Fix test_etcp_api: use single callback with connection check

etcp_bind uses global table - multiple binds with same ID overwrite.
Fixed by using single recv_callback that checks conn pointer:
- conn == server_conn: forward direction (client->server)
- conn == client_conn: backward direction (server->client)

Test now passes: All 100 packets transmitted in each direction.

tests/test_etcp_api.c

@@ -154,12 +154,11 @@ static int verify_packet_data(uint8_t* buffer, int size, int expected_seq) {
     return 1;
 }
 
-// Callback для получения пакетов на сервере (forward direction)
-static void server_recv_callback(struct ETCP_CONN* conn, struct ll_entry* entry) {
-    (void)conn;
-    
+// Универсальный callback для получения пакетов
+// Определяет направление по соединению (client_conn vs server_conn)
+static void recv_callback(struct ETCP_CONN* conn, struct ll_entry* entry) {
     if (!entry || !entry->dgram || entry->len < PACKET_HEADER_SIZE + 1) {
-        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Server received invalid packet");
+        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Received invalid packet");
         if (entry) {
             queue_entry_free(entry);
             queue_dgram_free(entry);
@@ -167,40 +166,27 @@ static void server_recv_callback(struct ETCP_CONN* conn, struct ll_entry* entry)
         return;
     }
     
-    // Verify packet with strict sequence checking
-    if (verify_packet_data(entry->dgram, entry->len, packets_received_fwd)) {
-        packets_received_fwd++;
-    } else {
-        int seq = entry->dgram[1] | (entry->dgram[2] << 8);
-        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Server packet verification failed, seq=%d, expected=%d", 
-                    seq, packets_received_fwd);
-    }
-    
-    // Освобождаем entry и dgram
-    queue_entry_free(entry);
-    queue_dgram_free(entry);
-}
-
-// Callback для получения пакетов на клиенте (backward direction)
-static void client_recv_callback(struct ETCP_CONN* conn, struct ll_entry* entry) {
-    (void)conn;
-    
-    if (!entry || !entry->dgram || entry->len < PACKET_HEADER_SIZE + 1) {
-        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Client received invalid packet");
-        if (entry) {
-            queue_entry_free(entry);
-            queue_dgram_free(entry);
+    // Определяем направление по соединению
+    if (conn == server_conn) {
+        // Пакет пришел на сервер (forward direction: client->server)
+        if (verify_packet_data(entry->dgram, entry->len, packets_received_fwd)) {
+            packets_received_fwd++;
+        } else {
+            int seq = entry->dgram[1] | (entry->dgram[2] << 8);
+            DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Server packet verification failed, seq=%d, expected=%d", 
+                        seq, packets_received_fwd);
+        }
+    } else if (conn == client_conn) {
+        // Пакет пришел на клиент (backward direction: server->client)
+        if (verify_packet_data(entry->dgram, entry->len, packets_received_back)) {
+            packets_received_back++;
+        } else {
+            int seq = entry->dgram[1] | (entry->dgram[2] << 8);
+            DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Client packet verification failed, seq=%d, expected=%d", 
+                        seq, packets_received_back);
         }
-        return;
-    }
-    
-    // Verify packet with strict sequence checking
-    if (verify_packet_data(entry->dgram, entry->len, packets_received_back)) {
-        packets_received_back++;
     } else {
-        int seq = entry->dgram[1] | (entry->dgram[2] << 8);
-        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Client packet verification failed, seq=%d, expected=%d", 
-                    seq, packets_received_back);
+        DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "Unknown connection %p", (void*)conn);
     }
     
     // Освобождаем entry и dgram
@@ -486,21 +472,14 @@ int main() {
     // Инициализация ETCP API
     etcp_api_init();
     
-    // Регистрируем callbacks для получения пакетов
-    if (etcp_bind(DATA_PACKET_ID, server_recv_callback) != 0) {
-        printf("Failed to bind server callback\n");
-        etcp_api_deinit();
-        return 1;
-    }
-    
-    if (etcp_bind(DATA_PACKET_ID, client_recv_callback) != 0) {
-        printf("Failed to bind client callback\n");
-        etcp_unbind(DATA_PACKET_ID);
+    // Регистрируем callback для получения пакетов (один на все соединения)
+    if (etcp_bind(DATA_PACKET_ID, recv_callback) != 0) {
+        printf("Failed to bind callback\n");
         etcp_api_deinit();
         return 1;
     }
     
-    printf("Callbacks registered for ID=%d\n", DATA_PACKET_ID);
+    printf("Callback registered for ID=%d\n", DATA_PACKET_ID);
 
     printf("Creating server...\n");
     ua = uasync_create();