tuerd: Get peer information from socket

[saartuer.git] / tuerd

diff --git a/tuerd b/tuerd
index a283f26d9221c47feae5b31758b7dc0181cb84ca..f679fa896c2bc1ab75f9c28155630f06ad783507 100755 (executable)
--- a/tuerd
+++ b/tuerd
@@ -1,7 +1,8 @@
 #!/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 *********
@@ -23,6 +24,15 @@ def doNothing (conn):
        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:
        # name is for logging and also used for mapping command names to instances of this class
@@ -52,6 +62,9 @@ pinlist = [Pinoutput("open", 12, [(True, 0.3), (False, 5.0)]),
 
 
 # ******** main *********
+# at the end do a cleanup
+atexit.register(GPIO.cleanup);
+
 # convert list of pin objects to dictionary for command lookup
 pindict = {}
 for pin in pinlist:
@@ -60,12 +73,12 @@ for pin in pinlist:
 # create socket
 sock = socket.socket (socket.AF_UNIX, socket.SOCK_STREAM)
 # delete old socket file and don't bitch around if it's not there
-try:
-       os.unlink (socketname)
-except OSError:
-       pass
+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)
@@ -77,7 +90,8 @@ sock.listen(1)
 while True:
        # accept connections
        conn, addr = sock.accept()
-       # TODO: use addr to determine the client for logging
+       # 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
@@ -88,6 +102,3 @@ while True:
        # close connection cleanly
        conn.close()
 
-# FIXME will this be executed after receiving a terminating signal?
-GPIO.cleanup()
-