[location/libloc.git] / src / network.c

/*
        libloc - A library to determine the location of someone on the Internet

        Copyright (C) 2017 IPFire Development Team <info@ipfire.org>

        This library is free software; you can redistribute it and/or
        modify it under the terms of the GNU Lesser General Public
        License as published by the Free Software Foundation; either
        version 2.1 of the License, or (at your option) any later version.

        This library is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        Lesser General Public License for more details.
*/

#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef HAVE_ENDIAN_H
#  include <endian.h>
#endif

#include <libloc/libloc.h>
#include <libloc/compat.h>
#include <libloc/country.h>
#include <libloc/network.h>
#include <libloc/network-list.h>
#include <libloc/private.h>

struct loc_network {
        struct loc_ctx* ctx;
        int refcount;

        int family;
        struct in6_addr first_address;
        struct in6_addr last_address;
        unsigned int prefix;

        char country_code[3];
        uint32_t asn;
        enum loc_network_flags flags;
};

static int valid_prefix(struct in6_addr* address, unsigned int prefix) {
        // The prefix cannot be larger than 128 bits
        if (prefix > 128)
                return 1;

        // And the prefix cannot be zero
        if (prefix == 0)
                return 1;

        // For IPv4-mapped addresses the prefix has to be 96 or lager
        if (IN6_IS_ADDR_V4MAPPED(address) && prefix <= 96)
                return 1;

        return 0;
}

static struct in6_addr prefix_to_bitmask(unsigned int prefix) {
        struct in6_addr bitmask;

        for (unsigned int i = 0; i < 16; i++)
                bitmask.s6_addr[i] = 0;

        for (int i = prefix, j = 0; i > 0; i -= 8, j++) {
                if (i >= 8)
                        bitmask.s6_addr[j] = 0xff;
                else
                        bitmask.s6_addr[j] = 0xff << (8 - i);
        }

        return bitmask;
}

static struct in6_addr make_first_address(const struct in6_addr* address, const struct in6_addr* bitmask) {
        struct in6_addr a;

        // Perform bitwise AND
        for (unsigned int i = 0; i < 4; i++)
                a.s6_addr32[i] = address->s6_addr32[i] & bitmask->s6_addr32[i];

        return a;
}

static struct in6_addr make_last_address(const struct in6_addr* address, const struct in6_addr* bitmask) {
        struct in6_addr a;

        // Perform bitwise OR
        for (unsigned int i = 0; i < 4; i++)
                a.s6_addr32[i] = address->s6_addr32[i] | ~bitmask->s6_addr32[i];

        return a;
}

LOC_EXPORT int loc_network_new(struct loc_ctx* ctx, struct loc_network** network,
                struct in6_addr* address, unsigned int prefix) {
        // Address cannot be unspecified
        if (IN6_IS_ADDR_UNSPECIFIED(address)) {
                DEBUG(ctx, "Start address is unspecified\n");
                return -EINVAL;
        }

        // Address cannot be loopback
        if (IN6_IS_ADDR_LOOPBACK(address)) {
                DEBUG(ctx, "Start address is loopback address\n");
                return -EINVAL;
        }

        // Address cannot be link-local
        if (IN6_IS_ADDR_LINKLOCAL(address)) {
                DEBUG(ctx, "Start address cannot be link-local\n");
                return -EINVAL;
        }

        // Address cannot be site-local
        if (IN6_IS_ADDR_SITELOCAL(address)) {
                DEBUG(ctx, "Start address cannot be site-local\n");
                return -EINVAL;
        }

        // Validate the prefix
        if (valid_prefix(address, prefix) != 0) {
                DEBUG(ctx, "Invalid prefix: %u\n", prefix);
                return -EINVAL;
        }

        struct loc_network* n = calloc(1, sizeof(*n));
        if (!n)
                return -ENOMEM;

        n->ctx = loc_ref(ctx);
        n->refcount = 1;

        // Store the prefix
        n->prefix = prefix;

        // Convert the prefix into a bitmask
        struct in6_addr bitmask = prefix_to_bitmask(n->prefix);

