From afad6424413533ddf60b66c61f19e016bee98435 Mon Sep 17 00:00:00 2001
From: "Ian K. Coolidge" <icoolidge@loon.com>
Date: Thu, 21 May 2020 21:07:52 -0700
Subject: [PATCH] ip addr: Accept 'optimistic' flag

Upstream status:
https://patchwork.ozlabs.org/project/netdev/patch/20200524015144.44017-1-icoolidge@google.com/

---
 ip/ipaddress.c           | 7 ++++++-
 man/man8/ip-address.8.in | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 80d27ce2..48cf5e41 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -72,7 +72,7 @@ static void usage(void)
 		"           [-]tentative | [-]deprecated | [-]dadfailed | temporary |\n"
 		"           CONFFLAG-LIST ]\n"
 		"CONFFLAG-LIST := [ CONFFLAG-LIST ] CONFFLAG\n"
-		"CONFFLAG  := [ home | nodad | mngtmpaddr | noprefixroute | autojoin ]\n"
+		"CONFFLAG  := [ home | nodad | optimistic | mngtmpaddr | noprefixroute | autojoin ]\n"
 		"LIFETIME := [ valid_lft LFT ] [ preferred_lft LFT ]\n"
 		"LFT := forever | SECONDS\n"
 		"TYPE := { vlan | veth | vcan | vxcan | dummy | ifb | macvlan | macvtap |\n"
@@ -2335,6 +2335,11 @@ static int ipaddr_modify(int cmd, int flags, int argc, char **argv)
 				ifa_flags |= IFA_F_HOMEADDRESS;
 			else
 				fprintf(stderr, "Warning: home option can be set only for IPv6 addresses\n");
+		} else if (strcmp(*argv, "optimistic") == 0) {
+			if (req.ifa.ifa_family == AF_INET6)
+				ifa_flags |= IFA_F_OPTIMISTIC;
+			else
+				fprintf(stderr, "Warning: optimistic option can be set only for IPv6 addresses\n");
 		} else if (strcmp(*argv, "nodad") == 0) {
 			if (req.ifa.ifa_family == AF_INET6)
 				ifa_flags |= IFA_F_NODAD;
diff --git a/man/man8/ip-address.8.in b/man/man8/ip-address.8.in
index 2a553190..fe773c91 100644
--- a/man/man8/ip-address.8.in
+++ b/man/man8/ip-address.8.in
@@ -92,7 +92,7 @@ ip-address \- protocol address management
 
 .ti -8
 .IR CONFFLAG " := "
-.RB "[ " home " | " mngtmpaddr " | " nodad " | " noprefixroute " | " autojoin " ]"
+.RB "[ " home " | " mngtmpaddr " | " nodad " | " optimstic " | " noprefixroute " | " autojoin " ]"
 
 .ti -8
 .IR LIFETIME " := [ "
@@ -258,6 +258,11 @@ stateless auto-configuration was active.
 (IPv6 only) do not perform Duplicate Address Detection (RFC 4862) when
 adding this address.
 
+.TP
+.B optimistic
+(IPv6 only) When performing Duplicate Address Detection, use the RFC 4429
+optimistic variant.
+
 .TP
 .B noprefixroute
 Do not automatically create a route for the network prefix of the added
-- 
2.27.0.rc0.183.gde8f92d652-goog