2 Manages the feed cache.
4 @var iface_cache: A singleton cache object. You should normally use this rather than
5 creating new cache objects.
8 # Copyright (C) 2009, Thomas Leonard
9 # See the README file for details, or visit http://0install.net.
13 # We need to know the modification time of each interface, because we refuse
14 # to update to an older version (this prevents an attack where the attacker
15 # sends back an old version which is correctly signed but has a known bug).
17 # The way we store this is a bit complicated due to backward compatibility:
19 # - GPG-signed interfaces have their signatures removed and a last-modified
20 # attribute is stored containing the date from the signature.
22 # - XML-signed interfaces are stored unmodified with their signatures. The
23 # date is extracted from the signature when needed.
25 # - Older versions used to add the last-modified attribute even to files
26 # with XML signatures - these files therefore have invalid signatures and
27 # we extract from the attribute for these.
29 # Eventually, support for the first and third cases will be removed.
32 from logging
import debug
, info
, warn
33 from cStringIO
import StringIO
35 from zeroinstall
import _
36 from zeroinstall
.support
import basedir
37 from zeroinstall
.injector
import reader
, model
38 from zeroinstall
.injector
.namespaces
import config_site
, config_prog
39 from zeroinstall
.injector
.model
import Interface
, escape
, unescape
40 from zeroinstall
import SafeException
43 assert isinstance(t
, (int, long)), t
44 return time
.strftime('%Y-%m-%d %H:%M:%S UTC', time
.localtime(t
))
46 class ReplayAttack(SafeException
):
47 """Attempt to import a feed that's older than the one in the cache."""
50 class PendingFeed(object):
51 """A feed that has been downloaded but not yet added to the interface cache.
52 Feeds remain in this state until the user confirms that they trust at least
53 one of the signatures.
54 @ivar url: URL for the feed
56 @ivar signed_data: the untrusted data
57 @type signed_data: stream
58 @ivar sigs: signatures extracted from signed_data
59 @type sigs: [L{gpg.Signature}]
60 @ivar new_xml: the payload of the signed_data, or the whole thing if XML
63 __slots__
= ['url', 'signed_data', 'sigs', 'new_xml']
65 def __init__(self
, url
, signed_data
):
66 """Downloaded data is a GPG-signed message.
67 @param url: the URL of the downloaded feed
69 @param signed_data: the downloaded data (not yet trusted)
70 @type signed_data: stream
71 @raise SafeException: if the data is not signed, and logs the actual data"""
73 self
.signed_data
= signed_data
76 def download_keys(self
, handler
, feed_hint
= None, key_mirror
= None):
77 """Download any required GPG keys not already on our keyring.
78 When all downloads are done (successful or otherwise), add any new keys
79 to the keyring, L{recheck}.
80 @param handler: handler to manage the download
81 @type handler: L{handler.Handler}
82 @param key_mirror: URL of directory containing keys, or None to use feed's directory
91 key_url
= urlparse
.urljoin(key_mirror
or self
.url
, '%s.gpg' % key_id
)
92 info(_("Fetching key from %s"), key_url
)
93 dl
= handler
.get_download(key_url
, hint
= feed_hint
)
94 downloads
[dl
.downloaded
] = (dl
, dl
.tempfile
)
95 blockers
.append(dl
.downloaded
)
100 from zeroinstall
.support
import tasks
105 old_blockers
= blockers
108 for b
in old_blockers
:
112 dl
, stream
= downloads
[b
]
114 self
._downloaded
_key
(stream
)
119 _type
, exception
, tb
= sys
.exc_info()
120 warn(_("Failed to import key for '%(url)s': %(exception)s"), {'url': self
.url
, 'exception': str(exception
)})
122 if exception
and not any_success
:
123 raise exception
, None, tb
127 def _downloaded_key(self
, stream
):
128 import shutil
, tempfile
129 from zeroinstall
.injector
import gpg
131 info(_("Importing key for feed '%s'"), self
.url
)
133 # Python2.4: can't call fileno() on stream, so save to tmp file instead
134 tmpfile
= tempfile
.TemporaryFile(prefix
= 'injector-dl-data-')
136 shutil
.copyfileobj(stream
, tmpfile
)
140 gpg
.import_key(tmpfile
)
145 """Set new_xml and sigs by reading signed_data.
