// tcp_proxy.c — TCP прокси: стек lwIP TCP → ETCP → удалённый exit узел
#include "tcp_proxy.h"
#include "lwip_tcp/lwip_tcp.h"
#include "lwip_tcp/lwip_tcp_priv.h"
#include "lwip_tcp/lwip_tcp_opts.h"
#include "config_parser.h"
#include "tun_if.h"
#include "utun_instance.h"
#include "etcp.h"
#include "etcp_api.h"
#include "etcp_router.h"
#include "remote_proxy.h"
#include "udp_proxy.h"
#include "icmp_proxy.h"
#include "../lib/u_async.h"
#include "../lib/debug_config.h"
#include "../lib/ll_queue.h"
#include "../lib/memory_pool.h"
#include "../lib/mem.h"
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#ifndef _WIN32
#include <unistd.h>
#include <arpa/inet.h>
#endif

#ifndef INADDR_ANY
#define INADDR_ANY 0
#endif

// ====================================================================
// Предварительные объявления
// ====================================================================
static err_t proxy_recv_cb(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err);
static err_t proxy_sent_cb(void *arg, struct tcp_pcb *pcb, uint16_t len);
static void  proxy_err_cb(void *arg, err_t err);
static err_t proxy_poll_cb(void *arg, struct tcp_pcb *pcb);
static err_t proxy_accept_cb(void *arg, struct tcp_pcb *newpcb, err_t err);
static err_t tcp_output_cb(void *arg, struct pbuf *p, uint32_t src_ip, uint32_t dst_ip);
static void  proxy_feed_from_transport(struct proxy_conn *pc);
static struct ll_entry* entry_from_data(struct memory_pool* pool, const uint8_t* data, uint16_t len);
static void  proxy_conn_free(struct proxy_conn *pc);
static int   proxy_send_msg(struct UTUN_INSTANCE* inst, uint64_t dst, uint8_t subcmd, uint32_t sid, const uint8_t* data, size_t len);
static int   send_data(struct proxy_conn* pc, const uint8_t* data, uint16_t len);

// ====================================================================
// Помощник ll_entry
// ====================================================================
static struct ll_entry* entry_from_data(struct memory_pool* pool, const uint8_t* data, uint16_t len) {
    struct ll_entry* e = queue_entry_new_from_pool(pool);
    if (!e) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "entry_from_data: pool exhausted"); return NULL; }
    e->len = 0; e->dgram = NULL;
    if (len > 0) {
        uint8_t* buf = u_malloc(len);
        if (!buf) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "entry_from_data: malloc(%u) failed", len); queue_entry_free(e); return NULL; }
        memcpy(buf, data, len); e->dgram = buf; e->len = len;
    }
    return e;
}

// ====================================================================
// Протокол: сборка и отправка сообщений прокси через ETCP
// ====================================================================
static int proxy_send_msg(struct UTUN_INSTANCE* inst, uint64_t dst, uint8_t subcmd,
                           uint32_t sid, const uint8_t* data, size_t len) {
    struct ll_entry* e = queue_entry_new(0);
    if (!e) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "proxy_send_msg: queue_entry_new failed subcmd=%02x sid=%08x", subcmd, sid); return -1; }
    e->dgram = u_malloc(TCP_PROXY_HDR_SIZE + len);
    if (!e->dgram) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "proxy_send_msg: malloc(%zu) failed subcmd=%02x sid=%08x", TCP_PROXY_HDR_SIZE + len, subcmd, sid); queue_entry_free(e); return -1; }
    e->dgram[0] = ETCP_ID_TCP_PROXY;
    e->dgram[1] = subcmd;
    memcpy(e->dgram + 2, &sid, 4);
    if (len > 0) memcpy(e->dgram + TCP_PROXY_HDR_SIZE, data, len);
    e->len = TCP_PROXY_HDR_SIZE + len;
    return etcp_route_send(inst, dst, e);
}

