utun2/src/route_lib.c

/**
 * @file route_lib.c
 * @brief Enhanced routing system with bandwidth support and route types
 */

#include "route_lib.h"
#include "etcp_connections.h"
#include "../lib/debug_config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../lib/platform_compat.h"
#include <time.h>

#define INITIAL_ROUTE_CAPACITY 100
#define ROUTE_EXPANSION_FACTOR 2
#define MAX_SUBNET_VALIDATION_RANGES 50
#define ROUTE_CACHE_SIZE 10

/**
 * @brief Структура кеша маршрутов (LRU)
 */
struct ROUTE_CACHE {
    struct ROUTE_ARRAY *entries[ROUTE_CACHE_SIZE];  /**< Массив кешированных результатов */
    uint32_t keys[ROUTE_CACHE_SIZE];                /**< IP-адреса (ключи) */
    uint64_t access_time[ROUTE_CACHE_SIZE];         /**< Время последнего доступа */
    int count;                                      /**< Текущее количество записей */
};

static struct ROUTE_CACHE g_route_cache = {0};

/**
 * @brief Парсит строку подсети в сетевой адрес и длину префикса
 * @param subnet_str Строка подсети (например, "192.168.1.0/24")
 * @param network Указатель для сохранения сетевого адреса
 * @param prefix_length Указатель для сохранения длины префикса
 * @return 0 при успехе, -1 при ошибке
 */
int parse_subnet(const char *subnet_str, uint32_t *network, uint8_t *prefix_length) {
    if (!subnet_str || !network || !prefix_length) return -1;
    char ip[64];
    int prefix;
    if (sscanf(subnet_str, "%[^/]/%d", ip, &prefix) != 2) return -1;
    if (prefix < 0 || prefix > 32) return -1;
    struct in_addr addr;
    if (inet_pton(AF_INET, ip, &addr) != 1) return -1;
    *network = ntohl(addr.s_addr);
    *prefix_length = (uint8_t)prefix;
    return 0;
}

/**
 * @brief Создает массив маршрутов
 * @param capacity Максимальное количество маршрутов
 * @return Указатель на созданный массив или NULL
 */
static struct ROUTE_ARRAY* route_array_create(uint32_t capacity) {
    struct ROUTE_ARRAY *array = calloc(1, sizeof(struct ROUTE_ARRAY) + 
                                        capacity * sizeof(struct ROUTE_ENTRY*));
    if (!array) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "route_array_create: failed to allocate memory");
        return NULL;
    }
    array->capacity = capacity;
    array->routes = 0;
    array->ip = 0;
    return array;
}

/**
 * @brief Освобождает память массива маршрутов
 * @param array Указатель на массив
 */
static void route_array_destroy(struct ROUTE_ARRAY *array) {
    if (!array) return;
    // entries[] содержит только указатели на ROUTE_ENTRY из таблицы,
    // их освобождать не нужно - они принадлежат таблице
    free(array);
}

/**
 * @brief Добавляет маршрут в массив
 * @param array Массив маршрутов
 * @param entry Указатель на запись маршрута
 * @return true при успехе, false если массив полон
 */
static bool route_array_add(struct ROUTE_ARRAY *array, struct ROUTE_ENTRY *entry) {
    if (!array || !entry) return false;
    if (array->routes >= array->capacity) return false;
    array->entries[array->routes++] = entry;
    return true;
}

/**
 * @brief Пересчитывает метрику quality на основе других метрик
 * @param entry Указатель на запись маршрута
 * @return true при успехе, false при ошибке
 */
bool route_update_quality(struct ROUTE_ENTRY *entry) {
    if (!entry) return false;
    
