utun2/src/etcp_connections.c

#include "etcp_connections.h"
#include "etcp_api.h"
#include "../lib/socket_compat.h"
#include "../lib/platform_compat.h"
#include "../lib/getmyip.h"
#ifndef _WIN32
#include <net/if.h>
#include <endian.h>
#else
#include <winsock2.h>
#endif
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include "utun_instance.h"
#include "config_parser.h"
#include "crc32.h"
#include "etcp.h"
#include "stcp_link.h"
#include "topo_node.h"
#include "topo_group.h"
#include "route_ping.h"
#include "../lib/memory_pool.h"
#include "../lib/u_async.h"
#include "../lib/debug_config.h"
#include "etcp_loadbalancer.h"
#include <stdlib.h>
#include <time.h>
#include "../lib/mem.h"
#include "etcp.h"

// TCP server: on new incoming connection → create minimal ETCP_CONN
static void tcp_server_on_link(struct stcp_link *link, void *arg) {
    struct UTUN_INSTANCE *inst = (struct UTUN_INSTANCE *)arg;
    struct ETCP_CONN *conn = etcp_connection_create(inst, NULL);
    if (!conn) return;
    conn->transport_link = link;
    snprintf(conn->log_name, sizeof(conn->log_name), "tcp-[%p]", (void*)link);
    struct etcp_cbk_entry* cbe = inst->new_conn_cbks;
    while (cbe) { struct etcp_cbk_entry* n = cbe->next; cbe->fn(conn, cbe->arg); cbe = n; }
    { struct etcp_cbk_entry* rcb = conn->ready_cbks; while (rcb) { struct etcp_cbk_entry* n = rcb->next; rcb->fn(conn, rcb->arg); rcb = n; } }
    DEBUG_INFO(DEBUG_CATEGORY_ETCP, "TCP server new conn=%p total=%d pending=%d",
               (void*)conn,
               queue_entry_count(inst->connections),
               queue_entry_count(inst->connections));
}

// Forward declaration
void etcp_connections_read_callback_socket(socket_t sock, void* arg);
static void etcp_link_remove_from_connections(struct ETCP_SOCKET* conn, struct ETCP_LINK* link);

static void etcp_link_send_init(struct ETCP_LINK* link, uint8_t reset, uint8_t collision);
//static int etcp_link_send_reset(struct ETCP_LINK* link);
static void etcp_link_init_timer_cbk(void* arg);
static void etcp_link_send_keepalive(struct ETCP_LINK* link);
static void keepalive_timer_cb(void* arg);
static void link_stats_timer_cb(void* arg);
static void burst_resp_timeout_cb(void* arg);

// === Burst sender functions ===

void etcp_link_burst_start(struct ETCP_LINK* link) {
    if (!link || !link->etcp || !link->etcp->instance) return;
    link->burst_active = 1;
    link->burst_seq = 0;
    link->burst_count = BURST_PACKET_COUNT;
    link->burst_id++;
    link->burst_last_time_tb = get_time_tb();
    link->burst_pkt_size = 0;
    DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[%s] burst start id=%u count=%u", link->etcp->log_name, link->burst_id, link->burst_count);
// resume send queue чтобы burst-пакеты были немедленно отправлены
    if (link->etcp->link_ready_for_send_fn) link->etcp->link_ready_for_send_fn(link->etcp);
}

void etcp_link_burst_check(struct ETCP_LINK* link) {
    if (!link || !link->etcp) return;
    if (link->burst_active) return;
    if (link->link_status != 1) return;
    if (link->inflight_bytes < link->inflight_lim_bytes) return;
    uint64_t now = get_time_tb();
    if (now - link->burst_last_time_tb < MIN_BURST_INTERVAL_TB) return;
    etcp_link_burst_start(link);
}

void etcp_link_burst_finish(struct ETCP_LINK* link) {
    if (!link || !link->etcp || !link->etcp->instance) return;
    link->burst_active = 0;
    DEBUG_DEBUG(DEBUG_CATEGORY_ETCP, "[%s] burst end id=%u pkt_sz=%u wait_resp", link->etcp->log_name, link->burst_id, link->burst_pkt_size);
    link->burst_resp_timer = uasync_set_timeout(link->etcp->instance->ua, BURST_RESP_TIMEOUT_TB, link, burst_resp_timeout_cb, "burst_resp");
    if (link->etcp->link_ready_for_send_fn) link->etcp->link_ready_for_send_fn(link->etcp);
}

static void burst_resp_timeout_cb(void* arg) {
    struct ETCP_LINK* link = (struct ETCP_LINK*)arg;
    if (!link) return;
    link->burst_resp_timer = NULL;
    DEBUG_DEBUG(DEBUG_CATEGORY_ETCP, "[%s] burst resp timeout id=%u", link->etcp->log_name, link->burst_id);
}

#define INIT_TIMEOUT_INITIAL 500
#define INIT_TIMEOUT_MAX 50000

static void etcp_link_send_init(struct ETCP_LINK* link, uint8_t reset, uint8_t collision) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "link=%p, is_server=%d, reset=%d, collision=%d", link, link ? link->is_server : -1, reset, collision);
    if (!link || !link->etcp || !link->etcp->instance) return;

    struct ETCP_DGRAM* dgram = u_malloc(PACKET_DATA_SIZE);
    if (!dgram) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "malloc failed");
        return;
    }

    dgram->link = link;
    dgram->noencrypt_len = SC_PUBKEY_ENC_SIZE;

    struct ETCP_INIT_REQUEST_PKT* req = (struct ETCP_INIT_REQUEST_PKT*)dgram->data;
    req->code = reset ? ETCP_INIT_REQUEST : ETCP_INIT_REQUEST_NOINIT;
    *(uint64_t*)req->node_id = htobe64(link->etcp->instance->node_id);
    *(uint32_t*)req->session_id = htobe32(link->etcp->session_id);
    *(uint16_t*)req->mtu = htobe16(link->mtu_local);
    *(uint16_t*)req->keepalive = htobe16(link->keepalive_interval);
    *(uint16_t*)req->recovery = htobe16(link->recovery_interval / 100);
    req->link_id = link->local_link_id;
    req->socket_id = link->conn ? link->conn->sock_id : 0;
    req->only_local = link->conn ? link->conn->only_local : 0;
    req->type = link->conn ? link->conn->type : CFG_SERVER_TYPE_UNKNOWN;
    if (link->conn && link->conn->interface_addr.ss_family == AF_INET) {
        struct sockaddr_in* sin = (struct sockaddr_in*)&link->conn->interface_addr;
        memcpy(req->src_ipv4, &sin->sin_addr.s_addr, 4);
        *(uint16_t*)req->src_port = sin->sin_port;
    } else {
        memset(req->src_ipv4, 0, 4);
        memset(req->src_port, 0, 2);
    }
    req->collision = collision;
    memcpy(req->ed25519_pubkey, link->etcp->instance->my_ed25519_pubkey, SC_PUBKEY_SIZE);
    size_t offset = ETCP_INIT_REQ_SIZE;

    // padding
    int s = rand() % (link->handshake_maxsize - link->handshake_minsize) + link->handshake_minsize;
    int s_max = (int)(link->mtu) - (int)SC_NONCE_SIZE - 3 - (int)SC_CRC32_SIZE - (int)SC_TAG_SIZE - (int)SC_PUBKEY_ENC_SIZE + (int)UDP_SC_HDR_SIZE;
    if (s > s_max) s = s_max;
    if (s < 0) s = 0;

    int to_add=s-offset-UDP_HDR_SIZE - UDP_SC_HDR_SIZE;
    if (to_add<0) to_add=0;
    int max_data = PACKET_DATA_SIZE - (int)sizeof(struct ETCP_DGRAM);
    if (offset + to_add + SC_PUBKEY_ENC_SIZE > max_data) {
        to_add = max_data - offset - SC_PUBKEY_ENC_SIZE;
        if (to_add<0) to_add=0;
    }

    for (int i=0; i<to_add; i++) dgram->data[offset++]=rand();// fill pad
    // padding end

    uint8_t salt[SC_PUBKEY_ENC_SALT_SIZE];
    random_bytes(salt, sizeof(salt));
    memcpy(dgram->data + offset, salt, SC_PUBKEY_ENC_SALT_SIZE);
    offset += SC_PUBKEY_ENC_SALT_SIZE;

    uint8_t obfuscated_pubkey[SC_PUBKEY_SIZE];
    sc_obfuscate_pubkey(salt, link->etcp->crypto_ctx.peer_public_key, 
                        link->etcp->instance->my_keys.public_key, obfuscated_pubkey);
    memcpy(dgram->data + offset, obfuscated_pubkey, SC_PUBKEY_SIZE);
    offset += SC_PUBKEY_SIZE;


    dgram->data_len = offset;
    
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Sending INIT request to link, node_id=%016llx, retry=%d", (unsigned long long)link->etcp->instance->node_id, link->init_retry_count);
    
    // Debug: print remote address before sending
    if (link->remote_addr.ss_family == AF_INET) {
        struct sockaddr_in* sin = (struct sockaddr_in*)&link->remote_addr;
        DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] INIT sending to %s:%d, link=%p, rst_req=%d", ip_to_str(&sin->sin_addr, AF_INET).str, ntohs(sin->sin_port), link, reset);
    } else if (link->remote_addr.ss_family == AF_INET6) {
        struct sockaddr_in6* sin6 = (struct sockaddr_in6*)&link->remote_addr;
        DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] INIT sending to %s:%d, link=%p, rst_req=%d", ip_to_str(&sin6->sin6_addr, AF_INET6).str, ntohs(sin6->sin6_port), link, reset);
    }
    
    etcp_encrypt_send(dgram);
    u_free(dgram);

    link->init_retry_count++;
}

static void etcp_link_init_timer_cbk(void* arg) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    struct ETCP_LINK* link = (struct ETCP_LINK*)arg;
    if (!link || !link->etcp || !link->etcp->instance) return;

    if ((link->init_retry_count % 10) == 0 && link->init_timeout < INIT_TIMEOUT_MAX) {
        link->init_timeout += link->init_timeout/4 +1;
        if (link->init_timeout > INIT_TIMEOUT_MAX) link->init_timeout = INIT_TIMEOUT_MAX;
    }
    link->init_timer = uasync_set_timeout(link->etcp->instance->ua, link->init_timeout, link, etcp_link_init_timer_cbk, "link_init");

    if (link->link_state == 1) etcp_link_send_init(link,1,0);// init (with etcp reset)
    else etcp_link_send_init(link,0,0);// no etcp reset (reinit)
}

void etcp_link_restart_init_timer(struct ETCP_LINK* link) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (link->init_timer) uasync_cancel_timeout(link->etcp->instance->ua, link->init_timer);
    link->init_timeout = INIT_TIMEOUT_INITIAL;
    link->init_timer = uasync_set_timeout(link->etcp->instance->ua, link->init_timeout, link, etcp_link_init_timer_cbk, "link_init");
}

void etcp_link_enter_init(struct ETCP_LINK* link) {// 
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!link) return;
    link->link_state = 1; // handshake
    if (link->is_server != 0) return;
    etcp_link_send_init(link,1,0);// init with reset
    etcp_link_restart_init_timer(link);
}

void etcp_link_enter_reinit(struct ETCP_LINK* link) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!link) return;
    link->link_state = 2; // reconnect
    etcp_on_link_down(link->etcp);
    if (link->is_server != 0) return;
    etcp_link_send_init(link,0,0);// init without reset

    if (link->keepalive_timer) {// keepalive заменяяется reinit запросами
        uasync_cancel_timeout(link->etcp->instance->ua, link->keepalive_timer);
        link->keepalive_timer = NULL;
    }

    etcp_link_restart_init_timer(link);
}


// Send empty keepalive packet (only timestamp, no sections)
static void etcp_link_send_keepalive(struct ETCP_LINK* link) {
    DEBUG_TRACE(DEBUG_CATEGORY_KEEPALIVE, "");
    if (!link || !link->etcp || !link->etcp->instance) return;

    struct ETCP_DGRAM* dgram = u_malloc(sizeof(struct ETCP_DGRAM) + 4);
    if (!dgram) {
        DEBUG_ERROR(DEBUG_CATEGORY_KEEPALIVE, "malloc failed");
        return;
    }

    dgram->link = link;
    dgram->data[0] = ETCP_KEEPALIVE;
    dgram->data[1] = link->ka_period_ms & 0xFF;
    dgram->data[2] = link->ka_period_ms >> 8;
    dgram->data_len = 3;
    dgram->noencrypt_len = 0;
    dgram->timestamp = get_current_timestamp();
    dgram->flag_up = link->recv_keepalive;

    link->keepalive_sent_count++;

    etcp_encrypt_send(dgram);
    u_free(dgram);
}

// Check if all links for an ETCP_CONN are down
// Returns 1 if all links are down or no links exist, 0 otherwise
static int etcp_all_links_down(struct ETCP_CONN* etcp) {
    if (!etcp || !etcp->links) return 1;

    struct ETCP_LINK* l = etcp->links;
    while (l) {
        if (l->link_status == 1) {
            return 0;  // At least one link is up
        }
        l = l->next;
    }
    return 1;  // All links are down
}

static void start_keepalive_timer(struct ETCP_LINK* link) {
    // Start keepalive timer
    if (link->init_timer) {// cancel init timer
        uasync_cancel_timeout(link->etcp->instance->ua, link->init_timer);
        link->init_timer = NULL;
    }

    if (link->keepalive_timer == NULL) {
        DEBUG_DEBUG(DEBUG_CATEGORY_KEEPALIVE, "[%s] Keepalive timer started on link %p (interval=%d ms)", link->etcp->log_name, link, link->keepalive_interval);
        link->keepalive_timer = uasync_set_timeout(link->etcp->instance->ua, link->keepalive_interval * 10, link, keepalive_timer_cb, "link_keepalive");
    }
}