static int send_connect(struct proxy_conn* pc) {
    uint8_t buf[6];
    memcpy(buf, pc->dest_ip, 4); memcpy(buf + 4, &pc->dest_port, 2);
    DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "TCP proxy: CONNECT sid=%08x to %d.%d.%d.%d:%d via node %016llx",
               pc->stream_id, pc->dest_ip[0], pc->dest_ip[1], pc->dest_ip[2], pc->dest_ip[3],
               ntohs(pc->dest_port), (unsigned long long)pc->proxy->via_node_id);
    return proxy_send_msg(pc->proxy->inst, pc->proxy->via_node_id,
                           TCP_PROXY_SUBCMD_CONNECT, pc->stream_id, buf, 6);
}

static int send_data(struct proxy_conn* pc, const uint8_t* data, uint16_t len) {
    DEBUG_INFO(DEBUG_CATEGORY_TRAFFIC, "PROXY SEND sid=%08x len=%u", pc->stream_id, len);
    return proxy_send_msg(pc->proxy->inst, pc->proxy->via_node_id,
                           TCP_PROXY_SUBCMD_DATA, pc->stream_id, data, len);
}

static int send_close(struct proxy_conn* pc) {
    return proxy_send_msg(pc->proxy->inst, pc->proxy->via_node_id,
                           TCP_PROXY_SUBCMD_CLOSE, pc->stream_id, NULL, 0);
}

static int send_error(struct proxy_conn* pc) {
    return proxy_send_msg(pc->proxy->inst, pc->proxy->via_node_id,
                           TCP_PROXY_SUBCMD_ERROR, pc->stream_id, NULL, 0);
}

// ====================================================================
// Вывод: lwIP TCP отправляет IP пакеты через этот callback
// ====================================================================
static err_t tcp_output_cb(void *arg, struct pbuf *p, uint32_t src_ip, uint32_t dst_ip) {
    struct tcp_proxy *proxy = (struct tcp_proxy *)arg;
    (void)src_ip; (void)dst_ip;
    uint16_t len = p->tot_len;
    if (len > 2000) return LERR_BUF;
    uint8_t buf[2002];
    if (proxy->tun) {
        pbuf_copy_partial(p, buf, len, 0);
        ssize_t wr = tun_platform_write(proxy->tun, buf, len);
        if (wr != (ssize_t)len) {
            uint16_t ip_total = ((uint16_t)buf[2] << 8) | buf[3];
            uint32_t sip, dip; memcpy(&sip, buf + 12, 4); memcpy(&dip, buf + 16, 4);
            DEBUG_ERROR(DEBUG_CATEGORY_TRAFFIC, "TUN_WRITE_ERR ret=%zd len=%u ip_total=%u", wr, len, ip_total);
        }
    }
    return LERR_OK;
}

// ====================================================================
// Обработчик не-TCP (UDP/ICMP прокси)
// ====================================================================
static int tcp_proxy_handle_non_tcp(struct tcp_proxy* p, uint8_t* buf, size_t len) {
    if (len < 20) return 0;
    uint8_t ip_ver = (buf[0] >> 4) & 0xF;
    if (ip_ver != 4) return 0;
    uint8_t proto = buf[9];
    if (proto == IPPROTO_UDP) {
        if (len < 28) return 0;
        uint32_t src_ip, dst_ip; uint16_t src_port, dst_port;
        memcpy(&src_ip, buf + 12, 4); memcpy(&dst_ip, buf + 16, 4);
        memcpy(&src_port, buf + 20, 2); memcpy(&dst_port, buf + 22, 2);
        udp_proxy_send_to_exit(p->inst, p->via_node_id, src_ip, src_port, dst_ip, dst_port, buf + 28, len - 28);
        return 1;
    }
    if (proto == IPPROTO_ICMP) {
        if (len < 28) return 0;
        uint8_t icmp_type = buf[20];
        if (icmp_type != 8) return 0;
        uint32_t src_ip, dst_ip;
        memcpy(&src_ip, buf + 12, 4); memcpy(&dst_ip, buf + 16, 4);
        uint16_t icmp_id, icmp_seq;
        memcpy(&icmp_id,  buf + 24, 2); memcpy(&icmp_seq, buf + 26, 2);
        icmp_proxy_send_to_exit(p->inst, p->via_node_id, dst_ip, src_ip, icmp_id, icmp_seq, buf + 28, len - 28);
        return 1;
    }
    return 0;
}