    // Простая формула: latency * 2 + loss * 10 + hops * 50
    // Меньше значение = лучше маршрут
    entry->metrics.metric = entry->metrics.latency_ms * 2 + 
                            entry->metrics.packet_loss_rate * 10 + 
                            entry->metrics.hop_count * 50;
    
    return true;
}

/**
 * @brief Сравнивает два маршрута для сортировки (лучший маршрут - меньшее значение)
 */
static int compare_routes_by_quality(const void *a, const void *b) {
    const struct ROUTE_ENTRY *route_a = *(const struct ROUTE_ENTRY **)a;
    const struct ROUTE_ENTRY *route_b = *(const struct ROUTE_ENTRY **)b;
    
    // Сначала сравниваем по quality (меньше - лучше)
    if (route_a->metrics.metric != route_b->metrics.metric) {
        return (int)(route_a->metrics.metric - route_b->metrics.metric);
    }
    
    // Затем по длине префикса (больше - лучше)
    if (route_b->prefix_length != route_a->prefix_length) {
        return route_b->prefix_length - route_a->prefix_length;
    }
    
    return 0;
}

/**
 * @brief Ищет запись в кеше по IP
 */
static struct ROUTE_ARRAY* cache_lookup(uint32_t dest_ip) {
    uint64_t current_time = (uint64_t)time(NULL) * 1000000;
    
    for (int i = 0; i < g_route_cache.count; i++) {
        if (g_route_cache.keys[i] == dest_ip && g_route_cache.entries[i]) {
            g_route_cache.access_time[i] = current_time;
            DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Cache hit for IP %u", dest_ip);
            return g_route_cache.entries[i];
        }
    }
    return NULL;
}

/**
 * @brief Добавляет результат в кеш (LRU замещение)
 */
static void cache_insert(uint32_t dest_ip, struct ROUTE_ARRAY *result) {
    uint64_t current_time = (uint64_t)time(NULL) * 1000000;
    int insert_idx = -1;
    
    // Ищем пустое место или самую старую запись
    if (g_route_cache.count < ROUTE_CACHE_SIZE) {
        insert_idx = g_route_cache.count++;
    } else {
        // LRU: находим запись с самым старым access_time
        uint64_t oldest_time = g_route_cache.access_time[0];
        insert_idx = 0;
        for (int i = 1; i < ROUTE_CACHE_SIZE; i++) {
            if (g_route_cache.access_time[i] < oldest_time) {
                oldest_time = g_route_cache.access_time[i];
                insert_idx = i;
            }
        }
        // Освобождаем старую запись
        if (g_route_cache.entries[insert_idx]) {
            route_array_destroy(g_route_cache.entries[insert_idx]);
        }
    }
    
    g_route_cache.keys[insert_idx] = dest_ip;
    g_route_cache.entries[insert_idx] = result;
    g_route_cache.access_time[insert_idx] = current_time;
    
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Cache insert for IP %u at slot %d", dest_ip, insert_idx);
}

/**
 * @brief Преобразует IP-адрес в строку
 * @param ip IP-адрес (в host byte order)
 * @param buffer Буфер для строки (минимум 16 байт)
 * @return Указатель на buffer или NULL
 */
static char *ip_to_string(uint32_t ip, char *buffer) {
    if (!buffer) return NULL;
    
    struct in_addr addr;
    addr.s_addr = htonl(ip);
    strncpy(buffer, inet_ntoa(addr), 15);
    buffer[15] = '\0';
    return buffer;
}

/**
 * @brief Преобразует тип маршрута в строку
 * @param type Тип маршрута
 * @return Строковое представление типа
 */
static const char *route_type_to_string(route_type_t type) {
    switch (type) {
        case ROUTE_TYPE_STATIC: return "STATIC";
        case ROUTE_TYPE_DYNAMIC: return "DYNAMIC";
        case ROUTE_TYPE_LOCAL: return "LOCAL";
        case ROUTE_TYPE_LEARNED: return "LEARNED";
        default: return "UNKNOWN";
    }
}

struct ROUTE_TABLE *route_table_create(void) {
    struct ROUTE_TABLE *table = calloc(1, sizeof(struct ROUTE_TABLE));
    if (!table) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "route_table_create: failed to allocate memory for routing table");
        return NULL;
    }
    
    table->capacity = INITIAL_ROUTE_CAPACITY;
    table->entries = calloc(table->capacity, sizeof(struct ROUTE_ENTRY));
    if (!table->entries) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "route_table_create: failed to allocate memory for %zu route entries", table->capacity);
        free(table);
        return NULL;
    }
    
