X-Git-Url: https://git.ralfj.de/saartuer.git/blobdiff_plain/6e7d90d419547705cb125adc7fe3626d9dc0fd49..afd14c9b67b6fb41219abf0dcd5e7fda37a1b8a9:/tuerd?ds=sidebyside

diff --git a/tuerd b/tuerd
index 7cc15d6..f679fa8 100755
--- a/tuerd
+++ b/tuerd
@@ -1,73 +1,104 @@
 #!/usr/bin/python3
-import time, socket, os, stat
+import time, socket, os, stat, atexit, errno, struct
 from datetime import datetime
 import RPi.GPIO as GPIO
+SO_PEERCRED = 17 # DO - NOT - TOUCH
 GPIO.setmode(GPIO.BOARD)
 
+# ******** definitions *********
+# logging function
+# TODO: loglevel, log like a real daemon
 def log (what):
 	print (datetime.now(),what)
 
+# send to client for information but don't care if it arrives
 def waynesend (conn, what):
 	try:
 		conn.send(what)
 	except:
 		log("Couldn't send %s" % str(what))
 
+# for command not found: do nothing with the pins and send a "0" to the client
+def doNothing (conn):
+	log ("doing nothing")
+	waynesend(conn,b"0")
+	pass
+
+# delete a file, don't care if it did not exist in the first place
+def forcerm(name):
+	try:
+		os.unlink (name)
+	except OSError as e:
+		# only ignore error if it was "file didn't exist"
+		if e.errno != errno.ENOENT:
+			raise
+
+# commands: on a pin do a series of timed on/off switches
 class Pinoutput:
-	# actionsanddelays is a list of pairs: (bool to send, delay in seconds to wait afterwards)
+	# name is for logging and also used for mapping command names to instances of this class
+	# actionsanddelays is a list of pairs: (bool to set on pin, delay in seconds to wait afterwards)
 	def __init__ (self, name, pinnumber, actionsanddelays):
 		self.name = name
 		self.pin = pinnumber
 		self.todo = actionsanddelays
 		GPIO.setup(pinnumber, GPIO.OUT)
 		log ("Pin %d set to be an output pin for %s." % (pinnumber,name))
-	
+	# actually send the signal to the pins
 	def __call__ (self, conn):
 		for (value,delay) in self.todo:
 			GPIO.output(self.pin, value)
 			log ("%s: Pin %d set to %s." % (self.name,self.pin,str(value)))
 			time.sleep(delay)
+		# notify success
 		waynesend(conn,b"1")
 
-tuergroupid = 1005
+# ******** configuration *********
 
+tuergroupid = 1005
+socketname = "/run/tuer.sock"
 pinlist = [Pinoutput("open", 12, [(True, 0.3), (False, 5.0)]),
 	Pinoutput("close", 16, [(True, 0.3), (False, 5.0)]),
-	Pinoutput("buzz", 22, [(True, 2.0), (False, 5.0)])]
+	Pinoutput("buzz", 22, [(True, 2.0), (False, 0.1)])]
 
-socketname = "/run/tuer.sock"
 
+# ******** main *********
+# at the end do a cleanup
+atexit.register(GPIO.cleanup);
 
-def doNothing (conn):
-	log ("doing nothing")
-	waynesend(conn,b"0")
-	pass
+# convert list of pin objects to dictionary for command lookup
+pindict = {}
+for pin in pinlist:
+	pindict[pin.name.encode()] = pin
 
+# create socket
 sock = socket.socket (socket.AF_UNIX, socket.SOCK_STREAM)
-
-try:
-	os.unlink (socketname)
-except OSError:
-	pass
-
+# delete old socket file and don't bitch around if it's not there
+forcerm(socketname)
+# bind socket to file name
 sock.bind (socketname)
-
+# ensure we close and delete the socket when we quit (atexit.register is LIFO!)
+atexit.register(forcerm, socketname)
+atexit.register(sock.close)
+# allow only users in the tuergroup to write to the socket
 os.chown (socketname, 0, tuergroupid)
 os.chmod (socketname, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IWGRP)
-
+# listen to the people, but not too many at once
 sock.listen(1)
 
-pindict = {}
-for pin in pinlist:
-	pindict[pin.name.encode()] = pin
-
+# main loop
+# FIXME: DoS by opening socket but not sending data, because this loop is single threaded; maybe settimeout helps a bit.
 while True:
+	# accept connections
 	conn, addr = sock.accept()
-	data = conn.recv (128)
+	# get peer information (TODO use it for logging)
+	(pid, uid, gid) = (struct.unpack('3i', conn.getsockopt(socket.SOL_SOCKET, SO_PEERCRED, struct.calcsize('3i'))))
+	# get some data from the client (enough to hold any valid command)
+	data = conn.recv (32)
+	# log the command
 	log("received command: %s" % str(data))
+	# lookup the command, if it's not in the dict, use the doNothing function instead
+	# and execute the looked up command or doNothing with the connection, so it can respond to the client
 	pindict.get(data,doNothing)(conn)
+	# close connection cleanly
 	conn.close()
 
-GPIO.cleanup()
-
-