From 34d4ccbd0e7b40da382f148f8c8778015d40a604 Mon Sep 17 00:00:00 2001
From: Roy Marples <roy@marples.name>
Date: Fri, 21 Jun 2024 12:58:38 +0100
Subject: [PATCH] IPv6: DUPLICATED could be announced by RTM_DELADDR

This at least is true on Linux when addresses are not permanent.
As such, update address flags on all paths and run DAD hooks
even for address deletions.

This helps to give reason to the messages that pid 0 has deleted
your newly added address.
---
 src/ipv4.c |   1 +
 src/ipv6.c | 107 ++++++++++++++++++++++++++++-------------------------
 2 files changed, 58 insertions(+), 50 deletions(-)

diff --git a/src/ipv4.c b/src/ipv4.c
index 21063e05..ada821b9 100644
--- a/src/ipv4.c
+++ b/src/ipv4.c
@@ -967,6 +967,7 @@ ipv4_handleifa(struct dhcpcd_ctx *ctx,
 		if (mask->s_addr != INADDR_ANY &&
 		    mask->s_addr != ia->mask.s_addr)
 			return;
+		ia->addr_flags = addrflags;
 		TAILQ_REMOVE(&state->addrs, ia, next);
 		break;
 	default:
diff --git a/src/ipv6.c b/src/ipv6.c
index ce985d4e..9fea96b2 100644
--- a/src/ipv6.c
+++ b/src/ipv6.c
@@ -1198,8 +1198,10 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 	anyglobal = ipv6_anyglobal(ifp) != NULL;
 
 	TAILQ_FOREACH(ia, &state->addrs, next) {
-		if (IN6_ARE_ADDR_EQUAL(&ia->addr, addr))
+		if (IN6_ARE_ADDR_EQUAL(&ia->addr, addr)) {
+			ia->addr_flags = addrflags;
 			break;
+		}
 	}
 
 	switch (cmd) {
@@ -1244,49 +1246,50 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 			 * generate a new temporary address on
 			 * restart. */
 			ia->acquired = ia->created;
+			ia->addr_flags = addrflags;
 			TAILQ_INSERT_TAIL(&state->addrs, ia, next);
 		}
-		ia->addr_flags = addrflags;
 		ia->flags &= ~IPV6_AF_STALE;
 #ifdef IPV6_MANAGETEMPADDR
 		if (ia->addr_flags & IN6_IFF_TEMPORARY)
 			ia->flags |= IPV6_AF_TEMPORARY;
 #endif
-		if (IN6_IS_ADDR_LINKLOCAL(&ia->addr) || ia->dadcallback) {
-#ifdef IPV6_POLLADDRFLAG
-			if (ia->addr_flags & IN6_IFF_TENTATIVE) {
-				eloop_timeout_add_msec(
-				    ia->iface->ctx->eloop,
-				    RETRANS_TIMER / 2, ipv6_checkaddrflags, ia);
-				break;
-			}
-#endif
 
-			if (ia->dadcallback)
-				ia->dadcallback(ia);
-
-			if (IN6_IS_ADDR_LINKLOCAL(&ia->addr) &&
-			    !(ia->addr_flags & IN6_IFF_NOTUSEABLE))
-			{
-				/* Now run any callbacks.
-				 * Typically IPv6RS or DHCPv6 */
-				while ((cb =
-				    TAILQ_FIRST(&state->ll_callbacks)))
-				{
-					TAILQ_REMOVE(
-					    &state->ll_callbacks,
-					    cb, next);
-					cb->callback(cb->arg);
-					free(cb);
-				}
-			}
+#ifdef IPV6_POLLADDRFLAG
+		if ((IN6_IS_ADDR_LINKLOCAL(&ia->addr) || ia->dadcallback) &&
+		    ia->addr_flags & IN6_IFF_TENTATIVE)
+		{
+			eloop_timeout_add_msec(
+			    ia->iface->ctx->eloop,
+			    RETRANS_TIMER / 2, ipv6_checkaddrflags, ia);
 		}
 		break;
+#endif
+	default:
+		return;
 	}
 
 	if (ia == NULL)
 		return;
 