    // Initialize subnet validation arrays
    table->dynamic_subnets = calloc(MAX_SUBNET_VALIDATION_RANGES, sizeof(uint32_t) * 2);
    table->local_subnets = calloc(MAX_SUBNET_VALIDATION_RANGES, sizeof(uint32_t) * 2);
    
    if (!table->dynamic_subnets || !table->local_subnets) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "route_table_create: failed to allocate memory for subnet validation arrays");
        free(table->entries);
        free(table->dynamic_subnets);
        free(table->local_subnets);
        free(table);
        return NULL;
    }
    
    return table;
}

void route_table_destroy(struct ROUTE_TABLE *table) {
    if (!table) return;
    
    // Free route entries
    free(table->entries);
    
    // Free validation ranges
    free(table->dynamic_subnets);
    free(table->local_subnets);
    
    free(table);
}

/**
 * @brief Очищает глобальный кеш маршрутов
 */
void route_cache_clear(void) {
    for (int i = 0; i < g_route_cache.count; i++) {
        if (g_route_cache.entries[i]) {
            route_array_destroy(g_route_cache.entries[i]);
            g_route_cache.entries[i] = NULL;
        }
    }
    g_route_cache.count = 0;
}

/**
 * @brief Валидирует маршрут на соответствие разрешенным подсетям
 */
static bool route_validate_route(struct ROUTE_TABLE *table, uint32_t network, 
                                  uint8_t prefix_length, route_type_t route_type) {
    if (!table) return false;
    
    uint32_t *validation_ranges = NULL;
    size_t range_count = 0;
    
    switch (route_type) {
        case ROUTE_TYPE_STATIC:
        case ROUTE_TYPE_LEARNED:
            return true; // No validation for static or learned routes
        case ROUTE_TYPE_DYNAMIC:
            validation_ranges = table->dynamic_subnets;
            range_count = table->dynamic_subnet_count;
            break;
        case ROUTE_TYPE_LOCAL:
            validation_ranges = table->local_subnets;
            range_count = table->local_subnet_count;
            break;
        default:
            return false;
    }

    if (range_count == 0) return true; // No validation ranges configured

    // Check if network falls within any validation range
    for (size_t i = 0; i < range_count; i += 2) {
        uint32_t range_network = validation_ranges[i];
        uint8_t range_prefix = (uint8_t)validation_ranges[i + 1];

        uint32_t mask = (range_prefix == 0) ? 0 : (0xFFFFFFFFU << (32 - range_prefix));
        if ((network & mask) == (range_network & mask)) {
            // Check if this route is more specific than or equal to the validation range
            if (prefix_length >= range_prefix) {
                return true;
            }
        }
    }

    return false;
}

bool route_table_insert(struct ROUTE_TABLE *table, const struct ROUTE_ENTRY *entry) {
    if (!table || !entry) return false;
    
    // Validate the route
    if (!route_validate_route(table, entry->network, entry->prefix_length, entry->type)) {
        char ip_str[16];
        ip_to_string(entry->network, ip_str);
        DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "Ignoring invalid route: %s/%d (type: %s)", 
                   ip_str, entry->prefix_length, route_type_to_string(entry->type));
        return false;
    }

    // Check if we need to expand the table
    if (table->count >= table->capacity) {
        size_t new_capacity = table->capacity * ROUTE_EXPANSION_FACTOR;
        struct ROUTE_ENTRY *new_entries = realloc(table->entries, new_capacity * sizeof(struct ROUTE_ENTRY));
        if (!new_entries) {
            DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "route_table_insert: failed to expand routing table to %zu entries", new_capacity);
            return false;
        }
        
