Check to make sure sudo works without password.

an unprivileged Python process

mininet/net.py

@@ -91,6 +91,7 @@ import re
 import select
 import signal
 from time import sleep
+from subprocess import check_output
 
 from mininet.cli import CLI
 from mininet.log import info, error, debug, output
@@ -561,13 +562,12 @@ def init():
     "Initialize Mininet."
     if init.inited:
         return
-    if os.getuid() != 0:
-        # Note: this script must be run as root
-        # Perhaps we should do so automatically!
-        print "*** Mininet must run as root."
-        exit( 1 )
-    # If which produces no output, then mnexec is not in the path.
-    # May want to loosen this to handle mnexec in the current dir.
+    # Make sure we can sudo without a password
+    try:
+        check_output( [ 'sudo', '-n', 'echo' ] )
+    except:
+        raise Exception( "Could not run sudo -n echo - check /etc/sudoers" )
+    # Make sure mnexec is in our path
     if not quietRun( 'which mnexec' ):
         raise Exception( "Could not find mnexec - check $PATH" )
     fixLimits()

mininet/node.py

@@ -76,12 +76,12 @@ class Node( object ):
         opts = '-cdp'
         if self.inNamespace:
             opts += 'n'
-        cmd = [ 'mnexec', opts, 'bash', '-m' ]
+        cmd = [ 'sudo', '-E', 'env', 'PATH=%s' % os.environ['PATH'],
+                'mnexec', opts, 'bash', '-m', '-p' ]
         self.shell = Popen( cmd, stdin=PIPE, stdout=PIPE, stderr=STDOUT,
             close_fds=False )
         self.stdin = self.shell.stdin
         self.stdout = self.shell.stdout
-        self.pid = self.shell.pid
         self.pollOut = select.poll()
         self.pollOut.register( self.stdout )
         # Maintain mapping between file descriptors and nodes
@@ -102,6 +102,8 @@ class Node( object ):
         self.waiting = False
         # Stash additional information as desired
         self.args = kwargs
+        # Read pid from mnexec
+        self.pid = int( self.readline()[ 1: ] )
 
     @classmethod
     def fdToNode( cls, fd ):
@@ -149,7 +151,7 @@ class Node( object ):
 
     def terminate( self ):
         "Send kill signal to Node and clean up after it."
-        os.kill( self.pid, signal.SIGKILL )
+        quietRun( 'kill ' + str( self.pid ) )
         self.cleanup()
 
     def stop( self ):

mininet/util.py

@@ -1,11 +1,12 @@
 "Utility functions for Mininet."
 
 from time import sleep
-from resource import setrlimit, RLIMIT_NPROC, RLIMIT_NOFILE
+from resource import setrlimit, getrlimit, RLIMIT_NPROC, RLIMIT_NOFILE
 import select
 from subprocess import call, check_call, Popen, PIPE, STDOUT
+import os
 
-from mininet.log import error
+from mininet.log import error, warn
 
 # Command execution support
 
@@ -29,6 +30,7 @@ def quietRun( *cmd ):
         cmd = cmd[ 0 ]
         if isinstance( cmd, str ):
             cmd = cmd.split( ' ' )
+    cmd = ["sudo", "-E", "env", "PATH=%s" % os.environ["PATH"]] + cmd
     popen = Popen( cmd, stdout=PIPE, stderr=STDOUT )
     # We can't use Popen.communicate() because it uses
     # select(), which can't handle
@@ -205,5 +207,22 @@ def makeNumeric( s ):
 
 def fixLimits():
     "Fix ridiculously small resource limits."
-    setrlimit( RLIMIT_NPROC, ( 4096, 8192 ) )
-    setrlimit( RLIMIT_NOFILE, ( 16384, 32768 ) )
+    manyprocs = 8192
+    manyfiles = 32768
+    minprocs, maxprocs = getrlimit( RLIMIT_NPROC )
+    minfiles, maxfiles = getrlimit( RLIMIT_NOFILE )
+    # Root can raise limits
+    if os.getuid() == 0:
+        maxprocs = max( maxprocs, manyprocs )
+        maxfiles = max( maxfiles, manyfiles )
+    minprocs = min( manyprocs, maxprocs )
+    minfiles = min( manyfiles, maxfiles )
+    setrlimit( RLIMIT_NPROC, ( minprocs, maxprocs ) )
+    setrlimit( RLIMIT_NOFILE, ( minfiles, maxfiles ) )
+    nprocs = max( getrlimit( RLIMIT_NPROC ) )
+    nfiles = max( getrlimit( RLIMIT_NOFILE ) )
+    # Complain if limits are too low
+    if nprocs < manyprocs:
+        warn( '*** Warning: process limit is low:', nprocs, 'procs\n' )
+    if nfiles < manyfiles:
+        warn( '*** Warning: open file limit is low:', nfiles, 'files \n' )