5 ### (c) 2013 Mark Wooding
8 ###----- Licensing notice ---------------------------------------------------
10 ### This file is part of Chopwood: a password-changing service.
12 ### Chopwood is free software; you can redistribute it and/or modify
13 ### it under the terms of the GNU Affero General Public License as
14 ### published by the Free Software Foundation; either version 3 of the
15 ### License, or (at your option) any later version.
17 ### Chopwood is distributed in the hope that it will be useful,
18 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ### GNU Affero General Public License for more details.
22 ### You should have received a copy of the GNU Affero General Public
23 ### License along with Chopwood; if not, see
24 ### <http://www.gnu.org/licenses/>.
26 from __future__ import with_statement
28 import contextlib as CTX
29 import os as OS; ENV = OS.environ
33 import traceback as TB
35 from auto import HOME, PACKAGE, VERSION
36 import config as CONF; CFG = CONF.CFG
38 import output as O; OUT = O.OUT; PRINT = O.PRINT
39 import subcommand as SC
42 ###--------------------------------------------------------------------------
43 ### Configuration tweaks.
45 _script_name = ENV.get('SCRIPT_NAME', '/cgi-bin/chpwd')
49 ## The URL of this program, when it's run through CGI.
50 SCRIPT_NAME = _script_name,
52 ## A (maybe relative) URL for static content. By default this comes from
53 ## the main script, but we hope that user agents cache it.
54 STATIC = _script_name + '/static')
56 ###--------------------------------------------------------------------------
57 ### Escaping and encoding.
59 ## Some handy regular expressions.
60 R_URLESC = RX.compile('%([0-9a-fA-F]{2})')
61 R_URLBAD = RX.compile('[^-\\w,.!]')
62 R_HTMLBAD = RX.compile('[&<>]')
65 """Decode a single form-url-encoded string S."""
66 return R_URLESC.sub(lambda m: chr(int(m.group(1), 16)),
71 """Encode a single string S using form-url-encoding."""
72 return R_URLBAD.sub(lambda m: '%%%02x' % ord(m.group(0)), s)
75 """Escape a literal string S so that HTML doesn't misinterpret it."""
76 return R_HTMLBAD.sub(lambda m: '&#x%02x;' % ord(m.group(0)), s)
78 ## Some standard character sequences, and HTML entity names for prettier
80 _quotify = U.StringSubst({
89 """Return a pretty HTML version of S."""
90 return _quotify(htmlescape(s))
92 ###--------------------------------------------------------------------------
95 class HTTPOutput (O.FileOutput):
97 Output driver providing an automatic HTTP header.
99 The `headerp' attribute is true if we've written a header. The `header'
100 method will print a custom header if this is wanted.
103 def __init__(me, *args, **kw):
104 """Constructor: initialize `headerp' flag."""
105 super(HTTPOutput, me).__init__(*args, **kw)
109 """Output protocol: print a header if we've not written one already."""
110 if not me.headerp: me.header('text/plain')
111 super(HTTPOutput, me).write(msg)
113 def header(me, content_type = 'text/plain', **kw):
115 Print a header, if none has yet been printed.
117 Keyword arguments can be passed to emit HTTP headers: see `http_header'
118 for the formatting rules.
120 if me.headerp: return
122 for h in O.http_headers(content_type = content_type, **kw):
126 def cookie(name, value, **kw):
128 Return a HTTP `Set-Cookie' header.
130 The NAME and VALUE give the name and value of the cookie; both are
131 form-url-encoded to prevent misinterpretation (fortunately, `cgiparse'
132 knows to undo this transformation). The KW are other attributes to
133 declare: the names are forced to lower-case and underscores `_' are
134 replaced by hyphens `-'; a `True' value is assumed to indicate that the
135 attribute is boolean, and omitted.
