Ta.py handles interrupts gracefully

README.md

@@ -56,15 +56,19 @@ General Usage:
 sudo python3 ca.py -v -c -h 1 -r 5 -t 10 -a dead:beef::1
 ```
 
+
 ## ta.py
 This program provides full TA functionality for the node. This program should only be run on the designated DODAG node of the system (normally IPv6 address dead:beef::1 by convention). The program is generally executed as:
 ```
-sudo python3 ta.py -e -d [D]
+sudo python3 ta.py -v -e -d [D]
 ```
 | CLI Parameters | Description |
 |----------------|-------------|
+| `-v` | Enable verbose mode |
 | `-e` | Enable AES encryption on packets |
-| `-d` | Relative path from the calling directory to the SQLite3 database containing the `usages` table, in which the TA will store received usage data
+| `-d [DB]` | Relative path from the calling directory to the SQLite3 database containing the `usages` table, in which the TA will store received usage data
+
+Ta.py handles interrupts gracefully, SIGKILL (2, ^C) will kill the program and close any open sockets. SIGQUIT (3, ^\\) will break the current iteration of the loop, this is useful for when SYNACKs are lost in the mesh and the receive socket livelocks (this appears to be a TCP 'bug' of sorts). Of course, any data currently in the socket will be lost.
 
 If not explicitly set using the CLI parameters, the database used is set to `dat/power-usages.db` (relative to the directory `ta.py` is called from). The sqlite3 database used by the TA **must** contain a table entitled "usages" which conforms to a predefined schema, given in [init.sql](https://github.com/carleton-smart-grid/smartgrid-comms/blob/master/startup/init.sql). Initial setup of the database can be done trivially using the provide `init.sql` file, given as:
 ```
@@ -88,6 +92,7 @@ sudo python cliReporter.py 0:1:2:3 192.168.1.50
 ```
 
 
+
 ## udpping.py
 TODO
 
@@ -180,3 +185,9 @@ Function Call | Precondition(s) | Postcondition(s)
 
 ## encryptiontool.py
 TODO @argRobertson
+
+Function Call | Precondition(s) | Postcondition(s)
+--------------|-----------------|-----------------
+... | ... | ...
+... | ... | ...
+... | ... | ...

mesh-comms/ta.py

@@ -4,9 +4,11 @@
 
 
 # import external libraries
+import signal
 import xml.etree.ElementTree as et
 import sqlite3
 import sys
+# import exception
 
 # import local py
 import tcpcomms
@@ -19,11 +21,32 @@
 VALID_PACKET = 16
 DEFAULT_DB_PATH = 'dat/power-usages.db'
 
+###############################################################################
+# GRACEFUL SIGNAL HANDLING
+###############################################################################
+class Killer: 
+    die = False
+    def __init__(self):
+        signal.signal(signal.SIGINT, self.terminate)
+        signal.signal(signal.SIGTERM, self.terminate)
+        signal.signal(signal.SIGQUIT, self.quit)
+
+    def terminate(self, signum, frame):
+        printv("Terminate caught " + str(signum))
+        self.die = True;
+        raise InterruptedError
+
+    def quit(self, signum, frame):
+        printv("Quit caught " + str(signum))
+        raise InterruptedError
 
 
 ###############################################################################
 # DECLARING FUNCTIONS
 ###############################################################################
+def printv(string):
+    if verbose:
+        print(string)
 
 # save xml data to database
 def write(xml, curser, connection):
@@ -67,6 +90,8 @@ def write(xml, curser, connection):
 # initialize parameters to default
 dbPath = DEFAULT_DB_PATH
 encryptOn = False
+verbose = False
+killer = Killer()
 
 # check for flags
 flags = sys.argv
@@ -78,6 +103,8 @@ def write(xml, curser, connection):
         dbPath = str(flags.pop(0))
     elif (flag == '-e'):
         encryptOn = True
+    elif (flag == '-v'):
+        verbose = True
 
 # setup server object
 server = tcpcomms.Server()
@@ -91,9 +118,14 @@ def write(xml, curser, connection):
     tool = encryptiontool.SecurityTool()
 
 # receive-unpack-write loop
-while(True):
+while(killer.die != True):
     # receive and unpack data
-    packet = server.receive()
+    try:
+        packet = server.receive()
+    except InterruptedError:
+        print("Interrupted socket receive, continuing") # This is an error and as such is printed regardless of verbosity
+        continue
+
     #if the packet is an RSA encrypted AES key
     if(len(packet[0]) == RSA_PACKET and encryptOn):
         tool.addAesKey(packet)
@@ -106,8 +138,13 @@ def write(xml, curser, connection):
     try:
         data = packer.unpack(data)
     except Exception as err:
-        print('IMF unpack error: ', err)
+        print('IMF unpack error: ', err)  # This is an error and as such is printed regardless of verbosity
         continue
 
     #save to SQLite3 server
     write(data, curser, connection)
+
+
+# Cleanup - any future cleanup can go here.
+del(server) # This doesn't necessarily have to be done, but it doesn't hurt.
+print("Exiting")

mesh-comms/tcpcomms.py

@@ -74,7 +74,7 @@ def setup(self):
         # socket setup
         printv('Binding Socket on port', PORT, '...')
         scope_id = socket.if_nametoindex('lowpan0')
-        #scope_id = socket.AF_INET
+        # scope_id = socket.AF_INET
         self.serverSocket = socket.socket(socket.AF_INET6, socket.SOCK_STREAM, 0)
         self.serverSocket.bind((HOST, PORT, 0, scope_id))
         #self.serverSocket.bind((HOST, PORT))
@@ -86,7 +86,7 @@ def setup(self):
     def teardown(self):
         if (self.serverSocket != None):
             print('Closing socket...')
-            self.serverSocket.close
+            self.serverSocket.shutdown(socket.SHUT_RDWR) # Shutdown reads and writes
 
 
     # recieve data over multiple transactions