146 You need to call this when previously-missing keys are added to the GPG keyring."""
149 self
.signed_data
.seek(0)
150 stream
, sigs
= gpg
.check_stream(self
.signed_data
)
154 if stream
is not self
.signed_data
:
160 self
.signed_data
.seek(0)
161 info(_("Failed to check GPG signature. Data received was:\n") + repr(self
.signed_data
.read()))
164 class IfaceCache(object):
166 The interface cache stores downloaded and verified interfaces in
167 ~/.cache/0install.net/interfaces (by default).
169 There are methods to query the cache, add to it, check signatures, etc.
171 The cache is updated by L{fetch.Fetcher}.
173 Confusingly, this class is really two caches combined: the in-memory
174 cache of L{model.Interface} objects, and an on-disk cache of L{model.ZeroInstallFeed}s.
175 It will probably be split into two in future.
177 @ivar distro: the native distribution proxy
178 @type distro: L{distro.Distribution}
180 @see: L{iface_cache} - the singleton IfaceCache instance.
183 __slots__
= ['_interfaces', '_feeds', '_distro', '_config']
185 def __init__(self
, distro
= None):
186 """@param distro: distribution used to fetch "distribution:" feeds (since 0.49)
187 @param distro: distribution used to resolve "distribution:" feeds
188 @type distro: L{distro.Distribution}, or None to use the host distribution
190 self
._interfaces
= {}
192 self
._distro
= distro
197 from zeroinstall
.injector
import policy
198 #raise Exception("iface_cache.stores")
199 return policy
.get_deprecated_singleton_config().stores
203 if self
._distro
is None:
204 from zeroinstall
.injector
.distro
import get_host_distribution
205 self
._distro
= get_host_distribution()
208 def update_interface_if_trusted(self
, interface
, sigs
, xml
):
210 warnings
.warn("Use update_feed_if_trusted instead", DeprecationWarning, stacklevel
= 2)
211 return self
.update_feed_if_trusted(interface
.uri
, sigs
, xml
)
213 def update_feed_if_trusted(self
, feed_url
, sigs
, xml
):
214 """Update a cached feed (using L{update_feed_from_network})
215 if we trust the signatures.
216 If we don't trust any of the signatures, do nothing.
217 @param feed_url: the feed being updated
219 @param sigs: signatures from L{gpg.check_stream}
220 @type sigs: [L{gpg.Signature}]
221 @param xml: the downloaded replacement feed document
223 @return: True if the feed was updated
228 updated
= self
._oldest
_trusted
(sigs
, trust
.domain_from_url(feed_url
))
229 if updated
is None: return False # None are trusted
231 self
.update_feed_from_network(feed_url
, xml
, updated
)
234 def update_interface_from_network(self
, interface
, new_xml
, modified_time
):
236 warnings
.warn("Use update_feed_from_network instead", DeprecationWarning, stacklevel
= 2)
237 self
.update_feed_from_network(interface
.uri
, new_xml
, modified_time
)
239 def update_feed_from_network(self
, feed_url
, new_xml
, modified_time
):
240 """Update a cached feed.
241 Called by L{update_feed_if_trusted} if we trust this data.
242 After a successful update, L{writer} is used to update the feed's
244 @param feed_url: the feed being updated
245 @type feed_url: L{model.Interface}
246 @param new_xml: the downloaded replacement feed document
248 @param modified_time: the timestamp of the oldest trusted signature
249 (used as an approximation to the feed's modification time)
250 @type modified_time: long
251 @raises ReplayAttack: if modified_time is older than the currently cached time
254 debug(_("Updating '%(interface)s' from network; modified at %(time)s") %
255 {'interface': feed_url
, 'time': _pretty_time(modified_time
)})
257 if '\n<!-- Base64 Signature' not in new_xml
:
258 # Only do this for old-style feeds without
259 # signatures Otherwise, we can get the time from the
260 # signature, and adding this attribute just makes the
262 from xml
.dom
import minidom
263 doc
= minidom
.parseString(new_xml
)
264 doc
.documentElement
.setAttribute('last-modified', str(modified_time
))
266 doc
.writexml(new_xml
)
267 new_xml
= new_xml
.getvalue()
269 self
._import
_new
_feed
(feed_url
, new_xml
, modified_time
)
271 feed
= self
.get_feed(feed_url
)
274 feed
.last_checked
= long(time
.time())
275 writer
.save_feed(feed
)
277 info(_("Updated feed cache entry for %(interface)s (modified %(time)s)"),
278 {'interface': feed
.get_name(), 'time': _pretty_time(modified_time
)})
280 def _import_new_feed(self
, feed_url
, new_xml
, modified_time
):
281 """Write new_xml into the cache.
