Add timeoffset option to gam version (#1002)

* Add timeoffset option to gam version

* Update timeOffset checking

src/GamCommands.txt

@@ -807,7 +807,7 @@ Specify a collection of Users by directly specifying them or by specifiying item
 	<UserBasicAttribute>|
 	<UserMultiAttribute>
 
-gam version [check|checkrc|simple|extended] [location <HostName>]
+gam version [check|checkrc|simple|extended] [timeoffset] [location <HostName>]
 gam help
 
 gam batch <FileName>|- [charset <Charset>]

src/gam.py

@@ -720,6 +720,14 @@ def SetGlobalVariables():
     GM_Globals[GM_CACHE_DISCOVERY_ONLY] = False
   return True
 
+def getLocalGoogleTimeOffset(testLocation='www.googleapis.com'):
+  localUTC = datetime.datetime.now(datetime.timezone.utc)
+  try:
+    googleUTC = dateutil.parser.parse(_createHttpObj().request('https://'+testLocation, 'HEAD')[0]['date'])
+    return (localUTC-googleUTC).total_seconds()
+  except (httplib2.ServerNotFoundError, RuntimeError, ValueError) as e:
+    systemErrorExit(4, str(e))
+
 def doGAMCheckForUpdates(forceCheck=False):
 
   def _gamLatestVersionNotAvailable():
@@ -774,9 +782,7 @@ def doGAMCheckForUpdates(forceCheck=False):
     return
 
 def doGAMVersion(checkForArgs=True):
-  force_check = False
-  simple = False
-  extended = False
+  force_check = extended = simple = timeOffset = False
   testLocation = 'www.googleapis.com'
   if checkForArgs:
     i = 2
@@ -791,6 +797,9 @@ def doGAMVersion(checkForArgs=True):
       elif myarg == 'extended':
         extended = True
         i += 1
+      elif myarg == 'timeoffset':
+        timeOffset = True
+        i += 1
       elif myarg == 'location':
         testLocation = sys.argv[i+1]
         i += 2
@@ -804,6 +813,8 @@ def doGAMVersion(checkForArgs=True):
                             sys.version_info[1], sys.version_info[2], struct.calcsize('P')*8,
                             sys.version_info[3], googleapiclient.__version__,
                             platform.platform(), platform.machine(), GM_Globals[GM_GAM_PATH]))
+  if timeOffset:
+    print('Time offset from Google, correct local time if more than %s seconds: %s' % (MAX_LOCAL_GOOGLE_TIME_OFFSET, getLocalGoogleTimeOffset(testLocation)))
   if force_check:
     doGAMCheckForUpdates(forceCheck=True)
   if extended:
@@ -1483,6 +1494,9 @@ def buildGmailGAPIObject(user):
   return (userEmail, buildGAPIServiceObject('gmail', userEmail))
 
 def doCheckServiceAccount(users):
+  timeOffset = getLocalGoogleTimeOffset()
+  if timeOffset > MAX_LOCAL_GOOGLE_TIME_OFFSET:
+    systemErrorExit(4, 'Time offset from Google is more than %s seconds, correct local time: %s' % (MAX_LOCAL_GOOGLE_TIME_OFFSET, timeOffset))
   all_scopes = []
   for _, scopes in list(API_SCOPE_MAPPING.items()):
     for scope in scopes:

src/var.py

@@ -39,6 +39,8 @@ FN_LAST_UPDATE_CHECK_TXT = 'lastupdatecheck.txt'
 MY_CUSTOMER = 'my_customer'
 # See https://support.google.com/drive/answer/37603
 MAX_GOOGLE_SHEET_CELLS = 5000000
+MAX_LOCAL_GOOGLE_TIME_OFFSET = 30
+
 SKUS = {
   '1010010001': {
     'product': '101001', 'aliases': ['identity', 'cloudidentity'], 'displayName': 'Cloud Identity'},