This patch adds a new API to the Asterisk core that acts as a media
cache. The core API itself is mostly a thin wrapper around some bucket
API provided implementation that itself acts as the mechanism of
retrieval for media. The media cache API in the core provides the
following:
 * A very thin in-memory cache of the active bucket_file items. Unlike a
   more traditional cache, it provides no expiration mechanisms. Most
   queries that hit the in-memory cache will also call into the bucket
   implementations as well. The bucket implementations are responsible
   for determining whether or not the active record is active and valid.
   This makes sense for the most likely implementation of a media cache
   backend, i.e., HTTP. The HTTP layer itself is the actual arbiter of
   whether or not a record is truly active; as such, the in-memory cache
   in the core has to defer to it.
 * The ability to create new items in the media cache from local
   resources. This allows for re-creation of items in the cache on
   restart.
 * Synchronization of items in the media cache to the AstDB. This
   also includes various pieces of important metadata.

The API provides sufficient access that higher level APIs, such as the
file or app APIs, do not have to worry about the semantics of the bucket
APIs when needing to playback a resource.

In addition, this patch provides unit tests for the media cache API. The
unit tests use a fake bucket backend to verify correctness.

Change-Id: I11227abbf14d8929eeb140ddd101dd5c3820391e

This patch adds a new function to the bucket API for ast_bucket_file
objects, ast_bucket_file_metadata_callback. It will call ao2_callback on
the ast_bucket_file's ao2_container of metadata, calling the provided
ao2_callback_fn callback on each piece of metadata associated with the
file.

This is particularly useful when a bucket backend has added metadata,
and a higher level API wants to be aware of/access said metadata,
without knowing for sure what the key is.

Change-Id: I96f6757717f47b650df91a437f7df16406227466

Having a debug message tell us that we attempted to look up an item but
failed is nice in circumstances when it isn't clear if the wizard was
queried correctly or not.

Change-Id: I2600c3bbea87f252196358f62e73f4c7da8632f7

Newlines are nice.

Change-Id: Icf0d915db02882e47cd9077ed9009f5d44140d42

This patch fixes some bad default value handling in the following
settings:

* The 'message_context' and 'accountcode' settings are not mandatory. As
  such, we can allow their stringfield values to be empty.
* The 'media_encryption' setting applies a default value of 'none' to
  the setting, which it then can't parse or understand. Since the value
  is documented to be 'no', this will now apply that as the default
  value.

Change-Id: Ib9be7f97a7a5b9bc7aee868edf5acf38774cff83

If a sorcery wizard does not support one of the 'optional' CRUD
operations (namely the CUD), log a WARNING message so we are aware of
why the operation failed. This also removes an assert in this case, as
the CUD operation may have been triggered by an external system, in
which case it is not a programming error but a configuration error.

Change-Id: Ifecd9df946d9deaa86235257b49c6e5e24423b53

This patch adds more tests that exercise the device state API. This includes:

* Tests that cover adding a device state provider, as well as deleting a
  device state provider. This also verifies that you cannot add an
  already added device state provider, and cannot delete an already
  deleted device state provider.
* A test that covers changing device state and receiving said updates
  from a device state subscriber. This also covers hitting both the
  device state cache as well as a custom device state provider.
* A test that covers converting device state to channel state and device
  state values to a string representation and back.
* A test that covers obtaining device state from an active channel and a
  channel driver that provides its own device state.

Change-Id: I2adca67ffb405cd8625a5d6df1e3f9b3d945c08d

Currently, the device state provider API will allow you to register a
device state provider with the same case insensitive name more than
once. This could cause strange issues, as the duplicate device state
providers will not be queried when a device's state has to be polled.
This patch updates the API such that a device state provider with the
same name as one that has already registered will be rejected.

Change-Id: I4a418a12280b7b6e4960bd44f302e27cd036ceb2

An http request can be sent to retrieve a list of all existing modules,
including the resource name, description, use count, status, and
support level.

The command "curl -v -u user:pass -X GET 'http://localhost:8088/ari/
asterisk/modules" (or something similar, depending on configuration)
can be run in the terminal to access this new functionality.

