lwip: Added support for configurable LwIP hooks

Added lwIP hooks which could be optionally overwritten in the
application code. These three options are provided in Kconfig:
* NONE: No hook support
* DEFAULT: Default implementation is provided. If IDF doesn't
have a specific hook implementation, an empty stub is provided, which
could be overwritten by strong implementation in application code.
* CUSTOM: Hooks are declared only to be implemented in application code.

Merges https://github.com/espressif/esp-idf/pull/6034

components/lwip/port/esp32/include/lwip_default_hooks.h

@@ -0,0 +1,51 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef _LWIP_DEFAULT_HOOKS_H_
+#define _LWIP_DEFAULT_HOOKS_H_
+#include "lwip/ip_addr.h"
+#include "lwip/arch.h"
+#include "lwip/err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef CONFIG_LWIP_HOOK_TCP_ISN_DEFAULT
+void lwip_init_tcp_isn(u32_t boot_time, const u8_t *secret_16_bytes);
+#endif
+#if defined(CONFIG_LWIP_HOOK_TCP_ISN_CUSTOM) || defined(CONFIG_LWIP_HOOK_TCP_ISN_DEFAULT)
+u32_t lwip_hook_tcp_isn(const ip_addr_t *local_ip, u16_t local_port,
+                        const ip_addr_t *remote_ip, u16_t remote_port);
+#define LWIP_HOOK_TCP_ISN lwip_hook_tcp_isn
+#endif /* CONFIG_LWIP_HOOK_TCP_ISN... */
+
+#if defined(CONFIG_LWIP_HOOK_IP6_ROUTE_CUSTOM) || defined(CONFIG_LWIP_HOOK_IP6_ROUTE_DEFAULT)
+struct netif *
+lwip_hook_ip6_route(const ip6_addr_t *src, const ip6_addr_t *dest);
+
+#define LWIP_HOOK_IP6_ROUTE lwip_hook_ip6_route
+#endif /* CONFIG_LWIP_HOOK_IP6_ROUTE... */
+
+#if defined(CONFIG_LWIP_HOOK_NETCONN_EXT_RESOLVE_CUSTOM) || defined(CONFIG_LWIP_HOOK_NETCONN_EXT_RESOLVE_DEFAULT)
+int lwip_hook_netconn_external_resolve(const char *name, ip_addr_t *addr, u8_t addrtype, err_t *err);
+
+#define LWIP_HOOK_NETCONN_EXTERNAL_RESOLVE lwip_hook_netconn_external_resolve
+#endif /* CONFIG_LWIP_HOOK_NETCONN_EXTERNAL_RESOLVE... */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _LWIP_DEFAULT_HOOKS_H_ */