Add a #define to compile ignoring the RA without a public address.

This is set for BSD systems at present so that working systems such as Linux
work by default as designed.
Fixes [f44b3b4817].

dhcp6.c

@@ -505,6 +505,7 @@ dhcp6_delegateaddr(struct in6_addr *addr, struct interface *ifp,
 	return sla->prefix_len;
 }
 
+#ifdef IGNORE_RA_NOPUBLICADDR
 int
 dhcp6_has_public_addr(const struct interface *ifp)
 {
@@ -519,6 +520,7 @@ dhcp6_has_public_addr(const struct interface *ifp)
 	}
 	return 0;
 }
+#endif
 
 static int
 dhcp6_makemessage(struct interface *ifp)
@@ -3025,7 +3027,9 @@ recv:
 			eloop_timeout_add_sec(ifp->ctx->eloop,
 			    (time_t)state->expire, dhcp6_startexpire, ifp);
 
+#ifdef IGNORE_RA_NOPUBLICADDR
 		ipv6nd_runignoredra(ifp);
+#endif
 		ipv6_addaddrs(&state->addrs);
 		dhcp6_delegate_prefix(ifp);
 

dhcp6.h

@@ -238,7 +238,6 @@ const struct ipv6_addr *dhcp6_iffindaddr(const struct interface *ifp,
 struct ipv6_addr *dhcp6_findaddr(struct dhcpcd_ctx *, const struct in6_addr *,
     short);
 size_t dhcp6_find_delegates(struct interface *);
-int dhcp6_has_public_addr(const struct interface *);
 int dhcp6_start(struct interface *, enum DH6S);
 void dhcp6_reboot(struct interface *);
 ssize_t dhcp6_env(char **, const char *, const struct interface *,
@@ -249,6 +248,10 @@ void dhcp6_handleifa(struct dhcpcd_ctx *, int, const char *,
 int dhcp6_dadcompleted(const struct interface *);
 void dhcp6_drop(struct interface *, const char *);
 int dhcp6_dump(struct interface *);
+
+#ifdef IGNORE_RA_NOPUBLICADDR
+int dhcp6_has_public_addr(const struct interface *);
+#endif
 #else
 #define dhcp6_find_delegates(a) {}
 #define dhcp6_start(a, b) (0)

dhcpcd.conf.5.in

@@ -371,9 +371,12 @@ and/or user selection rather than the kernel.
 .It Ic ipv6ra_accept_nopublic
 Some IPv6 routers advertise themselves as a default router without any
 public prefixes or managed addresses.
-Generally, this is incorrect behaviour and
+On non Linux systems
 .Nm dhcpcd
-will ignore the advertisement unless this option is turned on.
+will ignore the advertisement,
+unless this option is turned on,
+so that attempts to access a remote public IPv6 address without a local
+public IPv6 address fail quickly.
 .It Ic ipv6rs
 Enables IPv6 Router Advertisment solicitation.
 This is on by default, but is documented here in the case where it is disabled

ipv6.c

@@ -745,6 +745,7 @@ ipv6_addaddr(struct ipv6_addr *ap, const struct timespec *now)
 	return 0;
 }
 
+#ifdef IGNORE_RA_NOPUBLICADDR
 int
 ipv6_publicaddr(const struct ipv6_addr *ia)
 {
@@ -752,6 +753,7 @@ ipv6_publicaddr(const struct ipv6_addr *ia)
 	    (ia->addr.s6_addr[0] & 0xfe) != 0xfc &&
 	    !(ia->addr_flags & IN6_IFF_NOTUSEABLE));
 }
+#endif
 
 int
 ipv6_findaddrmatch(const struct ipv6_addr *addr, const struct in6_addr *match,

ipv6.h

@@ -104,6 +104,16 @@
 #define IPV6_MANAGETEMPADDR
 #endif
 
+/* NetBSD at least will try and contact a global address if there is a default
+ * route but there is no global address on the interface to connect with.
+ * As a safety measure, we ignore RA's until a public address is found.
+ * This is the wrong thing todo, as Linux seems to abort early - maybe
+ * because there is no matching source address for the destination address.
+ * Until this is resolved, we have this restriction in place. */
+#ifdef BSD
+#define IGNORE_RA_NOPUBLICADDR
+#endif
+
 struct ipv6_addr {
 	TAILQ_ENTRY(ipv6_addr) next;
 	struct interface *iface;

ipv6nd.c

@@ -731,6 +731,7 @@ try_script:
 	}
 }
 
+#ifdef IGNORE_RA_NOPUBLICADDR
 static int
 ipv6nd_ra_has_public_addr(const struct ra *rap)
 {
@@ -743,6 +744,7 @@ ipv6nd_ra_has_public_addr(const struct ra *rap)
 	}
 	return 0;
 }
+#endif
 
 static void
 ipv6nd_handlera(struct dhcpcd_ctx *dctx, struct interface *ifp,
@@ -1106,6 +1108,7 @@ ipv6nd_handlera(struct dhcpcd_ctx *dctx, struct interface *ifp,
 	if (new_rap)
 		add_router(ifp->ctx->ipv6, rap);
 
+#ifdef IGNORE_RA_NOPUBLICADDR
 	if (!ipv6nd_ra_has_public_addr(rap) &&
 	    !(rap->iface->options->options & DHCPCD_IPV6RA_ACCEPT_NOPUBLIC) &&
 	    (!(rap->flags & ND_RA_FLAG_MANAGED) ||
@@ -1119,6 +1122,8 @@ ipv6nd_handlera(struct dhcpcd_ctx *dctx, struct interface *ifp,
 		rap->no_public_warned = 1;
 		goto handle_flag;
 	}
+#endif
+
 	if (ifp->ctx->options & DHCPCD_TEST) {
 		script_runreason(ifp, "TEST");
 		goto handle_flag;
@@ -1166,6 +1171,7 @@ nodhcp6:
 	ipv6nd_expirera(ifp);
 }
 
+#ifdef IGNORE_RA_NOPUBLICADDR
 /* Run RA's we ignored becuase they had no public addresses
  * This should only be called when DHCPv6 applies a public address */
 void
@@ -1193,6 +1199,7 @@ ipv6nd_runignoredra(struct interface *ifp)
 		}
 	}
 }
+#endif
 
 int
 ipv6nd_hasra(const struct interface *ifp)

ipv6nd.h

@@ -110,13 +110,16 @@ ssize_t ipv6nd_free(struct interface *);
 void ipv6nd_expirera(void *arg);
 int ipv6nd_hasra(const struct interface *);
 int ipv6nd_hasradhcp(const struct interface *);
-void ipv6nd_runignoredra(struct interface *);
 void ipv6nd_handleifa(struct dhcpcd_ctx *, int,
     const char *, const struct in6_addr *, int);
 int ipv6nd_dadcompleted(const struct interface *);
 void ipv6nd_expire(struct interface *, uint32_t);
 void ipv6nd_drop(struct interface *);
 void ipv6nd_neighbour(struct dhcpcd_ctx *, struct in6_addr *, int);
+
+#ifdef IGNORE_RA_NOPUBLICADDR
+void ipv6nd_runignoredra(struct interface *);
+#endif
 #else
 #define ipv6nd_startrs(a) {}
 #define ipv6nd_free(a) {}