From: Roy Marples <roy@marples.name>
Date: Sun, 25 Aug 2019 13:40:20 +0000 (+0100)
Subject: inet6: Don't install a default route if no global address
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a3830c3f3d7af8db0353f11a3625979e122819a7;p=thirdparty%2Fdhcpcd.git

inet6: Don't install a default route if no global address

This works around an issue where some routers advertise themselves
as a default router, but offer no address to actually use.
Thus, it is actually useless as a router.
If an address is added by any other means (DHCPv6, static, etc)
then the default route is installed once more.

This is also dynamic - dhcpcd reacts to addresses being added,
removed, duplicated, detached, etc.
---

diff --git a/src/if-options.h b/src/if-options.h
index d0eb764a..79947885 100644
--- a/src/if-options.h
+++ b/src/if-options.h
@@ -61,7 +61,7 @@
 
 #define DHCPCD_ARP			(1ULL << 0)
 #define DHCPCD_RELEASE			(1ULL << 1)
-// unused				(1ULL << 2)
+#define DHCPCD_RTBUILD			(1ULL << 2)
 #define DHCPCD_GATEWAY			(1ULL << 3)
 #define DHCPCD_STATIC			(1ULL << 4)
 #define DHCPCD_DEBUG			(1ULL << 5)
diff --git a/src/ipv6.c b/src/ipv6.c
index 31a0cae0..8669f9c0 100644
--- a/src/ipv6.c
+++ b/src/ipv6.c
@@ -1060,6 +1060,28 @@ ipv6_getstate(struct interface *ifp)
 	return state;
 }
 
+struct ipv6_addr *
+ipv6_ifanyglobal(struct interface *ifp)
+{
+	struct ipv6_state *state;
+	struct ipv6_addr *ia;
+
+	if (ifp->carrier == LINK_DOWN)
+		return NULL;
+
+	state = IPV6_STATE(ifp);
+	if (state == NULL)
+		return NULL;
+
+	TAILQ_FOREACH(ia, &state->addrs, next) {
+		if (IN6_IS_ADDR_LINKLOCAL(&ia->addr))
+			continue;
+		if (!(ia->addr_flags & IN6_IFF_NOTUSEABLE))
+			break;
+	}
+	return ia;
+}
+
 void
 ipv6_handleifa(struct dhcpcd_ctx *ctx,
     int cmd, struct if_head *ifs, const char *ifname,
@@ -1069,6 +1091,7 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 	struct ipv6_state *state;
 	struct ipv6_addr *ia;
 	struct ll_callback *cb;
+	bool anyglobal;
 
 #if 0
 	char dbuf[INET6_ADDRSTRLEN];
@@ -1088,6 +1111,7 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 		return;
 	if ((state = ipv6_getstate(ifp)) == NULL)
 		return;
+	anyglobal = ipv6_ifanyglobal(ifp) != NULL;
 
 	TAILQ_FOREACH(ia, &state->addrs, next) {
 		if (IN6_ARE_ADDR_EQUAL(&ia->addr, addr))
@@ -1187,6 +1211,7 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 	if (ia == NULL)
 		return;
 
+	ctx->options &= ~DHCPCD_RTBUILD;
 	ipv6nd_handleifa(cmd, ia, pid);
 #ifdef DHCP6
 	dhcp6_handleifa(cmd, ia, pid);
@@ -1198,6 +1223,14 @@ out:
 		ipv6_freeaddr(ia);
 	else if (!(ia->addr_flags & IN6_IFF_NOTUSEABLE))
 		ia->flags |= IPV6_AF_DADCOMPLETED;
+
+	/* If we've not already called rt_build via the IPv6ND
+	 * or DHCP6 handlers and the existance of any useable
+	 * global address on the interface has changed,
+	 * call rt_build to add/remove the default route. */
+	if (!(ctx->options & DHCPCD_RTBUILD) &&
+	    (ipv6_ifanyglobal(ifp) != NULL) != anyglobal)
+		rt_build(ctx, AF_INET6);
 }
 
 int
@@ -2273,6 +2306,8 @@ inet6_raroutes(rb_tree_t *routes, struct dhcpcd_ctx *ctx)
 		}
 		if (rap->lifetime == 0)
 			continue;
+		if (ipv6_ifanyglobal(rap->iface) == NULL)
+			continue;
 		rt = inet6_makerouter(rap);
 		if (rt == NULL)
 			continue;
diff --git a/src/ipv6.h b/src/ipv6.h
index f07bc0f1..a95d9268 100644
--- a/src/ipv6.h
+++ b/src/ipv6.h
@@ -273,6 +273,7 @@ int ipv6_handleifa_addrs(int, struct ipv6_addrhead *, const struct ipv6_addr *,
 struct ipv6_addr *ipv6_iffindaddr(struct interface *,
     const struct in6_addr *, int);
 int ipv6_hasaddr(const struct interface *);
+struct ipv6_addr *ipv6_ifanyglobal(struct interface *);
 int ipv6_findaddrmatch(const struct ipv6_addr *, const struct in6_addr *,
     unsigned int);
 struct ipv6_addr *ipv6_findaddr(struct dhcpcd_ctx *,
diff --git a/src/ipv6nd.c b/src/ipv6nd.c
index 5f9c72cf..2a02a2a6 100644
--- a/src/ipv6nd.c
+++ b/src/ipv6nd.c
@@ -954,7 +954,7 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx,
 	struct in6_addr pi_prefix;
 	struct ipv6_addr *ap;
 	struct dhcp_opt *dho;
-	bool new_rap, new_data;
+	bool new_rap, new_data, has_address;
 	uint32_t old_lifetime;
 	__printflike(1, 2) void (*logfunc)(const char *, ...);
 #ifdef IPV6_MANAGETEMPADDR
@@ -1055,7 +1055,7 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx,
 	 * routers like to decrease the advertised valid and preferred times
 	 * in accordance with the own prefix times which would result in too
 	 * much needless log spam. */
-	logfunc = new_rap || !rap->isreachable ? loginfox : logdebugx,
+	logfunc = new_data || !rap->isreachable ? loginfox : logdebugx,
 	logfunc("%s: Router Advertisement from %s", ifp->name, rap->sfrom);
 