// Keepalive timer callback
static void keepalive_timer_cb(void* arg) {
    DEBUG_TRACE(DEBUG_CATEGORY_KEEPALIVE, "");
    struct ETCP_LINK* link = (struct ETCP_LINK*)arg;
    if (!link || !link->etcp || !link->etcp->instance) {
        DEBUG_ERROR(DEBUG_CATEGORY_KEEPALIVE, "KEEPALIVE NULL !!!!!!!!");
        return;
    }

    link->keepalive_timer = NULL;

    // Check if all links are down and start recovery if needed (client only)
    if (link->is_server == 0 && etcp_all_links_down(link->etcp)) {
        DEBUG_WARN(DEBUG_CATEGORY_KEEPALIVE, "[%s] All links are down, starting recovery", link->etcp->log_name);
        etcp_link_enter_reinit(link);// keepalive timr после reinit не нужен
        return;
    }

    // Skip if link is not initialized
    if (!link->initialized) {
        DEBUG_DEBUG(DEBUG_CATEGORY_KEEPALIVE, "[%s] Keepalive skipped - link not initialized",
                    link->etcp->log_name);
        goto restart_timer;
    }

    // Check keepalive timeout
    uint64_t now = get_time_tb();
    uint64_t timeout_units = (uint64_t)link->keepalive_timeout * 10;  // ms -> 0.1ms units
    uint64_t elapsed = now - link->last_recv_local_time;

    if (elapsed > timeout_units) {
        if (link->recv_keepalive != 0) {
            link->recv_keepalive = 0;
            link->link_status = 0;
            etcp_on_link_down(link->etcp);
            DEBUG_INFO(DEBUG_CATEGORY_KEEPALIVE, "[%s] Conn:%s Link down: link_id=%d ka=%d remote_ka=%d tmo: %d>%d", link->etcp->log_name, link->conn?link->conn->name:"???", link->local_link_id, link->recv_keepalive, link->remote_keepalive, elapsed, timeout_units);
            DEBUG_WARN(DEBUG_CATEGORY_KEEPALIVE, "[%s] Link %p (local_id=%d) recv status changed to DOWN - no packets for %llu ms", link->etcp->log_name, link, link->local_link_id, (unsigned long long)(elapsed/10));
        }
    }

    // Adaptive keepalive period (only if adaptive enabled)
    if (link->pkt_sent_since_keepalive)
    link->ka_period_ms = (uint16_t)link->keepalive_interval;
    else if (link->etcp->instance && link->etcp->instance->config &&
             link->etcp->instance->config->global.keepalive_adaptive) {
        uint32_t next = (uint32_t)link->ka_period_ms * 105 / 100 + 1;
        link->ka_period_ms = next > KA_PERIOD_MAX_MS ? KA_PERIOD_MAX_MS : (uint16_t)next;
    }
    link->pkt_sent_since_keepalive = 0;

    // Send keepalive (server stops if link lost, client always sends)
    if (!link->is_server || link->recv_keepalive)
        etcp_link_send_keepalive(link);

restart_timer:
    link->keepalive_timer = uasync_set_timeout(link->etcp->instance->ua, link->ka_period_ms * 10, link, keepalive_timer_cb, "link_keepalive");
}

static uint32_t sockaddr_hash(struct sockaddr_storage* addr) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    socklen_t addr_len = (addr->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6);
    return crc32_calc((void*)addr, addr_len);
    }

// Бинарный поиск линка по ip_port_hash
static int find_link_index(struct ETCP_SOCKET* e_sock, uint32_t hash) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!e_sock || e_sock->num_channels == 0) return -1;
    
    int left = 0;
    int right = e_sock->num_channels - 1;
    
    while (left <= right) {
        int mid = left + (right - left) / 2;
        if (e_sock->links[mid]->ip_port_hash == hash) {
            return mid;
        } else if (e_sock->links[mid]->ip_port_hash < hash) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }
    
    return -(left + 1);
}

// Реалокация массива линков с увеличением в 2 раза
static int realloc_links(struct ETCP_SOCKET* e_sock) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    size_t new_max = e_sock->max_channels == 0 ? 8 : e_sock->max_channels * 2;
    struct ETCP_LINK** new_links = u_realloc(e_sock->links, new_max * sizeof(struct ETCP_LINK*));
    if (!new_links) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "realloc failed");
        return -1;
    }
    
    e_sock->links = new_links;
    e_sock->max_channels = new_max;
    return 0;
}

// Вставка линка в отсортированный массив
static int insert_link(struct ETCP_SOCKET* e_sock, struct ETCP_LINK* link) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!e_sock || !link) return -1;
    
    if (e_sock->num_channels >= e_sock->max_channels) {
        if (realloc_links(e_sock) < 0) return -1;
    }
    
    int idx = find_link_index(e_sock, link->ip_port_hash);
    if (idx >= 0) return -1;
    
    idx = -(idx + 1);
    
    if (idx < (int)e_sock->num_channels) {
        memmove(&e_sock->links[idx + 1], &e_sock->links[idx], 
                (e_sock->num_channels - idx) * sizeof(struct ETCP_LINK*));
    }
    
    e_sock->links[idx] = link;
    e_sock->num_channels++;
    return 0;
}

// Удаление линка из массива
static void remove_link(struct ETCP_SOCKET* e_sock, uint32_t hash) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!e_sock || e_sock->num_channels == 0) return;
    
    int idx = find_link_index(e_sock, hash);
    if (idx < 0) return;
    
    if (idx < (int)e_sock->num_channels - 1) {
        memmove(&e_sock->links[idx], &e_sock->links[idx + 1], 
                (e_sock->num_channels - idx - 1) * sizeof(struct ETCP_LINK*));
    }
    
    e_sock->num_channels--;
}

static int sockaddr_equal(const struct sockaddr_storage* a, const struct sockaddr_storage* b) {
    if (!a || !b || a->ss_family != b->ss_family) return 0;
    if (a->ss_family == AF_INET) {
        const struct sockaddr_in *sa = (const struct sockaddr_in*)a;
        const struct sockaddr_in *sb = (const struct sockaddr_in*)b;
        return (sa->sin_addr.s_addr == sb->sin_addr.s_addr && sa->sin_port == sb->sin_port);
    }
    if (a->ss_family == AF_INET6) {
        const struct sockaddr_in6 *sa = (const struct sockaddr_in6*)a;
        const struct sockaddr_in6 *sb = (const struct sockaddr_in6*)b;
        return (memcmp(&sa->sin6_addr, &sb->sin6_addr, 16) == 0 && sa->sin6_port == sb->sin6_port);
    }
    return 0;
}

// надо править, используй sockaddr_hash
struct ETCP_LINK* etcp_link_find_by_addr(struct ETCP_SOCKET* e_sock, struct sockaddr_storage* addr) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!e_sock || !addr) return NULL;

    int idx = find_link_index(e_sock, sockaddr_hash(addr));
    if (idx < 0) return NULL;

    return e_sock->links[idx];
}

struct ETCP_LINK* etcp_link_find_by_remote_id(struct ETCP_CONN* conn, uint8_t remote_link_id) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!conn || remote_link_id == 0) return NULL;
    struct ETCP_LINK* l = conn->links;
    while (l) {
        if (l->remote_link_id == remote_link_id) return l;
        l = l->next;
    }
    return NULL;
}

int etcp_find_free_local_link_id(struct ETCP_CONN* etcp) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!etcp) return -1;

    // Битовый массив для 256 id (32 байта * 8 бит = 256)
    uint8_t used_ids[32] = {1};// индекс 0 всегда занят

    // Помечаем занятые id
    struct ETCP_LINK* link = etcp->links;
    while (link) {
        used_ids[link->local_link_id >> 3] |= (1 << (link->local_link_id & 7));
        link = link->next;
    }

    // Ищем первый свободный id
    for (int i = 0; i < 32; i++) {
        if (used_ids[i] != 0xFF) {
            // Есть свободные биты в этом байте
            for (int bit = 0; bit < 8; bit++) {
                if (!(used_ids[i] & (1 << bit))) {
                    return (i << 3) + bit;
                }
            }
        }
    }

    // Все id заняты
    return -1;
}


// ===============================

struct ETCP_SOCKET* etcp_socket_add(struct UTUN_INSTANCE* instance, struct CFG_SERVER* server) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!instance || !server) return NULL;

    struct sockaddr_storage* ip = &server->ip;
    uint32_t netif_index = server->netif_index;
    int so_mark = server->so_mark;
    int fib = server->fib;
    uint8_t type = server->type;
    int mtu = server->mtu ? server->mtu : instance->config->global.mtu;
    if (mtu == 0 || mtu > PACKET_DATA_MAX_MTU) mtu = PACKET_DATA_MAX_MTU;
    uint8_t only_local = server->only_local;
    char* name = server->name;
    
    struct ETCP_SOCKET* e_sock = u_calloc(1, sizeof(struct ETCP_SOCKET));
    if (!e_sock) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "Failed to allocate connection");
        return NULL;
    }
    e_sock->fd = SOCKET_INVALID;  // Initialize to invalid socket
    
    if (name && name[0]) {
        strncpy(e_sock->name, name, MAX_CONN_NAME_LEN - 1);
        e_sock->name[MAX_CONN_NAME_LEN - 1] = '\0';
    } else {
        e_sock->name[0] = '\0';
    }

    if (ip && (server->ipv6_mode == CFG_IPV6_MODE_TEMPORARY || server->ipv6_mode == CFG_IPV6_MODE_PERMANENT)) {
        if (netif_index == 0) {
            netif_index = get_default_route_netif_index(AF_INET6);
            if (netif_index == 0) {
                DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Cannot determine default route interface for IPv6 socket %s", name);
                u_free(e_sock);
                return NULL;
            }
        }
        int temp = (server->ipv6_mode == CFG_IPV6_MODE_TEMPORARY) ? 1 : 0;
        uint8_t v6addr[16];
        if (get_interface_ipv6_by_index(netif_index, temp, v6addr) != 0) {
            DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Failed to get %s IPv6 from netif_index=%u for socket %s",
                       temp ? "temporary" : "permanent", netif_index, name);
            u_free(e_sock);
            return NULL;
        }
        struct sockaddr_in6* sin6 = (struct sockaddr_in6*)ip;
        memcpy(&sin6->sin6_addr, v6addr, 16);
    }

    int family = AF_INET;
    if (ip) {
        family = ip->ss_family;
        if (family != AF_INET && family != AF_INET6) {
            DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Unsupported address family: %d", family);
            u_free(e_sock);
            return NULL;
        }
    }
    
    e_sock->fd = socket_create_udp(family);
    if (e_sock->fd == SOCKET_INVALID) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Failed to create socket: %s", 
                   socket_strerror(socket_get_error()));
        u_free(e_sock);
        return NULL;
    }
    
    // Строго не используем reuseaddr, даже в тестах!
    socket_set_reuseaddr(e_sock->fd, 0);

    // Increase socket buffers for high throughput
    socket_set_buffers(e_sock->fd, 4 * 1024 * 1024, 4 * 1024 * 1024);

    if (socket_set_nonblocking(e_sock->fd) != 0) {
        DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "Failed to set non-blocking mode");
    }
    
    // Set socket mark if specified (Linux only)
    if (so_mark > 0) {
        socket_set_mark(e_sock->fd, so_mark);
    }

    // Set FIB for FreeBSD
#ifdef __FreeBSD__
    if (fib > 0) {
        if (setsockopt(e_sock->fd, SOL_SOCKET, SO_SETFIB, &fib, sizeof(fib)) < 0) {
            DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "Failed to set FIB %d: %s", fib, strerror(errno));
        }
    }
#endif
    
    // Bind to interface if specified (Linux only)
#ifndef _WIN32
    if (netif_index > 0) {
        char ifname[IF_NAMESIZE];
        if (if_indextoname(netif_index, ifname)) {
            socket_bind_to_device(e_sock->fd, ifname);
        }
    }
#endif
    
    // Store the local address and bind socket if provided
    if (ip) {
        memcpy(&e_sock->local_addr, ip, sizeof(struct sockaddr_storage));
        
