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/esp_netif/lwip/esp_netif_lwip.c

@@ -33,8 +33,8 @@
 #include "lwip/dns.h"
 #endif
 
-#if CONFIG_LWIP_TCP_ISN_HOOK
+#if CONFIG_LWIP_HOOK_TCP_ISN_DEFAULT
-#include "tcp_isn.h"
+#include "lwip_default_hooks.h"
 #endif
 
 #include "esp_netif_lwip_ppp.h"
@@ -273,7 +273,7 @@ esp_err_t esp_netif_init(void)
 {
     if (tcpip_initialized == false) {
         tcpip_initialized = true;
-#if CONFIG_LWIP_TCP_ISN_HOOK
+#if CONFIG_LWIP_HOOK_TCP_ISN_DEFAULT
         uint8_t rand_buf[16];
         /*
          * This is early startup code where WiFi/BT is yet to be enabled and hence

components/lwip/CMakeLists.txt

@@ -4,7 +4,6 @@ set(include_dirs
     lwip/src/include
     port/esp32/include
     port/esp32/include/arch
-    port/esp32/tcp_isn
     )
 
 set(srcs
@@ -87,6 +86,8 @@ set(srcs
     "lwip/src/netif/ppp/upap.c"
     "lwip/src/netif/ppp/utils.c"
     "lwip/src/netif/ppp/vj.c"
+    "port/esp32/hooks/tcp_isn_default.c"
+    "port/esp32/hooks/lwip_default_hooks.c"
     "port/esp32/debug/lwip_debug.c"
     "port/esp32/freertos/sys_arch.c"
     "port/esp32/netif/dhcp_state.c"
@@ -136,10 +137,6 @@ else()
     list(APPEND srcs "port/esp32/no_vfs_syscalls.c")
 endif()
 
-if(CONFIG_LWIP_TCP_ISN_HOOK)
-    list(APPEND srcs "port/esp32/tcp_isn/tcp_isn.c")
-endif()
-
 idf_component_register(SRCS "${srcs}"
                     INCLUDE_DIRS "${include_dirs}"
                     LDFRAGMENTS linker.lf

components/lwip/Kconfig

@@ -327,17 +327,6 @@ menu "LWIP"
 
     menu "TCP"
 
-        config LWIP_TCP_ISN_HOOK
-            bool "Enable TCP ISN Hook"
-            default y
-            help
-                Enables custom TCP ISN hook to randomize initial sequence
-                number in TCP connection. This is recommended as default
-                lwIP implementation (`tcp_next_iss`) is not very strong,
-                as it does not take into consideration any platform
-                specific entropy source.
-
-
         config LWIP_MAX_ACTIVE_TCP
             int "Maximum active TCP Connections"
             range 1 1024
@@ -750,6 +739,74 @@ menu "LWIP"
             Enable this option allows lwip to check assert.
             It is recommended to keep it open, do not close it.
 
+    menu "Hooks"
+
+        choice LWIP_HOOK_TCP_ISN
+            prompt "TCP ISN Hook"
+            default LWIP_HOOK_TCP_ISN_DEFAULT
+            help
+                Enables to define a TCP ISN hook to randomize initial sequence
+                number in TCP connection.
+                The default TCP ISN algorithm used in IDF (standardized in RFC 6528)
+                produces ISN by combining an MD5 of the new TCP id and a stable
+                secret with the current time.
+                This is because the lwIP implementation (`tcp_next_iss`) is not
+                very strong, as it does not take into consideration any platform
+                specific entropy source.
+
+                Set to LWIP_HOOK_TCP_ISN_CUSTOM to provide custom implementation.
+                Set to LWIP_HOOK_TCP_ISN_NONE to use lwIP implementation.
+
+
+            config LWIP_HOOK_TCP_ISN_NONE
+                bool "No hook declared"
+            config LWIP_HOOK_TCP_ISN_DEFAULT
+                bool "Default implementation"
+            config LWIP_HOOK_TCP_ISN_CUSTOM
+                bool "Custom implementation"
+
+        endchoice
+
+        choice LWIP_HOOK_IP6_ROUTE
+            prompt "IPv6 route Hook"
+            default LWIP_HOOK_IP6_ROUTE_NONE
+            help
+                Enables custom IPv6 route hook.
+                Setting this to "default" provides weak implementation
+                stub that could be overwritten in application code.
+                Setting this to "custom" provides hook's declaration
+                only and expects the application to implement it.
+
+            config LWIP_HOOK_IP6_ROUTE_NONE
+                bool "No hook declared"
+            config LWIP_HOOK_IP6_ROUTE_DEFAULT
+                bool "Default (weak) implementation"
+            config LWIP_HOOK_IP6_ROUTE_CUSTOM
+                bool "Custom implementation"
+
+        endchoice
+
+        choice LWIP_HOOK_NETCONN_EXTERNAL_RESOLVE
+            prompt "Netconn external resolve Hook"
+            default LWIP_HOOK_NETCONN_EXT_RESOLVE_NONE
+            help
+                Enables custom DNS resolve hook.
+                Setting this to "default" provides weak implementation
+                stub that could be overwritten in application code.
+                Setting this to "custom" provides hook's declaration
+                only and expects the application to implement it.
+
+            config LWIP_HOOK_NETCONN_EXT_RESOLVE_NONE
+                bool "No hook declared"
+            config LWIP_HOOK_NETCONN_EXT_RESOLVE_DEFAULT
+                bool "Default (weak) implementation"
+            config LWIP_HOOK_NETCONN_EXT_RESOLVE_CUSTOM
+                bool "Custom implementation"
+
+        endchoice
+
+    endmenu # Hooks
+
     menu "Debug"
 
         config LWIP_NETIF_DEBUG

components/lwip/component.mk

@@ -8,8 +8,7 @@ COMPONENT_ADD_INCLUDEDIRS := \
 	include/apps/sntp \
 	lwip/src/include \
 	port/esp32/include \
-	port/esp32/include/arch \
+	port/esp32/include/arch
-	port/esp32/tcp_isn
 
