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