From f2911d67b7e62d6d750aa9cbe72b79fc5fa99b7d Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Thu, 13 Aug 2015 18:32:37 +0800
Subject: [PATCH] Enable TCP keepalive on the core device

Automatically runs the idle experiment a few seconds after the master stops responding.

Thanks Florent for figuring out TCP_KEEPIDLE_DEFAULT needed to be set in addition to the other options.

Closes #31
---
 soc/runtime/liblwip/lwipopts.h |  4 ++++
 soc/runtime/net_server.c       | 17 ++++++++++-------
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/soc/runtime/liblwip/lwipopts.h b/soc/runtime/liblwip/lwipopts.h
index bca6722a3..147322dd8 100644
--- a/soc/runtime/liblwip/lwipopts.h
+++ b/soc/runtime/liblwip/lwipopts.h
@@ -105,6 +105,10 @@ a lot of data that needs to be copied, this should be set high. */
 
 /* ---------- TCP options ---------- */
 #define LWIP_TCP                1
+#define LWIP_TCP_KEEPALIVE      1
+#define TCP_KEEPIDLE_DEFAULT    1250
+#define TCP_KEEPINTVL_DEFAULT   1000
+#define TCP_KEEPCNT_DEFAULT     3
 #define TCP_TTL                 255
 
 /* Controls if TCP should queue segments that arrive out of
diff --git a/soc/runtime/net_server.c b/soc/runtime/net_server.c
index a28b396bd..fa06474b6 100644
--- a/soc/runtime/net_server.c
+++ b/soc/runtime/net_server.c
@@ -60,14 +60,16 @@ static void net_server_close(struct net_server_connstate *cs, struct tcp_pcb *pc
         active_pcb = NULL;
     }
 
-    /* lwip loves to call back with broken pointers. Prevent that. */
-    tcp_arg(pcb, NULL);
-    tcp_recv(pcb, NULL);
-    tcp_sent(pcb, NULL);
-    tcp_err(pcb, NULL);
+    if(pcb) {
+        /* lwip loves to call back with broken pointers. Prevent that. */
+        tcp_arg(pcb, NULL);
+        tcp_recv(pcb, NULL);
+        tcp_sent(pcb, NULL);
+        tcp_err(pcb, NULL);
 
+        tcp_close(pcb);
+    }
     cs_free(cs);
-    tcp_close(pcb);
 }
 
 static err_t net_server_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
@@ -155,7 +157,7 @@ static void net_server_err(void *arg, err_t err)
     struct net_server_connstate *cs;
 
     cs = (struct net_server_connstate *)arg;
-    cs_free(cs);
+    net_server_close(cs, NULL);
 }
 
 static struct tcp_pcb *listen_pcb;
@@ -177,6 +179,7 @@ static err_t net_server_accept(void *arg, struct tcp_pcb *newpcb, err_t err)
 void net_server_init(void)
 {
     listen_pcb = tcp_new();
+    listen_pcb->so_options |= SOF_KEEPALIVE;
     tcp_bind(listen_pcb, IP_ADDR_ANY, 1381);
     listen_pcb = tcp_listen(listen_pcb);
     tcp_accept(listen_pcb, net_server_accept);