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# Copyright (C) 2007-2008 The University of Melbourne
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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# Runs a student script in a safe execution environment.
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from common import studpath
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def interpret_file(req, owner, filename, interpreter):
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"""Serves a file by interpreting it using one of IVLE's builtin
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interpreters. All interpreters are intended to run in the user's jail. The
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jail location is provided as an argument to the interpreter but it is up
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to the individual interpreters to create the jail.
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req: An IVLE request object.
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owner: Username of the user who owns the file being served.
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filename: Filename in the local file system.
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interpreter: A function object to call.
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# Make sure the file exists (otherwise some interpreters may not actually
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# Don't test for execute permission, that will only be required for
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# certain interpreters.
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if not os.access(filename, os.R_OK):
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req.throw_error(req.HTTP_NOT_FOUND)
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# Get the UID of the owner of the file
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# (Note: files are executed by their owners, not the logged in user.
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# This ensures users are responsible for their own programs and also
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# allows them to be executed by the public).
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(_,_,uid,_,_,_,_) = pwd.getpwnam(owner)
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# The user does not exist. This should have already failed the
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req.throw_error(req.HTTP_INTERNAL_SERVER_ERROR)
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# Split up req.path again, this time with respect to the jail
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(_, jail_dir, path) = studpath.url_to_jailpaths(req.path)
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path = os.path.join('/', path)
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(working_dir, _) = os.path.split(path)
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# jail_dir is the absolute jail directory.
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# path is the filename relative to the user's jail.
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# working_dir is the directory containing the file relative to the user's
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# (Note that paths "relative" to the jail actually begin with a '/' as
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# they are absolute in the jailspace)
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return interpreter(uid, jail_dir, working_dir, path, req)
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# Used to store mutable data
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def execute_cgi(trampoline, uid, jail_dir, working_dir, script_path, req):
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trampoline: Full path on the local system to the CGI wrapper program
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uid: User ID of the owner of the file.
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jail_dir: Absolute path of owner's jail directory.
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working_dir: Directory containing the script file relative to owner's
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script_path: CGI script relative to the owner's jail.
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req: IVLE request object.
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The called CGI wrapper application shall be called using popen and receive
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the HTTP body on stdin. It shall receive the CGI environment variables to
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# Get the student program's directory and execute it from that context.
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(tramp_dir, _) = os.path.split(trampoline)
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# TODO: Don't create a file if the body length is known to be 0
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# Write the HTTP body to a temporary file so it can be passed as a *real*
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f.seek(0) # Rewind, for reading
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# usage: tramp uid jail_dir working_dir script_path
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pid = subprocess.Popen(
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[trampoline, str(uid), jail_dir, working_dir, script_path],
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stdin=f, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
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# process_cgi_line: Reads a single line of CGI output and processes it.
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# Prints to req, and also does fancy HTML warnings if Content-Type
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cgiflags.got_cgi_header = False
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cgiflags.started_cgi_body = False
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cgiflags.wrote_html_warning = False
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def process_cgi_line(line):
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# FIXME? Issue with binary files (processing per-line?)
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if cgiflags.started_cgi_body:
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# FIXME: HTML escape text if wrote_html_warning
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if line.strip() == "" and cgiflags.got_cgi_header:
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cgiflags.started_cgi_body = True
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elif line.startswith("Content-Type:"):
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req.content_type = line[13:].strip()
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cgiflags.got_cgi_header = True
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elif line.startswith("Location:"):
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cgiflags.got_cgi_header = True
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elif line.startswith("Status:"):
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cgiflags.got_cgi_header = True
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elif cgiflags.got_cgi_header:
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req.write("Invalid header")
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# Assume the user is not printing headers and give a warning
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# User program did not print header.
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# Make a fancy HTML warning for them.
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req.content_type = "text/html"
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req.write("""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<meta http-equiv="Content-Type"
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content="text/html; charset=utf-8" />
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<body style="margin: 0; padding: 0; font-family: sans;">
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<div style="background-color: #faa; border-bottom: 1px solid black;
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<p><strong>Warning</strong>: You did not print a "Content-Type" header.
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CGI requires you to print some content type. You may wish to try:</p>
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<pre style="margin-left: 1em">Content-Type: text/html</pre>
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<div style="margin: 8px;">
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cgiflags.got_cgi_header = True
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cgiflags.wrote_html_warning = True
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cgiflags.started_cgi_body = True
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# Read from the process's stdout into req
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for line in pid.stdout:
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process_cgi_line(line)
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# If we wrote an HTML warning header, write the footer
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if cgiflags.wrote_html_warning:
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# TODO: Replace mytest with cgi trampoline handler script
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location_cgi_python = os.path.join(conf.ivlepath, "bin/trampoline-python")
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# Mapping of interpreter names (as given in conf/app/server.py) to
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# interpreter functions.
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interpreter_objects = {
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: functools.partial(execute_cgi, location_cgi_python),
added
removed
src/common/interpret.py
