1 files changed, 94 insertions, 0 deletions
diff --git a/package/network/services/ppp/patches/206-compensate_time_change.patch b/package/network/services/ppp/patches/206-compensate_time_change.patch
new file mode 100644
index 0000000..fb6c656
--- /dev/null
+++ b/package/network/services/ppp/patches/206-compensate_time_change.patch
@@ -0,0 +1,94 @@
+pppd: Watch out for time warps
+
+On many embedded systems there is no battery backed RTC and a proper system
+time only becomes available through NTP after establishing a connection.
+
+When the clock suddenly jumps forward, the internal accounting (connect time)
+is confused resulting in unreliable data.
+
+This patch implements periodic clock checking to look for time warps, if one
+is detected, the internal counters are adjusted accordingly.
+
+Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>
+
+--- a/pppd/main.c
++++ b/pppd/main.c
+@@ -90,6 +90,7 @@
+ #include <sys/socket.h>
+ #include <netinet/in.h>
+ #include <arpa/inet.h>
++#include <sys/sysinfo.h>
+ 
+ #include "pppd.h"
+ #include "magic.h"
+@@ -228,6 +229,7 @@ static struct subprocess *children;
+ 
+ /* Prototypes for procedures local to this file. */
+ 
++static void check_time(void);
+ static void setup_signals __P((void));
+ static void create_pidfile __P((int pid));
+ static void create_linkpidfile __P((int pid));
+@@ -535,6 +537,7 @@ main(argc, argv)
+ 	    info("Starting link");
+ 	}
+ 
++	check_time();
+ 	gettimeofday(&start_time, NULL);
+ 	script_unsetenv("CONNECT_TIME");
+ 	script_unsetenv("BYTES_SENT");
+@@ -1267,6 +1270,36 @@ struct	callout {
+ 
+ static struct callout *callout = NULL;	/* Callout list */
+ static struct timeval timenow;		/* Current time */
++static long uptime_diff = 0;
++static int uptime_diff_set = 0;
++
++static void check_time(void)
++{
++	long new_diff;
++	struct timeval t;
++	struct sysinfo i;
++    struct callout *p;
++	
++	gettimeofday(&t, NULL);
++	sysinfo(&i);
++	new_diff = t.tv_sec - i.uptime;
++	
++	if (!uptime_diff_set) {
++		uptime_diff = new_diff;
++		uptime_diff_set = 1;
++		return;
++	}
++
++	if ((new_diff - 5 > uptime_diff) || (new_diff + 5 < uptime_diff)) {
++		/* system time has changed, update counters and timeouts */
++		info("System time change detected.");
++		start_time.tv_sec += new_diff - uptime_diff;
++		
++    	for (p = callout; p != NULL; p = p->c_next)
++			p->c_time.tv_sec += new_diff - uptime_diff;
++	}
++	uptime_diff = new_diff;
++}
+ 
+ /*
+  * timeout - Schedule a timeout.
+@@ -1337,6 +1370,8 @@ calltimeout()
+ {
+     struct callout *p;
+ 
++	check_time();
++	
+     while (callout != NULL) {
+ 	p = callout;
+ 
+@@ -1364,6 +1399,8 @@ timeleft(tvp)
+ {
+     if (callout == NULL)
+ 	return NULL;
++	
++	check_time();
+ 
+     gettimeofday(&timenow, NULL);
+     tvp->tv_sec = callout->c_time.tv_sec - timenow.tv_sec;