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.
7 # Copyright (C) 2008, Thomas Leonard
8 # See the README file for details, or visit http://0install.net.
12 # We need to know the modification time of each interface, because we refuse
13 # to update to an older version (this prevents an attack where the attacker
14 # sends back an old version which is correctly signed but has a known bug).
16 # The way we store this is a bit complicated due to backward compatibility:
18 # - GPG-signed interfaces have their signatures removed and a last-modified
19 # attribute is stored containing the date from the signature.
21 # - XML-signed interfaces are stored unmodified with their signatures. The
22 # date is extracted from the signature when needed.
24 # - Older versions used to add the last-modified attribute even to files
25 # with XML signatures - these files therefore have invalid signatures and
26 # we extract from the attribute for these.
28 # Eventually, support for the first and third cases will be removed.
31 from logging
import debug
, info
, warn
32 from cStringIO
import StringIO
34 from zeroinstall
.support
import basedir
35 from zeroinstall
.injector
import reader
, model
36 from zeroinstall
.injector
.namespaces
import *
37 from zeroinstall
.injector
.model
import *
38 from zeroinstall
import zerostore
41 assert isinstance(t
, (int, long))
42 return time
.strftime('%Y-%m-%d %H:%M:%S UTC', time
.localtime(t
))
44 class PendingFeed(object):
45 """A feed that has been downloaded but not yet added to the interface cache.
46 Feeds remain in this state until the user confirms that they trust at least
47 one of the signatures.
48 @ivar url: URL for the feed
50 @ivar signed_data: the untrusted data
51 @type signed_data: stream
52 @ivar sigs: signatures extracted from signed_data
53 @type sigs: [L{gpg.Signature}]
54 @ivar new_xml: the payload of the signed_data, or the whole thing if XML
57 __slots__
= ['url', 'signed_data', 'sigs', 'new_xml']
59 def __init__(self
, url
, signed_data
):
60 """Downloaded data is a GPG-signed message.
61 @param url: the URL of the downloaded feed
63 @param signed_data: the downloaded data (not yet trusted)
64 @type signed_data: stream
65 @raise SafeException: if the data is not signed, and logs the actual data"""
67 self
.signed_data
= signed_data
70 def download_keys(self
, handler
, feed_hint
= None, key_mirror
= None):
71 """Download any required GPG keys not already on our keyring.
72 When all downloads are done (successful or otherwise), add any new keys
73 to the keyring, L{recheck}.
74 @param handler: handler to manage the download
75 @type handler: L{handler.Handler}
76 @param key_mirror: URL of directory containing keys, or None to use feed's directory
85 key_url
= urlparse
.urljoin(key_mirror
or self
.url
, '%s.gpg' % key_id
)
86 info("Fetching key from %s", key_url
)
87 dl
= handler
.get_download(key_url
, hint
= feed_hint
)
88 downloads
[dl
.downloaded
] = (dl
, dl
.tempfile
)
89 blockers
.append(dl
.downloaded
)
94 from zeroinstall
.support
import tasks
99 old_blockers
= blockers
102 for b
in old_blockers
:
106 dl
, stream
= downloads
[b
]
108 self
._downloaded
_key
(stream
)
113 _
, exception
, tb
= sys
.exc_info()
114 warn("Failed to import key for '%s': %s", self
.url
, str(exception
))
116 if exception
and not any_success
:
117 raise exception
, None, tb
121 def _downloaded_key(self
, stream
):
122 import shutil
, tempfile
123 from zeroinstall
.injector
import gpg
125 info("Importing key for feed '%s'", self
.url
)
127 # Python2.4: can't call fileno() on stream, so save to tmp file instead
128 tmpfile
= tempfile
.TemporaryFile(prefix
= 'injector-dl-data-')
130 shutil
.copyfileobj(stream
, tmpfile
)
134 gpg
.import_key(tmpfile
)
139 """Set new_xml and sigs by reading signed_data.
140 You need to call this when previously-missing keys are added to the GPG keyring."""
143 self
.signed_data
.seek(0)
144 stream
, sigs
= gpg
.check_stream(self
.signed_data
)
148 if stream
is not self
.signed_data
:
154 self
.signed_data
.seek(0)
155 info("Failed to check GPG signature. Data received was:\n" + `self
.signed_data
.read()`
)
158 class IfaceCache(object):
160 The interface cache stores downloaded and verified interfaces in
161 ~/.cache/0install.net/interfaces (by default).
163 There are methods to query the cache, add to it, check signatures, etc.
165 The cache is updated by L{fetch.Fetcher}.
167 Confusingly, this class is really two caches combined: the in-memory
168 cache of L{model.Interface} objects, and an on-disk cache of L{model.ZeroInstallFeed}s.
