4 ### Build a CDB file from configuration file
6 ### (c) 2007 Straylight/Edgeware
9 ###----- Licensing notice ---------------------------------------------------
11 ### This file is part of Trivial IP Encryption (TrIPE).
13 ### TrIPE is free software: you can redistribute it and/or modify it under
14 ### the terms of the GNU General Public License as published by the Free
15 ### Software Foundation; either version 3 of the License, or (at your
16 ### option) any later version.
18 ### TrIPE is distributed in the hope that it will be useful, but WITHOUT
19 ### ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
20 ### FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
23 ### You should have received a copy of the GNU General Public License
24 ### along with TrIPE. If not, see <https://www.gnu.org/licenses/>.
28 ###--------------------------------------------------------------------------
29 ### External dependencies.
32 from optparse import OptionParser
34 from sys import stdin, stdout, exit, argv
37 from cStringIO import StringIO
39 ###--------------------------------------------------------------------------
42 class CDBFake (object):
43 """Like cdbmake, but just outputs data suitable for cdb-map."""
44 def __init__(me, file = stdout):
46 def add(me, key, value):
47 me.file.write('%s:%s\n' % (key, value))
51 ###--------------------------------------------------------------------------
52 ### A bulk DNS resolver.
54 class BulkResolver (object):
56 Resolve a number of DNS names in parallel.
58 The BulkResovler resolves a number of hostnames in parallel. Using it
59 works in three phases:
61 1. You call prepare(HOSTNAME) a number of times, to feed in the hostnames
64 2. You call run() to actually drive the resolver.
66 3. You call lookup(HOSTNAME) to get the address you wanted. This will
67 fail with KeyError if the resolver couldn't resolve the HOSTNAME.
71 """Initialize the resolver."""
75 def prepare(me, host):
76 """Prime the resolver to resolve the name HOST."""
77 if host not in me._resolvers:
78 me._resolvers[host] = M.SelResolveByName \
80 lambda name, alias, addr:
81 me._resolved(host, addr[0]),
82 lambda: me._resolved(host, None))
85 """Run the background DNS resolver until it's finished."""
91 Fetch the address corresponding to HOST.
93 addr = me._namemap[host]
98 def _resolved(me, host, addr):
99 """Callback function: remember that ADDR is the address for HOST."""
100 me._namemap[host] = addr
101 del me._resolvers[host]
103 ###--------------------------------------------------------------------------
104 ### The configuration parser.
106 ## Match a comment or empty line.
107 RX_COMMENT = RX.compile(r'(?x) ^ \s* (?: $ | [;#])')
109 ## Match a section group header.
110 RX_GRPHDR = RX.compile(r'(?x) ^ \s* \[ (.*) \] \s* $')
112 ## Match an assignment line.
113 RX_ASSGN = RX.compile(r'''(?x) ^
114 ([^\s:=] (?: [^:=]* [^\s:=])?)
119 ## Match a continuation line.
120 RX_CONT = RX.compile(r'''(?x) ^ \s+
124 ## Match a $(VAR) configuration variable reference; group 1 is the VAR.
125 RX_REF = RX.compile(r'(?x) \$ \( ([^)]+) \)')
127 ## Match a $[HOST] name resolution reference; group 1 is the HOST.
128 RX_RESOLVE = RX.compile(r'(?x) \$ \[ ([^]]+) \]')
130 class ConfigSyntaxError (Exception):
131 def __init__(me, fname, lno, msg):
136 return '%s:%d: %s' % (me.fname, me.lno, me.msg)
139 return ' -> '.join(["`%s'" % hop for hop in path])
141 class AmbiguousOptionError (Exception):
142 def __init__(me, key, patha, vala, pathb, valb):
144 me.patha, me.vala = patha, vala
145 me.pathb, me.valb = pathb, valb
147 return "Ambiguous answer resolving key `%s': " \
148 "path %s yields `%s' but %s yields `%s'" % \
149 (me.key, _fmt_path(me.patha), me.vala, _fmt_path(me.pathb), me.valb)
151 class InheritanceCycleError (Exception):
152 def __init__(me, key, path):
156 return "Found a cycle %s looking up key `%s'" % \
157 (_fmt_path(me.path), me.key)
159 class MissingSectionException (Exception):
160 def __init__(me, sec):
163 return "Section `%s' not found" % (me.sec)
165 class MissingKeyException (Exception):
166 def __init__(me, sec, key):
170 return "Key `%s' not found in section `%s'" % (me.key, me.sec)
172 class ConfigSection (object):
174 A section in a configuration parser.
176 This is where a lot of the nitty-gritty stuff actually happens. The
177 `MyConfigParser' knows a lot about the internals of this class, which saves
178 on building a complicated interface.