138 for k, v in kw.iteritems():
139 k = '-'.join(i.lower() for i in k.split('_'))
141 try: maxage = int(attr['max-age'])
142 except KeyError: pass
144 attr['expires'] = T.strftime('%a, %d %b %Y %H:%M:%S GMT',
145 T.gmtime(U.NOW + maxage))
146 return '; '.join(['%s=%s' % (urlencode(name), urlencode(value))] +
147 [v is not True and '%s=%s' % (k, v) or k
148 for k, v in attr.iteritems()])
150 def action(*v, **kw):
152 Build a URL invoking this script.
154 The positional arguments V are used to construct a path which is appended
155 to the (deduced or configured) script name (and presumably will be read
156 back as `PATH_INFO'). The keyword arguments are (form-url-encoded and)
157 appended as a query string, if present.
159 url = '/'.join([CFG.SCRIPT_NAME] + list(v))
161 url += '?' + ';'.join('%s=%s' % (urlencode(k), urlencode(kw[k]))
163 return htmlescape(url)
166 """Build a URL for the static file NAME."""
167 return htmlescape(CFG.STATIC + '/' + name)
170 def html(title, **kw):
172 Context manager for HTML output.
174 Keyword arguments are output as HTTP headers (if no header has been written
175 yet). A `<head>' element is written, and a `<body>' opened, before the
176 context body is executed; the elements are closed off properly at the end.
179 kw = dict(kw, content_type = 'text/html')
182 ## Write the HTML header.
184 <!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01//EN'
185 'http://www.w3c.org/TR/html4/strict.dtd'>
188 <title>%(title)s</title>
189 <link rel=stylesheet type='text/css' media=screen href='%(style)s'>
190 <meta http-equiv='Content-Script-Type' content='text/javascript'>
191 <script type='text/javascript' src='%(script)s'></script>
192 </head>""" % dict(title = html_quotify(title),
193 style = static('chpwd.css'),
194 script = static('chpwd.js')))
202 <a href="%(about)s">Chopwood</a>, version %(version)s:
203 copyright © 2012 Mark Wooding
207 </html>''' % dict(about = static('about.html'),
210 def redirect(where, **kw):
212 Write a complete redirection to some other URL.
214 OUT.header(content_type = 'text/html',
215 status = 302, location = where,
219 <head><title>No, sorry, it's moved again.</title></head>
220 <body><p>I'm <a href="%s">over here</a> now.<body>
221 </html>""" % htmlescape(where))
223 ###--------------------------------------------------------------------------
226 ## Where we find our templates.
229 ## Keyword arguments for templates.
233 ## Set some basic keyword arguments.
235 def set_template_keywords():
239 script = CFG.SCRIPT_NAME,
242 class TemplateFinder (object):
244 A magical fake dictionary whose keys are templates.
246 def __init__(me, dir):
249 def __getitem__(me, key):
250 try: return me._cache[key]
251 except KeyError: pass
252 with open(OS.path.join(me._dir, key)) as f: tmpl = f.read()
253 me._cache[key] = tmpl
255 TMPL = TemplateFinder(TMPLDIR)
260 Context manager: execute the body with additional keyword arguments
265 with STATE.bind(kw = d): yield
269 class FormatHTML (F.SimpleFormatOperation):
271 ~H: escape output suitable for inclusion in HTML.
273 With `:', instead apply form-urlencoding.
275 def _convert(me, arg):
276 if me.colonp: return html_quotify(arg)
277 else: return htmlescape(arg)
278 FORMATOPS['H'] = FormatHTML
280 def format_tmpl(control, **kw):
281 with F.COMPILE.bind(opmaps = [FORMATOPS, F.BASEOPS]):
283 F.format(OUT, control, **STATE.kw)
285 def page(template, header = {}, title = 'Chopwood', **kw):
286 header = dict(header, content_type = 'text/html')
288 format_tmpl(TMPL['wrapper.fhtml'],
289 title = title, payload = TMPL[template], **kw)
291 ###--------------------------------------------------------------------------
294 def cgi_error_guts():
296 Report an exception while we're acting as a CGI, together with lots of
297 information about our state.
299 Our caller has, probably at great expense, arranged that we can format lots
303 ## Grab the exception information.
304 exty, exval, extb = SYS.exc_info()
306 ## Print the exception itself.
309 <pre>%s</pre>""" % html_quotify(
310 '\n'.join(TB.format_exception_only(exty, exval))))
312 ## Format a traceback so we can find out what has gone wrong.
