Make broadcast addresses configurable.

This adds a new option, BroadcastSubnet, that allows the user to
declare broadcast subnets, i.e. subnets which are considered broadcast
addresses by the tinc routing layer. Previously only the global IPv4
and IPv6 broadcast addresses were supported by virtue of being
hardcoded.

This is useful when using tinc in router mode with Ethernet virtual
devices, as it can be used to provide broadcast support for a local
broadcast address (e.g. 10.42.255.255) instead of just the global
address (255.255.255.255).

This is implemented by removing hardcoded broadcast addresses and
introducing "broadcast subnets", which are subnets with a NULL owner.
By default, behavior is unchanged; this is accomplished by adding
the global broadcast addresses for Ethernet, IPv4 and IPv6 at start
time.

diff --git a/doc/tinc.conf.5.in b/doc/tinc.conf.5.in
index 01c7480..9566afa 100644 (file)
--- a/doc/tinc.conf.5.in
+++ b/doc/tinc.conf.5.in
@@ -155,6 +155,13 @@ Broadcast packets are sent directly to all nodes that can be reached directly.
 Broadcast packets received from other nodes are never forwarded.
 If the IndirectData option is also set, broadcast packets will only be sent to nodes which we have a meta connection to.
 .El
+.It Va BroadcastSubnet Li = Ar address Ns Op Li / Ns Ar prefixlength
+Declares a broadcast subnet. Any packet with a destination address falling into such a subnet will be routed as a broadcast (provided all nodes have it declared).
+This is most useful to declare subnet broadcast addresses (e.g. 10.42.255.255), otherwise
+.Nm tinc
+won't know what to do with them.
+.Pp
+Note that global broadcast addresses (MAC ff:ff:ff:ff:ff:ff, IPv4 255.255.255.255), as well as IPv6 multicast space (ff00::/8) are always considered broadcast addresses and don't need to be declared.
 .It Va ConnectTo Li = Ar name
 Specifies which other tinc daemon to connect to on startup.
 Multiple

diff --git a/src/net.c b/src/net.c
index b6ddc57..8fe3c51 100644 (file)
--- a/src/net.c
+++ b/src/net.c
@@ -347,11 +347,14 @@ int reload_configuration(void) {
 
        if(strictsubnets) {
                for splay_each(subnet_t, subnet, subnet_tree)
-                       subnet->expires = 1;
+                       if (subnet->owner)
+                               subnet->expires = 1;
 
                load_all_subnets();
 
                for splay_each(subnet_t, subnet, subnet_tree) {
+                       if (!subnet->owner)
+                               continue;
                        if(subnet->expires == 1) {
                                send_del_subnet(everyone, subnet);
                                if(subnet->owner->status.reachable)

diff --git a/src/net_setup.c b/src/net_setup.c
index 0a97e03..0f8d31a 100644 (file)
--- a/src/net_setup.c
+++ b/src/net_setup.c
@@ -586,6 +586,20 @@ bool setup_myself_reloadable(void) {
                free(bmode);
        }
 
+       const char* const DEFAULT_BROADCAST_SUBNETS[] = { "ff:ff:ff:ff:ff:ff", "255.255.255.255", "ff00::/8" };
+       for (size_t i = 0; i < sizeof(DEFAULT_BROADCAST_SUBNETS) / sizeof(*DEFAULT_BROADCAST_SUBNETS); i++) {
+               subnet_t *s = new_subnet();
+               if (!str2net(s, DEFAULT_BROADCAST_SUBNETS[i]))
+                       abort();
+               subnet_add(NULL, s);
+       }
+       for (config_t* cfg = lookup_config(config_tree, "BroadcastSubnet"); cfg; cfg = lookup_config_next(config_tree, cfg)) {
+               subnet_t *s;
+               if (!get_config_subnet(cfg, &s))
+                       continue;
+               subnet_add(NULL, s);
+       }
+
 #if !defined(SOL_IP) || !defined(IP_TOS)
        if(priorityinheritance)
                logger(DEBUG_ALWAYS, LOG_WARNING, "%s not supported on this platform", "PriorityInheritance");

diff --git a/src/route.c b/src/route.c
index 00ba4c0..43d2697 100644 (file)
--- a/src/route.c
+++ b/src/route.c
@@ -371,7 +371,10 @@ static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet, length_t et
        }
 }
 
-static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) {
+static void route_ipv4(node_t *source, vpn_packet_t *packet) {
+       if(!checklength(source, packet, ether_size + ip_size))
+               return;
+
        subnet_t *subnet;
        node_t *via;
        ipv4_t dest;
@@ -391,6 +394,11 @@ static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) {
                return;
        }
 