// ====================================================================
// Помощник: передача данных из очереди to_lwip в lwIP TCP
// ====================================================================
static void proxy_feed_from_transport(struct proxy_conn *pc) {
    if (!pc->to_lwip || !pc->pcb) return;
    int sent_any = 0;
    uint32_t q_pre = queue_entry_count(pc->to_lwip);
    while (1) {
        uint16_t space = tcp_sndbuf(pc->pcb);
        if (space < TCP_MSS / 2) break;
        struct ll_entry *e = queue_data_get(pc->to_lwip);
        if (!e) break;
        if (e->len <= space) {
            err_t ret = tcp_write(pc->pcb, e->dgram, e->len, TCP_WRITE_FLAG_COPY);
            if (ret == LERR_OK) { sent_any = 1; queue_dgram_free(e); queue_entry_free(e); }
            else { queue_data_put_first(pc->to_lwip, e); break; }
        } else {
            queue_data_put_first(pc->to_lwip, e);
            break;
        }
        queue_resume_callback(pc->to_lwip);
    }
    queue_resume_callback(pc->to_lwip);
    if (sent_any) {
        uint32_t unsent = 0; struct tcp_seg* s;
        for (s = pc->pcb->unsent; s; s = s->next) unsent++;
        DEBUG_DEBUG(DEBUG_CATEGORY_TRAFFIC, "PROXY FEED exit->client sid=%08x fed=%u q=%u->%u snd_wnd=%u cwnd=%u unsent=%u",
                    pc->stream_id, sent_any, q_pre, queue_entry_count(pc->to_lwip), pc->pcb->snd_wnd, pc->pcb->cwnd, unsent);
        tcp_output(pc->pcb);
    }
}

// ====================================================================
// lwIP TCP коллбэки
// ====================================================================
static err_t proxy_accept_cb(void *arg, struct tcp_pcb *newpcb, err_t err) {
    struct tcp_proxy *p = (struct tcp_proxy *)arg;
    if (err != LERR_OK || !newpcb) return LERR_ABRT;

    struct proxy_conn *pc = u_calloc(1, sizeof(struct proxy_conn));
    if (!pc) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "TCP proxy: accept alloc failed"); return LERR_MEM; }
    pc->proxy = p; pc->pcb = newpcb; pc->stream_id = ++p->next_stream_id;

    int i;
    for (i = 0; i < p->mapping_count; i++) {
        if (p->mappings[i].local_port == newpcb->local_port) {
            struct in_addr ra; ra.s_addr = inet_addr(p->mappings[i].remote_ip);
            memcpy(pc->dest_ip, &ra.s_addr, 4);
            pc->dest_port = htons(p->mappings[i].remote_port);
            break;
        }
    }
    if (i == p->mapping_count) {
        memcpy(pc->dest_ip, &newpcb->local_ip, 4);
        pc->dest_port = htons(newpcb->local_port);
    }

    tcp_arg(newpcb, pc);
    tcp_recv(newpcb, proxy_recv_cb);
    tcp_sent(newpcb, proxy_sent_cb);
    tcp_err(newpcb, proxy_err_cb);
    tcp_poll(newpcb, proxy_poll_cb, 2);
    tcp_nagle_disable(newpcb);

    pc->to_lwip = queue_new(p->ua, 0, 0, 0, "to_lwip");

    if (send_connect(pc) != 0) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "TCP proxy: send_connect failed sid=%08x to %d.%d.%d.%d:%d", pc->stream_id, pc->dest_ip[0], pc->dest_ip[1], pc->dest_ip[2], pc->dest_ip[3], ntohs(pc->dest_port)); u_free(pc); return LERR_MEM; }