181 def __init__(me, name, cp):
182 """Initialize a new, empty section with a given NAME and parent CP."""
187 def _expand(me, string, resolvep):
189 Expands $(...) and (optionally) $[...] placeholders in STRING.
191 RESOLVEP is a boolean switch: do we bother to tax the resolver or not?
192 This is turned off by MyConfigParser's resolve() method while it's
193 collecting hostnames to be resolved.
195 string = RX_REF.sub \
196 (lambda m: me.get(m.group(1), resolvep), string)
198 string = RX_RESOLVE.sub(lambda m: me._cp._resolver.lookup(m.group(1)),
202 def _get(me, key, map = None, path = None):
204 Low-level option-fetching method.
206 Fetch the value for the named KEY in this section, or maybe (recursively)
207 a section which it inherits from.
209 Returns a pair VALUE, PATH. The value is not expanded; nor do we check
210 for the special `name' key. The caller is expected to do these things.
211 Returns None if no value could be found.
214 ## If we weren't given a memoization map or path, then we'd better make
216 if map is None: map = {}
217 if path is None: path = []
219 ## Extend the path to cover us, but remember to remove us again when
220 ## we've finished. If we need to pass the current path back upwards,
221 ## then remember to take a copy.
225 ## If we've been this way before on another pass through then return
226 ## the value we found then. If we're still thinking about it then
227 ## we've found a cycle.
228 try: threadp, value = map[me.name]
229 except KeyError: pass
231 if threadp: raise InheritanceCycleError(key, path[:])
233 ## See whether the answer is ready waiting for us.
234 try: v = me._itemmap[key]
235 except KeyError: pass
236 else: return v, path[:]
238 ## No, apparently, not. Find out our list of parents.
240 parents = [me._cp.section(p) for p in
241 me._itemmap['@inherit'].replace(',', ' ').split()]
245 ## Initially we have no idea.
249 ## Go through our parents and ask them what they think.
250 map[me.name] = True, None
253 ## See whether we get an answer. If not, keep on going.
254 v, pp = p._get(key, map, path)
255 if v is None: continue
257 ## If we got an answer, check that it matches any previous ones.
262 raise AmbiguousOptionError(key, winner, value, pp, v)
264 ## That's the best we could manage.
265 map[me.name] = False, value
269 ## Remove us from the path again.
272 def get(me, key, resolvep = True):
274 Retrieve the value of KEY from this section.
277 ## Special handling for the `name' key.
279 value = me._itemmap.get('name', me.name)
281 value, _ = me._get(key)
283 raise MissingKeyException(me.name, key)
285 ## Expand the value and return it.
286 return me._expand(value, resolvep)
288 def items(me, resolvep = True):
290 Yield a list of item names in the section.
293 ## Initialize for a depth-first walk of the inheritance graph.
298 ## Visit nodes, collecting their keys. Don't believe the values:
299 ## resolving inheritance is too hard to do like this.
301 sec = me._cp.section(stack.pop())
302 if sec.name in visited: continue
303 visited[sec.name] = True
305 for key, value in sec._itemmap.iteritems():
306 if key == '@inherit': stack += value.replace(',', ' ').split()
312 class MyConfigParser (object):
314 A more advanced configuration parser.
316 This has four major enhancements over the standard ConfigParser which are
319 * It recognizes `@inherits' keys and follows them when expanding a
322 * It recognizes `$(VAR)' references to configuration variables during
323 expansion and processes them correctly.
325 * It recognizes `$[HOST]' name-resolver requests and handles them
328 * Its parsing behaviour is well-defined.
332 1. Call parse(FILENAME) to slurp in the configuration data.
334 2. Call resolve() to collect the hostnames which need to be resolved and
335 actually do the name resolution.
337 3. Call sections() to get a list of the configuration sections, or
338 section(NAME) to find a named section.
340 4. Call get(ITEM) on a section to collect the results, or items() to
346 Initialize a new, empty configuration parser.
349 me._resolver = BulkResolver()
353 Parse configuration from a file F.
356 ## Initial parser state.
