From: Roy Marples <roy@marples.name>
Date: Sun, 28 Jul 2019 14:37:05 +0000 (+0100)
Subject: IP: If no address lifetime support don't re-add the address
X-Git-Tag: v8.0.2~11
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=377c8d1eafb5d76d1e1b6a5284d920d18f74c6d3;p=thirdparty%2Fdhcpcd.git

IP: If no address lifetime support don't re-add the address

Unless we need to. If we do, there is a chance that the OS
will scrub the subnet route and re-add it. We want to avoid
this as it's likely in use.
---

diff --git a/src/ipv4.c b/src/ipv4.c
index 0618da07..16ed3812 100644
--- a/src/ipv4.c
+++ b/src/ipv4.c
@@ -659,8 +659,13 @@ ipv4_addaddr(struct interface *ifp, const struct in_addr *addr,
 
 	ia->mask = *mask;
 	ia->brd = *bcast;
+#ifdef IP_LIFETIME
 	ia->vltime = vltime;
 	ia->pltime = pltime;
+#else
+	UNUSED(vltime);
+	UNUSED(pltime);
+#endif
 	snprintf(ia->saddr, sizeof(ia->saddr), "%s/%d",
 	    inet_ntoa(*addr), inet_ntocidr(*mask));
 
@@ -746,16 +751,27 @@ ipv4_applyaddr(void *arg)
 		return;
 	}
 
-#if __linux__
-	/* If the netmask or broadcast is different, re-add the addresss */
 	ia = ipv4_iffindaddr(ifp, &lease->addr, NULL);
-	if (ia != NULL &&
+	/* If the netmask or broadcast is different, re-add the addresss.
+	 * If IP addresses do not have lifetimes, there is a very real chance
+	 * that re-adding them will scrub the subnet route temporarily
+	 * which is a bad thing, so avoid it. */
+	if (ia == NULL &&
 	    (ia->mask.s_addr != lease->mask.s_addr ||
 	    ia->brd.s_addr != lease->brd.s_addr))
-		ipv4_deladdr(ia, 0);
+	{
+#ifdef __linux__
+		if (ia != NULL)
+			ipv4_deladdr(ia, 0);
+#elif !defined(IP_LIFETIME)
+		if (ipv4_daddaddr(ifp, lease) == -1 && errno != EEXIST)
+			return;
 #endif
+	}
+#if IP_LIFETIME
 	if (ipv4_daddaddr(ifp, lease) == -1 && errno != EEXIST)
 		return;
+#endif
 
 	ia = ipv4_iffindaddr(ifp, &lease->addr, NULL);
 	if (ia == NULL) {
diff --git a/src/ipv4.h b/src/ipv4.h
index 4e04e9b2..d8204a7d 100644
--- a/src/ipv4.h
+++ b/src/ipv4.h
@@ -75,6 +75,10 @@
 #define IN_ARE_ADDR_EQUAL(a, b)		((a)->s_addr == (b)->s_addr)
 #define IN_IS_ADDR_UNSPECIFIED(a)	((a)->s_addr == INADDR_ANY)
 
+#ifdef __linux__
+#define IP_LIFETIME
+#endif
+
 struct ipv4_addr {
 	TAILQ_ENTRY(ipv4_addr) next;
 	struct in_addr addr;
@@ -83,8 +87,10 @@ struct ipv4_addr {
 	struct interface *iface;
 	int addr_flags;
 	unsigned int flags;
+#ifdef IP_LIFETIME
 	uint32_t vltime;
 	uint32_t pltime;
+#endif
 	char saddr[INET_ADDRSTRLEN + 3];
 #ifdef ALIAS_ADDR
 	char alias[IF_NAMESIZE];