For more information, see:
https://wiki.asterisk.org/wiki.display/~bford/Asterisk+ARI+Resource

* Added new ARI functionality
* Information on modules can now be retrieved

Change-Id: I63cbbf0ec0c3544cc45ed2a588dceabe91c5e0b0

The bridge_native_rtp module adds a frame hook to channels which are in
a native RTP bridge. This frame hook is used to intercept when a hold
or unhold frame traverses the bridge so native RTP can be stopped or
started as appropriate. This is expected but exposes a specific bug
when attended transfers are involved.

Upon completion of an attended transfer an unhold frame is queued up
to take one of the channels involved off hold. After this is done
the channel is moved between bridges.

When the frame hook is involved in this case for the unhold it
releases the channel lock and acquires the bridge lock. This
allows the bridge core to step in and move the channel
(potentially changing the bridging techology) from another thread.
Once completed the bridge lock is released by the bridge core.
The frame hook is then able to acquire the bridge lock and
wrongfully starts native RTP again, despite the channel no longer
being in the bridge or needing to start native RTP. In fact at
this point the frame hook is no longer attached to the channel.

This change makes it so the native RTP bridge data is available to
the frame hook when it is invoked. Whether the frame hook has
been detached or not is stored on the native RTP bridge data and
is checked by the frame hook before starting or stopping native
RTP bridging. If the frame hook has been detached it does nothing.

ASTERISK-25240 #close

Change-Id: I13a73186a05f4e5a764f81e5cd0ccec1ed1891d2

This change fixes a bug where the DTLS timeout timer would be
initialized to 0 if DTLS was not used for an RTP session.

ASTERISK-25103

Change-Id: If8d26bb054f1d300838850da5b8db9044c2fe2ac

Prior to this patch, the DNS core present in master had no default system-level
resolver implementation. Therefore, it was not possible for the DNS core to
perform resolutions unless the libunbound library was installed and the
res_resolver_unbound module was loaded.

This patch introduces a system-level DNS resolver implementation that will
register itself with the lowest consideration priority available (to ensure
that it is to be used only as a last resort). The resolver relies on low-level
DNS search functions to perform a rudimentary DNS search based on a provided
query and then supplies the search results to the DNS core.

ASTERISK-25146 #close
Reported By: Joshua Colp

Change-Id: I3b36ea17b889a98df4f8d80d50bb7ee175afa077

* changes:
  res_pjsip_mwi.c: Eliminate a simple RAII_VAR.
  res_pjsip_mwi.c: Fix mid-line log message line breaks.

This change moves logic for setting up the DTLS SSL contexts to
when the SDP is done being processed instead of when ICE negotiation
completes. It also stops handshakes from being initiated when we
are acting as a server.

Manipulating the SSL context when ICE negotiation has completed
is problematic as the SSL context is not protected and if acting
as a client the remote side may have started DTLS negotiation
already.

The retransmission timeout timer code has also been split up
and simplified some. Both RTP and RTCP now have their own timers
and the points at which the timer is stopped and started is now
more specific. When a packet is sent the timer is started. When
a response is received but before it is processed the timer is
stopped. This provides a guarantee that the timeout is not
occurring while the response is processed.

ASTERISK-22805 #close
ASTERISK-24550 #close
ASTERISK-24651 #close
ASTERISK-24832 #close
ASTERISK-25103 #close
ASTERISK-25127 #close

Change-Id: Ib75ea2546f29d6efc3d2d37c58df6986c7bd9b91

MWI subscriptions can crash or corrupt memory when using the subscription
datastore to access the MWI subscription object because the datastore is
not holding a reference to the object.

* Give the subscription datastore a ref to the MWI subscription object.
It is unfortunate that the ref causes a circular ref chain that must be
explicitly broken to allow the memory to get released.  The loop is broken
when the subscription is shutdown and if the subscription setup fails.

ASTERISK-25168 #close
Reported by: Carl Fortin

Change-Id: Ice4fa823f138ff10a6c74d280699c41a82836d4f

When res_pjsip body generator modules were generating XML or XPIDF
response bodies, there was a chance that the generated body would be the
exact size of the supplied buffer.  Adding the nul string terminator would
then write beyond the end of the buffer and potentially corrupt memory.