 COMPONENT_SRCDIRS := \
 	apps/dhcpserver \
@@ -24,6 +23,7 @@ COMPONENT_SRCDIRS := \
 	lwip/src/netif \
 	port/esp32 \
 	port/esp32/freertos \
+	port/esp32/hooks \
 	port/esp32/netif \
 	port/esp32/debug
 
@@ -40,10 +40,6 @@ ifdef CONFIG_LWIP_PPP_SUPPORT
     COMPONENT_SRCDIRS += lwip/src/netif/ppp lwip/src/netif/ppp/polarssl
 endif
 
-ifdef CONFIG_LWIP_TCP_ISN_HOOK
-    COMPONENT_SRCDIRS += port/esp32/tcp_isn
-endif
-
 CFLAGS += -Wno-address  # lots of LWIP source files evaluate macros that check address of stack variables
 
 lwip/src/netif/ppp/ppp.o: CFLAGS += -Wno-uninitialized

components/lwip/port/esp32/hooks/lwip_default_hooks.c

@@ -0,0 +1,40 @@
+// 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.
+
+#include "lwip_default_hooks.h"
+
+#define __weak __attribute__((weak))
+
+#ifdef CONFIG_LWIP_HOOK_IP6_ROUTE_DEFAULT
+struct netif *__weak
+lwip_hook_ip6_route(const ip6_addr_t *src, const ip6_addr_t *dest)
+{
+    LWIP_UNUSED_ARG(src);
+    LWIP_UNUSED_ARG(dest);
+
+    return NULL;
+}
+#endif
+
+#ifdef CONFIG_LWIP_HOOK_NETCONN_EXT_RESOLVE_DEFAULT
+int __weak lwip_hook_netconn_external_resolve(const char *name, ip_addr_t *addr, u8_t addrtype, err_t *err)
+{
+    LWIP_UNUSED_ARG(name);
+    LWIP_UNUSED_ARG(addr);
+    LWIP_UNUSED_ARG(addrtype);
+    LWIP_UNUSED_ARG(err);
+
+    return 0;
+}
+#endif

components/lwip/port/esp32/hooks/tcp_isn_default.c

@@ -70,13 +70,13 @@
  * Author: David van Moolenbroek <david@minix3.org>
  */
 
-#include "tcp_isn.h"
+#include "lwip_default_hooks.h"
 #include "lwip/ip_addr.h"
 #include "lwip/sys.h"
 #include <string.h>
 #include "esp_rom_md5.h"
 
-#ifdef LWIP_HOOK_TCP_ISN
+#ifdef CONFIG_LWIP_HOOK_TCP_ISN_DEFAULT
 
 static u8_t input[64];
 static u32_t base_time;

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_ */

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

@@ -420,17 +420,6 @@
  */
 #define LWIP_TCP_RTO_TIME             CONFIG_LWIP_TCP_RTO_TIME
 
-/**
- * Set TCP hook for Initial Sequence Number (ISN)
- */
-#ifdef CONFIG_LWIP_TCP_ISN_HOOK
-#include <lwip/arch.h>
-struct ip_addr;
-u32_t lwip_hook_tcp_isn(const struct ip_addr *local_ip, u16_t local_port,
-                        const struct ip_addr *remote_ip, u16_t remote_port);
-#define LWIP_HOOK_TCP_ISN               lwip_hook_tcp_isn
-#endif
-
 /*
    ----------------------------------
    ---------- Pbuf options ----------
@@ -778,7 +767,9 @@ u32_t lwip_hook_tcp_isn(const struct ip_addr *local_ip, u16_t local_port,
    ---------- Hook options ---------------
    ---------------------------------------
 */
+#define LWIP_HOOK_FILENAME              "lwip_default_hooks.h"
 #define LWIP_HOOK_IP4_ROUTE_SRC         ip4_route_src_hook
+
 /*
    ---------------------------------------
    ---------- Debugging options ----------

components/lwip/port/esp32/tcp_isn/tcp_isn.h

@@ -1,48 +0,0 @@
-/*
- * Copyright (c) 2016 The MINIX 3 Project.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- *
- * Author: David van Moolenbroek <david@minix3.org>
- */
-
-#ifndef LWIP_TCP_ISN_H
-#define LWIP_TCP_ISN_H
-
-#include "lwip/opt.h"
-#include "lwip/ip_addr.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-void lwip_init_tcp_isn(u32_t boot_time, const u8_t *secret_16_bytes);
-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);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* LWIP_TCP_ISN_H */