        // CRITICAL: Actually bind the socket to the address
        socklen_t addr_len = (ip->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6);
        if (bind(e_sock->fd, (struct sockaddr*)ip, addr_len) < 0) {
            DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "[ETCP] Failed to bind socket to address family %d: %s", 
                       ip->ss_family, socket_strerror(socket_get_error()));
            if (ip->ss_family == AF_INET) {
                struct sockaddr_in* sin = (struct sockaddr_in*)ip;
                DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "[ETCP] Failed to bind to %s:%d", ip_to_str(&sin->sin_addr, AF_INET).str, ntohs(sin->sin_port));
            } else if (ip->ss_family == AF_INET6) {
                struct sockaddr_in6* sin6 = (struct sockaddr_in6*)ip;
                DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "[ETCP] Failed to bind to %s:%d", ip_to_str(&sin6->sin6_addr, AF_INET6).str, ntohs(sin6->sin6_port));
            }
            socket_close_wrapper(e_sock->fd);
            u_free(e_sock);
            return NULL;
        }

        if (ip->ss_family == AF_INET) {
            struct sockaddr_in* sin = (struct sockaddr_in*)ip;
            DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] Successfully bound socket to local address, family=AF_INET %s:%d", ip_to_str(&sin->sin_addr, AF_INET).str, ntohs(sin->sin_port));
            DEBUG_INFO(DEBUG_CATEGORY_GENERAL, "Listen socket initialized: name=%s fd=%d addr=%s:%d", e_sock->name, e_sock->fd, ip_to_str(&sin->sin_addr, AF_INET).str, ntohs(sin->sin_port));
        } else if (ip->ss_family == AF_INET6) {
            struct sockaddr_in6* sin6 = (struct sockaddr_in6*)ip;
            DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] Successfully bound socket to local address, family=AF_INET6 %s:%d", ip_to_str(&sin6->sin6_addr, AF_INET6).str, ntohs(sin6->sin6_port));
            DEBUG_INFO(DEBUG_CATEGORY_GENERAL, "Listen socket initialized: name=%s fd=%d addr=%s:%d", e_sock->name, e_sock->fd, ip_to_str(&sin6->sin6_addr, AF_INET6).str, ntohs(sin6->sin6_port));
        }
    }
    // Определяем interface_addr: IP интерфейса или из конфига
    memset(&e_sock->interface_addr, 0, sizeof(e_sock->interface_addr));
    if (netif_index > 0 && ip && ip->ss_family == AF_INET) {
        uint32_t if_ip = get_interface_ip_by_index(netif_index);
        if (if_ip != 0) {
            struct sockaddr_in* sin = (struct sockaddr_in*)&e_sock->interface_addr;
            sin->sin_family = AF_INET;
            sin->sin_addr.s_addr = if_ip;
        }
    } else if (ip) {
        if (ip->ss_family == AF_INET) {
            struct sockaddr_in* sin = (struct sockaddr_in*)ip;
            if (sin->sin_addr.s_addr == 0) {
                // 0.0.0.0 — определяем через default route
                struct sockaddr_storage remote;
                memset(&remote, 0, sizeof(remote));
                struct sockaddr_in* rem_sin = (struct sockaddr_in*)&remote;
                rem_sin->sin_family = AF_INET;
                rem_sin->sin_port = htons(53);
                inet_pton(AF_INET, "8.8.8.8", &rem_sin->sin_addr);
                if (get_outgoing_local_ip(ip, &remote, &e_sock->interface_addr) != 0) {
                    DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "Failed to detect outgoing local IP for socket %s", e_sock->name);
                }
            }
        } else if (ip->ss_family == AF_INET6) {
            struct sockaddr_in6* sin6 = (struct sockaddr_in6*)ip;
            if (memcmp(&sin6->sin6_addr, &in6addr_any, sizeof(struct in6_addr)) == 0) {
                // :: — определяем через default route
                struct sockaddr_storage remote;
                memset(&remote, 0, sizeof(remote));
                struct sockaddr_in6* rem_sin6 = (struct sockaddr_in6*)&remote;
                rem_sin6->sin6_family = AF_INET6;
                rem_sin6->sin6_port = htons(53);
                inet_pton(AF_INET6, "2001:4860:4860::8888", &rem_sin6->sin6_addr);
                if (get_outgoing_local_ip(ip, &remote, &e_sock->interface_addr) != 0) {
                    DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "Failed to detect outgoing local IPv6 for socket %s", e_sock->name);
                }
            }
        }
    }
    if (e_sock->interface_addr.ss_family == 0) {
        // Не удалось определить автоматически — используем адрес из конфига
        if (ip) memcpy(&e_sock->interface_addr, ip, sizeof(struct sockaddr_storage));
    }
    // Копируем порт из конфига в interface_addr
    if (ip && e_sock->interface_addr.ss_family == ip->ss_family) {
        if (ip->ss_family == AF_INET) {
            struct sockaddr_in* sin_cfg = (struct sockaddr_in*)ip;
            struct sockaddr_in* sin_if = (struct sockaddr_in*)&e_sock->interface_addr;
            sin_if->sin_port = sin_cfg->sin_port;
        } else if (ip->ss_family == AF_INET6) {
            struct sockaddr_in6* sin6_cfg = (struct sockaddr_in6*)ip;
            struct sockaddr_in6* sin6_if = (struct sockaddr_in6*)&e_sock->interface_addr;
            sin6_if->sin6_port = sin6_cfg->sin6_port;
        }
    }

    char config_str[64] = "none";
    char netif_str[64] = "none";
    if (e_sock->local_addr.ss_family != 0) {
        snprintf(config_str, sizeof(config_str), "%s", sockaddr_storage_to_str(&e_sock->local_addr).str);
    }
    if (e_sock->interface_addr.ss_family != 0) {
        snprintf(netif_str, sizeof(netif_str), "%s", sockaddr_storage_to_str(&e_sock->interface_addr).str);
    }
    DEBUG_INFO(DEBUG_CATEGORY_GENERAL, "Listen socket initialized: name=%s fd=%d config=%s, netif=%s", e_sock->name, e_sock->fd, config_str, netif_str);

    e_sock->instance = instance;
    e_sock->errorcode = 0;
    e_sock->pkt_format_errors = 0;
    e_sock->type = type;
    e_sock->sock_id = instance->next_socket_id++;
    e_sock->nat_type = NAT_TYPE_UNKNOWN; // только результат детекции NAT, серверные сокеты стартуют с unknown
    e_sock->mtu = mtu;
    e_sock->only_local = only_local;
    DEBUG_INFO(DEBUG_CATEGORY_BGP, "Add Socket type=%d", type);
    e_sock->next = instance->etcp_sockets;
    instance->etcp_sockets = e_sock;
    e_sock->socket_id = uasync_add_socket_t(instance->ua, e_sock->fd, etcp_connections_read_callback_socket, NULL, NULL, e_sock);
    if (!e_sock->socket_id) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Failed to register socket with uasync");
        socket_close_wrapper(e_sock->fd);
        u_free(e_sock);
        return NULL;
    }
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Registered ETCP socket with uasync");
    DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] Socket %p registered and active", e_sock);
    return e_sock;
}

void etcp_socket_remove(struct ETCP_SOCKET* conn) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!conn) return;
    
    DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] Removing socket %p, socket_id=%p", conn, conn->socket_id);
    
    // Remove from uasync if registered
    if (conn->socket_id) {
        DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] Removing socket from uasync, instance=%p, ua=%p", conn->instance, conn->instance->ua);
        uasync_remove_socket_t(conn->instance->ua, conn->fd);
        conn->socket_id = NULL;
        DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] Unregistered socket from uasync");
    }
    
    if (conn->fd != SOCKET_INVALID) {
        socket_close_wrapper(conn->fd);
        DEBUG_INFO(DEBUG_CATEGORY_ETCP, "[ETCP] Closed socket");
    }
    

    size_t i = 0;
    while (i < conn->num_channels) {
        struct ETCP_LINK* l = conn->links[i];
        etcp_link_close(l);          // remove_link inside shifts elements left → next at same i
    }
    u_free(conn->links);
    
    u_free(conn);
}


struct ETCP_LINK* etcp_link_new(struct ETCP_CONN* etcp, struct ETCP_SOCKET* conn, struct sockaddr_storage* remote_addr, uint8_t is_server) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!remote_addr) return NULL;

    struct ETCP_LINK* link = u_calloc(1, sizeof(struct ETCP_LINK));
    if (!link) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "calloc failed - out of memory or pool exhausted");
        return NULL;
    }

    link->conn = conn;
    link->etcp = etcp;
    link->is_server = is_server;
    int mtu = conn->mtu;
    if (mtu == 0) mtu = 1500;
    if (mtu > PACKET_DATA_MAX_MTU) mtu = PACKET_DATA_MAX_MTU;
    link->mtu_local = mtu;
    link->mtu = mtu;
    etcp_update_mtu(etcp);
    link->initialized = 0;
    link->init_timer = NULL;
    link->init_timeout = 0;
    link->init_retry_count = 0;
    link->link_status = 0;  // down initially
    link->send_hook = NULL;
    link->send_hook_ctx = NULL;
    link->handshake_minsize = 100;
    link->handshake_maxsize = mtu;// 28 = udp header size

    // Initialize keepalive timeout from global config
    if (etcp->instance && etcp->instance->config) {
        link->keepalive_timeout = etcp->instance->config->global.keepalive_timeout;
        link->keepalive_interval = etcp->instance->config->global.keepalive_interval;
    } else {
        link->keepalive_timeout = 2000;  // Default 2 seconds
        link->keepalive_interval = 200;  // Default 0.2 s
    }
    if (link->keepalive_interval < 10) link->keepalive_interval = 10;
    link->keepalive_sent_count = 0;
    link->keepalive_recv_count = 0;
    link->ka_period_ms = (uint16_t)link->keepalive_interval;
    link->inflight_lim_bytes = link->mtu * 4;     // BBR init_cwnd (~4 packets)
    link->bandwidth = 10000;                       // начальная оценка 10 Mbps для шейпера
    link->burst_id = 0;
    link->burst_active = 0;
    link->burst_last_time_tb = 0;
    link->burst_target_bdp = 0;

    link->delivered_bytes = 0;
    link->acked_bytes = 0;
    link->acked_packets = 0;
    link->last_ack_time_tb = get_time_tb();
    link->bbr_pacing_rate = 0;
    link->bbr_loss_since_ack = 0;
    link->bbr = u_calloc(1, sizeof(struct bbr));
    if (!link->bbr) {
        u_free(link);
        return NULL;
    }
    bbr_init(link->bbr);

    // Выделяем свободный local_link_id
    int free_id = etcp_find_free_local_link_id(etcp);
    if (free_id <= 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "no free local_link_id available");
        u_free(link);
        return NULL;
    }
    link->local_link_id = (uint8_t)free_id;
    if (link->bbr) link->bbr->link_id = (uint8_t)free_id;

    memcpy(&link->remote_addr, remote_addr, sizeof(struct sockaddr_storage));

    link->ip_port_hash = sockaddr_hash(remote_addr);
    link->last_recv_local_time = get_time_tb();  // Initialize to prevent immediate timeout

    link->total_retransmissions  = 0;

//    insert_link(conn, link);
    if (insert_link(conn, link) < 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Can not insert link to socket");
        u_free(link);
        return NULL;
    }

    struct ETCP_LINK* l=etcp->links;
    while (l && l->next) l=l->next;
    if (l) l->next = link; else etcp->links = link;

    etcp_link_update_inflight_lim(link, link->inflight_lim_bytes);

    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "NEW link initialized on etcp=[%s] link=%p socket=%s id=%d is_server=%d mtu=%d", etcp->log_name, link, conn->name, link->local_link_id, link->is_server, link->mtu);

    if (is_server == 0) {
        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "client link, calling etcp_link_send_init");
        etcp_link_enter_init(link);
    }

    return link;
}

void etcp_link_update_inflight_lim(struct ETCP_LINK* link, uint32_t new_lim) {
    if (!link || !link->etcp) return;
    if (new_lim < INFLIGHT_LIM_MIN) new_lim = INFLIGHT_LIM_MIN;
    if (new_lim > link->etcp->max_inflight) new_lim = link->etcp->max_inflight;

    link->inflight_lim_bytes = new_lim;
    etcp_conn_on_inflight_lim_changed(link->etcp);
}

void etcp_link_close(struct ETCP_LINK* link) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!link) return;

    if (link->burst_resp_timer) {
        uasync_cancel_timeout(link->etcp->instance->ua, link->burst_resp_timer);
        link->burst_resp_timer = NULL;
    }

    if (!link->conn) {
        struct ETCP_LINK **pp = &link->etcp->links;
        while (*pp && *pp != link) pp = &(*pp)->next;
        if (*pp) *pp = link->next;
        if (link->init_timer) uasync_cancel_timeout(link->etcp->instance->ua, link->init_timer);
        if (link->shaper_timer) uasync_cancel_timeout(link->etcp->instance->ua, link->shaper_timer);
        if (link->keepalive_timer) uasync_cancel_timeout(link->etcp->instance->ua, link->keepalive_timer);
        etcp_conn_on_inflight_lim_changed(link->etcp);
        u_free(link);
        return;
    }

    // Cancel init timer if active
    if (link->init_timer) {
        uasync_cancel_timeout(link->etcp->instance->ua, link->init_timer);
        link->init_timer = NULL;
    }

    // Cancel shaper timer if active
    if (link->shaper_timer) {
        uasync_cancel_timeout(link->etcp->instance->ua, link->shaper_timer);
        link->shaper_timer = NULL;
    }

