From 24aff639b62b443b15281c5fc44e28483c22236b Mon Sep 17 00:00:00 2001
From: Phil Sutter <psutter@redhat.com>
Date: Mon, 30 May 2016 18:37:49 +0200
Subject: [PATCH] ip: enable configuring multicast group autojoin

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1333513
Upstream Status: iproute2.git commit e31867ac30cf9
Conflicts: Minor context conflict due to previously applied commit
	   c079e121a73af ("libnetlink: add size argument to rtnl_talk").

commit e31867ac30cf95155d113bbfaedf6b99f98a677f
Author: Madhu Challa <challa@noironetworks.com>
Date:   Wed Mar 4 10:30:10 2015 -0800

    ip: enable configuring multicast group autojoin

    Joining multicast group on ethernet level via "ip maddr" command would
    not work if we have an Ethernet switch that does igmp snooping since
    the switch would not replicate multicast packets on ports that did not
    have IGMP reports for the multicast addresses.

    Linux vxlan interfaces created via "ip link add vxlan" have the group option
    that enables then to do the required join.

    By extending ip address command with option "autojoin" we can get similar
    functionality for openvswitch vxlan interfaces as well as other tunneling
    mechanisms that need to receive multicast traffic.

    example:
    ip address add 224.1.1.10/24 dev eth5 autojoin
    ip address del 224.1.1.10/24 dev eth5
---
 ip/ipaddress.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 8681bf9..ffcc076 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -83,7 +83,7 @@ static void usage(void)
 	fprintf(stderr, "           [-]tentative | [-]deprecated | [-]dadfailed | temporary |\n");
 	fprintf(stderr, "           CONFFLAG-LIST ]\n");
 	fprintf(stderr, "CONFFLAG-LIST := [ CONFFLAG-LIST ] CONFFLAG\n");
-	fprintf(stderr, "CONFFLAG  := [ home | nodad | mngtmpaddr | noprefixroute ]\n");
+	fprintf(stderr, "CONFFLAG  := [ home | nodad | mngtmpaddr | noprefixroute | autojoin ]\n");
 	fprintf(stderr, "LIFETIME := [ valid_lft LFT ] [ preferred_lft LFT ]\n");
 	fprintf(stderr, "LFT := forever | SECONDS\n");
 
@@ -868,6 +868,10 @@ int print_addrinfo(const struct sockaddr_nl *who, struct nlmsghdr *n,
 		ifa_flags &= ~IFA_F_NOPREFIXROUTE;
 		fprintf(fp, "noprefixroute ");
 	}
+	if (ifa_flags & IFA_F_MCAUTOJOIN) {
+		ifa_flags &= ~IFA_F_MCAUTOJOIN;
+		fprintf(fp, "autojoin ");
+	}
 	if (!(ifa_flags & IFA_F_PERMANENT)) {
 		fprintf(fp, "dynamic ");
 	} else
@@ -1272,6 +1276,9 @@ static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 		} else if (strcmp(*argv, "noprefixroute") == 0) {
 			filter.flags |= IFA_F_NOPREFIXROUTE;
 			filter.flagmask |= IFA_F_NOPREFIXROUTE;
+		} else if (strcmp(*argv, "autojoin") == 0) {
+			filter.flags |= IFA_F_MCAUTOJOIN;
+			filter.flagmask |= IFA_F_MCAUTOJOIN;
 		} else if (strcmp(*argv, "dadfailed") == 0) {
 			filter.flags |= IFA_F_DADFAILED;
 			filter.flagmask |= IFA_F_DADFAILED;
@@ -1408,6 +1415,16 @@ static int default_scope(inet_prefix *lcl)
 	return 0;
 }
 
+static bool ipaddr_is_multicast(inet_prefix *a)
+{
+	if (a->family == AF_INET)
+		return IN_MULTICAST(ntohl(a->data[0]));
+	else if (a->family == AF_INET6)
+		return IN6_IS_ADDR_MULTICAST(a->data);
+	else
+		return false;
+}
+
 static int ipaddr_modify(int cmd, int flags, int argc, char **argv)
 {
 	struct {
@@ -1515,6 +1532,8 @@ static int ipaddr_modify(int cmd, int flags, int argc, char **argv)
 			ifa_flags |= IFA_F_MANAGETEMPADDR;
 		} else if (strcmp(*argv, "noprefixroute") == 0) {
 			ifa_flags |= IFA_F_NOPREFIXROUTE;
+		} else if (strcmp(*argv, "autojoin") == 0) {
+			ifa_flags |= IFA_F_MCAUTOJOIN;
 		} else {
 			if (strcmp(*argv, "local") == 0) {
 				NEXT_ARG();
@@ -1605,6 +1624,11 @@ static int ipaddr_modify(int cmd, int flags, int argc, char **argv)
 			  sizeof(cinfo));
 	}
 
+	if ((ifa_flags & IFA_F_MCAUTOJOIN) && !ipaddr_is_multicast(&lcl)) {
+		fprintf(stderr, "autojoin needs multicast address\n");
+		return -1;
+	}
+
 	if (rtnl_talk(&rth, &req.n, NULL, 0) < 0)
 		return -2;
 
-- 
1.8.3.1