282 @param feed_url: the URL for the feed being updated
283 @param new_xml: the data to write
284 @param modified_time: when new_xml was modified
285 @raises ReplayAttack: if the new mtime is older than the current one
289 upstream_dir
= basedir
.save_cache_path(config_site
, 'interfaces')
290 cached
= os
.path
.join(upstream_dir
, escape(feed_url
))
293 if os
.path
.exists(cached
):
294 old_xml
= file(cached
).read()
295 if old_xml
== new_xml
:
296 debug(_("No change"))
297 # Update in-memory copy, in case someone else updated the disk copy
298 self
.get_feed(feed_url
, force
= True)
300 old_modified
= int(os
.stat(cached
).st_mtime
)
302 # Do we need to write this temporary file now?
303 stream
= file(cached
+ '.new', 'w')
304 stream
.write(new_xml
)
306 os
.utime(cached
+ '.new', (modified_time
, modified_time
))
307 new_mtime
= reader
.check_readable(feed_url
, cached
+ '.new')
308 assert new_mtime
== modified_time
310 old_modified
= self
._get
_signature
_date
(feed_url
) or old_modified
313 if new_mtime
< old_modified
:
314 os
.unlink(cached
+ '.new')
315 raise ReplayAttack(_("New feed's modification time is "
316 "before old version!\nInterface: %(iface)s\nOld time: %(old_time)s\nNew time: %(new_time)s\n"
318 % {'iface': feed_url
, 'old_time': _pretty_time(old_modified
), 'new_time': _pretty_time(new_mtime
)})
319 if new_mtime
== old_modified
:
320 # You used to have to update the modification time manually.
321 # Now it comes from the signature, this check isn't useful
322 # and often causes problems when the stored format changes
323 # (e.g., when we stopped writing last-modified attributes)
325 #raise SafeException("Interface has changed, but modification time "
326 # "hasn't! Refusing update.")
327 os
.rename(cached
+ '.new', cached
)
328 debug(_("Saved as %s") % cached
)
330 self
.get_feed(feed_url
, force
= True)
332 def get_feed(self
, url
, force
= False, selections_ok
= False):
333 """Get a feed from the cache.
334 @param url: the URL of the feed
335 @param force: load the file from disk again
336 @param selections_ok: if url is a local selections file, return that instead
337 @return: the feed, or None if it isn't cached
338 @rtype: L{model.ZeroInstallFeed}"""
340 feed
= self
._feeds
.get(url
, False)
344 if url
.startswith('distribution:'):
345 master_feed
= self
.get_feed(url
.split(':', 1)[1])
347 return None # Can't happen?
348 feed
= self
.distro
.get_feed(master_feed
)
350 feed
= reader
.load_feed_from_cache(url
, selections_ok
= selections_ok
)
351 if selections_ok
and feed
and not isinstance(feed
, model
.ZeroInstallFeed
):
352 assert feed
.selections
is not None
353 return feed
# (it's actually a selections document)
355 reader
.update_user_feed_overrides(feed
)
356 self
._feeds
[url
] = feed
359 def get_interface(self
, uri
):
360 """Get the interface for uri, creating a new one if required.
361 New interfaces are initialised from the disk cache, but not from
363 @param uri: the URI of the interface to find
364 @rtype: L{model.Interface}
368 assert isinstance(uri
, unicode)
370 if uri
in self
._interfaces
:
371 return self
._interfaces
[uri
]
373 debug(_("Initialising new interface object for %s"), uri
)
374 self
._interfaces
[uri
] = Interface(uri
)
375 reader
.update_from_cache(self
._interfaces
[uri
])
376 return self
._interfaces
[uri
]
378 def list_all_interfaces(self
):
379 """List all interfaces in the cache.
383 for d
in basedir
.load_cache_paths(config_site
, 'interfaces'):
384 for leaf
in os
.listdir(d
):
385 if not leaf
.startswith('.'):
386 all
.add(unescape(leaf
))
387 for d
in basedir
.load_config_paths(config_site
, config_prog
, 'user_overrides'):
388 for leaf
in os
.listdir(d
):
389 if not leaf
.startswith('.'):
390 all
.add(unescape(leaf
))
391 return list(all
) # Why not just return the set?