    // Cancel keepalive timer if active
    if (link->keepalive_timer) {
        uasync_cancel_timeout(link->etcp->instance->ua, link->keepalive_timer);
        link->keepalive_timer = NULL;
    }

    // универсальное удаление из односвязного списка
    struct ETCP_LINK **pp = &link->etcp->links;
    while (*pp) {
        if (*pp == link) {
            *pp = link->next;
            break;
        }
        pp = &(*pp)->next;
    }
    if (link->etcp->last_rr_link == link) link->etcp->last_rr_link = NULL;

    remove_link(link->conn, link->ip_port_hash);

    etcp_conn_on_inflight_lim_changed(link->etcp);
    u_free(link->bbr);
    u_free(link);
}

ssize_t etcp_udp_send(struct ETCP_LINK* link, socket_t fd, const void* buf, size_t len,
                       const struct sockaddr* addr, socklen_t addr_len) {
    if (link && link->send_hook)
        return link->send_hook(fd, buf, len, addr, addr_len, link, link->send_hook_ctx);
    return socket_sendto(fd, buf, len, addr, addr_len);
}

int etcp_encrypt_send(struct ETCP_DGRAM* dgram) {
    if (!dgram || !dgram->link) { DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Null pointer"); return -1; }

    DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTION, "[%s] Send rk=%d lk=%d up=%d",
                    dgram->link->etcp->log_name, dgram->link->recv_keepalive, dgram->link->remote_keepalive, dgram->link->link_status);

    // Mark that packet was sent (for keepalive logic)
    dgram->link->pkt_sent_since_keepalive = 1;
    dgram->flag_up=dgram->link->recv_keepalive;
// Размер зашифрованной части не должен превышать UDP payload = MTU - заголовки
    int errcode=0;
    sc_context_t* sc = &dgram->link->etcp->crypto_ctx;
    int len=dgram->data_len-dgram->noencrypt_len;// не забываем добавить timestamp (2 bytes)
    if (len<0 || len>dgram->link->mtu - UDP_HDR_SIZE) { dgram->link->send_errors++; errcode=1; goto es_err; }
    uint8_t enc_buf[1600];
    size_t enc_buf_len=0;
    dgram->timestamp=get_current_timestamp();
    
    dgram->link->total_encrypted += dgram->data_len;
    if (debug_should_output(DEBUG_LEVEL_DEBUG, DEBUG_CATEGORY_CRYPTO)) log_dump(DEBUG_LEVEL_DEBUG, DEBUG_CATEGORY_CRYPTO, "Before encryption", dgram->data, dgram->data_len);
    sc_encrypt(sc, (uint8_t*)&dgram->timestamp, 3 + len, enc_buf, &enc_buf_len);
    if (enc_buf_len == 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "eencryption failed for node %016llx", (unsigned long long)dgram->link->etcp->instance->node_id);
        dgram->link->send_errors++; errcode=2; goto es_err; }
    if (enc_buf_len + dgram->noencrypt_len > (size_t)(dgram->link->mtu - UDP_HDR_SIZE)) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "packet too long len=%d ne_len=%d", enc_buf_len, dgram->noencrypt_len);
        dgram->link->send_errors++; errcode=3; goto es_err; }
    memcpy(enc_buf+enc_buf_len, dgram->data+len, dgram->noencrypt_len);
    
    if (debug_should_output(DEBUG_LEVEL_DEBUG, DEBUG_CATEGORY_CRYPTO)) log_dump(DEBUG_LEVEL_DEBUG, DEBUG_CATEGORY_CRYPTO, "Encrypted", enc_buf, enc_buf_len + dgram->noencrypt_len);
    
    struct sockaddr_storage* addr=&dgram->link->remote_addr;
    socklen_t addr_len = (addr->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6);
    
    // Debug: print where we're sending the packet
    if (addr->ss_family == AF_INET) {
        struct sockaddr_in* sin = (struct sockaddr_in*)addr;
        // inet_ntop removed - use ip_to_str
    }

    ssize_t sent = etcp_udp_send(dgram->link, dgram->link->conn->fd, enc_buf, enc_buf_len + dgram->noencrypt_len,
                                  (struct sockaddr*)addr, addr_len);
    if (sent < 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "sendto failed, sock_err=%d dst=%s fd=%d",
                    socket_get_error(), sockaddr_storage_to_str(addr).str, dgram->link->conn->fd);
        dgram->link->send_errors++; errcode=4; goto es_err;
    }
    return (int)sent;
es_err:
    DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "error %d", errcode);
    return -1;
}

static int etcp_send_ping_raw(struct ETCP_DGRAM* dgram, socket_t fd, sc_context_t* sc, const struct sockaddr_storage* addr) {
    if (!dgram || !sc || !addr) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "Null pointer in ping send");
        return -1;
    }
    int len = dgram->data_len - dgram->noencrypt_len;
    if (len < 0 || len > PACKET_DATA_SIZE - UDP_HDR_SIZE) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "ping packet data invalid len=%d", len);
        return -1;
    }
    uint8_t enc_buf[1600];
    size_t enc_buf_len = 0;
    dgram->timestamp = get_current_timestamp();
    dgram->flag_up = 1;
    sc_encrypt(sc, (uint8_t*)&dgram->timestamp, 3 + len, enc_buf, &enc_buf_len);
    if (enc_buf_len == 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "encryption failed for ping");
        return -1;
    }
    if (enc_buf_len + dgram->noencrypt_len > (size_t)(PACKET_DATA_SIZE - UDP_HDR_SIZE)) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "ping packet too long enc=%zu ne=%d", enc_buf_len, dgram->noencrypt_len);
        return -1;
    }
    memcpy(enc_buf + enc_buf_len, dgram->data + len, dgram->noencrypt_len);
    socklen_t addr_len = (addr->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6);
    ssize_t sent = enc_buf_len + dgram->noencrypt_len;
//    uint8_t* xaddr=&((struct sockaddr_in*)addr)->sin_addr;
//xaddr[0]=192; xaddr[1]=168; xaddr[2]=10; xaddr[3]=1;
    sent = socket_sendto(fd, enc_buf, enc_buf_len + dgram->noencrypt_len, (struct sockaddr*)addr, addr_len);
    if (sent < 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "sendto failed for ping, err=%d addr=%s fd=%d len=%d", socket_get_error(), sockaddr_storage_to_str(addr).str, fd, enc_buf_len + dgram->noencrypt_len);
        return -1;
    }
    DEBUG_DEBUG(DEBUG_CATEGORY_BGP, "ping sendto succeeded to %s sent=%zd bytes fd=%d", sockaddr_storage_to_str(addr).str, sent, fd);
    return (int)sent;
}

static size_t etcp_build_ping_response_data(const uint8_t* req_data, size_t req_data_len,
                                            uint8_t* resp_buf, size_t resp_buf_len) {
    if (req_data_len > resp_buf_len) req_data_len = resp_buf_len;
    if (req_data_len && req_data) memcpy(resp_buf, req_data, req_data_len);
    return req_data_len;
}

static void ping_timeout_cbk(void* arg) {
    struct PING_CONTEXT* ctx = (struct PING_CONTEXT*)arg;
    if (!ctx || !ctx->cb) return;
    if (ctx->timeout_timer) {
        uasync_cancel_timeout(ctx->instance->ua, ctx->timeout_timer);
        ctx->timeout_timer = NULL;
    }
    ctx->cb(0, 0, ctx->arg, ctx->nonce, NULL, 0);
    if (ctx->instance->pending_pings == ctx) {
        ctx->instance->pending_pings = ctx->next;
    } else {
        struct PING_CONTEXT* prev = ctx->instance->pending_pings;
        while (prev && prev->next != ctx) prev = prev->next;
        if (prev) prev->next = ctx->next;
    }
    if (ctx->user_data) u_free(ctx->user_data);
    u_free(ctx);
}

int etcp_send_ping_to_socket(struct UTUN_INSTANCE* instance, struct ETCP_SOCKET* e_sock,
                               const uint8_t* peer_pubkey_bin, const struct sockaddr_storage* addr,
                               int timeout_ms, etcp_ping_callback_t cb, void* user_arg,
                               const uint8_t* user_data, size_t user_data_len) {
    if (!instance || !e_sock || !peer_pubkey_bin || !addr || timeout_ms <= 0 || !cb) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "bad args");
        return -1;
    }
    if (user_data_len > PACKET_DATA_SIZE - 24 - 2 - SC_PUBKEY_ENC_SIZE) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "user_data too long");
        return -2;
    }
    struct PING_CONTEXT* ctx = u_malloc(sizeof(struct PING_CONTEXT));
    if (!ctx) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "malloc ctx");
        return -3;
    }
    ctx->next = NULL;
    ctx->instance = instance;
    ctx->cb = cb;
    ctx->arg = user_arg;
    ctx->nonce = get_current_timestamp() ^ (uint64_t)rand();
    ctx->timeout_timer = NULL;
    ctx->send_time = get_time_tb();
    ctx->user_data = NULL;
    ctx->user_data_len = 0;
    if (user_data_len > 0) {
        ctx->user_data = u_malloc(user_data_len);
        if (!ctx->user_data) {
            u_free(ctx);
            DEBUG_ERROR(DEBUG_CATEGORY_BGP, "malloc user_data");
            return -3;
        }
        memcpy(ctx->user_data, user_data, user_data_len);
        ctx->user_data_len = user_data_len;
    }
    struct ETCP_DGRAM* dgram = u_malloc(PACKET_DATA_SIZE);
    if (!dgram) {
        if (ctx->user_data) u_free(ctx->user_data);
        u_free(ctx);
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "malloc dgram");
        return -4;
    }
    dgram->link = NULL;
    dgram->noencrypt_len = SC_PUBKEY_ENC_SIZE;
    size_t offset = 0;
    uint8_t* p = dgram->data;
    *p++ = ETCP_PING;
    uint64_t nid = htobe64(instance->node_id);
    memcpy(p, &nid, 8); p += 8;
    uint64_t nonce_be = htobe64(ctx->nonce);
    memcpy(p, &nonce_be, 8); p += 8;
    uint16_t ulen_be = htobe16((uint16_t)user_data_len);
    memcpy(p, &ulen_be, 2); p += 2;
    if (user_data_len) {
        memcpy(p, user_data, user_data_len);
        p += user_data_len;
    }
    uint8_t salt[SC_PUBKEY_ENC_SALT_SIZE];
    random_bytes(salt, sizeof(salt));
    memcpy(p, salt, SC_PUBKEY_ENC_SALT_SIZE); p += SC_PUBKEY_ENC_SALT_SIZE;
    uint8_t obfuscated_pubkey[SC_PUBKEY_SIZE];
    sc_obfuscate_pubkey(salt, peer_pubkey_bin, instance->my_keys.public_key, obfuscated_pubkey);
    memcpy(p, obfuscated_pubkey, SC_PUBKEY_SIZE); p += SC_PUBKEY_SIZE;
    dgram->data_len = (uint16_t)(p - dgram->data);
    struct secure_channel sc;
    sc_init_ctx(&sc, &instance->my_keys);
    if (sc_set_peer_public_key(&sc, peer_pubkey_bin, SC_PEER_PUBKEY_BIN) != SC_OK) {
        u_free(dgram);
        if (ctx->user_data) u_free(ctx->user_data);
        u_free(ctx);
        DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "set key failed");
        return -5;
    }
    DEBUG_DEBUG(DEBUG_CATEGORY_BGP, "ping sent nonce=%016llx timeout=%d ulen=%zu",
               (unsigned long long)ctx->nonce, timeout_ms, user_data_len);
    etcp_send_ping_raw(dgram, e_sock->fd, &sc, addr);
    u_free(dgram);
    if (instance->pending_pings == NULL) {
        instance->pending_pings = ctx;
    } else {
        struct PING_CONTEXT* last = instance->pending_pings;
        while (last->next) last = last->next;
        last->next = ctx;
    }
    ctx->timeout_timer = uasync_set_timeout(instance->ua, timeout_ms * 10, ctx, ping_timeout_cbk, "ping_timeout");
    return 0;
}

int etcp_send_ping(struct UTUN_INSTANCE* instance, const uint8_t* peer_pubkey_bin,
                   const struct sockaddr_storage* addr, int timeout_ms,
                   etcp_ping_callback_t cb, void* user_arg,
                   const uint8_t* user_data, size_t user_data_len) {
    if (!instance || !peer_pubkey_bin || !addr || timeout_ms <= 0 || !cb) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "bad args: inst=%p pubkey=%p addr=%p timeout=%d cb=%p udata=%p udata_len=%zu",
                   (void*)instance, (void*)peer_pubkey_bin, (void*)addr, timeout_ms,
                   (void*)(uintptr_t)cb, (void*)user_data, user_data_len);
        return -1;
    }
    struct ETCP_SOCKET* e_sock = instance->etcp_sockets;
    while (e_sock && e_sock->local_addr.ss_family != addr->ss_family) e_sock = e_sock->next;
    if (!e_sock) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "no socket for addr_family=%d", addr->ss_family);
        return -2;
    }
    DEBUG_DEBUG(DEBUG_CATEGORY_BGP, "ping N1 [%s]", sockaddr_storage_to_str(addr).str);
    return etcp_send_ping_to_socket(instance, e_sock, peer_pubkey_bin, addr, timeout_ms,
                                     cb, user_arg, user_data, user_data_len);
}