        // Zero new memory
        memset(new_entries + table->capacity, 0, (new_capacity - table->capacity) * sizeof(struct ROUTE_ENTRY));
        table->entries = new_entries;
        table->capacity = new_capacity;
    }
    
    // Проверяем, не существует ли уже такой маршрут (по network + prefix_length + next_hop)
    for (size_t i = 0; i < table->count; i++) {
        if (table->entries[i].network == entry->network &&
            table->entries[i].prefix_length == entry->prefix_length &&
            table->entries[i].next_hop == entry->next_hop) {
            // Обновляем существующий маршрут
            table->entries[i] = *entry;
            table->entries[i].last_update = (uint64_t)time(NULL) * 1000000;
            
            // Вызываем callback (action=1 - update)
            if (table->change_callback) {
                table->change_callback(table, &table->entries[i], 1, table->change_callback_arg);
            }
            
            return true;
        }
    }

    // Set timestamps
    struct ROUTE_ENTRY new_entry = *entry;
    new_entry.created_time = new_entry.last_update = (uint64_t)time(NULL) * 1000000;
    
    // Insert at the end (order doesn't matter, lookup will sort)
    table->entries[table->count++] = new_entry;
    
    // Вызываем callback (action=0 - insert)
    if (table->change_callback) {
        table->change_callback(table, &table->entries[table->count - 1], 0, table->change_callback_arg);
    }
    
    // Update stats
    if (new_entry.type == ROUTE_TYPE_LOCAL) {
        table->stats.local_routes++;
    } else if (new_entry.type == ROUTE_TYPE_LEARNED) {
        table->stats.learned_routes++;
    }
    
    char ip_str[16];
    ip_to_string(new_entry.network, ip_str);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Route inserted: %s/%d (%s)", 
               ip_str, new_entry.prefix_length, route_type_to_string(new_entry.type));
    
    return true;
}

void route_table_delete(struct ROUTE_TABLE *table, struct ETCP_CONN* conn) {
    if (!table || !conn) return;
    
    size_t removed = 0;
    size_t write_idx = 0;
    
    for (size_t i = 0; i < table->count; i++) {
        if (table->entries[i].next_hop == conn) {
            // Обновляем статистику
            if (table->entries[i].type == ROUTE_TYPE_LOCAL) {
                table->stats.local_routes--;
            } else if (table->entries[i].type == ROUTE_TYPE_LEARNED) {
                table->stats.learned_routes--;
            }
            removed++;
        } else {
            // Сохраняем запись
            if (write_idx != i) {
                table->entries[write_idx] = table->entries[i];
            }
            write_idx++;
        }
    }
    
    table->count = write_idx;
    
    // Очищаем освободившиеся записи
    for (size_t i = write_idx; i < write_idx + removed && i < table->capacity; i++) {
        memset(&table->entries[i], 0, sizeof(struct ROUTE_ENTRY));
    }
    
    // Инвалидируем кеш
    for (int i = 0; i < g_route_cache.count; i++) {
        if (g_route_cache.entries[i]) {
            route_array_destroy(g_route_cache.entries[i]);
            g_route_cache.entries[i] = NULL;
        }
    }
    g_route_cache.count = 0;
    
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Removed %zu routes for connection %p", removed, (void*)conn);
}

bool route_table_delete_entry(struct ROUTE_TABLE *table, uint32_t network, 
                               uint8_t prefix_length, struct ETCP_CONN* next_hop) {
    if (!table) return false;
    
    int found_idx = -1;
    
    // Ищем маршрут
    for (size_t i = 0; i < table->count; i++) {
        if (table->entries[i].network == network && 
            table->entries[i].prefix_length == prefix_length) {
            // Если указан next_hop - проверяем его тоже
            if (next_hop == NULL || table->entries[i].next_hop == next_hop) {
                found_idx = (int)i;
                break;
            }
        }
    }
    
    if (found_idx == -1) {
        // Маршрут не найден
        char ip_str[16];
        ip_to_string(network, ip_str);
        DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "Route to delete not found: %s/%d", 
                   ip_str, prefix_length);
        return false;
    }
    