* Fix MALLOC_DEBUG high fence violations caused by adding a nul string
terminator on the end of a buffer for XML or XPIDF response bodies.

* Made calls to pj_xml_print() safer if the XML prolog is requested.  Due
to a bug in pjproject, the return value could be -1 _or_
AST_PJSIP_XML_PROLOG_LEN if the supplied buffer is not large enough.

* Updated the doxygen comment of AST_PJSIP_XML_PROLOG_LEN to describe the
return value of pj_xml_print() when the supplied buffer is not large
enough.

ASTERISK-25168
Reported by: Carl Fortin

Change-Id: Id70e1d373a6a2b2bd9e678b5cbc5e55b308981de

When a caller calls a FAX number and then hangs up right after the call is
answered then the T.38 re-INVITE automatic reject timer may still be
running after the channel goes away.

* Added session NULL channel checks on the code paths that get executed by
t38_automatic_reject() to prevent a crash when the T.38 re-INVITE
automatic reject timer expires.

ASTERISK-25168
Reported by: Carl Fortin

Change-Id: I07b6cd23815aedce5044f8f32543779e2f7a2403

Change-Id: I6f39d809a6d1b47b35bb32b298f5a12f35d6f907

Change-Id: Ib1843f81e826a6c760c424c88eb70c350d9d61da

* Add create_mwi_subscriptions_for_endpoint() doxygen comment.

Change-Id: I3c3f921f4ec749fb65b62d2f6fa0d4d1888b94e2

Calling t38_change_state() sets the t38 state so it makes little sense to
then check the state right after the call for something else.

* Made the code in t38_interpret_parameters() reject or exit T.38 mode as
intended but not implemented.

Change-Id: Ib281263a6ed44da9448132c4e6df1e183b8a3df2

Previously Asterisk did not properly failover to the next resolved DNS
address when a endpoint could not be reached. With this patch, and while
using res_pjsip, SIP requests (both in/out of dialog) now attempt to use
the next address in the list of resolved addresses until a proper response
is received or no more addresses are left.

ASTERISK-25076 #close
Reported by: Joshua Colp

Change-Id: Ief14f4ebd82474881f72f4538f4577f30af2a764

In Jenkins there is currently a sporadic test failure of a
variable number of sorcery memory cache unit tests. I have not
been able to reproduce this on the build agents themselves or
on my development machine.

My working theory is that the stale unit test is causing a
sorcery instance to persist longer than expected, causing subsequent
tests to fail when setting up and initializing the next
sorcery instance.

To see if this is the case this change moves the stale unit test
to execute last so no subsequent unit tests can have issues
initializing their sorcery instance.

Change-Id: Ifd6550a949613be774b75fa5db12c02110f82c4a

This patch enhances the bucket API in two ways.

First, since ast_bucket and ast_bucket_file instances are immutable, a 'clone'
operation has been added that provides a 'clone' of an existing
ast_bucket/ast_bucket_file object. Note that this makes use of the
ast_sorcery_copy operation, along with the copy callback handler on the
"bucket" and "file" object types for the bucket sorcery instance.

Second, there is a need for the bucket API to ask a wizard if an object
is stale. This is particularly useful with the upcoming media cache
enhancements, where we want to ask the backing data storage if the
object we are currently operating on has known updates. This patch adds
API calls for ast_bucket and ast_bucket_file objects, which callback
into their respective sorcery wizards via the sorcery API.

Unit tests have also been added to cover the respective
ast_bucket/ast_bucket_file clone and staleness operations.

Change-Id: Ib0240ba915ece313f1678a085a716021d75d6b4a

This patch enhances the sorcery API to allow for sorcery wizards to
determine if an object is stale. This includes the following:

* Sorcery objects now have a timestamp that is set on creation. Since
  sorcery objects are immutable, this can be used by sorcery wizards to
  determine if an object is stale.

* A new API call has been added, ast_sorcery_is_stale. This API call
  queries the wizards associated with the object, calling a new callback
  function 'is_stale'. Note that if a wizard does not support the new
  callback, objects are always assumed to not be stale.

* Unit tests have been added that cover the new API call.

Change-Id: Ica93c6a4e8a06c0376ea43e00cf702920b806064