// === Helpers extracted from etcp_connections_read_callback_socket ===

static int handle_ping(struct ETCP_SOCKET* e_sock, struct ETCP_DGRAM* pkt, const struct sockaddr_storage* addr, const uint8_t* decrypted_pubkey, size_t pkt_len) {
    if (pkt_len < 22) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "PING too short: pkt_len=%zu from %s", pkt_len, sockaddr_storage_to_str(addr).str);
        return 7;
    }
    uint64_t nonce = be64toh(*(uint64_t*)(pkt->data + 9));
    uint16_t ulen = be16toh(*(uint16_t*)(pkt->data + 17));
    const uint8_t* udata = (ulen > 0) ? (pkt->data + 19) : NULL;
    struct ETCP_DGRAM* resp = u_malloc(PACKET_DATA_SIZE);
    if (resp) {
        resp->link = NULL;
        resp->noencrypt_len = SC_PUBKEY_ENC_SIZE;
        uint8_t* p = resp->data;
        *p++ = ETCP_PONG;
        uint64_t nid = htobe64(e_sock->instance->node_id);
        memcpy(p, &nid, 8); p += 8;
        uint64_t n = htobe64(nonce);
        memcpy(p, &n, 8); p += 8;
        uint16_t resp_ulen_be = htobe16(ulen);
        memcpy(p, &resp_ulen_be, 2); p += 2;
        size_t copied = etcp_build_ping_response_data(udata, ulen, p, PACKET_DATA_SIZE - (p - resp->data) - SC_PUBKEY_ENC_SIZE);
        p += copied;
        uint8_t salt[SC_PUBKEY_ENC_SALT_SIZE];
        random_bytes(salt, sizeof(salt));
        memcpy(p, salt, SC_PUBKEY_ENC_SALT_SIZE); p += SC_PUBKEY_ENC_SALT_SIZE;
        uint8_t obfuscated_pubkey[SC_PUBKEY_SIZE];
        sc_obfuscate_pubkey(salt, decrypted_pubkey, e_sock->instance->my_keys.public_key, obfuscated_pubkey);
        memcpy(p, obfuscated_pubkey, SC_PUBKEY_SIZE); p += SC_PUBKEY_SIZE;
        resp->data_len = (uint16_t)(p - resp->data);
        sc_context_t resp_sc;
        sc_init_ctx(&resp_sc, &e_sock->instance->my_keys);
        if (sc_set_peer_public_key(&resp_sc, decrypted_pubkey, SC_PEER_PUBKEY_BIN) == SC_OK) {
            DEBUG_DEBUG(DEBUG_CATEGORY_BGP, "PONG send nonce=%016llx to=%s fd=%d",
                       (unsigned long long)nonce, sockaddr_storage_to_str(addr).str, e_sock->fd);
            etcp_send_ping_raw(resp, e_sock->fd, &resp_sc, addr);
        }
        u_free(resp);
    }
    memory_pool_free(e_sock->instance->pkt_pool, pkt);
    return 0;
}

static int handle_pong(struct ETCP_SOCKET* e_sock, struct ETCP_DGRAM* pkt, const struct sockaddr_storage* addr, size_t pkt_len) {
    if (pkt_len < 20) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "PONG too short: pkt_len=%zu from %s", pkt_len, sockaddr_storage_to_str(addr).str);
        return 7;
    }
    uint64_t nonce = be64toh(*(uint64_t*)(pkt->data + 9));
    uint16_t ulen = 0;
    const uint8_t* udata = NULL;
    if (pkt->data_len >= 19) {
        ulen = be16toh(*(uint16_t*)(pkt->data + 17));
        if (ulen > 0 && pkt->data_len >= 19 + ulen) {
            udata = pkt->data + 19;
        }
    }
    DEBUG_DEBUG(DEBUG_CATEGORY_BGP, "PONG recv nonce=%016llx data_len=%u from=%s socket=%s",
               (unsigned long long)nonce, (unsigned)pkt->data_len,
               sockaddr_storage_to_str(addr).str, e_sock->name);
    struct PING_CONTEXT* ctx = e_sock->instance->pending_pings;
    struct PING_CONTEXT* prev = NULL;
    int found = 0;
    while (ctx) {
        if (ctx->nonce == nonce) {
            found = 1;
            if (prev) prev->next = ctx->next;
            else e_sock->instance->pending_pings = ctx->next;
            if (ctx->timeout_timer) {
                uasync_cancel_timeout(e_sock->instance->ua, ctx->timeout_timer);
                ctx->timeout_timer = NULL;
            }
            uint64_t now = get_time_tb();
            uint16_t rtt = (now >= ctx->send_time) ? (uint16_t)(now - ctx->send_time) : 0;
            DEBUG_DEBUG(DEBUG_CATEGORY_BGP, "PONG matched nonce=%016llx rtt=%u",
                       (unsigned long long)nonce, (unsigned)rtt);
            ctx->cb(1, rtt, ctx->arg, nonce, udata, ulen);
            if (ctx->user_data) u_free(ctx->user_data);
            u_free(ctx);
            break;
        }
        prev = ctx;
        ctx = ctx->next;
    }
    if (!found) {
        DEBUG_WARN(DEBUG_CATEGORY_BGP, "PONG nonce=%016llx NOT FOUND in pending (timeout?)",
                   (unsigned long long)nonce);
    }
    memory_pool_free(e_sock->instance->pkt_pool, pkt);
    return 0;
}

static void send_init_response(struct ETCP_SOCKET* e_sock, struct ETCP_DGRAM* pkt, struct ETCP_LINK* link, struct ETCP_CONN* conn, const struct ETCP_INIT_REQUEST_PKT* req, const struct sockaddr_storage* addr, uint8_t send_reset, uint32_t req_src_ip, uint16_t req_src_port, size_t pkt_len) {
    struct ETCP_INIT_RESPONSE_PKT* resp = (struct ETCP_INIT_RESPONSE_PKT*)pkt->data;

    // Set response code: 0x03 (with reset) or 0x05 (without reset)
    // response with init (0x03) only if reinit was actually done on server side
    if (send_reset != 0) {
        DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "send init_response with reset");
        resp->code = ETCP_INIT_RESPONSE;  // 0x03 - with reset
    } else {
        DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "send init_response without reset");
        resp->code = ETCP_INIT_RESPONSE_NOINIT;  // 0x05 - without reset
    }
    *(uint64_t*)resp->node_id = htobe64(e_sock->instance->node_id);
    *(uint32_t*)resp->session_id = htobe32(conn->session_id);

    resp->mtu[0]=link->mtu_local>>8;
    resp->mtu[1]=link->mtu_local;
    resp->link_id = link->local_link_id;
    resp->remote_socket_id = req->socket_id;
    resp->only_local = e_sock->only_local;
    resp->type = e_sock->type;
    // Add client's IP:port (so client behind NAT can know its external address)
    if (addr->ss_family == AF_INET) {
        struct sockaddr_in *sin = (struct sockaddr_in*)addr;
        memcpy(resp->peer_ipv4, &sin->sin_addr.s_addr, 4);
        uint16_t port = ntohs(sin->sin_port);
        resp->peer_port[0] = port >> 8;
        resp->peer_port[1] = port & 0xFF;
        link->nat_ip = sin->sin_addr.s_addr;
        link->nat_port = port;
    } else {
        // For IPv6, set to 0 (not supported for NAT traversal)
        memset(resp->peer_ipv4, 0, 4);
        memset(resp->peer_port, 0, 2);
        link->nat_ip = 0;
        link->nat_port = 0;
    }
    // DIRECT detection: if client reports its own address and it matches observed source → real public IP
    if (pkt_len >= ETCP_INIT_REQ_SIZE && addr->ss_family == AF_INET && link->nat_ip != 0) {
        if (req_src_ip != 0 && req_src_ip == link->nat_ip
            && req_src_port == link->nat_port
            && !is_local_subnet(link->nat_ip))
        {
            link->nat_type = NAT_TYPE_DIRECT;
            link->nat_check_status = NAT_CHECK_EIM;
            if (link->etcp->instance->topo_groups) {
                topo_group_send_nat_info(link->etcp, link->remote_socket_id,
                                        link->nat_ip, link->nat_port, NAT_TYPE_DIRECT);
            }
            DEBUG_INFO(DEBUG_CATEGORY_BGP, "DIRECT IP: %s:%u for %s",
                       ip_to_str(&link->nat_ip, AF_INET).str, link->nat_port,
                       link->etcp->log_name);
        }
    }
    /* Self-detection: if my IP is non-local, I'm on a public IP */
    DEBUG_INFO(DEBUG_CATEGORY_NAT, "self-detect check: socket=%s type=%d nat_type=%d if_addr=%s local_addr=%s",
               e_sock->name, e_sock->type, e_sock->nat_type,
               sockaddr_storage_to_str(&e_sock->interface_addr).str,
               sockaddr_storage_to_str(&e_sock->local_addr).str);
    if (e_sock->nat_type != NAT_VERIFIED_DIRECT && e_sock->interface_addr.ss_family == AF_INET) {
        uint32_t my_ip = ((struct sockaddr_in*)&e_sock->interface_addr)->sin_addr.s_addr;
        if (my_ip != 0 && !is_local_subnet(my_ip)) {
            e_sock->nat_type = NAT_VERIFIED_DIRECT;
            struct sockaddr_in* nat_sin = (struct sockaddr_in*)&e_sock->nat_addr;
            nat_sin->sin_family = AF_INET;
            nat_sin->sin_addr.s_addr = my_ip;
            nat_sin->sin_port = ((struct sockaddr_in*)&e_sock->interface_addr)->sin_port;
            { struct TOPO_GROUP* g = topo_groups_get_default(link->etcp->instance->topo_groups);
              if (g) {
                topo_group_update_my_nodeinfo(g->instance, g);
                if (g->local_node && g->senders_list) {
                    g->local_node->node->ver = (g->local_node->node->ver % 255) + 1;
                    g->local_node->dirty = 1;
                    struct ll_entry* se = g->senders_list->head;
                    while (se) {
                        struct TOPO_GROUP_CONN_ITEM* item = (struct TOPO_GROUP_CONN_ITEM*)se->data;
                        if (item && item->conn) topo_group_send_nodeinfo(g, g->local_node, item->conn);
                        se = se->next;
                    }
                }
              }
            }
            DEBUG_INFO(DEBUG_CATEGORY_NAT, "Self-detected PUBLIC: socket=%s ip=%s port=%u sock_id=%d",
                       e_sock->name, ip_to_str(&my_ip, AF_INET).str,
                       ntohs(nat_sin->sin_port), e_sock->sock_id);
        }
    }
    memcpy(resp->ed25519_pubkey, e_sock->instance->my_ed25519_pubkey, SC_PUBKEY_SIZE);
    pkt->noencrypt_len=0;
    pkt->link=link;
    link->recv_keepalive = 1;
    link->last_recv_local_time = get_time_tb();
    link->last_recv_timestamp = pkt->timestamp;

    int xoffset=sizeof(struct ETCP_INIT_RESPONSE_PKT);
    // padding
    int s = rand() % (link->handshake_maxsize - link->handshake_minsize) + link->handshake_minsize;
    if (s > (int)(link->mtu)) s = (int)(link->mtu);
    if (s < 0) s = 0;

    int to_add=s - xoffset - UDP_HDR_SIZE - UDP_SC_HDR_SIZE;
    if (to_add<0) to_add=0;
    if (xoffset + to_add > PACKET_DATA_SIZE) { to_add = PACKET_DATA_SIZE - xoffset; if (to_add<0) to_add=0; }

    for (int i=0; i<to_add; i++) pkt->data[xoffset++]=rand();// fill pad
    // padding end
    pkt->data_len=xoffset;
    DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTION, "Sending INIT RESPONSE, link=%p, local_link_id=%d, remote_link_id=%d, dst=%s fd=%d",
                link, link->local_link_id, link->remote_link_id,
                sockaddr_storage_to_str(&link->remote_addr).str, link->conn->fd);
    etcp_encrypt_send(pkt);

    memory_pool_free(e_sock->instance->pkt_pool, pkt);
    link->initialized = 1;
    link->link_state = 3;
    if (link->init_timer) {
        uasync_cancel_timeout(link->etcp->instance->ua, link->init_timer);
        link->init_timer = NULL;
    }
    if (link->etcp->initialized == 0) {
      etcp_conn_ready(link->etcp);
      DEBUG_INFO(DEBUG_CATEGORY_GENERAL, "Connection established: log_name=%s socket=%s link_id=%d status=UP", link->etcp->log_name, e_sock->name, link->local_link_id);
      }
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] Link %p (local_id=%d) initialized and marked as UP (server)", link->etcp->log_name, link, link->local_link_id);
    start_keepalive_timer(link);
    loadbalancer_link_ready(link);
    // Restart NAT check after link is up (e.g. after address change or reinit)
    { struct TOPO_GROUP* g = topo_groups_get_default(link->etcp->instance->topo_groups);
      if (g && link->nat_check_status < NAT_CHECK_IN_PROGRESS) topo_group_start_link_nat_check(g, link); }
}

static int handle_init_response_client(struct ETCP_SOCKET* e_sock, struct ETCP_DGRAM* pkt, struct ETCP_LINK* link, uint8_t pkt_code, size_t pkt_len) {
    if (pkt_len < ETCP_INIT_RESP_SIZE) {
        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "INIT_RESPONSE too short: pkt_len=%zu", pkt_len);
        return 46;
    }
    // ETCP_INIT_RESPONSE (0x03) - reset entire ETCP_CONN
    // ETCP_INIT_RESPONSE_NOINIT (0x05) - no reset
    struct ETCP_INIT_RESPONSE_PKT* resp = (struct ETCP_INIT_RESPONSE_PKT*)pkt->data;
    uint64_t server_node_id = be64toh(*(uint64_t*)resp->node_id);
    uint32_t resp_session_id = be32toh(*(uint32_t*)resp->session_id);
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "INIT_RESPONSE session_id=%08x", resp_session_id);
    // Check session_id: ignore response if it doesn't match our session
    if (resp_session_id != link->etcp->session_id) {
        DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "[%s] INIT_RESPONSE session_id mismatch: got %08x, expected %08x, ignoring",
                   link->etcp->log_name, resp_session_id, link->etcp->session_id);
        memory_pool_free(e_sock->instance->pkt_pool, pkt);
        return 0;
    }
    link->mtu_remote = be16toh(*(uint16_t*)resp->mtu);
    if (link->mtu_remote > PACKET_DATA_MAX_MTU) link->mtu_remote = PACKET_DATA_MAX_MTU;
    link->mtu = link->mtu_local < link->mtu_remote ? link->mtu_local : link->mtu_remote;
    etcp_update_mtu(link->etcp);
    link->remote_link_id = resp->link_id;
    link->remote_socket_id = resp->remote_socket_id;
    link->remote_only_local = resp->only_local;
    link->remote_type = resp->type;