    // Вызываем callback перед удалением (action=2 - delete)
    if (table->change_callback) {
        table->change_callback(table, &table->entries[found_idx], 2, table->change_callback_arg);
    }
    
    // Обновляем статистику
    if (table->entries[found_idx].type == ROUTE_TYPE_LOCAL) {
        table->stats.local_routes--;
    } else if (table->entries[found_idx].type == ROUTE_TYPE_LEARNED) {
        table->stats.learned_routes--;
    }
    
    // Сдвигаем все записи после удаляемой
    for (size_t i = found_idx; i < table->count - 1; i++) {
        table->entries[i] = table->entries[i + 1];
    }
    
    // Очищаем последнюю запись
    memset(&table->entries[table->count - 1], 0, sizeof(struct ROUTE_ENTRY));
    table->count--;
    
    // Инвалидируем кеш
    for (int i = 0; i < g_route_cache.count; i++) {
        if (g_route_cache.entries[i]) {
            route_array_destroy(g_route_cache.entries[i]);
            g_route_cache.entries[i] = NULL;
        }
    }
    g_route_cache.count = 0;
    
    char ip_str[16];
    ip_to_string(network, ip_str);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Deleted route: %s/%d", ip_str, prefix_length);
    
    return true;
}

struct ROUTE_ARRAY* route_table_lookup(struct ROUTE_TABLE *table, uint32_t dest_ip) {
    if (!table) return NULL;
    
    table->stats.routes_lookup_hits++;
    
    // Сначала проверяем кеш
    struct ROUTE_ARRAY *cached = cache_lookup(dest_ip);
    if (cached) {
        return cached;
    }
    
    // Создаем новый результат
    struct ROUTE_ARRAY *result = route_array_create(table->count);
    if (!result) {
        return NULL;
    }
    result->ip = dest_ip;
    
    // Ищем все подходящие маршруты (longest prefix match)
    for (size_t i = 0; i < table->count; i++) {
        struct ROUTE_ENTRY *entry = &table->entries[i];
        
        // Проверяем что маршрут активен
        if (!(entry->flags & ROUTE_FLAG_ACTIVE)) {
            continue;
        }
        
        // Проверяем совпадение по подсети
        uint32_t mask = (entry->prefix_length == 0) ? 0 : 
                        (0xFFFFFFFFU << (32 - entry->prefix_length));
        
        if ((dest_ip & mask) == (entry->network & mask)) {
            // Добавляем в результат
            if (!route_array_add(result, entry)) {
                DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "Route array full, skipping additional routes");
                break;
            }
        }
    }
    
    if (result->routes == 0) {
        // Нет маршрутов
        table->stats.routes_lookup_misses++;
        route_array_destroy(result);
        
        char ip_str[16];
        ip_to_string(dest_ip, ip_str);
        DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "No route found for destination IP %s", ip_str);
        return NULL;
    }
    
    // Обновляем quality для всех найденных маршрутов
    for (uint32_t i = 0; i < result->routes; i++) {
        route_update_quality(result->entries[i]);
    }
    
    // Сортируем по quality (лучший первый)
    qsort(result->entries, result->routes, sizeof(struct ROUTE_ENTRY*), 
          compare_routes_by_quality);
    
    // Сохраняем в кеш
    cache_insert(dest_ip, result);
    
    char ip_str[16];
    ip_to_string(dest_ip, ip_str);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Found %u routes for %s (best quality: %u)",
               result->routes, ip_str, result->entries[0]->metrics.metric);
    
    return result;
}

static bool enhanced_route_add_subnet_range(struct ROUTE_TABLE *table, uint32_t network, 
                                             uint8_t prefix_length, uint32_t **ranges, size_t *count) {
    if (!table || !ranges || !count) return false;

    if (*count >= MAX_SUBNET_VALIDATION_RANGES - 2) return false;

