Verify direct, reverse-only and incompatible NCD capability checks without side effects

tests/test_node_conn_direct.c

@@ -360,6 +360,31 @@ static int setup(void) {
     config_ensure_keys_and_node_id(ca); config_ensure_keys_and_node_id(cb);
     return 0;
 }
+
+/* Предварительный отбор не создаёт транспорт; reverse допускается при недоступном исходящем адресе. */
+static void test_compatibility(void) {
+    struct TOPO_NODE* peer = topo_node_registry_find(g_a->topo_groups, nid_b);
+    struct TOPO_NODE* self = topo_node_registry_find(g_a->topo_groups, nid_a);
+    if (!self) {
+        if (inject_node(g_a, nid_a, pubkey_a, pa) != 0) { fail("inject self compatibility snapshot"); return; }
+        self = topo_node_registry_find(g_a->topo_groups, nid_a);
+    }
+    struct ETCP_SOCKET* socket = test_etcp_bound_socket(g_a, "s1");
+    if (!peer || !self || !socket || !peer->v4_sock_meta || !self->v4_sock_meta) { fail("compatibility fixture"); return; }
+    if (!node_conn_direct_compatible(g_a, nid_b) || instance_find_conn(g_a, nid_b)) { fail("direct compatibility mutated transport"); return; }
+    struct sockaddr_storage saved_interface = socket->interface_addr;
+    struct sockaddr_in* interface = (struct sockaddr_in*)&socket->interface_addr;
+    interface->sin_addr.s_addr = htonl(UINT32_C(0x08080808));
+    uint8_t saved_cfg = peer->v4_sock_meta->config_type, saved_self = self->v4_sock_meta->config_type;
+    peer->v4_sock_meta->config_type = CFG_SERVER_TYPE_LOCAL;
+    int reverse = node_conn_direct_compatible(g_a, nid_b);
+    self->v4_sock_meta->config_type = CFG_SERVER_TYPE_LOCAL;
+    int incompatible = node_conn_direct_compatible(g_a, nid_b);
+    peer->v4_sock_meta->config_type = saved_cfg; self->v4_sock_meta->config_type = saved_self;
+    socket->interface_addr = saved_interface;
+    if (!reverse || incompatible || instance_find_conn(g_a, nid_b)) { fail("reverse/local compatibility or read-only contract"); return; }
+    fprintf(stderr, "[PASS] compatibility: direct, reverse-only, incompatible local and no transport mutation\n");
+}
 static void cleanup(void) { test_unlink(ca); test_unlink(cb); test_rmdir(tdir); }
 
 int main(void) {
@@ -377,6 +402,7 @@ int main(void) {
             (unsigned long long)nid_a, pa, (unsigned long long)nid_b, pb); fflush(stderr);
     utun_instance_init(g_a); utun_instance_init(g_b);
     if (inject_node(g_a, nid_b, pubkey_b, pb) != 0) { fail("inject_node"); goto done; }
+    test_compatibility(); if (g_result == 2) goto done;
     if (inject_node(g_b, nid_a, pubkey_a, pa) != 0) { fail("inject_node A→B"); goto done; }
     fprintf(stderr, "injected B→A and A→B registries\n"); fflush(stderr);
     uasync_call_soon(ua, NULL, t1);