362 ## An unpleasant hack. Python makes it hard to capture a value in a
363 ## variable and examine it in a single action, and this is the best that
366 def match(rx): m[0] = rx.match(line); return m[0]
368 ## Commit a key's value when we've determined that there are no further
369 ## continuation lines.
371 if key is not None: sect._itemmap[key] = val.getvalue()
373 ## Work through all of the input lines.
377 if match(RX_COMMENT):
378 ## A comment or a blank line. Nothing doing. (This means that we
379 ## leave out blank lines which look like they might be continuation
384 elif match(RX_GRPHDR):
385 ## A section header. Flush out any previous value and set up the new
390 try: sect = me._sectmap[name]
391 except KeyError: sect = me._sectmap[name] = ConfigSection(name, me)
394 elif match(RX_ASSGN):
395 ## A new assignment. Flush out the old one, and set up to store this
399 raise ConfigSyntaxError(f.name, lno, 'no active section to update')
402 val = StringIO(); val.write(m[0].group(2))
405 ## A continuation line. Accumulate the value.
408 raise ConfigSyntaxError(f.name, lno, 'no config value to continue')
409 val.write('\n'); val.write(m[0].group(1))
414 raise ConfigSyntaxError(f.name, lno, 'incomprehensible line')
416 ## Don't forget to commit any final value material.
419 def section(me, name):
420 """Return a ConfigSection with the given NAME."""
421 try: return me._sectmap[name]
422 except KeyError: raise MissingSectionException(name)
425 """Yield the known sections."""
426 return me._sectmap.itervalues()
430 Works out all of the hostnames which need resolving and resolves them.
432 Until you call this, attempts to fetch configuration items which need to
433 resolve hostnames will fail!
435 for sec in me.sections():
436 for key in sec.items():
437 value = sec.get(key, resolvep = False)
438 for match in RX_RESOLVE.finditer(value):
439 me._resolver.prepare(match.group(1))
442 ###--------------------------------------------------------------------------
443 ### Command-line handling.
445 def inputiter(things):
447 Iterate over command-line arguments, returning corresponding open files.
449 If none were given, or one is `-', assume standard input; if one is a
450 directory, scan it for files other than backups; otherwise return the
455 if OS.isatty(stdin.fileno()):
456 M.die('no input given, and stdin is a terminal')
462 elif OS.path.isdir(thing):
463 for item in OS.listdir(thing):
464 if item.endswith('~') or item.endswith('#'):
466 name = OS.path.join(thing, item)
467 if not OS.path.isfile(name):
473 def parse_options(argv = argv):
475 Parse command-line options, returning a pair (OPTS, ARGS).
478 op = OptionParser(usage = '%prog [-c CDB] INPUT...',
479 version = '%%prog (tripe, version %s)' % VERSION)
480 op.add_option('-c', '--cdb', metavar = 'CDB',
481 dest = 'cdbfile', default = None,
482 help = 'Compile output into a CDB file.')
483 opts, args = op.parse_args(argv)
486 ###--------------------------------------------------------------------------
491 Read the configuration files and return the accumulated result.
493 We make sure that all hostnames have been properly resolved.
495 conf = MyConfigParser()
496 for f in inputiter(args):
501 def output(conf, cdb):
503 Output the configuration information CONF to the database CDB.
505 This is where the special `user' and `auto' database entries get set.
508 for sec in sorted(conf.sections(), key = lambda sec: sec.name):
509 if sec.name.startswith('@'):
511 elif sec.name.startswith('$'):
514 label = 'P%s' % sec.name
515 try: a = sec.get('auto')
516 except MissingKeyException: pass
518 if a in ('y', 'yes', 't', 'true', '1', 'on'): auto.append(sec.name)
519 try: u = sec.get('user')
520 except MissingKeyException: pass
521 else: cdb.add('U%s' % u)
522 url = M.URLEncode(semip = True)
523 for key in sorted(sec.items()):
524 if not key.startswith('@'):
525 url.encode(key, sec.get(key))
526 cdb.add(label, url.result)
527 cdb.add('%AUTO', ' '.join(auto))
532 opts, args = parse_options()
534 cdb = CDB.cdbmake(opts.cdbfile, opts.cdbfile + '.new')
537 conf = getconf(args[1:])
540 if __name__ == '__main__':
543 ###----- That's all, folks --------------------------------------------------