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 html_quotify = U.StringSubst({
93 ###--------------------------------------------------------------------------
96 class HTTPOutput (O.FileOutput):
98 Output driver providing an automatic HTTP header.
100 The `headerp' attribute is true if we've written a header. The `header'
101 method will print a custom header if this is wanted.
104 def __init__(me, *args, **kw):
105 """Constructor: initialize `headerp' flag."""
106 super(HTTPOutput, me).__init__(*args, **kw)
110 """Output protocol: print a header if we've not written one already."""
111 if not me.headerp: me.header('text/plain')
112 super(HTTPOutput, me).write(msg)
114 def header(me, content_type = 'text/plain', **kw):
116 Print a header, if none has yet been printed.
118 Keyword arguments can be passed to emit HTTP headers: see `http_header'
119 for the formatting rules.
121 if me.headerp: return
123 for h in O.http_headers(content_type = content_type, **kw):
127 def cookie(name, value, **kw):
129 Return a HTTP `Set-Cookie' header.
131 The NAME and VALUE give the name and value of the cookie; both are
132 form-url-encoded to prevent misinterpretation (fortunately, `cgiparse'
133 knows to undo this transformation). The KW are other attributes to
134 declare: the names are forced to lower-case and underscores `_' are
135 replaced by hyphens `-'; a `True' value is assumed to indicate that the
136 attribute is boolean, and omitted.
139 for k, v in kw.iteritems():
140 k = '-'.join(i.lower() for i in k.split('_'))
142 try: maxage = int(attr['max-age'])
143 except KeyError: pass
145 attr['expires'] = T.strftime('%a, %d %b %Y %H:%M:%S GMT',
146 T.gmtime(U.NOW + maxage))
147 return '; '.join(['%s=%s' % (urlencode(name), urlencode(value))] +
148 [v is not True and '%s=%s' % (k, v) or k
149 for k, v in attr.iteritems() if v])
151 def action(*v, **kw):
153 Build a URL invoking this script.
155 The positional arguments V are used to construct a path which is appended
156 to the (deduced or configured) script name (and presumably will be read
157 back as `PATH_INFO'). The keyword arguments are (form-url-encoded and)
158 appended as a query string, if present.
160 url = '/'.join([CFG.SCRIPT_NAME] + list(v))
162 url += '?' + ';'.join('%s=%s' % (urlencode(k), urlencode(kw[k]))
164 return htmlescape(url)
167 """Build a URL for the static file NAME."""
168 return htmlescape(CFG.STATIC + '/' + name)
170 def redirect(where, **kw):
172 Write a complete redirection to some other URL.
174 OUT.header(content_type = 'text/html',
175 status = 302, location = where,
179 <head><title>No, sorry, it's moved again.</title></head>
180 <body><p>I'm <a href="%s">over here</a> now.<body>
181 </html>""" % htmlescape(where))
183 ###--------------------------------------------------------------------------
186 ## Where we find our templates.
189 ## Keyword arguments for templates.
193 ## Set some basic keyword arguments.
195 def set_template_keywords():
199 script = CFG.SCRIPT_NAME,
202 class TemplateFinder (object):
204 A magical fake dictionary whose keys are templates.
206 def __init__(me, dir):
209 def __getitem__(me, key):
210 try: return me._cache[key]
211 except KeyError: pass
212 with open(OS.path.join(me._dir, key)) as f: tmpl = f.read()
213 me._cache[key] = tmpl
215 TMPL = TemplateFinder(TMPLDIR)
220 Context manager: execute the body with additional keyword arguments
225 with STATE.bind(kw = d): yield
229 class FormatHTML (F.SimpleFormatOperation):
231 ~H: escape output suitable for inclusion in HTML.
233 With `:', additionally apply quotification.
235 def _convert(me, arg):
236 if me.colonp: return html_quotify(arg)
237 else: return htmlescape(arg)
238 FORMATOPS['H'] = FormatHTML
240 def format_tmpl(control, **kw):
241 with F.COMPILE.bind(opmaps = [FORMATOPS, F.BASEOPS]):
243 F.format(OUT, control, **STATE.kw)
245 def page(template, header = {}, title = 'Chopwood', **kw):
246 header = dict(header, content_type = 'text/html')
248 format_tmpl(TMPL['wrapper.fhtml'],
249 title = title, payload = TMPL[template], **kw)
251 ###--------------------------------------------------------------------------
255 def cgi_errors(hook = None):
257 Context manager: report errors in the body as useful HTML.
259 If HOOK is given, then call it before reporting errors. It may have set up
266 if isinstance(e, U.ExpectedError) and not OUT.headerp:
268 header = dict(status = e.code),
269 title = 'Chopwood: error', error = e)
271 exty, exval, extb = SYS.exc_info()
272 with tmplkw(exception = TB.format_exception_only(exty, exval),
273 traceback = TB.extract_tb(extb),
274 PARAM = sorted(PARAM),
275 COOKIE = sorted(COOKIE.items()),
277 ENV = sorted(ENV.items())):
279 format_tmpl(TMPL['exception.fhtml'], toplevel = False)
281 page('exception.fhtml',
282 header = dict(status = 500),
283 title = 'Chopwood: internal error',
286 ###--------------------------------------------------------------------------
289 ## Lots of global variables to be filled in by `cgiparse'.
297 ## Regular expressions for splitting apart query and cookie strings.