    // Expand array if needed
    if (*ranges == NULL) {
        *ranges = calloc(MAX_SUBNET_VALIDATION_RANGES, sizeof(uint32_t));
        if (!*ranges) return false;
        *count = 0;
    }

    // Add network and prefix length as a pair
    (*ranges)[*count] = network;
    (*ranges)[*count + 1] = prefix_length;
    *count += 2;
    
    char ip_str[16];
    ip_to_string(network, ip_str);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Added subnet validation range: %s/%d", ip_str, prefix_length);
    
    return true;
}

bool route_add_dynamic_subnet(struct ROUTE_TABLE *table, uint32_t network, uint8_t prefix_length) {
    return enhanced_route_add_subnet_range(table, network, prefix_length, 
                                           &table->dynamic_subnets, &table->dynamic_subnet_count);
}

bool route_add_local_subnet(struct ROUTE_TABLE *table, uint32_t network, uint8_t prefix_length) {
    return enhanced_route_add_subnet_range(table, network, prefix_length, 
                                           &table->local_subnets, &table->local_subnet_count);
}

bool route_get_all_routes(const struct ROUTE_TABLE *table, uint32_t network, uint8_t prefix_length, 
                          struct ROUTE_ENTRY **routes, size_t *count) {
    if (!table || !routes || !count) return false;

    *routes = NULL;
    *count = 0;

    // Count matching routes
    for (size_t i = 0; i < table->count; i++) {
        if (table->entries[i].network == network && table->entries[i].prefix_length == prefix_length) {
            (*count)++;
        }
    }

    if (*count == 0) return true; // No routes found, but not an error

    // Allocate result array
    *routes = calloc(*count, sizeof(struct ROUTE_ENTRY));
    if (!*routes) {
        *count = 0;
        return false;
    }

    // Copy matching routes
    size_t result_index = 0;
    for (size_t i = 0; i < table->count; i++) {
        if (table->entries[i].network == network && table->entries[i].prefix_length == prefix_length) {
            (*routes)[result_index] = table->entries[i];
            result_index++;
        }
    }

    return true;
}

void route_table_print(const struct ROUTE_TABLE *table) {
    if (!table) return;

    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "=== Routing Table ===");
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Total routes: %zu", table->count);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Dynamic subnets: %zu, Local subnets: %zu",
               table->dynamic_subnet_count / 2, table->local_subnet_count / 2);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Local routes: %lu, Learned routes: %lu",
               table->stats.local_routes, table->stats.learned_routes);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Cache hits: %lu, Misses: %lu",
               table->stats.routes_lookup_hits - table->stats.routes_lookup_misses,
               table->stats.routes_lookup_misses);

    if (table->count > 0) {
        DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Routes:");
        for (size_t i = 0; i < table->count; i++) {
            const struct ROUTE_ENTRY *entry = &table->entries[i];
            char network_str[16];

            ip_to_string(entry->network, network_str);

            DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "  %zu: %s/%d -> %p [%s] (quality: %u)",
                       i + 1, network_str, entry->prefix_length, 
                       (void*)entry->next_hop,
                       route_type_to_string(entry->type),
                       entry->metrics.metric);
            
            DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "      Bandwidth: %uK, Loss: %.2f%%, Latency: %ums, Hops: %d",
                       entry->metrics.bandwidth_kbps,
                       entry->metrics.packet_loss_rate / 100.0,
                       entry->metrics.latency_ms,
                       entry->metrics.hop_count);
            
            DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "      Flags: %s%s%s%s",
                       (entry->flags & ROUTE_FLAG_ACTIVE) ? "ACTIVE " : "",
                       (entry->flags & ROUTE_FLAG_VALIDATED) ? "VALIDATED " : "",
                       (entry->flags & ROUTE_FLAG_ADVERTISED) ? "ADVERTISED " : "",
                       (entry->flags & ROUTE_FLAG_LEARNED) ? "LEARNED" : "");
        }
    } else {
        DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "No routes configured.");
    }
}