GitHub CI: update list of container images
[tinc] / src / subnet.c
index dce5747..94000cc 100644 (file)
@@ -1,6 +1,6 @@
 /*
     subnet.c -- handle subnet lookups and lists
-    Copyright (C) 2000-2010 Guus Sliepen <guus@tinc-vpn.org>,
+    Copyright (C) 2000-2022 Guus Sliepen <guus@tinc-vpn.org>,
                   2000-2005 Ivo Timmermans
 
     This program is free software; you can redistribute it and/or modify
 
 #include "splay_tree.h"
 #include "control_common.h"
-#include "device.h"
+#include "crypto.h"
+#include "hash.h"
 #include "logger.h"
 #include "net.h"
 #include "netutl.h"
 #include "node.h"
-#include "process.h"
+#include "script.h"
 #include "subnet.h"
-#include "utils.h"
 #include "xalloc.h"
+#include "sandbox.h"
 
 /* lists type of subnet */
-
-splay_tree_t *subnet_tree;
+uint32_t hash_seed;
+splay_tree_t subnet_tree = {
+       .compare = (splay_compare_t) subnet_compare,
+       .delete = (splay_action_t) free_subnet,
+};
 
 /* Subnet lookup cache */
 
-static ipv4_t cache_ipv4_address[2];
-static subnet_t *cache_ipv4_subnet[2];
-static bool cache_ipv4_valid[2];
-static int cache_ipv4_slot;
-
-static ipv6_t cache_ipv6_address[2];
-static subnet_t *cache_ipv6_subnet[2];
-static bool cache_ipv6_valid[2];
-static int cache_ipv6_slot;
-
-static mac_t cache_mac_address[2];
-static subnet_t *cache_mac_subnet[2];
-static bool cache_mac_valid[2];
-static int cache_mac_slot;
-
-void subnet_cache_flush() {
-       cache_ipv4_valid[0] = cache_ipv4_valid[1] = false;
-       cache_ipv6_valid[0] = cache_ipv6_valid[1] = false;
-       cache_mac_valid[0] = cache_mac_valid[1] = false;
+static uint32_t wrapping_add32(uint32_t a, uint32_t b) {
+       return (uint32_t)((uint64_t)a + b);
 }
 
-/* Subnet comparison */
-
-static int subnet_compare_mac(const subnet_t *a, const subnet_t *b) {
-       int result;
-
-       result = memcmp(&a->net.mac.address, &b->net.mac.address, sizeof a->net.mac.address);
-
-       if(result)
-               return result;
-       
-       result = a->weight - b->weight;
-
-       if(result || !a->owner || !b->owner)
-               return result;
-
-       return strcmp(a->owner->name, b->owner->name);
+static uint32_t wrapping_mul32(uint32_t a, uint32_t b) {
+       return (uint32_t)((uint64_t)a * b);
 }
 
-static int subnet_compare_ipv4(const subnet_t *a, const subnet_t *b) {
-       int result;
-
-       result = b->net.ipv4.prefixlength - a->net.ipv4.prefixlength;
-
-       if(result)
-               return result;
+static uint32_t hash_function_ipv4_t(const ipv4_t *p) {
+       /*
+       This basic hash works because
+       a) Most IPv4 networks routed via tinc are not /0
+       b) Most IPv4 networks have more unique low order bits
+       */
+       uint16_t *halfwidth = (uint16_t *)p;
+       uint32_t hash = hash_seed;
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+       // 10.0.x.x/16 part
+       hash = wrapping_add32(hash, wrapping_mul32(halfwidth[1], 0x9e370001U));
+
+       // x.x.0.[0-255] part
+#if SUBNET_HASH_SIZE >= 0x10000
+       return hash ^ halfwidth[0];
+#else
+       // ensure that we have a /24 with no collisions on 32bit
+       return hash ^ ntohs(halfwidth[0]);
+#endif // _____LP64_____
+#else
+       // 10.0.x.x/16 part
+       hash = wrapping_add32(hash, wrapping_mul32(halfwidth[0], 0x9e370001U));
+
+       // x.x.0.[0-255] part (ntohs is nop on big endian)
+       return hash ^ halfwidth[1];
+#endif // __BYTE_ORDER == __LITTLE_ENDIAN
+}
 
