From ed59dc1adac1a14abfabce7a2cfc131b6f71a8fb Mon Sep 17 00:00:00 2001
From: likewise <likewise>
Date: Sun, 28 Nov 2004 18:00:20 +0000
Subject: [PATCH] Prevented a race condition between a new ARP request and the
 ARP timer. Timeouts stay the same (halved the ARP timer, doubled the counts),
 but ETHARP_MAX_PENDING should be at least 2 to prevent it from reaching 0
 right away, giving too little time for any ARP responses to be noted.

---
 src/include/netif/etharp.h |  3 ++-
 src/netif/etharp.c         | 15 +++++++++++----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/include/netif/etharp.h b/src/include/netif/etharp.h
index 5750c63f..08437afe 100644
--- a/src/include/netif/etharp.h
+++ b/src/include/netif/etharp.h
@@ -107,7 +107,8 @@ PACK_STRUCT_END
 #  include "arch/epstruct.h"
 #endif
 
-#define ARP_TMR_INTERVAL 10000
+/** 5 seconds period */
+#define ARP_TMR_INTERVAL 5000
 
 #define ETHTYPE_ARP 0x0806
 #define ETHTYPE_IP  0x0800
diff --git a/src/netif/etharp.c b/src/netif/etharp.c
index d44ef53d..632afe72 100644
--- a/src/netif/etharp.c
+++ b/src/netif/etharp.c
@@ -55,10 +55,17 @@
 #  include "lwip/dhcp.h"
 #endif
 
-/** the time an ARP entry stays valid after its last update, (120 * 10) seconds = 20 minutes. */
-#define ARP_MAXAGE 120
-/** the time an ARP entry stays pending after first request, (1 * 10) seconds = 10 seconds. */
-#define ARP_MAXPENDING 1
+/** the time an ARP entry stays valid after its last update,
+ * (240 * 5) seconds = 20 minutes.
+ */
+#define ARP_MAXAGE 240
+/** the time an ARP entry stays pending after first request,
+ * (2 * 5) seconds = 10 seconds.
+ * 
+ * @internal Keep this number at least 2, otherwise it might
+ * run out instantly if the timeout occurs directly after a request.
+ */
+#define ARP_MAXPENDING 2
 
 #define HWTYPE_ETHERNET 1