    // Parse NAT IP:port from response (new format includes 4+2 bytes)
    if (pkt_len >= ETCP_INIT_RESP_SIZE) {
        uint32_t new_nat_ip;
        memcpy(&new_nat_ip, resp->peer_ipv4, 4);
        uint16_t new_nat_port = be16toh(*(uint16_t*)resp->peer_port);
        
        // Check if NAT address changed
        if (link->nat_ip == 0 && link->nat_port == 0) {
            // First time receiving NAT info
            link->nat_ip = new_nat_ip;
            link->nat_port = new_nat_port;
            struct in_addr addr;
            addr.s_addr = new_nat_ip;
            DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] NAT address initialized: %s:%u", 
                       link->etcp->log_name, ip_to_str(&addr, AF_INET).str, new_nat_port);
        } else if (link->nat_ip != new_nat_ip || link->nat_port != new_nat_port) {
            // NAT address changed
            struct in_addr old_addr, new_addr;
            old_addr.s_addr = link->nat_ip;
            new_addr.s_addr = new_nat_ip;
            
            link->nat_ip = new_nat_ip;
            link->nat_port = new_nat_port;
            link->nat_changes_count++;
            
            DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] NAT address changed: %s:%u -> %s:%u (change #%u)", 
                       link->etcp->log_name, ip_to_str(&old_addr.s_addr, AF_INET).str, link->nat_port, ip_to_str(&new_addr.s_addr, AF_INET).str, new_nat_port, 
                       link->nat_changes_count);
        }
        
        // Update socket NAT address (only if not already verified)
        {
            DEBUG_INFO(DEBUG_CATEGORY_NAT, "init_resp nat: socket=%s nat_type=%d new_ip=%s new_port=%u",
                       e_sock->name, e_sock->nat_type,
                       ip_to_str(&new_nat_ip, AF_INET).str, new_nat_port);
            if (e_sock->nat_type < NAT_VERIFIED_UNKNOWN) {
                struct sockaddr_in* sin = (struct sockaddr_in*)&e_sock->nat_addr;
                sin->sin_family = AF_INET;
                sin->sin_addr.s_addr = new_nat_ip;
                sin->sin_port = htons(new_nat_port);
            } else {
                DEBUG_INFO(DEBUG_CATEGORY_NAT, "init_resp nat update SKIPPED (already verified): socket=%s nat_type=%d",
                           e_sock->name, e_sock->nat_type);
            }
        }
    } else {
        // Legacy format without NAT info
        DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTION, "[%s] Received legacy INIT_RESPONSE without NAT info", 
                    link->etcp->log_name);
    }

    memcpy(link->remote_ed25519_pubkey, resp->ed25519_pubkey, SC_PUBKEY_SIZE);
    memcpy(link->etcp->peer_ed25519_pubkey, resp->ed25519_pubkey, SC_PUBKEY_SIZE);
    DEBUG_INFO(DEBUG_CATEGORY_CRYPTO, "[%s] Received Ed25519 pubkey from peer", link->etcp->log_name);


//        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Received INIT_RESPONSE from server_node_id=%llu, mtu=%d", (unsigned long long)server_node_id, link->mtu);

    etcp_conn_set_peer_node_id(link->etcp, server_node_id);

    link->initialized = 1;// получен init response (client)
    link->link_state = 3; // connected
    if (link->init_timer) {
        uasync_cancel_timeout(link->etcp->instance->ua, link->init_timer);
        link->init_timer = NULL;
    }

    if (pkt_code == ETCP_INIT_RESPONSE && !link->etcp->reset_done) {
        DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT from client: INIT_RESPONSE(0x03) received, reinit conn=%p",
                   link->etcp->log_name, link->etcp);
        etcp_conn_reinit(link->etcp);
        }

    if (link->etcp->initialized == 0) {
      etcp_conn_ready(link->etcp);
      }

    loadbalancer_link_ready(link);
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] Link %p (local_id=%d) initialized and marked as UP (client): rk=%d lk=%d up=%d ki=%d",
                link->etcp->log_name, link, link->local_link_id, link->recv_keepalive, link->remote_keepalive, link->link_status, link->keepalive_interval);

    // Start keepalive timer
    etcp_link_send_keepalive(link);

    start_keepalive_timer(link);


    loadbalancer_link_ready(link);
    
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "etcp client: Link initialized successfully! Server node_id=%016llx, mtu=%d, local_link_id=%d, remote_link_id=%d", (unsigned long long)server_node_id, link->mtu, link->local_link_id, link->remote_link_id);
    
    memory_pool_free(e_sock->instance->pkt_pool, pkt);
    return 0;
}

void etcp_connections_read_callback_socket(socket_t sock, void* arg) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
//    DEBUG_DEBUG(DEBUG_CATEGORY_ETCP, "etcp_connections_read_callback fd=%d, socket=%p", fd, arg);
// !!!!!! DANGER: в этой функции ПРЕДЕЛЬНАЯ АККУРАТНОСТЬ. Если кажется что не туда указатель то невнимательно аланизировал !!!!!
// НЕ РУИНИТЬ (uint8_t*)&pkt->timestamp - это правильно !!!!
//
// Ошибки функции (errorcode):
// 1 - пакет слишком маленький для init (< SC_PUBKEY_SIZE)
// 2 - не удалось установить peer public key при init
// 3 - не удалось расшифровать init пакет
// 4 - не init/p ing пакет (неверный код)
// 5 - коллизия peer ID и ключей
// 6 - не удалось расшифровать обычный пакет
// 7 - слишком короткий пакет
// 8 - ключ не в списке allowed_keys
// 13 - переполнение при парсинге пакета
// 46 - расшифрованный пакет слишком маленький (< 3 байта)
// 55 - не удалось создать подключение
// 66 - не удалось создать линк
    struct ETCP_SOCKET* e_sock = (struct ETCP_SOCKET*)arg;
    if (!e_sock) return;
    
    struct sockaddr_storage addr;
    uint8_t data[PACKET_DATA_SIZE];
    socklen_t addr_len=sizeof(addr);
    memset(&addr, 0, sizeof(addr));
    ssize_t recv_len = socket_recvfrom(sock, data, PACKET_DATA_SIZE, (struct sockaddr*)&addr, &addr_len);
    
    if (recv_len <= 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "recvfrom failed, error=%zd, sock_err=%d", recv_len, socket_get_error());
        return;
    }

    // DUMP: Show received packet content
    if (debug_should_output(DEBUG_LEVEL_DEBUG, DEBUG_CATEGORY_CRYPTO)) log_dump(DEBUG_LEVEL_DEBUG, DEBUG_CATEGORY_CRYPTO, "RECV in:", data, recv_len);

    struct ETCP_DGRAM* pkt = memory_pool_alloc(e_sock->instance->pkt_pool);
    if (!pkt) return;
    size_t pkt_len=0;
    int errorcode=0;

    struct ETCP_LINK* link=etcp_link_find_by_addr(e_sock, &addr);

    // Try normal decryption first if we have an established link with session keys
    // This is the common case for data packets and responses
//    if (link) {
//        link->recv_keepalive = 1;  // Link is up after successful initialization - не ставим ап от неизвестных пакетов
//        }

    if (link!=NULL && link->etcp!=NULL && link->etcp->crypto_ctx.session_ready) {
        sc_status_t dec_rc = sc_decrypt(&link->etcp->crypto_ctx, data, recv_len, (uint8_t*)&pkt->timestamp, &pkt_len);
        if (!dec_rc) {
            goto process_decrypted;
        }
            DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "etcp: DECRYPT FAIL rc=%d link=%p log=%s sess=%d link_state=%d keepalive=%d enc_errs=%zu my_pub=%016llx peer_pub=%016llx",
                       dec_rc, link, link->etcp->log_name, link->etcp->crypto_ctx.session_ready,
                       link->link_state, link->recv_keepalive, link->encrypt_errors,
                       *(uint64_t*)link->etcp->crypto_ctx.pk->public_key, *(uint64_t*)link->etcp->crypto_ctx.peer_public_key);
    } else {
        DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "SKIP normal decrypt: link=%p session_ready=%d — trying init decrypt",
                    link, link && link->etcp ? link->etcp->crypto_ctx.session_ready : -1);
    }
    
    // Try INIT decryption (for incoming connection requests)
    // This handles: no link found, or link without session, or normal decrypt failed
    if (recv_len <= SC_PUBKEY_ENC_SIZE + UDP_SC_HDR_SIZE) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "packet too small for init, size=%zd from %s", recv_len, sockaddr_storage_to_str(&addr).str);
        errorcode=1;
        goto ec_fr;
    }
    
    struct secure_channel sc;
    sc_init_ctx(&sc, &e_sock->instance->my_keys);
    
    const uint8_t* salt = data + recv_len - SC_PUBKEY_ENC_SIZE;
    const uint8_t* encrypted_pubkey = salt + SC_PUBKEY_ENC_SALT_SIZE;
    
    uint8_t decrypted_pubkey[SC_PUBKEY_SIZE];
    sc_obfuscate_pubkey(salt, e_sock->instance->my_keys.public_key, encrypted_pubkey, decrypted_pubkey);
    
    if (sc_set_peer_public_key(&sc, decrypted_pubkey, SC_PEER_PUBKEY_BIN)!=SC_OK) { 
        DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "failed to set peer public key during init, from %s", sockaddr_storage_to_str(&addr).str);
        errorcode=2; 
        goto ec_fr; 
    }
    DEBUG_INFO(DEBUG_CATEGORY_CRYPTO, "X25519 decrypt OK from %s", sockaddr_storage_to_str(&addr).str);
    if (sc_decrypt(&sc, data, recv_len - SC_PUBKEY_ENC_SIZE, (uint8_t*)&pkt->timestamp, &pkt_len)) {
        DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "failed to decrypt init packet, from %s", sockaddr_storage_to_str(&addr).str);
        errorcode=3; 
        goto ec_fr; 
    }

    // INIT decryption succeeded - process packet
    if (pkt_len<3) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "too short packet, from %s", sockaddr_storage_to_str(&addr).str);
        errorcode=7;
        goto ec_fr; 
        }
    if (pkt_len<15) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "decrypted packet too short for INIT header, pkt_len=%zu from %s", pkt_len, sockaddr_storage_to_str(&addr).str);
        errorcode=7;
        goto ec_fr; 
        }

    pkt->data_len=pkt_len-3;
    pkt->noencrypt_len=0;
    uint8_t code = pkt->data[0];
    uint64_t peer_id = be64toh(*(uint64_t*)(pkt->data + 1));
    if (code == ETCP_PING) {
        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "X25519 decrypted: PING from peer=0x%016llx src=%s",
                   (unsigned long long)peer_id, sockaddr_storage_to_str(&addr).str);
        int ret = handle_ping(e_sock, pkt, &addr, decrypted_pubkey, pkt_len);
        if (ret) { errorcode = ret; goto ec_fr; }
        return;
    }
    if (code == ETCP_PONG) {
        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "X25519 decrypted: PONG from peer=0x%016llx src=%s",
                   (unsigned long long)peer_id, sockaddr_storage_to_str(&addr).str);
        int ret = handle_pong(e_sock, pkt, &addr, pkt_len);
        if (ret) { errorcode = ret; goto ec_fr; }
        return;
    }
    if (code!=ETCP_INIT_REQUEST && code!=ETCP_INIT_REQUEST_NOINIT) {
        DEBUG_ERROR(DEBUG_CATEGORY_DEBUG, "not an init packet: code=0x%02x (expected 0x02/0x04) from %s — packet dropped",
                    code, sockaddr_storage_to_str(&addr).str);
        errorcode=4;
        goto ec_fr;
    }// не init
    if (e_sock->type == CFG_SERVER_TYPE_PRIVATE) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "INIT rejected: socket %s (type=PRIVATE) does not accept incoming connections", e_sock->name);
        errorcode=8;
        goto ec_fr;
    }
    if (pkt_len < ETCP_INIT_REQ_SIZE) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "INIT REQUEST too short: pkt_len=%zu from %s", pkt_len, sockaddr_storage_to_str(&addr).str);
        errorcode=7;
        goto ec_fr;
    }

