Change session timer to monotonic when possible

Previously the ipmi session was using time.time().  This means
that retries and keepalives could be thrown off by things like ntp
or manual time corrections.

Ideally, we'd use the baked in time.monotonic(), but that doesn't exist
aside from python 3.3

Change-Id: Ia00026cef6df214f9463909309de44767c3752b5

ipmi/private/session.py

@@ -37,6 +37,22 @@ initialtimeout = 0.5  # minimum timeout for first packet to retry in any given
                      # in case of congestion
 
 
+def _monotonic_time():
+    """Provides a monotonic timer
+
+    This code is concerned with relative, not absolute time.
+    This function facilitates that prior to python 3.3
+    """
+    # Python does not provide one until 3.3, so we make do
+    # for most OSes, os.times()[4] works well.
+    # for microsoft, GetTickCount64
+    if (os.name == "posix"):
+        return os.times()[4]
+    else:  # last resort, non monotonic time
+        return time.time()
+    #TODO(jbjohnso): Windows variant
+
+
 def _aespad(data):
     """ipmi demands a certain pad scheme,
     per table 13-20 AES-CBC encrypted payload fields.
@@ -419,8 +435,8 @@ class Session:
         #advance idle timer since we don't need keepalive while sending packets
         #out naturally
         if self in Session.keepalive_sessions:
-            Session.keepalive_sessions[self]['timeout'] = time.time() + 25 + \
-                (random.random() * 4.9)
+            Session.keepalive_sessions[self]['timeout'] = _monotonic_time() + \
+                25 + (random.random() * 4.9)
         self._xmit_packet(retry)
 
     def _ipmi15authcode(self, payload, checkremotecode=False):
@@ -532,8 +548,8 @@ class Session:
         self.logged = 1
         Session.keepalive_sessions[self] = {}
         Session.keepalive_sessions[self]['ipmisession'] = self
-        Session.keepalive_sessions[self]['timeout'] = time.time() + 25 + \
-            (random.random() * 4.9)
+        Session.keepalive_sessions[self]['timeout'] = _monotonic_time() + \
+            25 + (random.random() * 4.9)
         call_with_optional_args(
             self.onlogon, {'success': True}, self.onlogonargs)
 
@@ -603,7 +619,7 @@ class Session:
         #Instance C gets to go ahead of Instance A, because
         #Instance C can get work done, but instance A cannot
 
-        curtime = time.time()
+        curtime = _monotonic_time()
         # There ar a number of parties that each has their own timeout
         # The caller can specify a deadline in timeout argument
         # each session with active outbound payload has callback to
@@ -1066,7 +1082,7 @@ class Session:
             Session.waiting_sessions[self] = {}
             Session.waiting_sessions[self]['ipmisession'] = self
             Session.waiting_sessions[self]['timeout'] = self.timeout + \
-                time.time()
+                _monotonic_time()
             Session.pending += 1
         if self.sockaddr:
             Session.socket.sendto(self.netpacket, self.sockaddr)

ipmictl.py

@@ -23,7 +23,7 @@ understand how the ipmi_command class workes.
 import os
 import sys
 
-from ipmi.command import Command
+from ipmi import command
 password = os.environ['IPMIPASSWORD']
 os.environ['IPMIPASSWORD'] = ""
 if (len(sys.argv) < 3):
@@ -32,23 +32,23 @@ if (len(sys.argv) < 3):
     sys.exit(1)
 bmc = sys.argv[1]
 userid = sys.argv[2]
-command = sys.argv[3]
+cmmand = sys.argv[3]
 args = None
 if len(sys.argv) >= 5:
     args = sys.argv[4:]
-ipmicmd = Command(bmc=bmc, userid=userid, password=password)
-if command == 'power':
+ipmicmd = command.Command(bmc=bmc, userid=userid, password=password)
+if cmmand == 'power':
     if args:
         print ipmicmd.set_power(args[0], wait=True)
     else:
         print ipmicmd.get_power()
-elif command == 'bootdev':
+elif cmmand == 'bootdev':
     if args:
         print ipmicmd.set_bootdev(args[0])
     else:
         print ipmicmd.get_bootdev()
-elif command == 'raw':
+elif cmmand == 'raw':
     netfn = args[0]
-    command = args[1]
+    cmmand = args[1]
     data = args[2:]
-    print ipmicmd.raw_command(netfn=netfn, command=command, data=data)
+    print ipmicmd.raw_command(netfn=netfn, command=cmmand, data=data)