316 for file, line, func, text in TB.extract_tb(extb, 20):
317 PRINT("<li><b>%s</b>:%d (<b>%s</b>)" % (
318 htmlescape(file), line, htmlescape(func)))
320 PRINT("<br><tt>%s</tt>" % htmlescape(text))
323 ## Format various useful tables.
325 fmt_kvlist(d.iteritems())
327 for k, v in sorted(l):
328 PRINT("<tr><th align=right valign=top>%s<td><tt>%s</tt>" % (
329 htmlescape(k), htmlescape(v)))
332 PRINT("<tr><tt>%s</tt>" % htmlescape(i))
335 <h2>Parameters</h2>""")
336 for what, thing, how in [('Query', PARAM, fmt_kvlist),
337 ('Cookies', COOKIE, fmt_dict),
338 ('Path', PATH, fmt_list),
339 ('Environment', ENV, fmt_dict)]:
340 PRINT("<h3>%s</h3>\n<table>" % what)
346 Report an exception while in CGI mode.
348 If we've not produced a header yet, then we can do that, and produce a
349 status code and everything; otherwise we'll have to make do with a small
353 PRINT("<div class=exception>")
355 PRINT("</div>\n</body></html>")
357 with html("chpwd internal error", status = 500):
358 PRINT("<h1>chpwd internal error</h1>")
363 def cgi_errors(hook = None):
365 Context manager: report errors in the body as useful HTML.
367 If HOOK is given, then call it before reporting errors. It may have set up
374 if isinstance(e, U.ExpectedError) and not OUT.headerp:
376 headers = dict(status = e.code),
377 title = 'Chopwood: error', error = e)
379 exty, exval, extb = SYS.exc_info()
380 with tmplkw(exception = TB.format_exception_only(exty, exval),
381 traceback = TB.extract_tb(extb),
382 PARAM = sorted(PARAM),
383 COOKIE = sorted(COOKIE.items()),
385 ENV = sorted(ENV.items())):
387 format_tmpl(TMPL['exception.fhtml'], toplevel = False)
389 page('exception.fhtml',
390 headers = dict(status = 500),
391 title = 'Chopwood: internal error',
394 ###--------------------------------------------------------------------------
397 ## Lots of global variables to be filled in by `cgiparse'.
404 ## Regular expressions for splitting apart query and cookie strings.
405 R_QSPLIT = RX.compile('[;&]')
406 R_CSPLIT = RX.compile(';')
408 def split_keyvalue(string, delim, default):
410 Split a STRING, and generate the resulting KEY=VALUE pairs.
412 The string is split at DELIM; the components are parsed into KEY[=VALUE]
413 pairs. The KEYs and VALUEs are stripped of leading and trailing
414 whitespace, and form-url-decoded. If the VALUE is omitted, then the
415 DEFAULT is used unless the DEFAULT is `None' in which case the component is
418 for kv in delim.split(string):
420 k, v = kv.split('=', 1)
422 if default is None: continue
423 else: k, v = kv, default
424 k, v = k.strip(), v.strip()
426 k, v = urldecode(k), urldecode(v)
431 Process all of the various exciting CGI environment variables.
433 We read environment variables and populate some tables left in global
434 variables: it's all rather old-school. Variables set are as follows.
437 A dictionary mapping cookie names to the values provided by the user
441 A dictionary holding some special query parameters which are of
442 interest at a global level, and should not be passed to a subcommand
443 handler. No new entries will be added to this dictionary, though
444 values will be modified to reflect the query parameters discovered.
445 Conventionally, such parameters have names beginning with `%'.
448 The query parameters as a list of (KEY, VALUE) pairs. Special
449 parameters are omitted.
452 The query parameters as a dictionary. Special parameters, and
453 parameters which appear more than once, are omitted.
456 The trailing `PATH_INFO' path, split at `/' markers, with any
457 trailing empty component removed.
462 except KeyError: raise U.ExpectedError, (500, "No `%s' supplied" % var)
464 ## Yes, we want the request method.