        // Store the first and last address in the network
        n->first_address = make_first_address(address, &bitmask);
        n->last_address = make_last_address(&n->first_address, &bitmask);

        // Set family
        n->family = loc_address_family(&n->first_address);

        DEBUG(n->ctx, "Network allocated at %p\n", n);
        *network = n;
        return 0;
}

LOC_EXPORT int loc_network_new_from_string(struct loc_ctx* ctx, struct loc_network** network,
                const char* address_string) {
        struct in6_addr first_address;
        char* prefix_string;
        unsigned int prefix = 128;
        int r = -EINVAL;

        DEBUG(ctx, "Attempting to parse network %s\n", address_string);

        // Make a copy of the string to work on it
        char* buffer = strdup(address_string);
        address_string = prefix_string = buffer;

        // Split address and prefix
        address_string = strsep(&prefix_string, "/");

        DEBUG(ctx, "  Split into address = %s, prefix = %s\n", address_string, prefix_string);

        // Parse the address
        r = loc_parse_address(ctx, address_string, &first_address);
        if (r) {
                DEBUG(ctx, "The address could not be parsed\n");
                goto FAIL;
        }

        // If a prefix was given, we will try to parse it
        if (prefix_string) {
                // Convert prefix to integer
                prefix = strtol(prefix_string, NULL, 10);

                if (!prefix) {
                        DEBUG(ctx, "The prefix was not parsable: %s\n", prefix_string);
                        goto FAIL;
                }

                // Map the prefix to IPv6 if needed
                if (IN6_IS_ADDR_V4MAPPED(&first_address))
                        prefix += 96;
        }

FAIL:
        // Free temporary buffer
        free(buffer);

        // Exit if the parsing was unsuccessful
        if (r)
                return r;

        // Create a new network
        return loc_network_new(ctx, network, &first_address, prefix);
}

LOC_EXPORT struct loc_network* loc_network_ref(struct loc_network* network) {
        network->refcount++;

        return network;
}

static void loc_network_free(struct loc_network* network) {
        DEBUG(network->ctx, "Releasing network at %p\n", network);

        loc_unref(network->ctx);
        free(network);
}

LOC_EXPORT struct loc_network* loc_network_unref(struct loc_network* network) {
        if (!network)
                return NULL;

        if (--network->refcount > 0)
                return network;

        loc_network_free(network);
        return NULL;
}

static int format_ipv6_address(const struct in6_addr* address, char* string, size_t length) {
        const char* ret = inet_ntop(AF_INET6, address, string, length);
        if (!ret)
                return -1;

        return 0;
}

static int format_ipv4_address(const struct in6_addr* address, char* string, size_t length) {
        struct in_addr ipv4_address;
        ipv4_address.s_addr = address->s6_addr32[3];

        const char* ret = inet_ntop(AF_INET, &ipv4_address, string, length);
        if (!ret)
                return -1;

        return 0;
}

LOC_EXPORT char* loc_network_str(struct loc_network* network) {
        int r;
        const size_t length = INET6_ADDRSTRLEN + 4;

        char* string = malloc(length);
        if (!string)
                return NULL;

        unsigned int prefix = network->prefix;

        switch (network->family) {
                case AF_INET6:
                        r = format_ipv6_address(&network->first_address, string, length);
                        break;

                case AF_INET:
                        r = format_ipv4_address(&network->first_address, string, length);
                        prefix -= 96;
                        break;

                default:
                        r = -1;
                        break;
        }

        if (r) {
                ERROR(network->ctx, "Could not convert network to string: %s\n", strerror(errno));
                free(string);

                return NULL;
        }

        // Append prefix
        sprintf(string + strlen(string), "/%u", prefix);

        return string;
}

LOC_EXPORT int loc_network_address_family(struct loc_network* network) {
        return network->family;
}