    pc->next = p->conns; p->conns = pc; p->conn_count++;
    DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "TCP proxy: new conn sid=%08x local_port=%u -> %d.%d.%d.%d:%d total_conns=%d snd_wnd=%u mss=%u",
               pc->stream_id, newpcb->local_port, pc->dest_ip[0], pc->dest_ip[1], pc->dest_ip[2], pc->dest_ip[3], ntohs(pc->dest_port), p->conn_count, newpcb->snd_wnd, newpcb->mss);
    return LERR_OK;
}

static err_t proxy_recv_cb(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err) {
    struct proxy_conn *pc = (struct proxy_conn *)arg;
    if (!pc) { if (p) pbuf_free(p); return LERR_OK; }

    if (p == NULL || err != LERR_OK) {
        DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY FIN sid=%08x pcb_state=%u sndbuf=%u cwnd=%u unsent=%p unacked=%p close_sent=%d",
                   pc->stream_id, pcb->state, pcb->snd_buf, pcb->cwnd,
                   (void*)pcb->unsent, (void*)pcb->unacked, pc->close_sent);
        { uint16_t wnd_gap = TCP_WND_MAX(pcb) - pcb->rcv_wnd;
          if (wnd_gap > 0) tcp_recved(pcb, wnd_gap); }
        pc->tun_closed = 1;
        if (!pc->close_sent) {
            if (send_close(pc) < 0) DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "PROXY FIN send_close failed sid=%08x", pc->stream_id);
            pc->close_sent = 1;
        }
        return LERR_OK;
    }

    uint16_t len = p->tot_len;
    if (pc->error || pc->rem_closed) {
        tcp_recved(pcb, len); pbuf_free(p); return LERR_OK;
    }

    uint8_t *data = u_malloc(len);
    if (data) {
        pbuf_copy_partial(p, data, len, 0);
        if (send_data(pc, data, len) < 0) DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "PROXY recv send_data failed sid=%08x len=%u", pc->stream_id, len);
        u_free(data);
    } else DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "PROXY recv malloc(%u) failed sid=%08x", len, pc->stream_id);
    DEBUG_INFO(DEBUG_CATEGORY_TRAFFIC, "PROXY RECV client->exit sid=%08x len=%u", pc->stream_id, len);
    tcp_recved(pcb, len); pbuf_free(p);
    return LERR_OK;
}

static err_t proxy_sent_cb(void *arg, struct tcp_pcb *pcb, uint16_t len) {
    (void)len;
    struct proxy_conn *pc = (struct proxy_conn *)arg;
    if (!pc) return LERR_OK;
    proxy_feed_from_transport(pc);
    return LERR_OK;
}

static void proxy_err_cb(void *arg, err_t err) {
    struct proxy_conn *pc = (struct proxy_conn *)arg;
    if (!pc) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "PROXY proxy_err_cb: pc=NULL err=%d", err); return; }
    DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "TCP proxy: error %d sid=%08x pcb_state=%u tun_closed=%d rem_closed=%d connected=%d",
                 err, pc->stream_id, pc->pcb ? pc->pcb->state : 0, pc->tun_closed, pc->rem_closed, pc->connected);
    pc->error = 1;
    if (send_error(pc) < 0) DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "PROXY send_error failed sid=%08x", pc->stream_id);
    pc->close_sent = 1;
}

static err_t proxy_poll_cb(void *arg, struct tcp_pcb *pcb) {
    struct proxy_conn *pc = (struct proxy_conn *)arg;
    if (!pc) return LERR_OK;

    if (pc->error) {
        DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "PROXY CLEANUP error sid=%08x tun_closed=%d rem_closed=%d connected=%d", pc->stream_id, pc->tun_closed, pc->rem_closed, pc->connected);
        if (pc->pcb) { tcp_arg(pc->pcb, NULL); tcp_abort(pc->pcb); pc->pcb = NULL; }
        proxy_conn_free(pc);
        return LERR_OK;
    }

