lldpd.h
@@ -61,6 +61,7 @@
 struct event;
 struct event_base;
 
+#define PROCFS_SYS_NET	"/proc/sys/net/"
 #define SYSFS_CLASS_NET "/sys/class/net/"
 #define SYSFS_CLASS_DMI "/sys/class/dmi/id/"
 #define LLDPD_TX_INTERVAL	30
diff --git a/src/daemon/priv-linux.c b/src/daemon/priv-linux.c
index 6b7d9f4b..315faf3e 100644
--- a/src/daemon/priv-linux.c
+++ b/src/daemon/priv-linux.c
@@ -58,7 +58,8 @@ void
 asroot_open()
 {
 	const char* authorized[] = {
-		"/proc/sys/net/ipv4/ip_forward",
+		PROCFS_SYS_NET "ipv4/ip_forward",
+		PROCFS_SYS_NET "ipv6/conf/all/forwarding",
 		"/proc/net/bonding/[^.][^/]*",
 		"/proc/self/net/bonding/[^.][^/]*",
 #ifdef ENABLE_OLDIES
-- 
2.39.5