LOC_EXPORT unsigned int loc_network_prefix(struct loc_network* network) {
        switch (network->family) {
                case AF_INET6:
                        return network->prefix;

                case AF_INET:
                        return network->prefix - 96;
        }

        return 0;
}

static char* loc_network_format_address(struct loc_network* network, const struct in6_addr* address) {
        const size_t length = INET6_ADDRSTRLEN;

        char* string = malloc(length);
        if (!string)
                return NULL;

        int r = 0;

        switch (network->family) {
                case AF_INET6:
                        r = format_ipv6_address(address, string, length);
                        break;

                case AF_INET:
                        r = format_ipv4_address(address, string, length);
                        break;

                default:
                        r = -1;
                        break;
        }

        if (r) {
                ERROR(network->ctx, "Could not format IP address to string: %s\n", strerror(errno));
                free(string);

                return NULL;
        }

        return string;
}

LOC_EXPORT const struct in6_addr* loc_network_get_first_address(struct loc_network* network) {
        return &network->first_address;
}

LOC_EXPORT char* loc_network_format_first_address(struct loc_network* network) {
        return loc_network_format_address(network, &network->first_address);
}

LOC_EXPORT const struct in6_addr* loc_network_get_last_address(struct loc_network* network) {
        return &network->last_address;
}

LOC_EXPORT char* loc_network_format_last_address(struct loc_network* network) {
        return loc_network_format_address(network, &network->last_address);
}

LOC_EXPORT int loc_network_match_address(struct loc_network* network, const struct in6_addr* address) {
        // Address must be larger than the start address
        if (in6_addr_cmp(&network->first_address, address) > 0)
                return 0;

        // Address must be smaller than the last address
        if (in6_addr_cmp(&network->last_address, address) < 0)
                return 0;

        // The address is inside this network
        return 1;
}

LOC_EXPORT const char* loc_network_get_country_code(struct loc_network* network) {
        return network->country_code;
}

LOC_EXPORT int loc_network_set_country_code(struct loc_network* network, const char* country_code) {
        // Set empty country code
        if (!country_code || !*country_code) {
                *network->country_code = '\0';
                return 0;
        }

        // Check country code
        if (!loc_country_code_is_valid(country_code))
                return -EINVAL;

        loc_country_code_copy(network->country_code, country_code);

        return 0;
}

LOC_EXPORT int loc_network_match_country_code(struct loc_network* network, const char* country_code) {
        // Check country code
        if (!loc_country_code_is_valid(country_code))
                return -EINVAL;

        return (network->country_code[0] == country_code[0])
                && (network->country_code[1] == country_code[1]);
}

LOC_EXPORT uint32_t loc_network_get_asn(struct loc_network* network) {
        return network->asn;
}

LOC_EXPORT int loc_network_set_asn(struct loc_network* network, uint32_t asn) {
        network->asn = asn;

        return 0;
}

LOC_EXPORT int loc_network_has_flag(struct loc_network* network, uint32_t flag) {
        return network->flags & flag;
}

LOC_EXPORT int loc_network_set_flag(struct loc_network* network, uint32_t flag) {
        network->flags |= flag;

        return 0;
}

LOC_EXPORT int loc_network_cmp(struct loc_network* self, struct loc_network* other) {
        // Compare address
        int r = in6_addr_cmp(&self->first_address, &other->first_address);
        if (r)
                return r;

        // Compare prefix
        if (self->prefix > other->prefix)
                return 1;
        else if (self->prefix < other->prefix)
                return -1;

        // Both networks are equal
        return 0;
}

LOC_EXPORT int loc_network_overlaps(struct loc_network* self, struct loc_network* other) {
        // Either of the start addresses must be in the other subnet
        if (loc_network_match_address(self, &other->first_address))
                return 1;

        if (loc_network_match_address(other, &self->first_address))
                return 1;

        // Or either of the end addresses is in the other subnet
        if (loc_network_match_address(self, &other->last_address))
                return 1;

        if (loc_network_match_address(other, &self->last_address))
                return 1;

        return 0;
}

LOC_EXPORT int loc_network_is_subnet(struct loc_network* self, struct loc_network* other) {
        // The prefix must be smaller (this avoids the more complex comparisons later)
        if (self->prefix > other->prefix)
                return 0;

