From 06263efe0be36eb1592611cfb13e4a503f0541c8 Mon Sep 17 00:00:00 2001
From: David Cermak <cermak@espressif.com>
Date: Thu, 17 Mar 2022 12:43:57 +0100
Subject: [PATCH] lwip: Add IPv4 route hook to the esp32 port

---
 .../port/esp32/hooks/lwip_default_hooks.c     | 50 +++++++++++++++++++
 .../port/esp32/include/lwip_default_hooks.h   |  3 ++
 2 files changed, 53 insertions(+)

diff --git a/components/lwip/port/esp32/hooks/lwip_default_hooks.c b/components/lwip/port/esp32/hooks/lwip_default_hooks.c
index f053c16f15..db34443334 100644
--- a/components/lwip/port/esp32/hooks/lwip_default_hooks.c
+++ b/components/lwip/port/esp32/hooks/lwip_default_hooks.c
@@ -50,3 +50,53 @@ int __weak lwip_hook_ip6_input(struct pbuf *p, struct netif *inp)
     return 0;
 }
 #endif
+
+#ifdef LWIP_HOOK_IP4_ROUTE_SRC
+#if ESP_IP4_ROUTE
+#include "lwip/netif.h"
+
+bool ip4_netif_exist(const ip4_addr_t *src, const ip4_addr_t *dest)
+{
+    struct netif *netif = NULL;
+
+    for (netif = netif_list; netif != NULL; netif = netif->next) {
+        /* is the netif up, does it have a link and a valid address? */
+        if (netif_is_up(netif) && netif_is_link_up(netif) && !ip4_addr_isany_val(*netif_ip4_addr(netif))) {
+            /* source netif and dest netif match? */
+            if (ip4_addr_netcmp(src, netif_ip4_addr(netif), netif_ip4_netmask(netif)) || ip4_addr_netcmp(dest, netif_ip4_addr(netif), netif_ip4_netmask(netif))) {
+                /* return false when both netif don't match */
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+/**
+ * Source based IPv4 routing hook function.
+ */
+struct netif *
+ip4_route_src_hook(const ip4_addr_t *src,const ip4_addr_t *dest)
+{
+    struct netif *netif = NULL;
+
+    /* destination IP is broadcast IP? */
+    if ((src != NULL) && !ip4_addr_isany(src)) {
+        /* iterate through netifs */
+        for (netif = netif_list; netif != NULL; netif = netif->next) {
+            /* is the netif up, does it have a link and a valid address? */
+            if (netif_is_up(netif) && netif_is_link_up(netif) && !ip4_addr_isany_val(*netif_ip4_addr(netif))) {
+                /* source IP matches? */
+                if (ip4_addr_cmp(src, netif_ip4_addr(netif))) {
+                    /* return netif on which to forward IP packet */
+
+                    return netif;
+                }
+            }
+        }
+    }
+    return netif;
+}
+#endif
+#endif /* LWIP_HOOK_IP4_ROUTE_SRC */
diff --git a/components/lwip/port/esp32/include/lwip_default_hooks.h b/components/lwip/port/esp32/include/lwip_default_hooks.h
index 2388d4f3a0..82f30c8bbb 100644
--- a/components/lwip/port/esp32/include/lwip_default_hooks.h
+++ b/components/lwip/port/esp32/include/lwip_default_hooks.h
@@ -53,6 +53,9 @@ int lwip_hook_ip6_input(struct pbuf *p, struct netif *inp);
 #define LWIP_HOOK_IP6_INPUT lwip_hook_ip6_input
 #endif /* CONFIG_LWIP_HOOK_IP6_INPUT_CUSTIOM... */
 
+struct netif *
+ip4_route_src_hook(const ip4_addr_t *src,const ip4_addr_t *dest);
+
 #ifdef __cplusplus
 }
 #endif