+       if (!subnet->owner) {
+               broadcast_packet(source, packet);
+               return;
+       }
+
        if(subnet->owner == source) {
                logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
                return;
@@ -432,20 +440,6 @@ static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) {
        send_packet(subnet->owner, packet);
 }
 
-static void route_ipv4(node_t *source, vpn_packet_t *packet) {
-       if(!checklength(source, packet, ether_size + ip_size))
-               return;
-
-       if(broadcast_mode && (((packet->data[30] & 0xf0) == 0xe0) || (
-                       packet->data[30] == 255 &&
-                       packet->data[31] == 255 &&
-                       packet->data[32] == 255 &&
-                       packet->data[33] == 255)))
-               broadcast_packet(source, packet);
-       else
-               route_ipv4_unicast(source, packet);
-}
-
 /* RFC 2463 */
 
 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
@@ -526,7 +520,17 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_
        send_packet(source, packet);
 }
 
-static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet) {
+static void route_neighborsol(node_t *source, vpn_packet_t *packet);
+
+static void route_ipv6(node_t *source, vpn_packet_t *packet) {
+       if(!checklength(source, packet, ether_size + ip6_size))
+               return;
+
+       if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
+               route_neighborsol(source, packet);
+               return;
+       }
+
        subnet_t *subnet;
        node_t *via;
        ipv6_t dest;
@@ -550,6 +554,11 @@ static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet) {
                return;
        }
 
+       if (!subnet->owner) {
+               broadcast_packet(source, packet);
+               return;
+       }
+
        if(subnet->owner == source) {
                logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
                return;
@@ -724,21 +733,6 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet) {
        send_packet(source, packet);
 }
 
-static void route_ipv6(node_t *source, vpn_packet_t *packet) {
-       if(!checklength(source, packet, ether_size + ip6_size))
-               return;
-
-       if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
-               route_neighborsol(source, packet);
-               return;
-       }
-
-       if(broadcast_mode && packet->data[38] == 255)
-               broadcast_packet(source, packet);
-       else
-               route_ipv6_unicast(source, packet);
-}
-
 /* RFC 826 */
 
 static void route_arp(node_t *source, vpn_packet_t *packet) {
@@ -822,7 +816,7 @@ static void route_mac(node_t *source, vpn_packet_t *packet) {
        memcpy(&dest, &packet->data[0], sizeof dest);
        subnet = lookup_subnet_mac(NULL, &dest);
 
-       if(!subnet) {
+       if(!subnet || !subnet->owner) {
                broadcast_packet(source, packet);
                return;
        }

diff --git a/src/subnet.c b/src/subnet.c
index 7ff8f7a..23160e5 100644 (file)
--- a/src/subnet.c
+++ b/src/subnet.c
@@ -92,13 +92,15 @@ void subnet_add(node_t *n, subnet_t *subnet) {
        subnet->owner = n;
 
        splay_insert(subnet_tree, subnet);
-       splay_insert(n->subnet_tree, subnet);
+       if (n)
+               splay_insert(n->subnet_tree, subnet);
 
        subnet_cache_flush();
 }
 
 void subnet_del(node_t *n, subnet_t *subnet) {
-       splay_delete(n->subnet_tree, subnet);
+       if (n)
+               splay_delete(n->subnet_tree, subnet);
        splay_delete(subnet_tree, subnet);
 
        subnet_cache_flush();
@@ -126,7 +128,7 @@ subnet_t *lookup_subnet_mac(const node_t *owner, const mac_t *address) {
 
                if(!memcmp(address, &p->net.mac.address, sizeof *address)) {
                        r = p;
-                       if(p->owner->status.reachable)
+                       if(!p->owner || p->owner->status.reachable)
                                break;
                }
        }
@@ -155,7 +157,7 @@ subnet_t *lookup_subnet_ipv4(const ipv4_t *address) {
 
                if(!maskcmp(address, &p->net.ipv4.address, p->net.ipv4.prefixlength)) {
                        r = p;
-                       if(p->owner->status.reachable)
+                       if(!p->owner || p->owner->status.reachable)
                                break;
                }
        }
@@ -184,7 +186,7 @@ subnet_t *lookup_subnet_ipv6(const ipv6_t *address) {
 
                if(!maskcmp(address, &p->net.ipv6.address, p->net.ipv6.prefixlength)) {
                        r = p;
-                       if(p->owner->status.reachable)
+                       if(!p->owner || p->owner->status.reachable)
                                break;
                }
        }