platform: support pref option for IPv6 routes (RTA_PREF)

Support IPv6 router preference (RFC4191) in platform code.

src/platform/nm-linux-platform.c

@@ -104,6 +104,11 @@
 #define IFLA_IPTUN_MAX                  (__IFLA_IPTUN_MAX - 1)
 #endif
 
+G_STATIC_ASSERT (RTA_MAX == (__RTA_MAX - 1));
+#define RTA_PREF                        20
+#undef  RTA_MAX
+#define RTA_MAX                        (MAX ((__RTA_MAX - 1), RTA_PREF))
+
 #ifndef MACVLAN_FLAG_NOPROMISC
 #define MACVLAN_FLAG_NOPROMISC          1
 #endif
@@ -2020,6 +2025,7 @@ _new_from_nl_route (struct nlmsghdr *nlh, gboolean id_only)
 		[RTA_IIF]       = { .type = NLA_U32 },
 		[RTA_OIF]       = { .type = NLA_U32 },
 		[RTA_PRIORITY]  = { .type = NLA_U32 },
+		[RTA_PREF]      = { .type = NLA_U8 },
 		[RTA_FLOW]      = { .type = NLA_U32 },
 		[RTA_CACHEINFO] = { .minlen = nm_offsetofend (struct rta_cacheinfo, rta_tsage) },
 		[RTA_METRICS]   = { .type = NLA_NESTED },
@@ -2224,6 +2230,10 @@ _new_from_nl_route (struct nlmsghdr *nlh, gboolean id_only)
 	obj->ip_route.lock_initrwnd = NM_FLAGS_HAS (lock, 1 << RTAX_INITRWND);
 	obj->ip_route.lock_mtu      = NM_FLAGS_HAS (lock, 1 << RTAX_MTU);
 
+	if (   !is_v4
+	    && tb[RTA_PREF])
+		obj->ip6_route.rt_pref = nla_get_u8 (tb[RTA_PREF]);
+
 	if (NM_FLAGS_HAS (rtm->rtm_flags, RTM_F_CLONED)) {
 		/* we must not straight way reject cloned routes, because we might have cached
 		 * a non-cloned route. If we now receive an update of the route with the route
@@ -2719,6 +2729,10 @@ _nl_msg_new_route (int nlmsg_type,
 	}
 	NLA_PUT_U32 (msg, RTA_OIF, obj->ip_route.ifindex);
 
+	if (   !is_v4
+	    && obj->ip6_route.rt_pref != NM_ICMPV6_ROUTER_PREF_MEDIUM)
+		NLA_PUT_U8 (msg, RTA_PREF, obj->ip6_route.rt_pref);
+
 	return msg;
 
 nla_put_failure:

src/platform/nm-platform.c

@@ -3873,6 +3873,16 @@ _ip_route_scope_inv_get_normalized (const NMPlatformIP4Route *route)
 	return route->scope_inv;
 }
 
+static guint8
+_route_pref_normalize (guint8 pref)
+{
+	/* for kernel (and ICMPv6) pref can only have one of 3 values. Normalize. */
+	return NM_IN_SET (pref, NM_ICMPV6_ROUTER_PREF_LOW,
+	                        NM_ICMPV6_ROUTER_PREF_HIGH)
+	       ? pref
+	       : NM_ICMPV6_ROUTER_PREF_MEDIUM;
+}
+
 /**
  * nm_platform_ip_route_normalize:
  * @addr_family: AF_INET or AF_INET6
@@ -5053,6 +5063,8 @@ nm_platform_ip6_route_to_string (const NMPlatformIP6Route *route, char *buf, gsi
 	char s_network[INET6_ADDRSTRLEN], s_gateway[INET6_ADDRSTRLEN], s_pref_src[INET6_ADDRSTRLEN];
 	char s_src_all[INET6_ADDRSTRLEN + 40], s_src[INET6_ADDRSTRLEN];
 	char str_table[30];
+	char str_pref[40];
+	char str_pref2[30];
 	char str_dev[TO_STRING_DEV_BUF_SIZE], s_source[50];
 	char str_window[32], str_cwnd[32], str_initcwnd[32], str_initrwnd[32], str_mtu[32];
 