 	clock_gettime(CLOCK_MONOTONIC, &rap->acquired);
@@ -1078,6 +1078,7 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx,
 	rap->expired = false;
 	rap->hasdns = false;
 	rap->isreachable = true;
+	has_address = false;
 
 #ifdef IPV6_AF_TEMPORARY
 	ipv6_markaddrsstale(ifp, IPV6_AF_TEMPORARY);
@@ -1211,6 +1212,9 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx,
 			    ntohl(pi.nd_opt_pi_valid_time);
 			ap->prefix_pltime =
 			    ntohl(pi.nd_opt_pi_preferred_time);
+			if (ap->prefix_vltime != 0 &&
+			    ap->flags & IPV6_AF_AUTOCONF)
+				has_address = true;
 
 #ifdef IPV6_MANAGETEMPADDR
 			/* RFC4941 Section 3.3.3 */
@@ -1277,6 +1281,10 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx,
 		}
 	}
 
+	if (new_data && !has_address && rap->lifetime && !ipv6_ifanyglobal(ifp))
+		logwarnx("%s: no global addresses for default route",
+		    ifp->name);
+
 	if (new_rap)
 		add_router(ifp->ctx, rap);
 
@@ -1327,20 +1335,21 @@ nodhcp6:
 	ipv6nd_expirera(ifp);
 }
 
-int
-ipv6nd_hasra(const struct interface *ifp)
+bool
+ipv6nd_hasralifetime(const struct interface *ifp, bool lifetime)
 {
 	const struct ra *rap;
 
 	if (ifp->ctx->ra_routers) {
 		TAILQ_FOREACH(rap, ifp->ctx->ra_routers, next)
-			if (rap->iface == ifp && !rap->expired)
-				return 1;
+			if (rap->iface == ifp && !rap->expired &&
+			    (!lifetime ||rap->lifetime))
+				return true;
 	}
-	return 0;
+	return false;
 }
 
-int
+bool
 ipv6nd_hasradhcp(const struct interface *ifp)
 {
 	const struct ra *rap;
@@ -1349,11 +1358,11 @@ ipv6nd_hasradhcp(const struct interface *ifp)
 		TAILQ_FOREACH(rap, ifp->ctx->ra_routers, next) {
 			if (rap->iface == ifp &&
 			    !rap->expired &&
-			    (rap->flags & (ND_RA_FLAG_MANAGED | ND_RA_FLAG_OTHER)))
-				return 1;
+			    (rap->flags &(ND_RA_FLAG_MANAGED|ND_RA_FLAG_OTHER)))
+				return true;
 		}
 	}
-	return 0;
+	return false;
 }
 
 static const uint8_t *
diff --git a/src/ipv6nd.h b/src/ipv6nd.h
index e51271eb..b169b8be 100644
--- a/src/ipv6nd.h
+++ b/src/ipv6nd.h
@@ -104,8 +104,9 @@ struct ipv6_addr *ipv6nd_findaddr(struct dhcpcd_ctx *,
     const struct in6_addr *, unsigned int);
 ssize_t ipv6nd_free(struct interface *);
 void ipv6nd_expirera(void *arg);
-int ipv6nd_hasra(const struct interface *);
-int ipv6nd_hasradhcp(const struct interface *);
+bool ipv6nd_hasralifetime(const struct interface *, bool);
+#define	ipv6nd_hasra(i)		ipv6nd_hasralifetime((i), false)
+bool ipv6nd_hasradhcp(const struct interface *);
 void ipv6nd_handleifa(int, struct ipv6_addr *, pid_t);
 int ipv6nd_dadcompleted(const struct interface *);
 void ipv6nd_advertise(struct ipv6_addr *);
diff --git a/src/route.c b/src/route.c
index c1d19eb0..01bf8df9 100644
--- a/src/route.c
+++ b/src/route.c
@@ -39,6 +39,7 @@
 #include "common.h"
 #include "dhcpcd.h"
 #include "if.h"
+#include "if-options.h"
 #include "ipv4.h"
 #include "ipv4ll.h"
 #include "ipv6.h"
@@ -685,6 +686,7 @@ rt_build(struct dhcpcd_ctx *ctx, int af)
 	rb_tree_init(&kroutes, &rt_compare_os_ops);
 	if_initrt(ctx, &kroutes, af);
 	ctx->rt_order = 0;
+	ctx->options |= DHCPCD_RTBUILD;
 
 	switch (af) {
 #ifdef INET