-       result = memcmp(&a->net.ipv4.address, &b->net.ipv4.address, sizeof(ipv4_t));
 
-       if(result)
-               return result;
-       
-       result = a->weight - b->weight;
+static uint32_t hash_function_ipv6_t(const ipv6_t *p) {
+       uint32_t *fullwidth = (uint32_t *)p;
+       uint32_t hash = hash_seed;
 
-       if(result || !a->owner || !b->owner)
-               return result;
+       for(int i = 0; i < 4; i++) {
+               hash = wrapping_add32(hash, fullwidth[i]);
+               hash = wrapping_mul32(hash, 0x9e370001U);
+       }
 
-       return strcmp(a->owner->name, b->owner->name);
+       return hash;
 }
 
-static int subnet_compare_ipv6(const subnet_t *a, const subnet_t *b) {
-       int result;
+static uint32_t hash_function_mac_t(const mac_t *p) {
+       uint16_t *halfwidth = (uint16_t *)p;
+       uint32_t hash = hash_seed;
 
-       result = b->net.ipv6.prefixlength - a->net.ipv6.prefixlength;
+       for(int i = 0; i < 3; i++) {
+               hash = wrapping_add32(hash, halfwidth[i]);
+               hash = wrapping_mul32(hash, 0x9e370001U);
+       }
 
-       if(result)
-               return result;
-       
-       result = memcmp(&a->net.ipv6.address, &b->net.ipv6.address, sizeof(ipv6_t));
+       return hash;
+}
 
-       if(result)
-               return result;
-       
-       result = a->weight - b->weight;
+hash_define(ipv4_t, SUBNET_HASH_SIZE)
+hash_define(ipv6_t, SUBNET_HASH_SIZE)
+hash_define(mac_t, SUBNET_HASH_SIZE)
 
-       if(result || !a->owner || !b->owner)
-               return result;
+hash_new(ipv4_t, ipv4_cache);
+hash_new(ipv6_t, ipv6_cache);
+hash_new(mac_t, mac_cache);
 
-       return strcmp(a->owner->name, b->owner->name);
-}
 
-int subnet_compare(const subnet_t *a, const subnet_t *b) {
-       int result;
+void subnet_cache_flush_table(subnet_type_t stype) {
+       // NOTE: a subnet type of SUBNET_TYPES can be used to clear all hash tables
 
-       result = a->type - b->type;
-
-       if(result)
-               return result;
+       if(stype != SUBNET_IPV6) { // ipv4
+               hash_clear(ipv4_t, &ipv4_cache);
+       }
 
-       switch (a->type) {
-       case SUBNET_MAC:
-               return subnet_compare_mac(a, b);
-       case SUBNET_IPV4:
-               return subnet_compare_ipv4(a, b);
-       case SUBNET_IPV6:
-               return subnet_compare_ipv6(a, b);
-       default:
-               logger(LOG_ERR, "subnet_compare() was called with unknown subnet type %d, exitting!",
-                          a->type);
-               exit(0);
+       if(stype != SUBNET_IPV4) { // ipv6
+               hash_clear(ipv6_t, &ipv6_cache);
        }
 
-       return 0;
+       hash_clear(mac_t, &mac_cache);
 }
 
 /* Initialising trees */
 
 void init_subnets(void) {
-       subnet_tree = splay_alloc_tree((splay_compare_t) subnet_compare, (splay_action_t) free_subnet);
+       hash_seed = prng(UINT32_MAX);
 
-       subnet_cache_flush();
+       // tables need to be cleared on startup
+       subnet_cache_flush_tables();
 }
 
 void exit_subnets(void) {
-       splay_delete_tree(subnet_tree);
-}
-
-splay_tree_t *new_subnet_tree(void) {
-       return splay_alloc_tree((splay_compare_t) subnet_compare, NULL);
+       splay_empty_tree(&subnet_tree);
+       subnet_cache_flush_tables();
 }
 
-void free_subnet_tree(splay_tree_t *subnet_tree) {
-       splay_delete_tree(subnet_tree);
+void init_subnet_tree(splay_tree_t *tree) {
+       memset(tree, 0, sizeof(*tree));
+       tree->compare = (splay_compare_t) subnet_compare;
 }
 