    if (pc->tun_closed && pc->rem_closed && pc->pcb) {
        uint32_t pending = pc->to_lwip ? queue_entry_count(pc->to_lwip) : 0;
        int done = (pending == 0 && pcb->unsent == NULL && pcb->unacked == NULL);
        uint32_t sndbuf = tcp_sndbuf(pcb);
        if (done || sndbuf == 0) {
            DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY CLEANUP sid=%08x state=%u sndbuf=%u cwnd=%u pending=%u unsent=%p unacked=%p",
                       pc->stream_id, pcb->state, pcb->snd_buf, pcb->cwnd,
                       pending, (void*)pcb->unsent, (void*)pcb->unacked);
            struct tcp_pcb *save = pc->pcb; pc->pcb = NULL;
            tcp_arg(save, NULL);
            { uint16_t wnd_gap = TCP_WND_MAX(save) - save->rcv_wnd;
              if (wnd_gap > 0) tcp_recved(save, wnd_gap); }
            while (save->unsent) { struct tcp_seg *seg = save->unsent; save->unsent = seg->next; u_free(seg); }
            tcp_close(save);
            proxy_conn_free(pc);
        }
    }
    return LERR_OK;
}

// ====================================================================
// Обеспечить динамический listen pcb для прозрачного исходящего TCP проксирования
// ====================================================================
static void tcp_proxy_ensure_outbound_listen(struct tcp_proxy* p, uint16_t dport_net) {
    uint16_t dport_host = ntohs(dport_net);
    struct tcp_pcb* lp = p->lwip->listen_pcbs;
    while (lp) { if (lp->local_port == dport_host) return; lp = lp->next; }
    struct tcp_pcb* lpcb = tcp_new(p->lwip);
    if (!lpcb) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "TCP proxy: tcp_new failed for dynamic listen port %u", dport_host); return; }
    tcp_bind(lpcb, INADDR_ANY, dport_net);
    struct tcp_pcb* listen_pcb = tcp_listen(lpcb);
    if (listen_pcb) {
        tcp_arg(listen_pcb, p); tcp_accept(listen_pcb, proxy_accept_cb);
        DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "TCP proxy: dynamic listen on port %u", dport_host);
    }
}

// ====================================================================
// Ввод: IP пакет → lwip_tcp (из TUN output_queue)
// ====================================================================
static void tcp_proxy_tun_input(struct ll_queue* q, void* arg) {
    struct tcp_proxy* p = (struct tcp_proxy*)arg;
    struct ll_entry* entry = queue_data_get(q);
    if (!entry) return;
    if (entry->dgram && entry->len > 1) {
        uint8_t* ip = entry->dgram + 1; size_t len = entry->len - 1;
        if (len > 20 && len <= 2000) {
            if (!tcp_proxy_handle_non_tcp(p, ip, len)) {
                uint8_t proto = ip[9];
                if (proto == IPPROTO_TCP) {
                    uint16_t ip_hdr_len = (ip[0] & 0x0F) * 4;
                    uint16_t ip_total = ((uint16_t)ip[2] << 8) | ip[3];
                    if (ip_hdr_len >= 20 && ip_total >= ip_hdr_len && len >= ip_total) {
                        uint16_t dport_net; memcpy(&dport_net, ip + ip_hdr_len + 2, 2);
                        tcp_proxy_ensure_outbound_listen(p, dport_net);
                        uint32_t src_ip, dst_ip;
                        memcpy(&src_ip, ip + 12, 4); memcpy(&dst_ip, ip + 16, 4);
                        uint16_t tcp_len = ip_total - ip_hdr_len;
                        struct pbuf *pb = pbuf_alloc(PBUF_RAW, tcp_len);
                        if (pb) { pbuf_take(pb, ip + ip_hdr_len, tcp_len); lwip_tcp_input(p->lwip, pb, src_ip, dst_ip); }
                    }
                }
            }
        }
    }
    queue_dgram_free(entry); queue_entry_free(entry); queue_resume_callback(q);
}