393 def get_icon_path(self
, iface
):
394 """Get the path of a cached icon for an interface.
395 @param iface: interface whose icon we want
396 @return: the path of the cached icon, or None if not cached.
398 return basedir
.load_first_cache(config_site
, 'interface_icons',
401 def get_cached_signatures(self
, uri
):
402 """Verify the cached interface using GPG.
403 Only new-style XML-signed interfaces retain their signatures in the cache.
404 @param uri: the feed to check
406 @return: a list of signatures, or None
407 @rtype: [L{gpg.Signature}] or None
410 if os
.path
.isabs(uri
):
413 old_iface
= basedir
.load_first_cache(config_site
, 'interfaces', escape(uri
))
414 if old_iface
is None:
417 return gpg
.check_stream(file(old_iface
))[1]
418 except SafeException
, ex
:
419 debug(_("No signatures (old-style interface): %s") % ex
)
422 def _get_signature_date(self
, uri
):
423 """Read the date-stamp from the signature of the cached interface.
424 If the date-stamp is unavailable, returns None."""
426 sigs
= self
.get_cached_signatures(uri
)
428 return self
._oldest
_trusted
(sigs
, trust
.domain_from_url(uri
))
430 def _oldest_trusted(self
, sigs
, domain
):
431 """Return the date of the oldest trusted signature in the list, or None if there
432 are no trusted sigs in the list."""
433 trusted
= [s
.get_timestamp() for s
in sigs
if s
.is_trusted(domain
)]
438 def mark_as_checking(self
, url
):
439 """Touch a 'last_check_attempt_timestamp' file for this feed.
440 If url is a local path, nothing happens.
441 This prevents us from repeatedly trying to download a failing feed many
442 times in a short period."""
443 if os
.path
.isabs(url
):
445 feeds_dir
= basedir
.save_cache_path(config_site
, config_prog
, 'last-check-attempt')
446 timestamp_path
= os
.path
.join(feeds_dir
, model
._pretty
_escape
(url
))
447 fd
= os
.open(timestamp_path
, os
.O_WRONLY | os
.O_CREAT
, 0644)
449 os
.utime(timestamp_path
, None) # In case file already exists
451 def get_last_check_attempt(self
, url
):
452 """Return the time of the most recent update attempt for a feed.
453 @see: L{mark_as_checking}
454 @return: The time, or None if none is recorded
455 @rtype: float | None"""
456 timestamp_path
= basedir
.load_first_cache(config_site
, config_prog
, 'last-check-attempt', model
._pretty
_escape
(url
))
458 return os
.stat(timestamp_path
).st_mtime
461 def get_feed_imports(self
, iface
):
462 """Get all feeds that add to this interface.
463 This is the feeds explicitly added by the user, feeds added by the distribution,
464 and feeds imported by a <feed> in the main feed (but not recursively, at present).
467 main_feed
= self
.get_feed(iface
.uri
)
469 return iface
.extra_feeds
+ main_feed
.feeds
471 return iface
.extra_feeds
473 def get_feeds(self
, iface
):
474 """Get all feeds for this interface. This is a mapping from feed URLs
475 to ZeroInstallFeeds. It includes the interface's main feed, plus the
476 resolution of every feed returned by L{get_feed_imports}. Uncached
477 feeds are indicated by a value of None.
478 @rtype: {str: L{ZeroInstallFeed} | None}
480 main_feed
= self
.get_feed(iface
.uri
)
481 results
= {iface
.uri
: main_feed
}
482 for imp
in iface
.extra_feeds
:
484 results
[imp
.uri
] = self
.get_feed(imp
.uri
)
485 except SafeException
, ex
:
486 warn("Failed to load feed '%s: %s", imp
.uri
, ex
)
488 for imp
in main_feed
.feeds
:
489 results
[imp
.uri
] = self
.get_feed(imp
.uri
)
492 def get_implementations(self
, iface
):
493 """Return all implementations from all of iface's feeds.
494 @rtype: [L{Implementation}]
497 for feed
in self
.get_feeds(iface
).itervalues():
499 impls
+= feed
.implementations
.values()
502 #iface_cache = IfaceCache()