 /* Allocating and freeing space for subnets */
 
 subnet_t *new_subnet(void) {
-       return xmalloc_and_zero(sizeof(subnet_t));
+       return xzalloc(sizeof(subnet_t));
 }
 
 void free_subnet(subnet_t *subnet) {
        free(subnet);
 }
 
-/* Adding and removing subnets */
-
-void subnet_add(node_t *n, subnet_t *subnet) {
-       subnet->owner = n;
-
-       splay_insert(subnet_tree, subnet);
-       splay_insert(n->subnet_tree, subnet);
-
-       subnet_cache_flush();
+void subnet_cache_flush_tables(void) {
+       // flushes all the tables
+       hash_clear(ipv4_t, &ipv4_cache);
+       hash_clear(ipv6_t, &ipv6_cache);
+       hash_clear(mac_t, &mac_cache);
 }
 
-void subnet_del(node_t *n, subnet_t *subnet) {
-       splay_delete(n->subnet_tree, subnet);
-       splay_delete(subnet_tree, subnet);
-
-       subnet_cache_flush();
-}
-
-/* Ascii representation of subnets */
-
-bool str2net(subnet_t *subnet, const char *subnetstr) {
-       int i, l;
-       uint16_t x[8];
-       int weight = 10;
-
-       if(sscanf(subnetstr, "%hu.%hu.%hu.%hu/%d#%d",
-                         &x[0], &x[1], &x[2], &x[3], &l, &weight) >= 5) {
-               if(l < 0 || l > 32)
-                       return false;
-
-               subnet->type = SUBNET_IPV4;
-               subnet->net.ipv4.prefixlength = l;
-               subnet->weight = weight;
-
-               for(i = 0; i < 4; i++) {
-                       if(x[i] > 255)
-                               return false;
-                       subnet->net.ipv4.address.x[i] = x[i];
+static void subnet_cache_flush(subnet_t *subnet) {
+       switch(subnet->type) {
+       case SUBNET_IPV4:
+               if(subnet->net.ipv4.prefixlength == 32) {
+                       hash_delete(ipv4_t, &ipv4_cache, &subnet->net.ipv4.address);
+                       return;
                }
 
-               return true;
-       }
-
-       if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx/%d#%d",
-                         &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7],
-                         &l, &weight) >= 9) {
-               if(l < 0 || l > 128)
-                       return false;
-
-               subnet->type = SUBNET_IPV6;
-               subnet->net.ipv6.prefixlength = l;
-               subnet->weight = weight;
+               break;
 
-               for(i = 0; i < 8; i++)
-                       subnet->net.ipv6.address.x[i] = htons(x[i]);
-
-               return true;
-       }
-
-       if(sscanf(subnetstr, "%hu.%hu.%hu.%hu#%d", &x[0], &x[1], &x[2], &x[3], &weight) >= 4) {
-               subnet->type = SUBNET_IPV4;
-               subnet->net.ipv4.prefixlength = 32;
-               subnet->weight = weight;
-
-               for(i = 0; i < 4; i++) {
-                       if(x[i] > 255)
-                               return false;
-                       subnet->net.ipv4.address.x[i] = x[i];
+       case SUBNET_IPV6:
+               if(subnet->net.ipv4.prefixlength == 128) {
+                       hash_delete(ipv6_t, &ipv6_cache, &subnet->net.ipv6.address);
+                       return;
                }
 
-               return true;
-       }
+               break;
 
-       if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx#%d",
-                         &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &weight) >= 8) {
-               subnet->type = SUBNET_IPV6;
-               subnet->net.ipv6.prefixlength = 128;
-               subnet->weight = weight;
+       case SUBNET_MAC:
+               hash_delete(mac_t, &mac_cache, &subnet->net.mac.address);
+               return;
+       }
 
-               for(i = 0; i < 8; i++)
-                       subnet->net.ipv6.address.x[i] = htons(x[i]);
+       subnet_cache_flush_table(subnet->type);
+}
 
-               return true;
-       }
+/* Adding and removing subnets */
 
-       if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx#%d",
-                         &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &weight) >= 6) {
-               subnet->type = SUBNET_MAC;
-               subnet->weight = weight;
+void subnet_add(node_t *n, subnet_t *subnet) {
+       subnet->owner = n;
 