        // If the start address of the other network is smaller than this network,
        // it cannot be a subnet.
        if (in6_addr_cmp(&self->first_address, &other->first_address) > 0)
                return 0;

        // If the end address of the other network is greater than this network,
        // it cannot be a subnet.
        if (in6_addr_cmp(&self->last_address, &other->last_address) < 0)
                return 0;

        return 1;
}

LOC_EXPORT int loc_network_subnets(struct loc_network* network,
                struct loc_network** subnet1, struct loc_network** subnet2) {
        int r;
        *subnet1 = NULL;
        *subnet2 = NULL;

        // New prefix length
        unsigned int prefix = network->prefix + 1;

        // Check if the new prefix is valid
        if (valid_prefix(&network->first_address, prefix))
                return -1;

        // Create the first half of the network
        r = loc_network_new(network->ctx, subnet1, &network->first_address, prefix);
        if (r)
                return r;

        // The next subnet starts after the first one
        struct in6_addr first_address = address_increment(&(*subnet1)->last_address);

        // Create the second half of the network
        r = loc_network_new(network->ctx, subnet2, &first_address, prefix);
        if (r)
                return r;

        // Copy country code
        const char* country_code = loc_network_get_country_code(network);
        if (country_code) {
                loc_network_set_country_code(*subnet1, country_code);
                loc_network_set_country_code(*subnet2, country_code);
        }

        // Copy ASN
        uint32_t asn = loc_network_get_asn(network);
        if (asn) {
                loc_network_set_asn(*subnet1, asn);
                loc_network_set_asn(*subnet2, asn);
        }

        // Copy flags
        loc_network_set_flag(*subnet1, network->flags);
        loc_network_set_flag(*subnet2, network->flags);

        return 0;
}

static int __loc_network_exclude(struct loc_network* network,
                struct loc_network* other, struct loc_network_list* list) {
        struct loc_network* subnet1 = NULL;
        struct loc_network* subnet2 = NULL;

        int r = loc_network_subnets(network, &subnet1, &subnet2);
        if (r)
                goto ERROR;

        if (loc_network_cmp(other, subnet1) == 0) {
                r = loc_network_list_push(list, subnet2);
                if (r)
                        goto ERROR;

        } else if (loc_network_cmp(other, subnet2) == 0) {
                r = loc_network_list_push(list, subnet1);
                if (r)
                        goto ERROR;

        } else  if (loc_network_is_subnet(subnet1, other)) {
                r = loc_network_list_push(list, subnet2);
                if (r)
                        goto ERROR;

                r = __loc_network_exclude(subnet1, other, list);
                if (r)
                        goto ERROR;

        } else if (loc_network_is_subnet(subnet2, other)) {
                r = loc_network_list_push(list, subnet1);
                if (r)
                        goto ERROR;

                r = __loc_network_exclude(subnet2, other, list);
                if (r)
                        goto ERROR;

        } else {
                ERROR(network->ctx, "We should never get here\n");
                r = 1;
                goto ERROR;
        }

ERROR:
        if (subnet1)
                loc_network_unref(subnet1);

        if (subnet2)
                loc_network_unref(subnet2);

        return r;
}

static int __loc_network_exclude_to_list(struct loc_network* self,
                struct loc_network* other, struct loc_network_list* list) {
        // Other must be a subnet of self
        if (!loc_network_is_subnet(self, other)) {
                DEBUG(self->ctx, "Network %p is not contained in network %p\n", other, self);

                // Exit silently
                return 0;
        }

        // We cannot perform this operation if both networks equal
        if (loc_network_cmp(self, other) == 0) {
                DEBUG(self->ctx, "Networks %p and %p are equal\n", self, other);

                // Exit silently
                return 0;
        }

        return __loc_network_exclude(self, other, list);
}

LOC_EXPORT struct loc_network_list* loc_network_exclude(
                struct loc_network* self, struct loc_network* other) {
        struct loc_network_list* list;

#ifdef ENABLE_DEBUG
        char* n1 = loc_network_str(self);
        char* n2 = loc_network_str(other);