298 R_QSPLIT = RX.compile('[;&]')
299 R_CSPLIT = RX.compile(';')
301 def split_keyvalue(string, delim, default):
303 Split a STRING, and generate the resulting KEY=VALUE pairs.
305 The string is split at DELIM; the components are parsed into KEY[=VALUE]
306 pairs. The KEYs and VALUEs are stripped of leading and trailing
307 whitespace, and form-url-decoded. If the VALUE is omitted, then the
308 DEFAULT is used unless the DEFAULT is `None' in which case the component is
311 for kv in delim.split(string):
313 k, v = kv.split('=', 1)
315 if default is None: continue
316 else: k, v = kv, default
317 k, v = k.strip(), v.strip()
319 k, v = urldecode(k), urldecode(v)
324 Process all of the various exciting CGI environment variables.
326 We read environment variables and populate some tables left in global
327 variables: it's all rather old-school. Variables set are as follows.
330 A dictionary mapping cookie names to the values provided by the user
334 A dictionary holding some special query parameters which are of
335 interest at a global level, and should not be passed to a subcommand
336 handler. No new entries will be added to this dictionary, though
337 values will be modified to reflect the query parameters discovered.
338 Conventionally, such parameters have names beginning with `%'.
341 The query parameters as a list of (KEY, VALUE) pairs. Special
342 parameters are omitted.
345 The query parameters as a dictionary. Special parameters, and
346 parameters which appear more than once, are omitted.
349 The trailing `PATH_INFO' path, split at `/' markers, with any
350 trailing empty component removed.
353 True if the client connection is carried over SSL or TLS.
360 except KeyError: raise U.ExpectedError, (500, "No `%s' supplied" % var)
362 ## Yes, we want the request method.
363 method = getenv('REQUEST_METHOD')
365 ## Acquire the query string.
367 q = getenv('QUERY_STRING')
369 elif method == 'POST':
371 ## We must read the query string from stdin.
372 n = getenv('CONTENT_LENGTH')
374 raise U.ExpectedError, (500, "Invalid CONTENT_LENGTH")
376 if getenv('CONTENT_TYPE') != 'application/x-www-form-urlencoded':
377 raise U.ExpectedError, (500, "Unexpected content type `%s'" % ct)
378 q = SYS.stdin.read(n)
380 raise U.ExpectedError, (500, "Failed to read correct length")
383 raise U.ExpectedError, (500, "Unexpected request method `%s'" % method)
385 ## Populate the `SPECIAL', `PARAM' and `PARAMDICT' tables.
387 for k, v in split_keyvalue(q, R_QSPLIT, 't'):
398 ## Parse out the cookies, if any.
399 try: c = ENV['HTTP_COOKIE']
400 except KeyError: pass
402 for k, v in split_keyvalue(c, R_CSPLIT, None): COOKIE[k] = v
404 ## Set up the `PATH'.
405 try: p = ENV['PATH_INFO']
406 except KeyError: pass
408 pp = p.lstrip('/').split('/')
409 if pp and not pp[-1]: pp.pop()
412 ## Check the crypto for the connection.
413 if ENV.get('SSL_PROTOCOL'):
416 ###--------------------------------------------------------------------------
419 class Subcommand (SC.Subcommand):
421 A CGI subcommand object.
423 As for `subcommand.Subcommand', but with additional protocol for processing
427 def cgi(me, param, path):
429 Invoke the subcommand given a collection of CGI parameters.
431 PARAM is a list of (KEY, VALUE) pairs from the CGI query. The CGI query
432 parameters are checked against the subcommand's parameters (making sure
433 that mandatory parameters are supplied, that any switches are given
434 boolean values, and that only the `rest' parameter, if any, is
437 PATH is a list of trailing path components. They are used to satisfy the
438 `rest' parameter if there is one and there are no query parameters which
439 satisfy the `rest' parameter; otherwise, an `ExpectedError' is raised if
440 the list of path elements is non-empty.
443 ## We're going to make a pass over the supplied parameters, and we'll
444 ## check them off against the formal parameters as we go; so we'll need
445 ## to be able to look them up. We'll also keep track of the ones we've
446 ## seen so that we can make sure that all of the mandatory parameters
447 ## were actually supplied.
449 ## To that end: `want' is a dictionary mapping parameter names to
450 ## functions which will do something useful with the value; `seen' is a
451 ## set of the parameters which have been assigned; and `kw' is going to
452 ## be the keyword-argument dictionary we pass to the handler function.
457 """Set a simple value: we shouldn't see multiple values."""
459 raise U.ExpectedError, (400, "Repeated parameter `%s'" % k)
462 """Set a simple boolean value: for switches."""
463 set_value(k, v.lower() in ['true', 't', 'yes', 'y'])
465 """Append the value to a list: for the `rest' parameter."""
466 kw.setdefault(k, []).append(v)
468 ## Set up the `want' map.
470 if o.argname: want[o.name] = set_value
471 else: want[o.name] = set_bool
472 for p in me.params: want[p.name] = set_value
473 for p in me.oparams: want[p.name] = set_value
474 if me.rparam: want[me.rparam.name] = set_list
476 ## Work through the list of supplied parameters.
482 raise U.ExpectedError, (400, "Unexpected parameter `%s'" % k)
486 ## Deal with a path, if there is one.
488 if me.rparam and me.rparam.name not in kw:
489 kw[me.rparam.name] = path
491 raise U.ExpectedError, (404, "Superfluous path elements")
493 ## Make sure we saw all of the mandatory parameters.
496 raise U.ExpectedError, (400, "Missing parameter `%s'" % p.name)
498 ## Invoke the subcommand.
501 def subcommand(name, contexts, desc, cls = Subcommand, *args, **kw):
502 """Decorator for defining CGI subcommands."""
503 return SC.subcommand(name, contexts, desc, cls = cls, *args, **kw)
505 ###----- That's all, folks --------------------------------------------------