169 It will probably be split into two in future.
171 @ivar pending: downloaded feeds which are not yet trusted
172 @type pending: str -> PendingFeed
173 @see: L{iface_cache} - the singleton IfaceCache instance.
176 __slots__
= ['_interfaces', 'stores', 'pending']
179 self
._interfaces
= {}
182 self
.stores
= zerostore
.Stores()
184 def add_pending(self
, pending
):
185 """Add a PendingFeed to the pending dict.
186 @param pending: the untrusted download to add
187 @type pending: PendingFeed
189 assert isinstance(pending
, PendingFeed
)
190 self
.pending
[pending
.url
] = pending
192 def update_interface_if_trusted(self
, interface
, sigs
, xml
):
193 """Update a cached interface (using L{update_interface_from_network})
194 if we trust the signatures, and remove it from L{pending}.
195 If we don't trust any of the signatures, do nothing.
196 @param interface: the interface being updated
197 @type interface: L{model.Interface}
198 @param sigs: signatures from L{gpg.check_stream}
199 @type sigs: [L{gpg.Signature}]
200 @param xml: the downloaded replacement interface document
202 @return: True if the interface was updated
204 @precondition: call L{add_pending}
207 updated
= self
._oldest
_trusted
(sigs
, trust
.domain_from_url(interface
.uri
))
208 if updated
is None: return False # None are trusted
210 if interface
.uri
in self
.pending
:
211 del self
.pending
[interface
.uri
]
213 raise Exception("update_interface_if_trusted, but '%s' not pending!" % interface
.uri
)
215 self
.update_interface_from_network(interface
, xml
, updated
)
218 def update_interface_from_network(self
, interface
, new_xml
, modified_time
):
219 """Update a cached interface.
220 Called by L{update_interface_if_trusted} if we trust this data.
221 After a successful update, L{writer} is used to update the interface's
223 @param interface: the interface being updated
224 @type interface: L{model.Interface}
225 @param new_xml: the downloaded replacement interface document
227 @param modified_time: the timestamp of the oldest trusted signature
228 (used as an approximation to the interface's modification time)
229 @type modified_time: long
230 @raises SafeException: if modified_time is older than the currently cached time
232 debug("Updating '%s' from network; modified at %s" %
233 (interface
.name
or interface
.uri
, _pretty_time(modified_time
)))
235 if '\n<!-- Base64 Signature' not in new_xml
:
236 # Only do this for old-style interfaces without
237 # signatures Otherwise, we can get the time from the
238 # signature, and adding this attribute just makes the
240 from xml
.dom
import minidom
241 doc
= minidom
.parseString(new_xml
)
242 doc
.documentElement
.setAttribute('last-modified', str(modified_time
))
244 doc
.writexml(new_xml
)
245 new_xml
= new_xml
.getvalue()
247 self
._import
_new
_interface
(interface
, new_xml
, modified_time
)
250 interface
._main
_feed
.last_checked
= long(time
.time())
251 writer
.save_interface(interface
)
253 info("Updated interface cache entry for %s (modified %s)",
254 interface
.get_name(), _pretty_time(modified_time
))
256 def _import_new_interface(self
, interface
, new_xml
, modified_time
):
257 """Write new_xml into the cache.
258 @param interface: updated once the new XML is written
259 @param new_xml: the data to write
260 @param modified_time: when new_xml was modified
261 @raises SafeException: if the new mtime is older than the current one
265 upstream_dir
= basedir
.save_cache_path(config_site
, 'interfaces')
266 cached
= os
.path
.join(upstream_dir
, escape(interface
.uri
))
268 if os
.path
.exists(cached
):
269 old_xml
= file(cached
).read()
270 if old_xml
== new_xml
:
274 stream
= file(cached
+ '.new', 'w')
275 stream
.write(new_xml
)
277 os
.utime(cached
+ '.new', (modified_time
, modified_time
))
278 new_mtime
= reader
.check_readable(interface
.uri
, cached
+ '.new')
279 assert new_mtime
== modified_time
281 old_modified
= self
._get
_signature
_date
(interface
.uri
)
282 if old_modified
is None:
283 old_modified
= interface
.last_modified
286 if new_mtime
< old_modified
:
287 raise SafeException("New interface's modification time is before old "
289 "\nOld time: " + _pretty_time(old_modified
) +
290 "\nNew time: " + _pretty_time(new_mtime
) +
291 "\nRefusing update (leaving new copy as " +
293 if new_mtime
== old_modified
:
294 # You used to have to update the modification time manually.