        DEBUG(self->ctx, "Returning %s excluding %s...\n", n1, n2);

        free(n1);
        free(n2);
#endif

        // Create a new list with the result
        int r = loc_network_list_new(self->ctx, &list);
        if (r) {
                ERROR(self->ctx, "Could not create network list: %d\n", r);

                return NULL;
        }

        r = __loc_network_exclude_to_list(self, other, list);
        if (r) {
                loc_network_list_unref(list);

                return NULL;
        }

        // Return the result
        return list;
}

LOC_EXPORT struct loc_network_list* loc_network_exclude_list(
                struct loc_network* network, struct loc_network_list* list) {
        struct loc_network_list* to_check;

        // Create a new list with all networks to look at
        int r = loc_network_list_new(network->ctx, &to_check);
        if (r)
                return NULL;

        struct loc_network* subnet = NULL;
        struct loc_network_list* subnets = NULL;

        for (unsigned int i = 0; i < loc_network_list_size(list); i++) {
                subnet = loc_network_list_get(list, i);

                // Find all excluded networks
                if (!loc_network_list_contains(to_check, subnet)) {
                        r = __loc_network_exclude_to_list(network, subnet, to_check);
                        if (r) {
                                loc_network_list_unref(to_check);
                                loc_network_unref(subnet);

                                return NULL;
                        }
                }

                // Cleanup
                loc_network_unref(subnet);
        }

        r = loc_network_list_new(network->ctx, &subnets);
        if (r) {
                loc_network_list_unref(to_check);
                return NULL;
        }

        off_t smallest_subnet = 0;

        while (!loc_network_list_empty(to_check)) {
                struct loc_network* subnet_to_check = loc_network_list_pop_first(to_check);

                // Check whether the subnet to check is part of the input list
                if (loc_network_list_contains(list, subnet_to_check)) {
                        loc_network_unref(subnet_to_check);
                        continue;
                }

                // Marks whether this subnet passed all checks
                int passed = 1;

                for (unsigned int i = smallest_subnet; i < loc_network_list_size(list); i++) {
                        subnet = loc_network_list_get(list, i);

                        // Drop this subnet if is a subnet of another subnet
                        if (loc_network_is_subnet(subnet, subnet_to_check)) {
                                passed = 0;
                                loc_network_unref(subnet);
                                break;
                        }

                        // Break it down if it overlaps
                        if (loc_network_overlaps(subnet, subnet_to_check)) {
                                passed = 0;

                                __loc_network_exclude_to_list(subnet_to_check, subnet, to_check);

                                loc_network_unref(subnet);
                                break;
                        }

                        // If the subnet is strictly greater, we do not need to continue the search
                        r = loc_network_cmp(subnet, subnet_to_check);
                        if (r > 0) {
                                loc_network_unref(subnet);
                                break;

                        // If it is strictly smaller, we can continue the search from here next
                        // time because all networks that are to be checked can only be larger
                        // than this one.
                        } else if (r < 0) {
                                smallest_subnet = i;
                        }

                        loc_network_unref(subnet);
                }

                if (passed) {
                        r = loc_network_list_push(subnets, subnet_to_check);
                }

                loc_network_unref(subnet_to_check);
        }

        loc_network_list_unref(to_check);

        return subnets;
}

int loc_network_to_database_v1(struct loc_network* network, struct loc_database_network_v1* dbobj) {
        // Add country code
        loc_country_code_copy(dbobj->country_code, network->country_code);

        // Add ASN
        dbobj->asn = htobe32(network->asn);

        // Flags
        dbobj->flags = htobe16(network->flags);

        return 0;
}

int loc_network_new_from_database_v1(struct loc_ctx* ctx, struct loc_network** network,
                struct in6_addr* address, unsigned int prefix, const struct loc_database_network_v1* dbobj) {
        char country_code[3] = "\0\0";

        int r = loc_network_new(ctx, network, address, prefix);
        if (r) {
                ERROR(ctx, "Could not allocate a new network: %s", strerror(-r));
                return r;
        }

