ENH: Running remote code safely via XMLRPC.

Adding a python_server which executes code as nobody safely so users
cannot do too much damage.

1 files changed, 65 insertions, 0 deletions

diff --git a/python_server.py b/python_server.py
new file mode 100755
index 0000000..debd73d
--- /dev/null
+++ b/python_server.py
@@ -0,0 +1,65 @@
+#!/usr/bin/env python
+"""This server runs an XMLRPC server that can be submitted code and tests
+and returns the output.  It *should* be run as root and will run as the user 
+'nobody' so as to minimize any damange by errant code.
+"""
+import sys
+from SimpleXMLRPCServer import SimpleXMLRPCServer
+import pwd
+import os
+
+
+# Set the effective uid
+nobody = pwd.getpwnam('nobody')
+os.seteuid(nobody.pw_uid)
+
+
+def run_code(answer, test_code, in_dir=None):
+    """Tests given Python function (`answer`) with the `test_code` supplied.  
+    If the optional `in_dir` keyword argument is supplied it changes the 
+    directory to that directory (it does not change it back to the original when
+    done).
+
+    Returns
+    -------
+    
+    A tuple: (success, error message).
+    
+    """
+    if in_dir is not None:
+        os.chdir(in_dir)
+        
+    success = False
+    tb = None
+    try:
+        submitted = compile(answer, '<string>', mode='exec')
+        g = {}
+        exec submitted in g
+        _tests = compile(test_code, '<string>', mode='exec')
+        exec _tests in g
+    except AssertionError:
+        type, value, tb = sys.exc_info()
+        info = traceback.extract_tb(tb)
+        fname, lineno, func, text = info[-1]
+        text = str(test_code).splitlines()[lineno-1]
+        err = "{0} {1} in: {2}".format(type.__name__, str(value), text)
+    except:
+        type, value = sys.exc_info()[:2]
+        err = "Error: {0}".format(repr(value))
+    else:
+        success = True
+        err = 'Correct answer'
+    finally:
+        del tb
+
+    return success, err
+
+
+def main():
+    server = SimpleXMLRPCServer(("localhost", 8001))
+    server.register_function(run_code)
+    server.serve_forever()
+    
+if __name__ == '__main__':
+    main()
+    
\ No newline at end of file