// ====================================================================
// Очистка proxy_conn
// ====================================================================
static void proxy_conn_free(struct proxy_conn *pc) {
    if (!pc) return;
    struct tcp_proxy *p = pc->proxy;
    uint32_t pending = pc->to_lwip ? queue_entry_count(pc->to_lwip) : 0;
    DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY FREE sid=%08x total_conns=%d to_lwip_q=%u",
               pc->stream_id, p->conn_count, pending);
    struct proxy_conn **prev = &p->conns;
    while (*prev) { if (*prev == pc) { *prev = pc->next; p->conn_count--; break; } prev = &(*prev)->next; }
    if (pc->to_lwip) {
        struct ll_entry *e;
        while ((e = queue_data_get(pc->to_lwip))) { queue_dgram_free(e); queue_entry_free(e); }
        queue_free(pc->to_lwip); pc->to_lwip = NULL;
    }
    u_free(pc);
}

// ====================================================================
// Обработчики входящих сообщений (сторона клиента)
// ====================================================================
static struct proxy_conn* find_pc_by_stream(struct tcp_proxy* p, uint32_t stream_id) {
    struct proxy_conn* pc;
    for (pc = p->conns; pc; pc = pc->next) if (pc->stream_id == stream_id) return pc;
    return NULL;
}

static void handle_connected(struct tcp_proxy* p, uint32_t stream_id, struct ll_entry* entry) {
    struct proxy_conn* pc = find_pc_by_stream(p, stream_id);
    if (!pc) { DEBUG_WARN(DEBUG_CATEGORY_SOCKET, "PROXY CONNECTED sid=%08x — no conn, drop", stream_id); queue_dgram_free(entry); queue_entry_free(entry); return; }
    if (entry->len >= TCP_PROXY_CONNECTED_HDR_SIZE) {
        uint8_t status = entry->dgram[TCP_PROXY_HDR_SIZE + 2];
        if (status == TCP_PROXY_CONNECTED_OK) {
            pc->connected = 1;
            uint16_t local_port = 0; memcpy(&local_port, entry->dgram + TCP_PROXY_HDR_SIZE, 2);
            DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY CONNECTED sid=%08x exit_port=%u", stream_id, ntohs(local_port));
        } else {
            DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "TCP proxy: remote refused sid=%08x", stream_id);
            pc->rem_closed = 1;
        }
    }
    queue_dgram_free(entry); queue_entry_free(entry);
}

static void handle_data(struct tcp_proxy* p, struct ETCP_CONN* conn, uint32_t stream_id, struct ll_entry* entry) {
    struct proxy_conn* pc = find_pc_by_stream(p, stream_id);
    if (!pc) {
        DEBUG_WARN(DEBUG_CATEGORY_SOCKET, "PROXY DATA sid=%08x — нет соединения, шлём CLOSE", stream_id);
        if (conn) proxy_send_msg(p->inst, conn->peer_node_id, TCP_PROXY_SUBCMD_CLOSE, stream_id, NULL, 0);
        queue_dgram_free(entry); queue_entry_free(entry); return;
    }
    if (pc->rem_closed || pc->error) { queue_dgram_free(entry); queue_entry_free(entry); return; }
    size_t data_len = entry->len - TCP_PROXY_HDR_SIZE;
    DEBUG_INFO(DEBUG_CATEGORY_TRAFFIC, "PROXY DATA <- sid=%08x len=%zu", stream_id, data_len);
    if (data_len > 0) {
        struct ll_entry* e = entry_from_data(pc->proxy->entry_pool, entry->dgram + TCP_PROXY_HDR_SIZE, (uint16_t)data_len);
        if (e) queue_data_put(pc->to_lwip, e);
        proxy_feed_from_transport(pc);
    }
    queue_dgram_free(entry); queue_entry_free(entry);
}

static void handle_close(struct tcp_proxy* p, uint32_t stream_id) {
    struct proxy_conn* pc = find_pc_by_stream(p, stream_id);
    if (pc) {
        DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY REM_CLOSED sid=%08x tun_closed=%d connected=%d",
                   stream_id, pc->tun_closed, pc->connected);
        pc->rem_closed = 1;
    } else DEBUG_WARN(DEBUG_CATEGORY_SOCKET, "PROXY CLOSE sid=%08x — no conn", stream_id);
}

