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 Return a list of (NAME, VALUE) items in this section.
292 This extends the default method by handling the inheritance chain.
295 ## Initialize for a depth-first walk of the inheritance graph.
300 ## Visit nodes, collecting their keys. Don't believe the values:
301 ## resolving inheritance is too hard to do like this.
303 sec = me._cp.section(stack.pop())
304 if sec.name in visited: continue
305 visited[sec.name] = True
307 for key, value in sec._itemmap.iteritems():
308 if key == '@inherit': stack += value.replace(',', ' ').split()
311 ## Now collect the values for the known keys, one by one.
313 for key in d: items.append((key, me.get(key, resolvep)))
318 class MyConfigParser (object):
320 A more advanced configuration parser.
322 This has four major enhancements over the standard ConfigParser which are
325 * It recognizes `@inherits' keys and follows them when expanding a
328 * It recognizes `$(VAR)' references to configuration variables during
329 expansion and processes them correctly.
331 * It recognizes `$[HOST]' name-resolver requests and handles them
334 * Its parsing behaviour is well-defined.
338 1. Call parse(FILENAME) to slurp in the configuration data.
340 2. Call resolve() to collect the hostnames which need to be resolved and
341 actually do the name resolution.
343 3. Call sections() to get a list of the configuration sections, or
344 section(NAME) to find a named section.
346 4. Call get(ITEM) on a section to collect the results, or items() to
352 Initialize a new, empty configuration parser.
355 me._resolver = BulkResolver()
359 Parse configuration from a file F.
362 ## Initial parser state.
368 ## An unpleasant hack. Python makes it hard to capture a value in a
369 ## variable and examine it in a single action, and this is the best that
372 def match(rx): m[0] = rx.match(line); return m[0]
374 ## Commit a key's value when we've determined that there are no further
375 ## continuation lines.
377 if key is not None: sect._itemmap[key] = val.getvalue()
379 ## Work through all of the input lines.
383 if match(RX_COMMENT):
384 ## A comment or a blank line. Nothing doing. (This means that we
385 ## leave out blank lines which look like they might be continuation
390 elif match(RX_GRPHDR):
391 ## A section header. Flush out any previous value and set up the new
396 try: sect = me._sectmap[name]
397 except KeyError: sect = me._sectmap[name] = ConfigSection(name, me)
400 elif match(RX_ASSGN):
401 ## A new assignment. Flush out the old one, and set up to store this
405 raise ConfigSyntaxError(f.name, lno, 'no active section to update')
408 val = StringIO(); val.write(m[0].group(2))
411 ## A continuation line. Accumulate the value.
414 raise ConfigSyntaxError(f.name, lno, 'no config value to continue')
415 val.write('\n'); val.write(m[0].group(1))
420 raise ConfigSyntaxError(f.name, lno, 'incomprehensible line')
422 ## Don't forget to commit any final value material.
425 def section(me, name):
426 """Return a ConfigSection with the given NAME."""
427 try: return me._sectmap[name]
428 except KeyError: raise MissingSectionException(name)
431 """Yield the known sections."""
432 return me._sectmap.itervalues()
436 Works out all of the hostnames which need resolving and resolves them.
438 Until you call this, attempts to fetch configuration items which need to
439 resolve hostnames will fail!
441 for sec in me.sections():
442 for key, value in sec.items(resolvep = False):
443 for match in RX_RESOLVE.finditer(value):
444 me._resolver.prepare(match.group(1))
447 ###--------------------------------------------------------------------------
448 ### Command-line handling.
450 def inputiter(things):
452 Iterate over command-line arguments, returning corresponding open files.
454 If none were given, or one is `-', assume standard input; if one is a
455 directory, scan it for files other than backups; otherwise return the
460 if OS.isatty(stdin.fileno()):
461 M.die('no input given, and stdin is a terminal')
467 elif OS.path.isdir(thing):
468 for item in OS.listdir(thing):
469 if item.endswith('~') or item.endswith('#'):
471 name = OS.path.join(thing, item)
472 if not OS.path.isfile(name):
478 def parse_options(argv = argv):
480 Parse command-line options, returning a pair (OPTS, ARGS).
483 op = OptionParser(usage = '%prog [-c CDB] INPUT...',
484 version = '%%prog (tripe, version %s)' % VERSION)
485 op.add_option('-c', '--cdb', metavar = 'CDB',
486 dest = 'cdbfile', default = None,
487 help = 'Compile output into a CDB file.')
488 opts, args = op.parse_args(argv)
491 ###--------------------------------------------------------------------------
496 Read the configuration files and return the accumulated result.
498 We make sure that all hostnames have been properly resolved.
500 conf = MyConfigParser()
501 for f in inputiter(args):
506 def output(conf, cdb):
508 Output the configuration information CONF to the database CDB.
510 This is where the special `user' and `auto' database entries get set.
513 for sec in sorted(conf.sections(), key = lambda sec: sec.name):
514 if sec.name.startswith('@'):
516 elif sec.name.startswith('$'):
519 label = 'P%s' % sec.name
520 try: a = sec.get('auto')
521 except MissingKeyException: pass
523 if a in ('y', 'yes', 't', 'true', '1', 'on'): auto.append(sec.name)
524 try: u = sec.get('user')
525 except MissingKeyException: pass
526 else: cdb.add('U%s' % u)
527 url = M.URLEncode(laxp = True, semip = True)
528 for key, value in sorted(sec.items(), key = lambda (k, v): k):
529 if not key.startswith('@'):
530 url.encode(key, ' '.join(M.split(value)[0]))
531 cdb.add(label, url.result)
532 cdb.add('%AUTO', ' '.join(auto))
537 opts, args = parse_options()
539 cdb = CDB.cdbmake(opts.cdbfile, opts.cdbfile + '.new')
542 conf = getconf(args[1:])
545 if __name__ == '__main__':
548 ###----- That's all, folks --------------------------------------------------