-               for(i = 0; i < 6; i++)
-                       subnet->net.mac.address.x[i] = x[i];
+       splay_insert(&subnet_tree, subnet);
 
-               return true;
+       if(n) {
+               splay_insert(&n->subnet_tree, subnet);
        }
 
-       return false;
+       subnet_cache_flush(subnet);
 }
 
-bool net2str(char *netstr, int len, const subnet_t *subnet) {
-       if(!netstr || !subnet) {
-               logger(LOG_ERR, "net2str() was called with netstr=%p, subnet=%p!", netstr, subnet);
-               return false;
+void subnet_del(node_t *n, subnet_t *subnet) {
+       if(n) {
+               splay_delete(&n->subnet_tree, subnet);
        }
 
-       switch (subnet->type) {
-               case SUBNET_MAC:
-                       snprintf(netstr, len, "%hx:%hx:%hx:%hx:%hx:%hx#%d",
-                                        subnet->net.mac.address.x[0],
-                                        subnet->net.mac.address.x[1],
-                                        subnet->net.mac.address.x[2],
-                                        subnet->net.mac.address.x[3],
-                                        subnet->net.mac.address.x[4],
-                                        subnet->net.mac.address.x[5],
-                                        subnet->weight);
-                       break;
-
-               case SUBNET_IPV4:
-                       snprintf(netstr, len, "%hu.%hu.%hu.%hu/%d#%d",
-                                        subnet->net.ipv4.address.x[0],
-                                        subnet->net.ipv4.address.x[1],
-                                        subnet->net.ipv4.address.x[2],
-                                        subnet->net.ipv4.address.x[3],
-                                        subnet->net.ipv4.prefixlength,
-                                        subnet->weight);
-                       break;
-
-               case SUBNET_IPV6:
-                       snprintf(netstr, len, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx/%d#%d",
-                                        ntohs(subnet->net.ipv6.address.x[0]),
-                                        ntohs(subnet->net.ipv6.address.x[1]),
-                                        ntohs(subnet->net.ipv6.address.x[2]),
-                                        ntohs(subnet->net.ipv6.address.x[3]),
-                                        ntohs(subnet->net.ipv6.address.x[4]),
-                                        ntohs(subnet->net.ipv6.address.x[5]),
-                                        ntohs(subnet->net.ipv6.address.x[6]),
-                                        ntohs(subnet->net.ipv6.address.x[7]),
-                                        subnet->net.ipv6.prefixlength,
-                                        subnet->weight);
-                       break;
-
-               default:
-                       logger(LOG_ERR,
-                                  "net2str() was called with unknown subnet type %d, exiting!",
-                                  subnet->type);
-                       exit(0);
-       }
+       splay_delete(&subnet_tree, subnet);
 
-       return true;
+       subnet_cache_flush(subnet);
 }
 
 /* Subnet lookup routines */
 
-subnet_t *lookup_subnet(const node_t *owner, const subnet_t *subnet) {
-       return splay_search(owner->subnet_tree, subnet);
+subnet_t *lookup_subnet(node_t *owner, const subnet_t *subnet) {
+       return splay_search(&owner->subnet_tree, subnet);
 }
 
 subnet_t *lookup_subnet_mac(const node_t *owner, const mac_t *address) {
-       subnet_t *p, *r = NULL;
-       splay_node_t *n;
-       int i;
+       subnet_t *r = NULL;
 
        // Check if this address is cached
 
-       for(i = 0; i < 2; i++) {
-               if(!cache_mac_valid[i])
-                       continue;
-               if(owner && cache_mac_subnet[i] && cache_mac_subnet[i]->owner != owner)
-                       continue;
-               if(!memcmp(address, &cache_mac_address[i], sizeof *address))
-                       return cache_mac_subnet[i];
+       if((r = hash_search(mac_t, &mac_cache, address))) {
+               return r;
        }
 
        // Search all subnets for a matching one
 
-       for(n = owner ? owner->subnet_tree->head : subnet_tree->head; n; n = n->next) {
-               p = n->data;
-               
-               if(!p || p->type != SUBNET_MAC)
+       for splay_each(subnet_t, p, owner ? &owner->subnet_tree : &subnet_tree) {
+               if(!p || p->type != SUBNET_MAC) {
                        continue;
+               }
 
