From e20e143f1e99bdc0a7d92e97da1bd0dc40e8a83b Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@tinc-vpn.org>
Date: Sun, 14 May 2000 13:02:20 +0000
Subject: [PATCH] Changed ping behaviour (backwards compatible). If we don't
 have any data to send, we don't need to check if the connection is still
 alive. Furthermore, if we receive any kind of data from the other end, we
 know it's alive, so we don't need to check it either. So, PING requests are
 only sent if we send packets but there is no response.

---
 src/net.c | 84 +++++++++++++++++++++++++++----------------------------
 src/net.h |  2 ++
 2 files changed, 43 insertions(+), 43 deletions(-)

diff --git a/src/net.c b/src/net.c
index dc632b60..b6007b48 100644
--- a/src/net.c
+++ b/src/net.c
@@ -51,8 +51,6 @@ int total_tap_out = 0;
 int total_socket_in = 0;
 int total_socket_out = 0;
 
-time_t last_ping_time = 0;
-
 /* The global list of existing connections */
 conn_list_t *conn_list = NULL;
 conn_list_t *myself = NULL;
@@ -107,6 +105,8 @@ cp
     }
 
   total_socket_out += r;
+
+  cl->want_ping = 1;
 cp
   return 0;
 }
@@ -123,6 +123,9 @@ cp
     syslog(LOG_ERR, "Can't write to tap device: %m");
   else
     total_tap_out += lenin;
+
+  cl->want_ping = 0;
+  cl->last_ping_time = time(NULL);
 cp
   return 0;
 }
@@ -546,7 +549,7 @@ int setup_network_connections(void)
   config_t const *cfg;
 cp
   if((cfg = get_config_val(pingtimeout)) == NULL)
-    timeout = 10;
+    timeout = 5;
   else
     timeout = cfg->data.val;
 
@@ -692,6 +695,8 @@ cp
   p->meta_socket = sfd;
   p->status.meta = 1;
   p->buflen = 0;
+  p->last_ping_time = time(NULL);
+  p->want_ping = 0;
   
   syslog(LOG_NOTICE, "Connection from %s:%d", p->hostname, htons(ci.sin_port));
 
@@ -826,52 +831,41 @@ cp
 }
 
 /*
-  send out a ping request to all active
-  connections
-*/
-int send_broadcast_ping(void)
-{
-  conn_list_t *p;
-cp
-  for(p = conn_list; p != NULL; p = p->next)
-    {
-      if(p->status.remove)
-	continue;
-      if(p->status.active && p->status.meta)
-	{
-	  if(send_ping(p))
-	    terminate_connection(p);
-	  else
-	    {
-	      p->status.pinged = 1;
-	      p->status.got_pong = 0;
-	    }
-	}
-    }
-
-  last_ping_time = time(NULL);
-cp
-  return 0;
-}
-
-/*
-  end all connections that did not respond
-  to the ping probe in time
+  Check if the other end is active.
+  If we have sent packets, but didn't receive any,
+  then possibly the other end is dead. We send a
+  PING request over the meta connection. If the other
+  end does not reply in time, we consider them dead
+  and close the connection.
 */
 int check_dead_connections(void)
 {
   conn_list_t *p;
+  time_t now;
 cp
+  now = time(NULL);
   for(p = conn_list; p != NULL; p = p->next)
     {
       if(p->status.remove)
 	continue;
-      if(p->status.active && p->status.meta && p->status.pinged && !p->status.got_pong)
+      if(p->status.active && p->status.meta)
 	{
-	  syslog(LOG_INFO, "%s (" IP_ADDR_S ") didn't respond to ping",
-		 p->hostname, IP_ADDR_V(p->vpn_ip));
-	  p->status.timeout = 1;
-	  terminate_connection(p);
+          if(p->last_ping_time + timeout < now)
+            if(p->status.pinged && !p->status.got_pong)
+              {
+	        syslog(LOG_INFO, "%s (" IP_ADDR_S ") didn't respond to ping",
+		       p->hostname, IP_ADDR_V(p->vpn_ip));
+	        p->status.timeout = 1;
+	        terminate_connection(p);
+              }
+            else if(p->want_ping)
+              {
+                send_ping(p);
+                p->last_ping_time = now;
+                p->status.pinged = 1;
+                p->status.get_pong = 0;
+              }
+          }
 	}
     }
 cp
@@ -989,6 +983,9 @@ cp
           break;
         }
     }
+
+  cl->last_ping_time = time(NULL);
+  cl->want_ping = 0;
 cp  
   return 0;
 }
@@ -1100,8 +1097,9 @@ void main_loop(void)
   fd_set fset;
   struct timeval tv;
   int r;
+  time_t last_ping_check;
 cp
-  last_ping_time = time(NULL);
+  last_ping_check = time(NULL);
 
   for(;;)
     {
@@ -1119,11 +1117,11 @@ cp
           return;
         }
 
-      if(r == 0 || last_ping_time + timeout < time(NULL))
-	/* Timeout... hm... something might be wrong. */
+      if(last_ping_check + timeout < time(NULL))
+	/* Let's check if everybody is still alive */
 	{
 	  check_dead_connections();
-	  send_broadcast_ping();
+          last_ping_check = time(NULL);
 	  continue;
 	}
 
diff --git a/src/net.h b/src/net.h
index 8e067475..3dfc3a56 100644
--- a/src/net.h
+++ b/src/net.h
@@ -115,6 +115,8 @@ typedef struct conn_list_t {
   char buffer[MAXBUFSIZE+1];       /* metadata input buffer */
   int buflen;                      /* bytes read into buffer */
   int reqlen;                      /* length of first request in buffer */
+  time_t last_ping_time;           /* last time we saw some activity from the other end */  
+  int want_ping;                   /* 0 if there's no need to check for activity */
   struct conn_list_t *nexthop;     /* nearest meta-hop in this direction */
   struct conn_list_t *next;        /* after all, it's a list of connections */
 } conn_list_t;
-- 
2.20.1