From 03e3b137bfcc88d521f56be4d0a26c10256215af Mon Sep 17 00:00:00 2001
From: qiyueixa <qiyuexia@espressif.com>
Date: Sun, 22 Jan 2017 20:32:39 +0800
Subject: [PATCH] lwip: optimize the dhcp client

1. modify the discover retry backoff time from (2,4,8,16,32,60,60)s to (500m,1,2,4,8,15,15)s.
2. add DHCP_DOES_ARP_CHECK to menuconfig for users to specify if do a ARP check on the offered address.
   If enable, one more second will be taken in obtaining IP address.
3. update wifi libs
---
 components/esp32/lib                         | 2 +-
 components/lwip/Kconfig                      | 7 +++++++
 components/lwip/core/ipv4/dhcp.c             | 7 ++++++-
 components/lwip/include/lwip/port/lwipopts.h | 5 +++++
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/components/esp32/lib b/components/esp32/lib
index fc92f2e5b..6e50eb85a 160000
--- a/components/esp32/lib
+++ b/components/esp32/lib
@@ -1 +1 @@
-Subproject commit fc92f2e5bcd34fa945445e8cad47cbf1f2a4bdb6
+Subproject commit 6e50eb85a07d12ded45d8765fc82bb7ab929e441
diff --git a/components/lwip/Kconfig b/components/lwip/Kconfig
index f7bae3258..0070ef466 100644
--- a/components/lwip/Kconfig
+++ b/components/lwip/Kconfig
@@ -82,6 +82,13 @@ config TCP_SYNMAXRTX
     help
         Set maximum number of retransmissions of SYN segments.
 
+config LWIP_DHCP_DOES_ARP_CHECK
+    bool "Enable an ARP check on the offered address"
+    default 1
+    help
+        Enabling this option allows check if the offered IP address is not already
+        in use by another host on the network.
+
 endmenu
 
 
diff --git a/components/lwip/core/ipv4/dhcp.c b/components/lwip/core/ipv4/dhcp.c
index 887af91fe..86336d4f7 100755
--- a/components/lwip/core/ipv4/dhcp.c
+++ b/components/lwip/core/ipv4/dhcp.c
@@ -1029,7 +1029,12 @@ dhcp_discover(struct netif *netif)
     autoip_start(netif);
   }
 #endif /* LWIP_DHCP_AUTOIP_COOP */
-  msecs = (dhcp->tries < 6 ? 1 << dhcp->tries : 60) * 1000;
+
+  /* Since for embedded devices it's not that hard to miss a discover packet, so lower
+   * the discover retry backoff time from (2,4,8,16,32,60,60)s to (500m,1,2,4,8,15,15)s.
+   * Original msecs = (dhcp->tries < 6 ? 1 << dhcp->tries : 60) * 1000;
+   */
+  msecs = (dhcp->tries < 6 ? 1 << dhcp->tries : 60) * 250;
   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_discover(): set request timeout %"U16_F" msecs\n", msecs));
   return result;
diff --git a/components/lwip/include/lwip/port/lwipopts.h b/components/lwip/include/lwip/port/lwipopts.h
index 638c1f740..dc8264947 100644
--- a/components/lwip/include/lwip/port/lwipopts.h
+++ b/components/lwip/include/lwip/port/lwipopts.h
@@ -206,6 +206,11 @@
 
 #define DHCP_MAXRTX                     0
 
+/**
+ * DHCP_DOES_ARP_CHECK==1: Do an ARP check on the offered address.
+ */
+#define DHCP_DOES_ARP_CHECK             CONFIG_LWIP_DHCP_DOES_ARP_CHECK
+
 /*
    ------------------------------------
    ---------- AUTOIP options ----------