Implement filtering networks for the ASN they belong to

[people/ms/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 <endian.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <loc/libloc.h>
#include <loc/network.h>
#include <loc/private.h>

struct loc_network {
        struct loc_ctx* ctx;
        int refcount;

        struct in6_addr start_address;
        unsigned int prefix;

        char country_code[3];
        uint32_t asn;
};

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_start_address(const struct in6_addr* address, unsigned int prefix) {
        struct in6_addr a;
        struct in6_addr bitmask = prefix_to_bitmask(prefix);

        // 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, unsigned int prefix) {
        struct in6_addr a;
        struct in6_addr bitmask = prefix_to_bitmask(prefix);

        // 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 first address in the network
        n->start_address = make_start_address(address, prefix);
        n->prefix = prefix;

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

static int loc_network_address_family(struct loc_network* network) {
        if (IN6_IS_ADDR_V4MAPPED(&network->start_address))
                return AF_INET;

        return AF_INET6;
}

LOC_EXPORT int loc_network_new_from_string(struct loc_ctx* ctx, struct loc_network** network,
                const char* address_string) {
        struct in6_addr start_address;
        unsigned int prefix = 0;
        char* prefix_string;
        int r = 1;

        // 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, "/");

        // Did we find a prefix?
        if (prefix_string) {
                // Convert prefix to integer
                prefix = strtol(prefix_string, NULL, 10);

                if (prefix) {
                        // Parse the address
                        r = loc_parse_address(ctx, address_string, &start_address);

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

        // Free temporary buffer
        free(buffer);

        if (r == 0) {
                r = loc_network_new(ctx, network, &start_address, prefix);
        }

        return r;
}

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;

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

                case AF_INET:
                        r = format_ipv4_address(&network->start_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_match_address(struct loc_network* network, const struct in6_addr* address) {
        // Address must be larger than the start address
        if (in6_addr_cmp(&network->start_address, address) > 0)
                return 1;

        // Determine the last address in this network
        struct in6_addr last_address = make_last_address(&network->start_address, network->prefix);

        // Address must be smaller than the last address
        if (in6_addr_cmp(address, &last_address) > 0)
                return 1;

        // The address is inside this network
        return 0;
}

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;
        }

        // Country codes must be two characters
        if (strlen(country_code) != 2)
                return -EINVAL;

        for (unsigned int i = 0; i < 3; i++) {
                network->country_code[i] = country_code[i];
        }

        return 0;
}

LOC_EXPORT int loc_network_match_country_code(struct loc_network* network, const char* country_code) {
        // Country codes must be two characters
        if (strlen(country_code) != 2)
                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_match_asn(struct loc_network* network, uint32_t asn) {
        return network->asn == asn;
}

LOC_EXPORT int loc_network_to_database_v0(struct loc_network* network, struct loc_database_network_v0* dbobj) {
        // Add country code
        for (unsigned int i = 0; i < 2; i++) {
                dbobj->country_code[i] = network->country_code[i] ? network->country_code[i] : '\0';
        }

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

        return 0;
}

LOC_EXPORT int loc_network_new_from_database_v0(struct loc_ctx* ctx, struct loc_network** network,
                struct in6_addr* address, unsigned int prefix, const struct loc_database_network_v0* dbobj) {
        int r = loc_network_new(ctx, network, address, prefix);
        if (r)
                return r;

        // Import country code
        char country_code[3];
        for (unsigned int i = 0; i < 2; i++) {
                country_code[i] = dbobj->country_code[i];
        }
        country_code[2] = '\0';

        r = loc_network_set_country_code(*network, country_code);
        if (r)
                return r;

        // Import ASN
        r = loc_network_set_asn(*network, be32toh(dbobj->asn));
        if (r)
                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;
};

LOC_EXPORT 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;
}

LOC_EXPORT 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;
}

LOC_EXPORT 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);
}

LOC_EXPORT 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;
}

LOC_EXPORT 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);
}

LOC_EXPORT 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->start_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;
}

LOC_EXPORT 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;
}

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

LOC_EXPORT 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;
}

LOC_EXPORT 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);
}

LOC_EXPORT 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;
}

LOC_EXPORT 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);
}

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

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