465 method = getenv('REQUEST_METHOD')
467 ## Acquire the query string.
469 q = getenv('QUERY_STRING')
471 elif method == 'POST':
473 ## We must read the query string from stdin.
474 n = getenv('CONTENT_LENGTH')
476 raise U.ExpectedError, (500, "Invalid CONTENT_LENGTH")
478 if getenv('CONTENT_TYPE') != 'application/x-www-form-urlencoded':
479 raise U.ExpectedError, (500, "Unexpected content type `%s'" % ct)
480 q = SYS.stdin.read(n)
482 raise U.ExpectedError, (500, "Failed to read correct length")
485 raise U.ExpectedError, (500, "Unexpected request method `%s'" % method)
487 ## Populate the `SPECIAL', `PARAM' and `PARAMDICT' tables.
489 for k, v in split_keyvalue(q, R_QSPLIT, 't'):
500 ## Parse out the cookies, if any.
501 try: c = ENV['HTTP_COOKIE']
502 except KeyError: pass
504 for k, v in split_keyvalue(c, R_CSPLIT, None): COOKIE[k] = v
506 ## Set up the `PATH'.
507 try: p = ENV['PATH_INFO']
508 except KeyError: pass
510 pp = p.lstrip('/').split('/')
511 if pp and not pp[-1]: pp.pop()
514 ###--------------------------------------------------------------------------
517 class Subcommand (SC.Subcommand):
519 A CGI subcommand object.
521 As for `subcommand.Subcommand', but with additional protocol for processing
525 def cgi(me, param, path):
527 Invoke the subcommand given a collection of CGI parameters.
529 PARAM is a list of (KEY, VALUE) pairs from the CGI query. The CGI query
530 parameters are checked against the subcommand's parameters (making sure
531 that mandatory parameters are supplied, that any switches are given
532 boolean values, and that only the `rest' parameter, if any, is
535 PATH is a list of trailing path components. They are used to satisfy the
536 `rest' parameter if there is one and there are no query parameters which
537 satisfy the `rest' parameter; otherwise, an `ExpectedError' is raised if
538 the list of path elements is non-empty.
541 ## We're going to make a pass over the supplied parameters, and we'll
542 ## check them off against the formal parameters as we go; so we'll need
543 ## to be able to look them up. We'll also keep track of the ones we've
544 ## seen so that we can make sure that all of the mandatory parameters
545 ## were actually supplied.
547 ## To that end: `want' is a dictionary mapping parameter names to
548 ## functions which will do something useful with the value; `seen' is a
549 ## set of the parameters which have been assigned; and `kw' is going to
550 ## be the keyword-argument dictionary we pass to the handler function.
555 """Set a simple value: we shouldn't see multiple values."""
557 raise U.ExpectedError, (400, "Repeated parameter `%s'" % k)
560 """Set a simple boolean value: for switches."""
561 set_value(k, v.lower() in ['true', 't', 'yes', 'y'])
563 """Append the value to a list: for the `rest' parameter."""
564 kw.setdefault(k, []).append(v)
566 ## Set up the `want' map.
568 if o.argname: want[o.name] = set_value
569 else: want[o.name] = set_bool
570 for p in me.params: want[p.name] = set_value
571 for p in me.oparams: want[p.name] = set_value
572 if me.rparam: want[me.rparam.name] = set_list
574 ## Work through the list of supplied parameters.
580 raise U.ExpectedError, (400, "Unexpected parameter `%s'" % k)
584 ## Deal with a path, if there is one.
586 if me.rparam and me.rparam.name not in kw:
587 kw[me.rparam.name] = path
589 raise U.ExpectedError, (404, "Superfluous path elements")
591 ## Make sure we saw all of the mandatory parameters.
594 raise U.ExpectedError, (400, "Missing parameter `%s'" % p.name)
596 ## Invoke the subcommand.
599 def subcommand(name, contexts, desc, cls = Subcommand, *args, **kw):
600 """Decorator for defining CGI subcommands."""
601 return SC.subcommand(name, contexts, desc, cls = cls, *args, **kw)
603 ###----- That's all, folks --------------------------------------------------