295 # Now it comes from the signature, this check isn't useful
296 # and often causes problems when the stored format changes
297 # (e.g., when we stopped writing last-modified attributes)
299 #raise SafeException("Interface has changed, but modification time "
300 # "hasn't! Refusing update.")
301 os
.rename(cached
+ '.new', cached
)
302 debug("Saved as " + cached
)
304 reader
.update_from_cache(interface
)
306 def get_feed(self
, url
):
307 """Get a feed from the cache.
308 @param url: the URL of the feed
309 @return: the feed, or None if it isn't cached
310 @rtype: L{model.ZeroInstallFeed}"""
311 # TODO: This isn't a good implementation
312 iface
= self
.get_interface(url
)
313 feed
= iface
._main
_feed
314 if not isinstance(feed
, model
.DummyFeed
):
318 def get_interface(self
, uri
):
319 """Get the interface for uri, creating a new one if required.
320 New interfaces are initialised from the disk cache, but not from
322 @param uri: the URI of the interface to find
323 @rtype: L{model.Interface}
327 assert isinstance(uri
, unicode)
329 if uri
in self
._interfaces
:
330 return self
._interfaces
[uri
]
332 debug("Initialising new interface object for %s", uri
)
333 self
._interfaces
[uri
] = Interface(uri
)
334 reader
.update_from_cache(self
._interfaces
[uri
])
335 return self
._interfaces
[uri
]
337 def list_all_interfaces(self
):
338 """List all interfaces in the cache.
342 for d
in basedir
.load_cache_paths(config_site
, 'interfaces'):
343 for leaf
in os
.listdir(d
):
344 if not leaf
.startswith('.'):
345 all
.add(unescape(leaf
))
346 for d
in basedir
.load_config_paths(config_site
, config_prog
, 'user_overrides'):
347 for leaf
in os
.listdir(d
):
348 if not leaf
.startswith('.'):
349 all
.add(unescape(leaf
))
350 return list(all
) # Why not just return the set?
352 def get_icon_path(self
, iface
):
353 """Get the path of a cached icon for an interface.
354 @param iface: interface whose icon we want
355 @return: the path of the cached icon, or None if not cached.
357 return basedir
.load_first_cache(config_site
, 'interface_icons',
360 def get_cached_signatures(self
, uri
):
361 """Verify the cached interface using GPG.
362 Only new-style XML-signed interfaces retain their signatures in the cache.
363 @param uri: the feed to check
365 @return: a list of signatures, or None
366 @rtype: [L{gpg.Signature}] or None
369 if uri
.startswith('/'):
372 old_iface
= basedir
.load_first_cache(config_site
, 'interfaces', escape(uri
))
373 if old_iface
is None:
376 return gpg
.check_stream(file(old_iface
))[1]
377 except SafeException
, ex
:
378 debug("No signatures (old-style interface): %s" % ex
)
381 def _get_signature_date(self
, uri
):
382 """Read the date-stamp from the signature of the cached interface.
383 If the date-stamp is unavailable, returns None."""
385 sigs
= self
.get_cached_signatures(uri
)
387 return self
._oldest
_trusted
(sigs
, trust
.domain_from_url(uri
))
389 def _oldest_trusted(self
, sigs
, domain
):
390 """Return the date of the oldest trusted signature in the list, or None if there
391 are no trusted sigs in the list."""
392 trusted
= [s
.get_timestamp() for s
in sigs
if s
.is_trusted(domain
)]
397 def mark_as_checking(self
, url
):
398 """Touch a 'last_check_attempt_timestamp' file for this feed.
399 If url is a local path, nothing happens.
400 This prevents us from repeatedly trying to download a failing feed many
401 times in a short period."""
402 if url
.startswith('/'):
404 feeds_dir
= basedir
.save_cache_path(config_site
, config_prog
, 'last-check-attempt')
405 timestamp_path
= os
.path
.join(feeds_dir
, model
._pretty
_escape
(url
))
406 fd
= os
.open(timestamp_path
, os
.O_WRONLY | os
.O_CREAT
, 0644)
409 def get_last_check_attempt(self
, url
):
410 """Return the time of the most recent update attempt for a feed.
411 @see: L{mark_as_checking}
412 @return: The time, or None if none is recorded
413 @rtype: float | None"""
414 timestamp_path
= basedir
.load_first_cache(config_site
, config_prog
, 'last-check-attempt', model
._pretty
_escape
(url
))
416 return os
.stat(timestamp_path
).st_mtime
419 iface_cache
= IfaceCache()