-               if(!memcmp(address, &p->net.mac.address, sizeof *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;
+                       }
                }
        }
 
        // Cache the result
 
-       cache_mac_slot = !cache_mac_slot;
-       memcpy(&cache_mac_address[cache_mac_slot], address, sizeof *address);
-       cache_mac_subnet[cache_mac_slot] = r;
-       cache_mac_valid[cache_mac_slot] = true;
+       if(r) {
+               hash_insert(mac_t, &mac_cache, address, r);
+       }
 
        return r;
 }
 
 subnet_t *lookup_subnet_ipv4(const ipv4_t *address) {
-       subnet_t *p, *r = NULL;
-       splay_node_t *n;
-       int i;
+       subnet_t *r = NULL;
 
        // Check if this address is cached
 
-       for(i = 0; i < 2; i++) {
-               if(!cache_ipv4_valid[i])
-                       continue;
-               if(!memcmp(address, &cache_ipv4_address[i], sizeof *address))
-                       return cache_ipv4_subnet[i];
+       if((r = hash_search(ipv4_t, &ipv4_cache, address))) {
+               return r;
        }
 
        // Search all subnets for a matching one
 
-       for(n = subnet_tree->head; n; n = n->next) {
-               p = n->data;
-               
-               if(!p || p->type != SUBNET_IPV4)
+       for splay_each(subnet_t, p, &subnet_tree) {
+               if(!p || p->type != SUBNET_IPV4) {
                        continue;
+               }
 
                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;
+                       }
                }
        }
 
        // Cache the result
 
-       cache_ipv4_slot = !cache_ipv4_slot;
-       memcpy(&cache_ipv4_address[cache_ipv4_slot], address, sizeof *address);
-       cache_ipv4_subnet[cache_ipv4_slot] = r;
-       cache_ipv4_valid[cache_ipv4_slot] = true;
+       if(r) {
+               hash_insert(ipv4_t, &ipv4_cache, address, r);
+       }
 
        return r;
 }
 
 subnet_t *lookup_subnet_ipv6(const ipv6_t *address) {
-       subnet_t *p, *r = NULL;
-       splay_node_t *n;
-       int i;
+       subnet_t *r = NULL;
 
        // Check if this address is cached
 
-       for(i = 0; i < 2; i++) {
-               if(!cache_ipv6_valid[i])
-                       continue;
-               if(!memcmp(address, &cache_ipv6_address[i], sizeof *address))
-                       return cache_ipv6_subnet[i];
+       if((r = hash_search(ipv6_t, &ipv6_cache, address))) {
+               return r;
        }
 
        // Search all subnets for a matching one
 
-       for(n = subnet_tree->head; n; n = n->next) {
-               p = n->data;
-               
-               if(!p || p->type != SUBNET_IPV6)
+       for splay_each(subnet_t, p, &subnet_tree) {
+               if(!p || p->type != SUBNET_IPV6) {
                        continue;
+               }
 
                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;
+                       }
                }
        }
 
        // Cache the result
 
-       cache_ipv6_slot = !cache_ipv6_slot;
-       memcpy(&cache_ipv6_address[cache_ipv6_slot], address, sizeof *address);
-       cache_ipv6_subnet[cache_ipv6_slot] = r;
-       cache_ipv6_valid[cache_ipv6_slot] = true;
+       if(r) {
+               hash_insert(ipv6_t, &ipv6_cache, address, r);
+       }
 
        return r;
 }
 
 void subnet_update(node_t *owner, subnet_t *subnet, bool up) {
-       splay_node_t *node;
-       int i;
-       char *envp[9] = {0};
+       if(!sandbox_can(START_PROCESSES, RIGHT_NOW)) {
+               return;
+       }
+
        char netstr[MAXNETSTR];
-       char *name, *address, *port;
+       char *address, *port;
        char empty[] = "";
 