static void handle_error(struct tcp_proxy* p, uint32_t stream_id) {
    struct proxy_conn* pc = find_pc_by_stream(p, stream_id);
    if (pc) {
        DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "PROXY ERROR from exit sid=%08x tun_closed=%d rem_closed=%d connected=%d",
                    stream_id, pc->tun_closed, pc->rem_closed, pc->connected);
        pc->error = 1;
    } else DEBUG_WARN(DEBUG_CATEGORY_SOCKET, "PROXY ERROR sid=%08x — no conn", stream_id);
}

// ====================================================================
// Единый обработчик etcp_router (диспетчеризация в tcp_proxy или remote_proxy)
// ====================================================================
void tcp_proxy_etcp_recv_cb(struct ETCP_CONN* conn, struct ll_entry* entry) {
    if (!entry || !entry->dgram || entry->len < TCP_PROXY_HDR_SIZE) {
        if (entry) { DEBUG_WARN(DEBUG_CATEGORY_SOCKET, "TCP proxy: bad entry len=%u", entry->len); queue_dgram_free(entry); queue_entry_free(entry); }
        return;
    }
    uint8_t   subcmd    = entry->dgram[1];
    uint32_t  stream_id; memcpy(&stream_id, entry->dgram + 2, 4);
    struct UTUN_INSTANCE* inst = conn ? conn->instance : NULL;
    struct tcp_proxy* proxy = inst ? inst->tcp_proxy : NULL;

    if (subcmd == TCP_PROXY_SUBCMD_CONNECT) {
        uint64_t src_node_id = conn ? conn->peer_node_id : (inst ? inst->node_id : 0);
        remote_proxy_handle_connect(inst, entry, stream_id, src_node_id);
        return;
    }
    if (inst && inst->remote_proxy.enabled) {
        struct remote_proxy_conn* rc = remote_proxy_find_conn(&inst->remote_proxy, stream_id);
        if (rc) {
            if (subcmd == TCP_PROXY_SUBCMD_DATA)  { remote_proxy_handle_data(inst, conn, entry, stream_id); return; }
            if (subcmd == TCP_PROXY_SUBCMD_CLOSE) { remote_proxy_handle_close(inst, stream_id); queue_dgram_free(entry); queue_entry_free(entry); return; }
            if (subcmd == TCP_PROXY_SUBCMD_ERROR) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "RP ERROR recv sid=%08x", stream_id); rc->error = 1; rp_conn_free(rc); queue_dgram_free(entry); queue_entry_free(entry); return; }
        }
    }
    if (proxy) {
        if (subcmd == TCP_PROXY_SUBCMD_CONNECTED) { handle_connected(proxy, stream_id, entry); return; }
        if (subcmd == TCP_PROXY_SUBCMD_DATA)      { handle_data(proxy, conn, stream_id, entry); return; }
        if (subcmd == TCP_PROXY_SUBCMD_CLOSE)      { handle_close(proxy, stream_id); queue_dgram_free(entry); queue_entry_free(entry); return; }
        if (subcmd == TCP_PROXY_SUBCMD_ERROR)      { handle_error(proxy, stream_id); queue_dgram_free(entry); queue_entry_free(entry); return; }
    }
    DEBUG_WARN(DEBUG_CATEGORY_SOCKET, "TCP proxy: unhandled subcmd=%02x sid=%08x", subcmd, stream_id);
    queue_dgram_free(entry); queue_entry_free(entry);
}