        // Import country code
        loc_country_code_copy(country_code, dbobj->country_code);

        r = loc_network_set_country_code(*network, country_code);
        if (r) {
                ERROR(ctx, "Could not set country code: %s\n", country_code);
                return r;
        }

        // Import ASN
        uint32_t asn = be32toh(dbobj->asn);
        r = loc_network_set_asn(*network, asn);
        if (r) {
                ERROR(ctx, "Could not set ASN: %d\n", asn);
                return r;
        }

        // Import flags
        int flags = be16toh(dbobj->flags);
        r = loc_network_set_flag(*network, flags);
        if (r) {
                ERROR(ctx, "Could not set flags: %d\n", flags);
                return r;
        }

        return 0;
}

struct loc_network_tree {
        struct loc_ctx* ctx;
        int refcount;

        struct loc_network_tree_node* root;
};

struct loc_network_tree_node {
        struct loc_ctx* ctx;
        int refcount;

        struct loc_network_tree_node* zero;
        struct loc_network_tree_node* one;

        struct loc_network* network;
};

int loc_network_tree_new(struct loc_ctx* ctx, struct loc_network_tree** tree) {
        struct loc_network_tree* t = calloc(1, sizeof(*t));
        if (!t)
                return -ENOMEM;

        t->ctx = loc_ref(ctx);
        t->refcount = 1;

        // Create the root node
        int r = loc_network_tree_node_new(ctx, &t->root);
        if (r) {
                loc_network_tree_unref(t);
                return r;
        }

        DEBUG(t->ctx, "Network tree allocated at %p\n", t);
        *tree = t;
        return 0;
}

struct loc_network_tree_node* loc_network_tree_get_root(struct loc_network_tree* tree) {
        return loc_network_tree_node_ref(tree->root);
}

static struct loc_network_tree_node* loc_network_tree_get_node(struct loc_network_tree_node* node, int path) {
        struct loc_network_tree_node** n;

        if (path == 0)
                n = &node->zero;
        else
                n = &node->one;

        // If the desired node doesn't exist, yet, we will create it
        if (*n == NULL) {
                int r = loc_network_tree_node_new(node->ctx, n);
                if (r)
                        return NULL;
        }

        return *n;
}

static struct loc_network_tree_node* loc_network_tree_get_path(struct loc_network_tree* tree, const struct in6_addr* address, unsigned int prefix) {
        struct loc_network_tree_node* node = tree->root;

        for (unsigned int i = 0; i < prefix; i++) {
                // Check if the ith bit is one or zero
                node = loc_network_tree_get_node(node, in6_addr_get_bit(address, i));
        }

        return node;
}

static int __loc_network_tree_walk(struct loc_ctx* ctx, struct loc_network_tree_node* node,
                int(*filter_callback)(struct loc_network* network, void* data),
                int(*callback)(struct loc_network* network, void* data), void* data) {
        int r;

        // Finding a network ends the walk here
        if (node->network) {
                if (filter_callback) {
                        int f = filter_callback(node->network, data);
                        if (f < 0)
                                return f;

                        // Skip network if filter function returns value greater than zero
                        if (f > 0)
                                return 0;
                }

                r = callback(node->network, data);
                if (r)
                        return r;
        }

        // Walk down on the left side of the tree first
        if (node->zero) {
                r = __loc_network_tree_walk(ctx, node->zero, filter_callback, callback, data);
                if (r)
                        return r;
        }

        // Then walk on the other side
        if (node->one) {
                r = __loc_network_tree_walk(ctx, node->one, filter_callback, callback, data);
                if (r)
                        return r;
        }

        return 0;
}

int loc_network_tree_walk(struct loc_network_tree* tree,
                int(*filter_callback)(struct loc_network* network, void* data),
                int(*callback)(struct loc_network* network, void* data), void* data) {
        return __loc_network_tree_walk(tree->ctx, tree->root, filter_callback, callback, data);
}

static void loc_network_tree_free(struct loc_network_tree* tree) {
        DEBUG(tree->ctx, "Releasing network tree at %p\n", tree);

        loc_network_tree_node_unref(tree->root);

        loc_unref(tree->ctx);
        free(tree);
}

struct loc_network_tree* loc_network_tree_unref(struct loc_network_tree* tree) {
        if (--tree->refcount > 0)
                return tree;

        loc_network_tree_free(tree);
        return NULL;
}

static int __loc_network_tree_dump(struct loc_network* network, void* data) {
        DEBUG(network->ctx, "Dumping network at %p\n", network);

        char* s = loc_network_str(network);
        if (!s)
                return 1;