    // Check allowed keys for incoming connections
    struct global_config *global = &e_sock->instance->config->global;
    if (!global->allowed_keys_allow_all) {
        if (global->allowed_keys_count == 0) {
            DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Connection rejected: no allowed_keys configured, allow_all=0");
            errorcode=8;
            goto ec_fr;
        }
        int found = 0;
        struct CFG_ALLOWED_KEY *ak = global->allowed_keys;
        while (ak) {
            if (memcmp(ak->key_bin, sc.peer_public_key, SC_PUBKEY_SIZE) == 0) {
                found = 1;
                break;
            }
            ak = ak->next;
        }
        if (!found) {
            DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Connection rejected: peer public key not in allowed_keys list");
            errorcode=8;
            goto ec_fr;
        }
    }

    struct ETCP_INIT_REQUEST_PKT* req = (struct ETCP_INIT_REQUEST_PKT*)pkt->data;
    uint32_t session_id = be32toh(*(uint32_t*)req->session_id);
    uint16_t mtu = be16toh(*(uint16_t*)req->mtu);
    uint16_t src_port = be16toh(*(uint16_t*)req->src_port);
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION,
               "INIT accepted: peer=0x%016llx mtu=%u link=%u sock=%u type=%d local=%d"
               " src_ip=%d.%d.%d.%d:%u session=%08x src=%s",
               (unsigned long long)peer_id, mtu, req->link_id, req->socket_id,
               req->type, req->only_local,
               req->src_ipv4[0], req->src_ipv4[1], req->src_ipv4[2], req->src_ipv4[3],
               src_port, session_id, sockaddr_storage_to_str(&addr).str);

    struct ETCP_CONN* conn = NULL;
    {
        struct ll_entry* e = queue_find_data_by_index(e_sock->instance->connections, (const uint8_t*)&peer_id);
        if (e) { struct conn_queue_entry* ce = (struct conn_queue_entry*)e->data; conn = ce->conn; }
    }

    int new_conn=0;
    if (!conn || conn->peer_node_id!=peer_id) {// создаём новое подключение [new etcp]
        new_conn=1;
        conn=etcp_connection_create(e_sock->instance,"");
        if (!conn) { errorcode=55; DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "failed to create connection"); goto ec_fr; }
        memcpy(&conn->crypto_ctx, &sc, sizeof(sc));
        etcp_conn_set_peer_node_id(conn, peer_id);
        DEBUG_INFO(DEBUG_CATEGORY_GENERAL, "New connection received on socket %s: log_name=%s peer_id=%lu peer:%s", e_sock->name, conn->log_name, (unsigned long)peer_id, sockaddr_storage_to_str(&addr).str);
        DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTION, "New connection from %s peer_id=%ld etcp=%p total=%d",
                     ip_to_str(&addr, addr.ss_family).str, peer_id, conn,
                     queue_entry_count(e_sock->instance->connections));
        }
    else {// check keys если существующее подключение
        if (memcmp(conn->crypto_ctx.peer_public_key, sc.peer_public_key, SC_PUBKEY_SIZE)) { errorcode=5; DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "peer key mismatch for node %016llx", (unsigned long long)peer_id); goto ec_fr; }// коллизия - peer id совпал а ключи разные.
        }

    // Check if link already exists (for CHANNEL_INIT recovery)

    struct ETCP_LINK* existing_link = etcp_link_find_by_remote_id(conn, req->link_id);
    if (!existing_link) {
        existing_link = etcp_link_find_by_addr(e_sock, &addr);
        if (existing_link && existing_link->etcp == conn) {
            DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] found existing outbound link by addr for incoming INIT, reusing link=%p",
                       conn->log_name, existing_link);
        } else {
            existing_link = NULL;
        }
    }

    uint8_t send_reset = 0;

    if (existing_link && existing_link->etcp == conn) {// существующий линк
        DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTION, "[%s] found existing link for id=%d, socket=[%s]", conn->log_name, req->link_id, e_sock->name);
        link = existing_link;
        if (!sockaddr_equal(&link->remote_addr, &addr)) {
            DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "[%s] IP:port changed for remote_link_id=%d socket:[%s]", conn->log_name, req->link_id, e_sock->name);
            if (link->conn) remove_link(link->conn, link->ip_port_hash);  // remove old connection from old socket
            link->conn=e_sock;
            memcpy(&link->remote_addr, &addr, sizeof(addr));
            link->ip_port_hash = sockaddr_hash(&addr);
            if (insert_link(link->conn, link) < 0) {
                DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Failed to reinsert link after addr change");
                goto ec_fr;
                }
                // Cancel pending NAT check and reset status
                { struct TOPO_GROUP* g = topo_groups_get_default(link->etcp->instance->topo_groups);
                  if (g) route_ping_cancel_for_conn(g, link->etcp); }
                link->nat_check_status = NAT_CHECK_NONE;
                link->nat_type = NAT_TYPE_UNKNOWN;
            }

        // Link exists - reuse it for recovery
        link->remote_link_id = req->link_id;
        link->remote_socket_id = req->socket_id;
        link->remote_only_local = req->only_local;
        link->remote_type = req->type;

        // ── Collision handling ──
        if (req->collision) {
            DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] INIT collision=1 from peer=%016llx — remote is master, becoming slave",
                       conn->log_name, (unsigned long long)peer_id);
            conn->session_id = session_id;
            etcp_conn_reinit(conn);
            send_reset = 1;
        } else {
            // Check if WE have an outbound (master) link on this conn
            struct ETCP_LINK* ml = conn->links;
            while (ml) { if (ml->is_server == 0) break; ml = ml->next; }
            if (ml) {
                if (conn->instance->node_id < peer_id) {
                    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] COLLISION: we=master node_id=%016llx < peer=%016llx — sending collision INIT",
                               conn->log_name, (unsigned long long)conn->instance->node_id, (unsigned long long)peer_id);
                    memory_pool_free(e_sock->instance->pkt_pool, pkt);
                    etcp_link_send_init(ml, 0, 1);
                    return;
                }
                DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] COLLISION: peer smaller, yielding master, processing as slave",
                           conn->log_name);
            }

            // Normal reinit check (skip if reset_done=1 unless session_id changed)
            if (!conn->reset_done) {
                if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || !conn->got_initial_pkt) {
                    send_reset = 1;
                    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT existing link: code=0x%02x sess=%08x→%08x got_init=%d initialized=%d links_up=%d",
                               conn->log_name, code, conn->session_id, session_id, conn->got_initial_pkt, conn->initialized, conn->links_up);
                    conn->session_id = session_id;
                    etcp_conn_reinit(conn);
                }
            } else if (conn->session_id != session_id) {
                send_reset = 1;
                DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT existing link (session changed): sess=%08x→%08x",
                           conn->log_name, conn->session_id, session_id);
                conn->session_id = session_id;
                etcp_conn_reinit(conn);
            } else {
                send_reset = 0;
                DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "same session_id, skip reinit");
            }
        }

        // Cancel existing timers
        if (link->init_timer) {
            uasync_cancel_timeout(link->etcp->instance->ua, link->init_timer);
            link->init_timer = NULL;
        }
    } else {
        DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTION, "[%s] NO existing link for id=%d, socket=[%s]", conn->log_name, req->link_id, e_sock->name);
        // Create new link
        link = etcp_link_new(conn, e_sock, &addr, 1);
        if (!link) { if (new_conn) etcp_connection_close(conn); errorcode=66; DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "failed to create link for connection"); goto ec_fr; }// облом
        link->remote_link_id = req->link_id;
        link->remote_socket_id = req->socket_id;
        link->remote_only_local = req->only_local;
        link->remote_type = req->type;

        // ── Collision handling ──
        if (req->collision) {
            DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] INIT collision=1 from peer=%016llx — remote is master, becoming slave",
                       conn->log_name, (unsigned long long)peer_id);
            conn->session_id = session_id;
            etcp_conn_reinit(conn);
            send_reset = 1;
        } else {
            // Check if WE have an outbound (master) link
            struct ETCP_LINK* ml = conn->links;
            while (ml) { if (ml->is_server == 0) break; ml = ml->next; }
            if (ml && conn->instance->node_id < peer_id) {
                DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] COLLISION: we=master node_id=%016llx < peer=%016llx — sending collision INIT",
                           conn->log_name, (unsigned long long)conn->instance->node_id, (unsigned long long)peer_id);
                memory_pool_free(e_sock->instance->pkt_pool, pkt);
                etcp_link_send_init(ml, 0, 1);
                return;
            }

            // Normal reinit check (skip if reset_done=1 unless session_id changed)
            if (!conn->reset_done) {
                if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || !conn->got_initial_pkt) {
                    send_reset = 1;
                    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT new link: code=0x%02x sess=%08x→%08x got_init=%d initialized=%d links_up=%d",
                               conn->log_name, code, conn->session_id, session_id, conn->got_initial_pkt, conn->initialized, conn->links_up);
                    conn->session_id = session_id;
                    etcp_conn_reinit(conn);
                }
            } else if (conn->session_id != session_id) {
                send_reset = 1;
                DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "[%s] REINIT new link (session changed): sess=%08x→%08x",
                           conn->log_name, conn->session_id, session_id);
                conn->session_id = session_id;
                etcp_conn_reinit(conn);
            }
        }
        link->keepalive_interval=(req->keepalive[0]<<8) | req->keepalive[1];
        link->recovery_interval=((req->recovery[0]<<8) | req->recovery[1])*100;// timebase в link, timebase/100 в кодограмме
        if (link->keepalive_interval < 10) link->keepalive_interval = 10;
        DEBUG_DEBUG(DEBUG_CATEGORY_KEEPALIVE, "set keepalive for link=%d", link->keepalive_interval);
    }

    link->mtu_remote = (req->mtu[0] << 8) | req->mtu[1];
    if (link->mtu_remote > PACKET_DATA_MAX_MTU) link->mtu_remote = PACKET_DATA_MAX_MTU;
    link->mtu = link->mtu_local < link->mtu_remote ? link->mtu_local : link->mtu_remote;
    etcp_update_mtu(link->etcp);

    uint32_t req_src_ip; memcpy(&req_src_ip, req->src_ipv4, 4);
    uint16_t req_src_port = be16toh(*(uint16_t*)req->src_port);

    memcpy(conn->peer_ed25519_pubkey, req->ed25519_pubkey, SC_PUBKEY_SIZE);

    send_init_response(e_sock, pkt, link, conn, req, &addr, send_reset, req_src_ip, req_src_port, pkt_len);
    return;


process_decrypted:
    DEBUG_TRACE(DEBUG_CATEGORY_ETCP, "Decrypt ok - normal pkt");
    if (pkt_len<3) { errorcode=46; DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "decrypted packet too small, size=%zu", pkt_len); goto ec_fr; }
    pkt->data_len=pkt_len-3;
    pkt->noencrypt_len=0;
    pkt->link=link;

    link->remote_keepalive = pkt->flag_up;

    /* restore recv_keepalive BEFORE computing link_status = remote && local */
    if (link->recv_keepalive != 1) {
        link->recv_keepalive = 1;
        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] Link %p (local_id=%d) status changed to UP - packet received",
                   link->etcp->log_name, link, link->local_link_id);
    }

    int was_up = link->link_status;
    link->link_status = link->remote_keepalive && link->recv_keepalive;
    if (link->link_status && !was_up && link->initialized)
        loadbalancer_link_ready(link);

    link->last_recv_local_time=get_time_tb();
    link->last_recv_timestamp=pkt->timestamp;
    link->last_recv_updated=1;
    
    // Count decrypted bytes
    link->total_decrypted += pkt->data_len;

    size_t offset = 0;
    uint8_t pkt_code = pkt->data[offset++];

    if (pkt_code == ETCP_KEEPALIVE) {
        if (pkt->data_len >= 3) {
            uint16_t peer_period = pkt->data[1] | ((uint16_t)pkt->data[2] << 8);
            link->keepalive_timeout = (uint32_t)peer_period * KA_TIMEOUT_MULT;
        }
        link->keepalive_recv_count++;
        memory_pool_free(e_sock->instance->pkt_pool, pkt);
        return;  // KA handled, nothing more to process
    }

    if (pkt_code == ETCP_INIT_RESPONSE || pkt_code == ETCP_INIT_RESPONSE_NOINIT) {
        int ret = handle_init_response_client(e_sock, pkt, link, pkt_code, pkt_len);
        if (ret) { errorcode = ret; goto ec_fr; }
        return;
    }

    if (link->link_state == 2) {// из recovery получен нормальный пакет - восстанавливаем линк в нормальный режим
        start_keepalive_timer(link);
        etcp_link_send_keepalive(link); // Start keepalive timer
        link->link_state = 3; // connected
    }


