From 95048339bf0af380f15373f22bf2a8f2ff29aea5 Mon Sep 17 00:00:00 2001
From: yuanjm <yuanjianmin@espressif.com>
Date: Tue, 12 Oct 2021 20:11:42 +0800
Subject: [PATCH] dns: Add API to clear dns cache

Picked from espressif/esp-lwip@ee59f77d
Ref IDF-4839
---
 src/core/dns.c         | 9 +++++++++
 src/include/lwip/dns.h | 4 +---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/core/dns.c b/src/core/dns.c
index e0318882..1f6777f2 100644
--- a/src/core/dns.c
+++ b/src/core/dns.c
@@ -382,6 +382,15 @@ dns_setserver(u8_t numdns, const ip_addr_t *dnsserver)
   }
 }
 
+/**
+ * Clears the DNS cache
+ */
+void
+dns_clear_cache(void)
+{
+  memset(dns_table, 0, sizeof(struct dns_table_entry) * DNS_TABLE_SIZE);
+}
+
 /**
  * @ingroup dns
  * Obtain one of the currently configured DNS server.
diff --git a/src/include/lwip/dns.h b/src/include/lwip/dns.h
index db52fedd..fad97230 100644
--- a/src/include/lwip/dns.h
+++ b/src/include/lwip/dns.h
@@ -111,9 +111,7 @@ err_t            dns_gethostbyname(const char *hostname, ip_addr_t *addr,
 err_t            dns_gethostbyname_addrtype(const char *hostname, ip_addr_t *addr,
                                    dns_found_callback found, void *callback_arg,
                                    u8_t dns_addrtype);
-#if ESP_DNS
-void             dns_clear_servers(bool keep_fallback);
-#endif
+void             dns_clear_cache(void);
 
 #if DNS_LOCAL_HOSTLIST
 size_t         dns_local_iterate(dns_found_callback iterator_fn, void *iterator_arg);