+	if (ia->dadcallback && ((ia->addr_flags &
+	    (IN6_IFF_DETACHED | IN6_IFF_TENTATIVE)) == 0 ||
+	    ia->addr_flags & IN6_IFF_DUPLICATED))
+		ia->dadcallback(ia);
+
+	if (IN6_IS_ADDR_LINKLOCAL(&ia->addr) &&
+	    !(ia->addr_flags & IN6_IFF_NOTUSEABLE))
+	{
+		/* Now run any callbacks.
+		 * Typically IPv6RS or DHCPv6 */
+		while ((cb = TAILQ_FIRST(&state->ll_callbacks)))
+		{
+			TAILQ_REMOVE(&state->ll_callbacks, cb, next);
+			cb->callback(cb->arg);
+			free(cb);
+		}
+	}
+
 	ctx->options &= ~DHCPCD_RTBUILD;
 	ipv6nd_handleifa(cmd, ia, pid);
 #ifdef DHCP6
@@ -1883,10 +1886,13 @@ ipv6_handleifa_addrs(int cmd,
     struct ipv6_addrhead *addrs, const struct ipv6_addr *addr, pid_t pid)
 {
 	struct ipv6_addr *ia, *ian;
-	uint8_t found, alldadcompleted;
+	int found = 0, alldadcompleted = 1;
+
+	if (cmd != RTM_NEWADDR && cmd != RTM_DELADDR) {
+		errno = EINVAL;
+		return -1;
+	}
 
-	alldadcompleted = 1;
-	found = 0;
 	TAILQ_FOREACH_SAFE(ia, addrs, next, ian) {
 		if (!IN6_ARE_ADDR_EQUAL(&addr->addr, &ia->addr)) {
 			if (ia->flags & IPV6_AF_ADDED &&
@@ -1894,8 +1900,25 @@ ipv6_handleifa_addrs(int cmd,
 				alldadcompleted = 0;
 			continue;
 		}
-		switch (cmd) {
-		case RTM_DELADDR:
+
+		ia->addr_flags = addr->addr_flags;
+
+		/* Check DAD.
+		 * On Linux we can get IN6_IFF_DUPLICATED via RTM_DELADDR. */
+		if (((ia->addr_flags &
+		    (IN6_IFF_DETACHED | IN6_IFF_TENTATIVE)) == 0 ||
+		    ia->addr_flags & IN6_IFF_DUPLICATED) &&
+		    (ia->flags & IPV6_AF_DADCOMPLETED) == 0)
+		{
+			found++;
+			if (ia->dadcallback)
+				ia->dadcallback(ia);
+			/* We need to set this here in-case the
+			 * dadcallback function checks it */
+			ia->flags |= IPV6_AF_DADCOMPLETED;
+		}
+
+		if (cmd == RTM_DELADDR) {
 			if (ia->flags & IPV6_AF_ADDED) {
 				logwarnx("%s: pid %d deleted address %s",
 				    ia->iface->name, pid, ia->saddr);
@@ -1906,22 +1929,6 @@ ipv6_handleifa_addrs(int cmd,
 				TAILQ_REMOVE(addrs, ia, next);
 				ipv6_freeaddr(ia);
 			}
-			break;
-		case RTM_NEWADDR:
-			ia->addr_flags = addr->addr_flags;
-			/* Safety - ignore tentative announcements */
-			if (ia->addr_flags &
-			    (IN6_IFF_DETACHED | IN6_IFF_TENTATIVE))
-				break;
-			if ((ia->flags & IPV6_AF_DADCOMPLETED) == 0) {
-				found++;
-				if (ia->dadcallback)
-					ia->dadcallback(ia);
-				/* We need to set this here in-case the
-				 * dadcallback function checks it */
-				ia->flags |= IPV6_AF_DADCOMPLETED;
-			}
-			break;
 		}
 	}
 
-- 
2.47.2