@@ -5085,6 +5097,7 @@ nm_platform_ip6_route_to_string (const NMPlatformIP6Route *route, char *buf, gsi
 	            "%s" /* initcwnd */
 	            "%s" /* initrwnd */
 	            "%s" /* mtu */
+	            "%s" /* pref */
 	            "",
 	            route->table_coerced ? nm_sprintf_buf (str_table, "table %u ", nm_platform_route_table_uncoerce (route->table_coerced, FALSE)) : "",
 	            s_network,
@@ -5104,7 +5117,8 @@ nm_platform_ip6_route_to_string (const NMPlatformIP6Route *route, char *buf, gsi
 	            route->cwnd     || route->lock_cwnd     ? nm_sprintf_buf (str_cwnd,     " cwnd %s%"G_GUINT32_FORMAT,     route->lock_cwnd     ? "lock " : "", route->cwnd)     : "",
 	            route->initcwnd || route->lock_initcwnd ? nm_sprintf_buf (str_initcwnd, " initcwnd %s%"G_GUINT32_FORMAT, route->lock_initcwnd ? "lock " : "", route->initcwnd) : "",
 	            route->initrwnd || route->lock_initrwnd ? nm_sprintf_buf (str_initrwnd, " initrwnd %s%"G_GUINT32_FORMAT, route->lock_initrwnd ? "lock " : "", route->initrwnd) : "",
-	            route->mtu      || route->lock_mtu      ? nm_sprintf_buf (str_mtu,      " mtu %s%"G_GUINT32_FORMAT,      route->lock_mtu      ? "lock " : "", route->mtu)      : "");
+	            route->mtu      || route->lock_mtu      ? nm_sprintf_buf (str_mtu,      " mtu %s%"G_GUINT32_FORMAT,      route->lock_mtu      ? "lock " : "", route->mtu)      : "",
+	            route->rt_pref ? nm_sprintf_buf (str_pref, " pref %s", nm_icmpv6_router_pref_to_string (route->rt_pref, str_pref2, sizeof (str_pref2))) : "");
 
 	return buf;
 }
@@ -5730,6 +5744,10 @@ nm_platform_ip6_route_hash (const NMPlatformIP6Route *obj, NMPlatformIPRouteCmpT
 			h = NM_HASH_COMBINE (h, obj->initcwnd);
 			h = NM_HASH_COMBINE (h, obj->initrwnd);
 			h = NM_HASH_COMBINE (h, obj->mtu);
+			if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
+				h = NM_HASH_COMBINE (h, _route_pref_normalize (obj->rt_pref));
+			else
+				h = NM_HASH_COMBINE (h, obj->rt_pref);
 			break;
 		}
 	}
@@ -5796,6 +5814,10 @@ nm_platform_ip6_route_cmp (const NMPlatformIP6Route *a, const NMPlatformIP6Route
 		NM_CMP_FIELD (a, b, initcwnd);
 		NM_CMP_FIELD (a, b, initrwnd);
 		NM_CMP_FIELD (a, b, mtu);
+		if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
+			NM_CMP_DIRECT (_route_pref_normalize (a->rt_pref), _route_pref_normalize (b->rt_pref));
+		else
+			NM_CMP_FIELD (a, b, rt_pref);
 		break;
 	}
 	return 0;

src/platform/nm-platform.h

@@ -517,6 +517,12 @@ struct _NMPlatformIP6Route {
 	 */
 	struct in6_addr src;
 	guint8 src_plen;
+
+	/* RTA_PREF router preference.
+	 *
+	 * The type is guint8 to keep the struct size small. But the values are compatible with
+	 * the NMIcmpv6RouterPref enum. */
+	guint8 rt_pref;
 };
 
 typedef union {