From: Roy Marples <roy@marples.name>
Date: Tue, 31 Mar 2020 21:33:25 +0000 (+0100)
Subject: ND: If a secondary router adds the same prefix, use it's address
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=67d90035be1ec5286de30b9e50094cae9223b83f;p=thirdparty%2Fdhcpcd.git

ND: If a secondary router adds the same prefix, use it's address

With slaac private, it will generate a new address which would
be wrong.
---

diff --git a/src/ipv6.c b/src/ipv6.c
index 000db984..51b4c9b7 100644
--- a/src/ipv6.c
+++ b/src/ipv6.c
@@ -1509,17 +1509,26 @@ struct ipv6_addr *
 ipv6_newaddr(struct interface *ifp, const struct in6_addr *addr,
     uint8_t prefix_len, unsigned int flags)
 {
-	struct ipv6_addr *ia;
+	struct ipv6_addr *ia, *iaf;
 	char buf[INET6_ADDRSTRLEN];
 	const char *cbp;
 	bool tempaddr;
 	int addr_flags;
 
+#ifdef IPV6_AF_TEMPORARY
+	tempaddr = flags & IPV6_AF_TEMPORARY;
+#else
+	tempaddr = false;
+#endif
+
 	/* If adding a new DHCP / RA derived address, check current flags
 	 * from an existing address. */
-	ia = ipv6_iffindaddr(ifp, addr, 0);
-	if (ia != NULL) {
-		addr_flags = ia->addr_flags;
+	if (flags & IPV6_AF_AUTOCONF)
+		iaf = ipv6nd_iffindprefix(ifp, addr, prefix_len);
+	else
+		iaf = ipv6_iffindaddr(ifp, addr, 0);
+	if (iaf != NULL) {
+		addr_flags = iaf->addr_flags;
 		flags |= IPV6_AF_ADDED;
 	} else
 		addr_flags = IN6_IFF_TENTATIVE;
@@ -1540,21 +1549,19 @@ ipv6_newaddr(struct interface *ifp, const struct in6_addr *addr,
 	TAILQ_INIT(&ia->pd_pfxs);
 #endif
 
-#ifdef IPV6_AF_TEMPORARY
-	tempaddr = ia->flags & IPV6_AF_TEMPORARY;
-#else
-	tempaddr = false;
-#endif
-
 	if (prefix_len == 128)
 		goto makepfx;
 	else if (ia->flags & IPV6_AF_AUTOCONF && !tempaddr) {
 		ia->prefix = *addr;
-		ia->dadcounter = ipv6_makeaddr(&ia->addr, ifp,
-		                               &ia->prefix,
-					       ia->prefix_len);
-		if (ia->dadcounter == -1)
-			goto err;
+		if (iaf != NULL)
+			memcpy(&ia->addr, &iaf->addr, sizeof(ia->addr));
+		else {
+			ia->dadcounter = ipv6_makeaddr(&ia->addr, ifp,
+			                               &ia->prefix,
+						       ia->prefix_len);
+			if (ia->dadcounter == -1)
+				goto err;
+		}
 	} else if (ia->flags & IPV6_AF_RAPFX) {
 		ia->prefix = *addr;
 #ifdef __sun
diff --git a/src/ipv6nd.c b/src/ipv6nd.c
index ca5f4335..81a80550 100644
--- a/src/ipv6nd.c
+++ b/src/ipv6nd.c
@@ -746,6 +746,40 @@ ipv6nd_findaddr(struct dhcpcd_ctx *ctx, const struct in6_addr *addr,
 	return NULL;
 }
 
+static struct ipv6_addr *
+ipv6nd_rapfindprefix(struct ra *rap,
+    const struct in6_addr *pfx, uint8_t pfxlen)
+{
+	struct ipv6_addr *ia;
+
+	TAILQ_FOREACH(ia, &rap->addrs, next) {
+		if (ia->prefix_vltime == 0)
+			continue;
+		if (ia->prefix_len == pfxlen &&
+		    IN6_ARE_ADDR_EQUAL(&ia->prefix, pfx))
+			break;
+	}
+	return ia;
+}
+
+struct ipv6_addr *
+ipv6nd_iffindprefix(struct interface *ifp,
+    const struct in6_addr *pfx, uint8_t pfxlen)
+{
+	struct ra *rap;
+	struct ipv6_addr *ia;
+
+	ia = NULL;
+	TAILQ_FOREACH(rap, ifp->ctx->ra_routers, next) {
+		if (rap->iface != ifp)
+			continue;
+		ia = ipv6nd_rapfindprefix(rap, pfx, pfxlen);
+		if (ia != NULL)
+			break;
+	}
+	return ia;
+}
+
 static void
 ipv6nd_removefreedrop_ra(struct ra *rap, int remove_ra, int drop_ra)
 {
@@ -1229,10 +1263,8 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx,
 				logmessage(loglevel, "%s: pltime > vltime", ifp->name);
 				continue;
 			}
-			TAILQ_FOREACH(ia, &rap->addrs, next)
-				if (ia->prefix_len == pi.nd_opt_pi_prefix_len &&
-				    IN6_ARE_ADDR_EQUAL(&ia->prefix, &pi_prefix))
-					break;
+			ia = ipv6nd_rapfindprefix(rap,
+			    &pi_prefix, pi.nd_opt_pi_prefix_len);
 			if (ia == NULL) {
 				unsigned int flags;
 
diff --git a/src/ipv6nd.h b/src/ipv6nd.h
index 0c85239d..bb14d7b3 100644
--- a/src/ipv6nd.h
+++ b/src/ipv6nd.h
@@ -112,6 +112,8 @@ const struct ipv6_addr *ipv6nd_iffindaddr(const struct interface *ifp,
     const struct in6_addr *addr, unsigned int flags);
 struct ipv6_addr *ipv6nd_findaddr(struct dhcpcd_ctx *,
     const struct in6_addr *, unsigned int);
+struct ipv6_addr *ipv6nd_iffindprefix(struct interface *,
+    const struct in6_addr *, uint8_t);
 ssize_t ipv6nd_free(struct interface *);
 void ipv6nd_expirera(void *arg);
 bool ipv6nd_hasralifetime(const struct interface *, bool);