        INFO(network->ctx, "%s\n", s);
        free(s);

        return 0;
}

int loc_network_tree_dump(struct loc_network_tree* tree) {
        DEBUG(tree->ctx, "Dumping network tree at %p\n", tree);

        return loc_network_tree_walk(tree, NULL, __loc_network_tree_dump, NULL);
}

int loc_network_tree_add_network(struct loc_network_tree* tree, struct loc_network* network) {
        DEBUG(tree->ctx, "Adding network %p to tree %p\n", network, tree);

        struct loc_network_tree_node* node = loc_network_tree_get_path(tree,
                        &network->first_address, network->prefix);
        if (!node) {
                ERROR(tree->ctx, "Could not find a node\n");
                return -ENOMEM;
        }

        // Check if node has not been set before
        if (node->network) {
                DEBUG(tree->ctx, "There is already a network at this path\n");
                return -EBUSY;
        }

        // Point node to the network
        node->network = loc_network_ref(network);

        return 0;
}

static int __loc_network_tree_count(struct loc_network* network, void* data) {
        size_t* counter = (size_t*)data;

        // Increase the counter for each network
        counter++;

        return 0;
}

size_t loc_network_tree_count_networks(struct loc_network_tree* tree) {
        size_t counter = 0;

        int r = loc_network_tree_walk(tree, NULL, __loc_network_tree_count, &counter);
        if (r)
                return r;

        return counter;
}

static size_t __loc_network_tree_count_nodes(struct loc_network_tree_node* node) {
        size_t counter = 1;

        if (node->zero)
                counter += __loc_network_tree_count_nodes(node->zero);

        if (node->one)
                counter += __loc_network_tree_count_nodes(node->one);

        return counter;
}

size_t loc_network_tree_count_nodes(struct loc_network_tree* tree) {
        return __loc_network_tree_count_nodes(tree->root);
}

int loc_network_tree_node_new(struct loc_ctx* ctx, struct loc_network_tree_node** node) {
        struct loc_network_tree_node* n = calloc(1, sizeof(*n));
        if (!n)
                return -ENOMEM;

        n->ctx = loc_ref(ctx);
        n->refcount = 1;

        n->zero = n->one = NULL;

        DEBUG(n->ctx, "Network node allocated at %p\n", n);
        *node = n;
        return 0;
}

struct loc_network_tree_node* loc_network_tree_node_ref(struct loc_network_tree_node* node) {
        if (node)
                node->refcount++;

        return node;
}

static void loc_network_tree_node_free(struct loc_network_tree_node* node) {
        DEBUG(node->ctx, "Releasing network node at %p\n", node);

        if (node->network)
                loc_network_unref(node->network);

        if (node->zero)
                loc_network_tree_node_unref(node->zero);

        if (node->one)
                loc_network_tree_node_unref(node->one);

        loc_unref(node->ctx);
        free(node);
}

struct loc_network_tree_node* loc_network_tree_node_unref(struct loc_network_tree_node* node) {
        if (!node)
                return NULL;

        if (--node->refcount > 0)
                return node;

        loc_network_tree_node_free(node);
        return NULL;
}

struct loc_network_tree_node* loc_network_tree_node_get(struct loc_network_tree_node* node, unsigned int index) {
        if (index == 0)
                node = node->zero;
        else
                node = node->one;

        if (!node)
                return NULL;

        return loc_network_tree_node_ref(node);
}

int loc_network_tree_node_is_leaf(struct loc_network_tree_node* node) {
        return (!!node->network);
}

struct loc_network* loc_network_tree_node_get_network(struct loc_network_tree_node* node) {
        return loc_network_ref(node->network);
}