// ====================================================================
// Публичное API
// ====================================================================
struct tcp_proxy* tcp_proxy_create(struct UTUN_INSTANCE* inst, struct UASYNC* ua,
    const char* tun_name, const char* tun_ip, int mtu, int test_mode,
    struct tcp_proxy_mapping_config* mappings, int mapping_count,
    uint64_t via_node_id)
{
    if (!ua) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "tcp_proxy_create: ua is NULL"); return NULL; }
    if (!tun_name || !tun_ip) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "tcp_proxy_create: tun name/ip required"); return NULL; }

    struct tcp_proxy* p = u_calloc(1, sizeof(struct tcp_proxy));
    if (!p) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "tcp_proxy_create: u_calloc failed"); return NULL; }
    p->inst = inst; p->ua = ua; p->next_stream_id = 1;
    p->via_node_id = via_node_id;
    p->mappings = mappings; p->mapping_count = mapping_count;

    p->entry_pool = memory_pool_init(sizeof(struct ll_entry));
    if (!p->entry_pool) { DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "tcp_proxy_create: memory_pool_init failed"); u_free(p); return NULL; }

    p->tun = tun_init_nat(ua, tun_name, tun_ip, mtu > 0 ? mtu : 1500, test_mode);
    if (!p->tun) { DEBUG_ERROR(DEBUG_CATEGORY_TUN, "tcp_proxy: failed to create TUN %s", tun_name); memory_pool_destroy(p->entry_pool); u_free(p); return NULL; }
    queue_set_callback(p->tun->output_queue, tcp_proxy_tun_input, p);

    p->lwip = lwip_tcp_init(ua, tcp_output_cb, p);
    if (!p->lwip) {
        DEBUG_ERROR(DEBUG_CATEGORY_SOCKET, "tcp_proxy_create: lwip_tcp_init failed");
        tun_close(p->tun);
        memory_pool_destroy(p->entry_pool); u_free(p); return NULL;
    }

    if (mapping_count > 0) {
        int j; for (j = 0; j < mapping_count; j++) {
            uint16_t port_net = htons(mappings[j].local_port);
            struct tcp_pcb *lpcb = tcp_new(p->lwip);
            if (!lpcb) continue;
            tcp_bind(lpcb, INADDR_ANY, port_net);
            struct tcp_pcb *listen_pcb = tcp_listen(lpcb);
            if (listen_pcb) {
                tcp_arg(listen_pcb, p);
                tcp_accept(listen_pcb, proxy_accept_cb);
            }
        }
    }

    if (inst) {
        if (etcp_router_bind(inst, ETCP_ID_TCP_PROXY, tcp_proxy_etcp_recv_cb) != 0) {
            DEBUG_WARN(DEBUG_CATEGORY_SOCKET, "TCP proxy: etcp_router_bind failed");
        } else {
            DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "TCP proxy: etcp_router bind registered for ID=0x%02x", ETCP_ID_TCP_PROXY);
            udp_proxy_init(inst, ua);
            icmp_proxy_init(inst, ua);
        }
    }

    DEBUG_INFO(DEBUG_CATEGORY_TUN, "TCP proxy created: mappings=%d via_node=%016llx", mapping_count, (unsigned long long)via_node_id);
    return p;
}

void tcp_proxy_destroy(struct tcp_proxy* p) {
    if (!p) return;
    DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "TCP proxy destroying: conns=%d", p->conn_count);
    if (p->inst) etcp_router_unbind(p->inst, ETCP_ID_TCP_PROXY);
    udp_proxy_destroy(p->inst);
    icmp_proxy_destroy(p->inst);

    if (p->lwip) { lwip_tcp_destroy(p->lwip); p->lwip = NULL; }

    struct proxy_conn* pc = p->conns;
    while (pc) {
        struct proxy_conn* next = pc->next;
        if (pc->pcb) { tcp_arg(pc->pcb, NULL); tcp_abort(pc->pcb); pc->pcb = NULL; }
        if (pc->to_lwip) {
            struct ll_entry *e;
            while ((e = queue_data_get(pc->to_lwip))) { queue_dgram_free(e); queue_entry_free(e); }
            queue_free(pc->to_lwip); pc->to_lwip = NULL;
        }
        u_free(pc); pc = next;
    }
    p->conns = NULL;

    if (p->tun) tun_close(p->tun);
    if (p->entry_pool) memory_pool_destroy(p->entry_pool);
    u_free(p);
}