feat: per-connection diagnostic timer in tcp_proxy_server

1-sec diag_timer_cb prints rq/wq counts+bytes, outstanding pool
allocations, tcp kernel buffer sizes (SO_RCVBUF/SO_SNDBUF).
Started in handle_connect, cancelled in conn_free.

src/proxy/tcp_proxy_server.c

@@ -32,6 +32,7 @@ static void on_flushed_cb(struct tcp_conn* tc, void* arg);
 static void read_queue_drain_cb(struct ll_queue* q, void* arg);
 static void pause_resume_cb(struct ll_queue* q, void* arg);
 static void close_retry_cb(void* arg);
+static void diag_timer_cb(void* arg);
 static int  send_msg(struct UTUN_INSTANCE* inst, uint64_t dst, uint8_t subcmd,
                      uint32_t sid, const uint8_t* data, size_t len);
 static void send_close(struct tcp_proxy_server_conn* rc);
@@ -123,6 +124,35 @@ static void on_error_cb(struct tcp_conn* tc, int err, void* arg) {
     tcp_proxy_server_conn_free(rc);
 }
 
+static void diag_timer_cb(void* arg) {
+    struct tcp_proxy_server_conn* rc = (struct tcp_proxy_server_conn*)arg;
+    struct tcp_conn* tc = rc->tc;
+    if (!tc || tc->sock == SOCKET_INVALID) return;
+
+    size_t ea, er, da, dr;
+    memory_pool_get_stats(tc->entry_pool, &ea, &er);
+    memory_pool_get_stats(tc->data_pool,  &da, &dr);
+
+    int rcv_buf = 0, snd_buf = 0;
+    socklen_t optlen = sizeof(int);
+    getsockopt(tc->sock, SOL_SOCKET, SO_RCVBUF, &rcv_buf, &optlen);
+    getsockopt(tc->sock, SOL_SOCKET, SO_SNDBUF, &snd_buf, &optlen);
+
+    DEBUG_INFO(DEBUG_CATEGORY_SOCKET,
+        "SOCK:DIAG fd=%d sid=%08x conn=%d err=%d fin=%d "
+        "rpaused=%d wmon=%d rq=%d(%zdb) wq=%d(%zdb) wbuf=%s "
+        "entry=%zd data=%zd tcp_rb=%d tcp_sb=%d",
+        (int)tc->sock, rc->stream_id, tc->connected, tc->error, tc->fin,
+        tc->read_paused, tc->write_monitor,
+        tc->read_queue->count,  queue_total_bytes(tc->read_queue),
+        tc->write_queue->count, queue_total_bytes(tc->write_queue),
+        tc->write_buf ? "y" : "n",
+        (ssize_t)(ea - er), (ssize_t)(da - dr),
+        rcv_buf, snd_buf);
+
+    rc->diag_timer = uasync_set_timeout(rc->ua, 10000, rc, diag_timer_cb, "tps_diag");
+}
+
 // ====================================================================
 // Дрейн read_queue → ETCP (автозабор + backpressure)
 // ====================================================================
@@ -173,6 +203,7 @@ void tcp_proxy_server_conn_free(struct tcp_proxy_server_conn* rc) {
     }
     if (rc->tc) { tcp_conn_destroy(rc->tc); rc->tc = NULL; }
     if (rc->close_timer) { uasync_cancel_timeout(rc->ua, rc->close_timer); rc->close_timer = NULL; }
+    if (rc->diag_timer) { uasync_cancel_timeout(rc->ua, rc->diag_timer); rc->diag_timer = NULL; }
     if (rc->ctx && rc->ctx->inst) etcp_router_waiter_cancel(rc->ctx->inst, rc->peer_node_id, &rc->pause_waiter);
     u_free(rc);
 }
@@ -224,6 +255,7 @@ int tcp_proxy_server_handle_connect(struct UTUN_INSTANCE* inst, struct ll_entry*
     }
 
     rc->next = ctx->conns; ctx->conns = rc;
+    rc->diag_timer = uasync_set_timeout(rc->ua, 10000, rc, diag_timer_cb, "tps_diag");
     queue_dgram_free(entry); queue_entry_free(entry);
     return 0;
 }

src/proxy/tcp_proxy_server.h

@@ -34,6 +34,7 @@ struct tcp_proxy_server_conn {
 
     void*    close_timer;      // таймер повтора CLOSE/ERROR
     int      close_backoff;    // backoff: 50..5000 tb (5ms..500ms)
+    void*    diag_timer;       // 1-секундный таймер диагностики
 
     struct queue_waiter_handle pause_waiter;
     struct UASYNC* ua;