//    log_dump("RECV decrypted:", pkt->data, pkt->data_len, link);

    if (link->link_state == 3) {
        if (memory_pool_is_freed(e_sock->instance->pkt_pool, pkt)) {
            DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "pkt=%p ALREADY FREED in pkt_pool — HALTING", (void*)pkt);
            volatile int _halt = 1; while (_halt) {}
        }
        etcp_conn_input(pkt);
    } else memory_pool_free(e_sock->instance->pkt_pool, pkt);
    return;

ec_fr:
    DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "error %d, from %s", errorcode, sockaddr_storage_to_str(&addr).str);
    e_sock->pkt_format_errors++;
    e_sock->errorcode=errorcode;
    memory_pool_free(e_sock->instance->pkt_pool, pkt);
    return;
}

// Initialize only sockets (servers for incoming connections)
// Called before topo_group_init() to populate etcp_sockets for nodeinfo
// Returns: 0 = all OK, 1 = partial success (some sockets failed), -1 = fatal error (no sockets)
int init_sockets(struct UTUN_INSTANCE* instance) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!instance || !instance->config) return -1;
    if (instance->etcp_sockets || instance->stcp_server) {
        DEBUG_INFO(DEBUG_CATEGORY_ETCP, "Sockets already initialized, skipping");
        return 0;
    }

    struct utun_config* config = instance->config;
    int success_count = 0;
    int fail_count = 0;

    // Create sockets for servers (incoming connections)
    struct CFG_SERVER* server = config->servers;
    while (server) {
        // Auto-detect local IP for public servers with 0.0.0.0
        uint32_t default_ip = 0;
        uint8_t default_ip6[16] = {0};
        int have_default_ip6 = 0;
        if (server->type == CFG_SERVER_TYPE_PUBLIC) {
            if (server->ip.ss_family == AF_INET) {
                struct sockaddr_in* sin = (struct sockaddr_in*)&server->ip;
                if (sin->sin_addr.s_addr == 0) {
                    struct sockaddr_storage remote;
                    memset(&remote, 0, sizeof(remote));
                    struct sockaddr_in* rem_sin = (struct sockaddr_in*)&remote;
                    rem_sin->sin_family = AF_INET;
                    rem_sin->sin_port = htons(53);
                    inet_pton(AF_INET, "8.8.8.8", &rem_sin->sin_addr);
                    struct sockaddr_storage local;
                    if (get_outgoing_local_ip(&server->ip, &remote, &local) == 0) {
                        struct sockaddr_in* local_sin = (struct sockaddr_in*)&local;
                        default_ip = local_sin->sin_addr.s_addr;
                    }
                    if (default_ip == 0) {
                        DEBUG_WARN(DEBUG_CATEGORY_ETCP, "Failed to detect default route IP for server %s", server->name);
                    }
                }
            } else if (server->ip.ss_family == AF_INET6) {
                struct sockaddr_in6* sin6 = (struct sockaddr_in6*)&server->ip;
                if (memcmp(&sin6->sin6_addr, &in6addr_any, 16) == 0) {
                    struct sockaddr_storage remote;
                    memset(&remote, 0, sizeof(remote));
                    struct sockaddr_in6* rem_sin6 = (struct sockaddr_in6*)&remote;
                    rem_sin6->sin6_family = AF_INET6;
                    rem_sin6->sin6_port = htons(53);
                    inet_pton(AF_INET6, "2001:4860:4860::8888", &rem_sin6->sin6_addr);
                    struct sockaddr_storage local;
                    if (get_outgoing_local_ip(&server->ip, &remote, &local) == 0) {
                        struct sockaddr_in6* local_sin6 = (struct sockaddr_in6*)&local;
                        memcpy(default_ip6, &local_sin6->sin6_addr, 16);
                        have_default_ip6 = 1;
                    }
                    if (!have_default_ip6) {
                        DEBUG_WARN(DEBUG_CATEGORY_ETCP, "Failed to detect default route IPv6 for server %s", server->name);
                    }
                }
            }
        }
        
        // TCP transport: create stcp_server instead of UDP socket
        if (server->transport) {
            uint16_t port = ntohs(((struct sockaddr_in*)&server->ip)->sin_port);
            struct stcp_link_config scfg = {.ua = instance->ua, .my_keys = &instance->my_keys, .inst = instance};
            struct stcp_server *tsrv = stcp_server_listen(&scfg, port, tcp_server_on_link, instance);
            if (!tsrv) {
                DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Failed to create TCP server for %s", server->name);
                fail_count++;
            } else {
                instance->stcp_server = tsrv;
                success_count++;
                DEBUG_INFO(DEBUG_CATEGORY_ETCP, "TCP server %s on port %u", server->name, port);
            }
            server = server->next;
            continue;
        }

        struct ETCP_SOCKET* e_sock = etcp_socket_add(instance, server);
        if (e_sock && default_ip != 0) {
            e_sock->local_defaultroute_ip = default_ip;
            if (server->ip.ss_family == AF_INET) {
                struct in_addr addr;
                addr.s_addr = default_ip;
                DEBUG_INFO(DEBUG_CATEGORY_ETCP, "Server %s type %d ip=%s", server->name, server->type, ip_to_str(&addr, AF_INET).str);
            }
        }
        if (e_sock && have_default_ip6) {
            memcpy(e_sock->local_defaultroute_ip6, default_ip6, 16);
        }
        if (!e_sock) {
            DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Failed to create socket for server %s", server->name);
            fail_count++;
            server = server->next;
            continue;
        }
        success_count++;
        
        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Initialized server %s on %s (links: %zu)",
               server->name, sockaddr_storage_to_str(&server->ip).str, e_sock->num_channels);
        server = server->next;
    }

    if (success_count == 0 && fail_count > 0) return -1;  // All failed - fatal
    if (fail_count > 0) return 1;  // Partial failure - non-fatal warning
    return 0;  // All OK
}

int init_connections(struct UTUN_INSTANCE* instance) {
    DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "");
    if (!instance || !instance->config) return -1;

    struct utun_config* config = instance->config;
    int socket_result = 0;

    // If sockets already exist (created by init_sockets), check stored status
    if (instance->etcp_sockets || instance->stcp_server) {
        if (instance->socket_init_status == 1) {
            socket_result = 1;
        }
    } else {
        DEBUG_INFO(DEBUG_CATEGORY_ETCP, "Sockets not initialized, calling init_sockets()");
        socket_result = init_sockets(instance);
        instance->socket_init_status = socket_result;
        if (socket_result < 0) {
            return -1;
        }
    }

    // Initialize clients - create outgoing connections
    struct CFG_CLIENT* client = config->clients;
    DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTION, "init_connections called, instance=%p, config=%p, clients=%p, total_conns=%d", 
                instance, config, config ? config->clients : NULL, instance ? queue_entry_count(instance->connections) : -1);
    while (client) {
        // Check if client has required configuration
        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Client %s - keepalive=%d, links=%p, peer_key_len=%zu", 
                    client->name, client->keepalive, client->links, 
                    strlen(client->peer_public_key_hex));
        
        // Create ETCP connection for this client
        struct ETCP_CONN* etcp_conn = etcp_connection_create(instance, client->name);

        if (!etcp_conn) {
            DEBUG_ERROR(DEBUG_CATEGORY_CONNECTION, "Failed to create ETCP connection for client %s", client->name);
            client = client->next;
            continue;
        }

        // Generate session_id for this client connection
        if (random_bytes((uint8_t*)&etcp_conn->session_id, sizeof(etcp_conn->session_id)) != 0) {
            DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "Failed to generate session_id for client %s", client->name);
            etcp_connection_close(etcp_conn);
            client = client->next;
            continue;
        }
        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Client %s session_id=%08x", client->name, etcp_conn->session_id);

        // Initialize crypto context for this connection
        if (sc_init_ctx(&etcp_conn->crypto_ctx, &instance->my_keys) != SC_OK) {
            DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "failed to initialize crypto context for client %s", client->name);
            etcp_connection_close(etcp_conn);
            client = client->next;
            continue;
        }
        // If client has peer public key configured, set it
        if (strlen(client->peer_public_key_hex) > 0) {
            // For now, set peer node ID to indicate we have peer key
            // The actual peer key will be exchanged during connection establishment
            etcp_conn->peer_node_id = 1; // Simple indicator
            etcp_update_log_name(etcp_conn);  // Update log_name with peer_node_id
            
            DEBUG_INFO(DEBUG_CATEGORY_CRYPTO, "setting peer public key for client %s", client->name);
            // Set peer public key (assuming hex format)
            if (sc_set_peer_public_key(&etcp_conn->crypto_ctx, (const uint8_t*)client->peer_public_key_hex, 1) != SC_OK) {
                DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "failed to set peer public key for client %s", client->name);
            } else {
                DEBUG_INFO(DEBUG_CATEGORY_CRYPTO, "successfully set peer public key for client %s", client->name);
            }
        } else {
            DEBUG_WARN(DEBUG_CATEGORY_CONFIG, "no peer public key configured for client %s", client->name);
        }

        etcp_set_routing_exchange_state(etcp_conn, 1);  // инициируем обмен маршрутами

        // Create links for this client
        struct CFG_CLIENT_LINK* client_link = client->links;
        while (client_link) {
            // Find the local server for this link
            struct CFG_SERVER* local_server = client_link->local_srv;
            if (!local_server) {
                client_link = client_link->next;
                continue;
            }
            
            // Find the socket for this server
            struct ETCP_SOCKET* e_sock = NULL;
            struct ETCP_SOCKET* sock = instance->etcp_sockets;
            while (sock) {
                if (sock->local_addr.ss_family == local_server->ip.ss_family) {
                    if (sock->local_addr.ss_family == AF_INET) {
                        struct sockaddr_in* sock_addr = (struct sockaddr_in*)&sock->local_addr;
                        struct sockaddr_in* srv_addr = (struct sockaddr_in*)&local_server->ip;
                        if (sock_addr->sin_addr.s_addr == srv_addr->sin_addr.s_addr && 
                            sock_addr->sin_port == srv_addr->sin_port) {
                            e_sock = sock;
                            break;
                        }
                    } else if (sock->local_addr.ss_family == AF_INET6) {
                        struct sockaddr_in6* sock_addr6 = (struct sockaddr_in6*)&sock->local_addr;
                        struct sockaddr_in6* srv_addr6 = (struct sockaddr_in6*)&local_server->ip;
                        if (memcmp(&sock_addr6->sin6_addr, &srv_addr6->sin6_addr, 16) == 0 && 
                            sock_addr6->sin6_port == srv_addr6->sin6_port) {
                            e_sock = sock;
                            break;
                        }
                    }
                }
                sock = sock->next;
            }
            
            if (local_server->transport) {
                if (strlen(client->peer_public_key_hex) == 0) {
                    DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "TCP client %s has no peer key", client->name);
                    client_link = client_link->next; continue;
                }
                // TCP transport — use stcp_link instead of etcp_link_new
                uint16_t rport = ntohs(((struct sockaddr_in*)&client_link->remote_addr)->sin_port);
                struct stcp_link_config scfg = {
                    .ua = instance->ua, .my_keys = &instance->my_keys, .inst = instance,
                    .peer_pubkey = (const uint8_t*)client->peer_public_key_hex,
                    .peer_pubkey_mode = 1,  // hex
                    .remote_addr = &client_link->remote_addr, .remote_port = rport
                };
                struct stcp_link *slink = stcp_link_connect(&scfg);
                if (!slink) {
                    DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Failed to create TCP link for client %s", client->name);
                    client_link = client_link->next; continue;
                }
                etcp_conn->transport_link = slink;
                DEBUG_INFO(DEBUG_CATEGORY_ETCP, "TCP link created for client %s", client->name);
                client_link = client_link->next; continue;
            }

            if (!e_sock) {
                DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "No socket found for client %s link", client->name);
                client_link = client_link->next;
                continue;
            }
            
            // Create link for this client connection
            struct ETCP_LINK* link = etcp_link_new(etcp_conn, e_sock, &client_link->remote_addr, 0); // 0 = client initiates
            if (!link) {
                DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Failed to create link for client %s", client->name);
                client_link = client_link->next;
                continue;
            }
            DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Created link %p for client %s, socket=%p", 
                       link, client->name, e_sock);
            
            client_link = client_link->next;
        }

        client = client->next;
    }
    
    // If there are clients configured but no connections created, that's an error
    // If there are no clients (server-only mode), 0 connections is OK (server will accept incoming)
    int total_conns = queue_entry_count(instance->connections);
    if (total_conns == 0 && config->clients != NULL) {
        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Clients configured but no connections initialized");
        return -1;
    }
    
    DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "Initialized %d connections", total_conns);
    // Return 1 if there was a partial socket initialization error
    if (socket_result == 1) return 1;
    return 0;
}