From ea0c3d3e9a44ba738c681b616c643afa6caa9a8a Mon Sep 17 00:00:00 2001
From: Jonathan Harris <jonathan@marginal.org.uk>
Date: Wed, 28 Jun 2017 10:17:36 +0100
Subject: [PATCH] Check system time against NTP on startup

---
 EDMarketConnector.py |  5 +++++
 L10n/en.template     |  9 +++++++++
 README.md            |  6 +++---
 ntp.py               | 28 ++++++++++++++++++++++++++++
 4 files changed, 45 insertions(+), 3 deletions(-)
 create mode 100644 ntp.py

diff --git a/EDMarketConnector.py b/EDMarketConnector.py
index 6b7b818a..9f7750e0 100755
--- a/EDMarketConnector.py
+++ b/EDMarketConnector.py
@@ -57,6 +57,7 @@ import coriolis
 import eddb
 import edshipyard
 import loadout
+from ntp import NTPCheck
 import stats
 import prefs
 import plug
@@ -309,6 +310,10 @@ class AppWindow:
             except:
                 if __debug__: print_exc()
 
+        if not NTPCheck(self.w):	# Check system time
+            self.w.destroy()
+            return
+
         self.postprefs(False)	# Companion login happens in callback from monitor
 
         if keyring.get_keyring().priority < 1:
diff --git a/L10n/en.template b/L10n/en.template
index 42e6f967..1df03c72 100644
--- a/L10n/en.template
+++ b/L10n/en.template
@@ -52,6 +52,12 @@
 /* Menu item. [EDMarketConnector.py] */
 "Check for Updates..." = "Check for Updates...";
 
+/* Error message shown if system time is wrong. [ntp.py] */
+"Check your system's Date and Time settings." = "Check your system's Date and Time settings.";
+
+/* Error message shown if system time is wrong. [ntp.py] */
+"Check your system's Time Zone setting." = "Check your system's Time Zone setting.";
+
 /* Federation rank. [stats.py] */
 "Chief Petty Officer" = "Chief Petty Officer";
 
@@ -475,6 +481,9 @@
 /* Appearance setting. [prefs.py] */
 "Theme" = "Theme";
 
+/* Error message shown if system time is wrong. [ntp.py] */
+"This app requires accurate timestamps." = "This app requires accurate timestamps.";
+
 /* Help text in settings. [prefs.py] */
 "Tip: You can disable a plugin by{CR}adding '{EXT}' to it's folder name" = "Tip: You can disable a plugin by{CR}adding '{EXT}' to it's folder name";
 
diff --git a/README.md b/README.md
index 08762db5..a505dcbd 100644
--- a/README.md
+++ b/README.md
@@ -178,17 +178,17 @@ Download and extract the source code of the [latest release](https://github.com/
 
 Mac:
 
-* Requires the Python “keyring”, “requests” and “watchdog” modules, plus an up-to-date “py2app” module if you also want to package the app - install these with `easy_install -U keyring requests watchdog py2app` .
+* Requires the Python “keyring”, “ntplib”, “requests” and “watchdog” modules, plus an up-to-date “py2app” module if you also want to package the app - install these with `easy_install -U keyring ntplib requests watchdog py2app` .
 * Run with `./EDMarketConnector.py` .
 
 Windows:
 
-* Requires Python2.7 and the Python “keyring”, “requests” and “watchdog” modules, plus “py2exe” 0.6 if you also want to package the app.
+* Requires Python2.7 and the Python “keyring”, “ntplib”, “requests” and “watchdog” modules, plus “py2exe” 0.6 if you also want to package the app.
 * Run with `EDMarketConnector.py` .
 
 Linux:
 
-* Requires the Python “imaging-tk”, “iniparse”, “keyring” and “requests” modules. On Debian-based systems install these with `sudo apt-get install python-imaging-tk python-iniparse python-keyring python-requests` .
+* Requires the Python “imaging-tk”, “iniparse”, “keyring”, “ntplib” and “requests” modules. On Debian-based systems install these with `sudo apt-get install python-imaging-tk python-iniparse python-ntplib python-keyring python-requests` .
 * Run with `./EDMarketConnector.py` .
 
 Command-line
diff --git a/ntp.py b/ntp.py
new file mode 100644
index 00000000..5b8789d9
--- /dev/null
+++ b/ntp.py
@@ -0,0 +1,28 @@
+from ntplib import NTPClient
+from tkMessageBox import showerror
+
+from config import applongname
+
+if __debug__:
+    from traceback import print_exc
+
+def NTPCheck(parent):
+
+    DRIFT_THRESHOLD = 3 * 60
+    TZ_THRESHOLD = 30 * 60
+    CLOCK_THRESHOLD = 12 * 60 * 60 + DRIFT_THRESHOLD
+
+    try:
+        response = NTPClient().request('pool.ntp.org')
+        if abs(response.offset) > DRIFT_THRESHOLD:
+            showerror(applongname,
+                      _('This app requires accurate timestamps.') + '\n' +	# Error message shown if system time is wrong
+                      (TZ_THRESHOLD < abs(response.offset) < CLOCK_THRESHOLD and
+                       _("Check your system's Time Zone setting.") or		# Error message shown if system time is wrong
+                       _("Check your system's Date and Time settings.")),	# Error message shown if system time is wrong
+                      parent = parent)
+            return False
+    except:
+        if __debug__: print_exc()
+
+    return True