From 41a68b86bc2ec52c60da8ad0c7ebff7eb9ce710b Mon Sep 17 00:00:00 2001
From: evgeny <evgeny@adaptto.ru>
Date: Wed, 21 Oct 2026 22:43:54 +0200
Subject: [PATCH] Close NAT channels after cancelling producers and quiet
 transient TUN backpressure

---
 src/nat_transport.c     | 10 ++++++++++
 src/tun_if.c            |  4 +++-
 tests/test_nat_engine.c |  2 ++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/nat_transport.c b/src/nat_transport.c
index 5fa40162..5f804a44 100644
--- a/src/nat_transport.c
+++ b/src/nat_transport.c
@@ -315,6 +315,16 @@ void nat_transport_destroy(struct UTUN_INSTANCE* inst) {
     struct ll_entry* peer;
     while ((peer = queue_data_get(tr->peers))) nat_peer_free((struct nat_peer*)peer);
     queue_free(tr->peers);
+    // После отмены producers закрыть только каналы NAT; остальные сервисы ядра продолжают работать.
+    while (inst->router_conns) {
+        struct ETCP_ROUTER_CONN* route = NULL;
+        for (struct ll_entry* e = inst->router_conns->head; e; e = e->next) {
+            struct ETCP_ROUTER_CONN* candidate = (struct ETCP_ROUTER_CONN*)e;
+            if (candidate->svc_id == ETCP_RT_ID_NAT) { route = candidate; break; }
+        }
+        if (!route) break;
+        etcp_router_conn_close(route);
+    }
     nat_packet_free(tr->tun_pending);
     tun_close(tr->nat_tun);
     eim_nat_destroy_ctx(&inst->nat);
diff --git a/src/tun_if.c b/src/tun_if.c
index 1593346d..96c765ff 100644
--- a/src/tun_if.c
+++ b/src/tun_if.c
@@ -255,7 +255,9 @@ ssize_t tun_write(struct tun_if* tun, const uint8_t* buf, size_t len) {
     } while (n < 0 && errno == EINTR);
     if (n != (ssize_t)len) {
         int error = n < 0 ? errno : EIO;
-        DEBUG_ERROR(DEBUG_CATEGORY_TUN, "TUN %s write failed: requested=%zu written=%zd error=%s", tun->ifname, len, n, strerror(error));
+        if (error == EAGAIN || error == EWOULDBLOCK)
+            DEBUG_DEBUG(DEBUG_CATEGORY_TUN, "TUN %s write backpressure: requested=%zu", tun->ifname, len);
+        else DEBUG_ERROR(DEBUG_CATEGORY_TUN, "TUN %s write failed: requested=%zu written=%zd error=%s", tun->ifname, len, n, strerror(error));
         tun->write_errors++;
         errno = error;
         return -1;
diff --git a/tests/test_nat_engine.c b/tests/test_nat_engine.c
index be325ef4..98d2455d 100644
--- a/tests/test_nat_engine.c
+++ b/tests/test_nat_engine.c
@@ -1163,6 +1163,8 @@ static void test_hash_lifecycle(void) {
         ASSERT_EQ(eim_nat_egress(&ctx, packet, 42, 100000 + i, NULL), EIM_NAT_OK, "reuse freed port");
         uint16_t external; memcpy(&external, packet + 20, 2);
         ASSERT_EQ(be16toh(external), removed[i], "free ports reused in FIFO order");
+    }
+    for (size_t i = 0; i < 3; i++) {
         memcpy(packet, original, 42);
         ASSERT_EQ(eim_nat_egress(&ctx, packet, 42, removed[i], NULL), EIM_NAT_ERROR, "removed key does not alias reused slot");
         ASSERT(memcmp(packet, original, 42) == 0, "full-pool error preserves packet");