From 0b882cd516d5fa63472ce137b17e015e3a459f1c Mon Sep 17 00:00:00 2001
From: Adam Dunkels <adam@thingsquare.com>
Date: Sun, 17 Mar 2013 10:49:11 +0100
Subject: [PATCH] Telnetd improvement: allow specifying a maximum silence time
 and kill the connection after that time. This is to avoid the telnet
 connection getting stuck forever if the connecting host reboots.

---
 apps/telnetd/telnetd.c | 22 +++++++++++++++++-----
 apps/telnetd/telnetd.h |  2 ++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/apps/telnetd/telnetd.c b/apps/telnetd/telnetd.c
index e0967e6c2..95786442b 100644
--- a/apps/telnetd/telnetd.c
+++ b/apps/telnetd/telnetd.c
@@ -72,8 +72,8 @@ struct telnetd_state {
 #define STATE_WONT   3
 #define STATE_DO     4
 #define STATE_DONT   5
-  
 #define STATE_CLOSE  6
+  struct timer silence_timer;
 };
 static struct telnetd_state s;
 
@@ -101,6 +101,8 @@ static struct telnetd_buf buf;
 
 static uint8_t connected;
 
+#define MAX_SILENCE_TIME (CLOCK_SECOND * 30)
+
 #define MIN(a, b) ((a) < (b)? (a): (b))
 /*---------------------------------------------------------------------------*/
 static void
@@ -357,6 +359,7 @@ telnetd_appcall(void *ts)
       s.state = STATE_NORMAL;
       connected = 1;
       shell_start();
+      timer_set(&s.silence_timer, MAX_SILENCE_TIME);
       ts = (char *)0;
     } else {
       uip_send(telnetd_reject_text, strlen(telnetd_reject_text));
@@ -378,9 +381,11 @@ telnetd_appcall(void *ts)
       connected = 0;
     }
     if(uip_acked()) {
+      timer_set(&s.silence_timer, MAX_SILENCE_TIME);
       acked();
     }
     if(uip_newdata()) {
+      timer_set(&s.silence_timer, MAX_SILENCE_TIME);
       newdata();
     }
     if(uip_rexmit() ||
@@ -389,15 +394,22 @@ telnetd_appcall(void *ts)
        uip_connected() ||
        uip_poll()) {
       senddata();
+      if(s.numsent > 0) {
+	timer_set(&s.silence_timer, MAX_SILENCE_TIME);
+      }
     }
-  } else {
     if(uip_poll()) {
-      if(ts == (char *)10) {
+      if(timer_expired(&s.silence_timer)) {
         uip_close();
-      } else {
-        tcp_markconn(uip_conn, (char *)ts + 1);
+        tcp_markconn(uip_conn, NULL);
       }
     }
   }
 }
 /*---------------------------------------------------------------------------*/
+void
+telnetd_init(void)
+{
+  process_start(&telnetd_process, NULL);
+}
+/*---------------------------------------------------------------------------*/
diff --git a/apps/telnetd/telnetd.h b/apps/telnetd/telnetd.h
index 3c9d6c015..9db26ebec 100644
--- a/apps/telnetd/telnetd.h
+++ b/apps/telnetd/telnetd.h
@@ -38,6 +38,8 @@
 
 PROCESS_NAME(telnetd_process);
 
+void telnetd_init(void);
+
 void telnetd_gui_eventhandler(process_event_t ev, process_data_t data);
 void telnetd_appcall(void *data);
 void telnetd_gui_init(void);