        // Prepare environment variables to be passed to the script
 
-       xasprintf(&envp[0], "NETNAME=%s", netname ? : "");
-       xasprintf(&envp[1], "DEVICE=%s", device ? : "");
-       xasprintf(&envp[2], "INTERFACE=%s", iface ? : "");
-       xasprintf(&envp[3], "NODE=%s", owner->name);
+       environment_t env;
+       environment_init(&env);
+       environment_add(&env, "NODE=%s", owner->name);
 
        if(owner != myself) {
                sockaddr2str(&owner->address, &address, &port);
-               // 4 and 5 are reserved for SUBNET and WEIGHT
-               xasprintf(&envp[6], "REMOTEADDRESS=%s", address);
-               xasprintf(&envp[7], "REMOTEPORT=%s", port);
+               environment_add(&env, "REMOTEADDRESS=%s", address);
+               environment_add(&env, "REMOTEPORT=%s", port);
+               free(port);
+               free(address);
        }
 
-       name = up ? "subnet-up" : "subnet-down";
+       int env_subnet = environment_add(&env, NULL);
+       int env_weight = environment_add(&env, NULL);
+
+       const char *name = up ? "subnet-up" : "subnet-down";
 
        if(!subnet) {
-               for(node = owner->subnet_tree->head; node; node = node->next) {
-                       subnet = node->data;
-                       if(!net2str(netstr, sizeof netstr, subnet))
+               for splay_each(subnet_t, subnet, &owner->subnet_tree) {
+                       if(!net2str(netstr, sizeof(netstr), subnet)) {
                                continue;
+                       }
+
                        // Strip the weight from the subnet, and put it in its own environment variable
                        char *weight = strchr(netstr, '#');
-                       if(weight)
+
+                       if(weight) {
                                *weight++ = 0;
-                       else
+                       } else {
                                weight = empty;
+                       }
 
                        // Prepare the SUBNET and WEIGHT variables
-                       if(envp[4])
-                               free(envp[4]);
-                       if(envp[5])
-                               free(envp[5]);
-                       xasprintf(&envp[4], "SUBNET=%s", netstr);
-                       xasprintf(&envp[5], "WEIGHT=%s", weight);
-
-                       execute_script(name, envp);
+                       environment_update(&env, env_subnet, "SUBNET=%s", netstr);
+                       environment_update(&env, env_weight, "WEIGHT=%s", weight);
+
+                       execute_script(name, &env);
                }
        } else {
-               if(net2str(netstr, sizeof netstr, subnet)) {
+               if(net2str(netstr, sizeof(netstr), subnet)) {
                        // Strip the weight from the subnet, and put it in its own environment variable
                        char *weight = strchr(netstr, '#');
-                       if(weight)
+
+                       if(weight) {
                                *weight++ = 0;
-                       else
+                       } else {
                                weight = empty;
+                       }
 
                        // Prepare the SUBNET and WEIGHT variables
-                       xasprintf(&envp[4], "SUBNET=%s", netstr);
-                       xasprintf(&envp[5], "WEIGHT=%s", weight);
+                       environment_update(&env, env_subnet, "SUBNET=%s", netstr);
+                       environment_update(&env, env_weight, "WEIGHT=%s", weight);
 
-                       execute_script(name, envp);
+                       execute_script(name, &env);
                }
        }
 
-       for(i = 0; envp[i] && i < 9; i++)
-               free(envp[i]);
+       environment_exit(&env);
 }
 
 bool dump_subnets(connection_t *c) {
-       char netstr[MAXNETSTR];
-       subnet_t *subnet;
-       splay_node_t *node;
+       for splay_each(subnet_t, subnet, &subnet_tree) {
+               char netstr[MAXNETSTR];
 
-       for(node = subnet_tree->head; node; node = node->next) {
-               subnet = node->data;
-               if(!net2str(netstr, sizeof netstr, subnet))
+               if(!net2str(netstr, sizeof(netstr), subnet)) {
                        continue;
-               send_request(c, "%d %d %s owner %s",
-                               CONTROL, REQ_DUMP_SUBNETS,
-                               netstr, subnet->owner->name);
+               }
+
+               send_request(c, "%d %d %s %s",
+                            CONTROL, REQ_DUMP_SUBNETS,
+                            netstr, subnet->owner ? subnet->owner->name : "(broadcast)");
        }
 
        return send_request(c, "%d %d", CONTROL, REQ_DUMP_SUBNETS);