fix: initial consumer_ack in handle_connect + diag: send_q, BACKPRESSURE, ACK logs

handle_connect: send first consumer_ack after setting consumer_ack=1
to unblock client router — fixes rq=32/send_q=256 deadlock.

diag_timer_cb: added send_q=N to DIAG line for instant root cause visibility.
read_queue_drain_cb: SOCK:BACKPRESSURE log with send_q count.
write_on_get_cb: SOCK:ACK debug log on each consumer_ack.

src/proxy/tcp_proxy_server.c

@@ -104,10 +104,13 @@ static void send_error(struct tcp_proxy_server_conn* rc) {
 // ====================================================================
 
 static void write_on_get_cb(struct ll_queue* q, void* arg) {
-    (void)q;
     struct tcp_proxy_server_conn* rc = (struct tcp_proxy_server_conn*)arg;
     struct UTUN_INSTANCE* inst = rc->ctx ? rc->ctx->inst : NULL;
-    if (inst) etcp_router_consumer_ack(inst, rc->peer_node_id, ETCP_ID_TCP_PROXY);
+    if (!inst) return;
+    DEBUG_DEBUG(DEBUG_CATEGORY_SOCKET, "SOCK:ACK fd=%d sid=%08x write_q=%d",
+                rc->tc ? (int)rc->tc->sock : -1, rc->stream_id,
+                queue_entry_count(q));
+    etcp_router_consumer_ack(inst, rc->peer_node_id, ETCP_ID_TCP_PROXY);
 }
 
 static void on_fin_cb(struct tcp_conn* tc, void* arg) {
@@ -140,6 +143,15 @@ static void diag_timer_cb(void* arg) {
     int ent_f = tc->entry_pool->free_count;
     int dat_f = tc->data_pool->free_count;
 
+    int sq = 0;
+    {
+        struct UTUN_INSTANCE* inst = rc->ctx ? rc->ctx->inst : NULL;
+        if (inst) {
+            struct ETCP_ROUTER_CONN* rconn = etcp_router_conn_get(inst, rc->peer_node_id, ETCP_ID_TCP_PROXY);
+            if (rconn && rconn->send_q) sq = queue_entry_count(rconn->send_q);
+        }
+    }
+
     int rcv_buf = 0, snd_buf = 0;
     socklen_t optlen = sizeof(int);
     getsockopt(tc->sock, SOL_SOCKET, SO_RCVBUF, &rcv_buf, &optlen);
@@ -147,11 +159,12 @@ static void diag_timer_cb(void* arg) {
 
     DEBUG_INFO(DEBUG_CATEGORY_SOCKET,
         "SOCK:DIAG fd=%d sid=%08x conn=%d fin=%d "
-        "rq=%d(%zub) wq=%d(%zub) wbuf=%s "
+        "rq=%d(%zub) wq=%d(%zub) send_q=%d wbuf=%s "
         "ent_f=%d dat_f=%d tcp_rb=%zu tcp_sb=%zu",
         (int)tc->sock, rc->stream_id, tc->connected, tc->fin,
         tc->read_queue->count,  queue_total_bytes(tc->read_queue),
         tc->write_queue->count, queue_total_bytes(tc->write_queue),
+        sq,
         tc->write_buf ? "y" : "n",
         ent_f, dat_f,
         (size_t)rcv_buf, (size_t)snd_buf);
@@ -177,9 +190,11 @@ static void read_queue_drain_cb(struct ll_queue* q, void* arg) {
         queue_resume_callback(q);
     } else {
         struct ETCP_ROUTER_CONN* rconn = etcp_router_conn_get(inst, rc->peer_node_id, ETCP_ID_TCP_PROXY);
-        if (rconn && rconn->send_q)
+        if (rconn && rconn->send_q) {
+            DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "SOCK:BACKPRESSURE fd=%d sid=%08x send_q=%d — pausing drain",
+                       (int)rc->tc->sock, rc->stream_id, queue_entry_count(rconn->send_q));
             queue_waiter_wait(rconn->send_q, &rc->pause_waiter, pause_resume_cb, rc);
-        else
+        } else
             etcp_router_waiter_register(inst, rc->peer_node_id, &rc->pause_waiter, pause_resume_cb, rc);
     }
 }
@@ -274,7 +289,10 @@ int tcp_proxy_server_handle_connect(struct UTUN_INSTANCE* inst, struct ll_entry*
 
     {
         struct ETCP_ROUTER_CONN* rconn = etcp_router_conn_get(inst, src_node_id, ETCP_ID_TCP_PROXY);
-        if (rconn) rconn->consumer_ack = 1;
+        if (rconn) {
+            rconn->consumer_ack = 1;
+            etcp_router_consumer_ack(inst, src_node_id, ETCP_ID_TCP_PROXY);
+        }
     }
     queue_set_on_get(rc->tc->write_queue, write_on_get_cb, rc);