MFC r326276:

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

For functions that return -1 on failure check exactly for -1 and not for
any negative number.

MFC after: 3 days

No need to use KEEP_ERRNO() macro around pjdlog functions, as they don't
modify errno.

MFC after: 3 days

Now that hell is fully frozen it is good time to add IPv6 support to HAST.

MFC after: 3 weeks

Rename tcp4 to tcp in preparation for IPv6 support.

MFC after: 3 weeks

Rename proto_tcp4.c to proto_tcp.c in preparation for IPv6 support.

MFC after: 2 weeks

The proto API is a general purpose API, so don't use 'hast' in structures or
function names. It can now be used outside of HAST.

MFC after: 1 week

White space cleanups.

MFC after: 1 week

In hast.conf we define the other node's address in 'remote' variable.
This way we know how to connect to secondary node when we are primary.
The same variable is used by the secondary node - it only accepts
connections from the address stored in 'remote' variable.
In cluster configurations it is common that each node has its individual
IP address and there is one addtional shared IP address which is assigned
to primary node. It seems it is possible that if the shared IP address is
from the same network as the individual IP address it might be choosen by
the kernel as a source address for connection with the secondary node.
Such connection will be rejected by secondary, as it doesn't come from
primary node individual IP.

Add 'source' variable that allows to specify source IP address we want to
bind to before connecting to the secondary node.

MFC after: 1 week

Use %S to print IP address and port number.

MFC after: 2 weeks

- Rename proto_descriptor_{send,recv}() functions to
proto_connection_{send,recv} and change them to return proto_conn
structure. We don't operate directly on descriptors, but on
proto_conns.
- Add wrap method to wrap descriptor with proto_conn.
- Remove methods to send and receive descriptors and implement this
functionality as additional argument to send and receive methods.

MFC after: 1 week

Add proto_connect_wait() to wait for connection to finish.
If timeout argument to proto_connect() is -1, then the caller needs to use
this new function to wait for connection.

This change is in preparation for capsicum, where sandboxed worker wants
to ask main process to connect in worker's behalf and pass descriptor
to the worker. Because we don't want the main process to wait for the
connection, it will start async connection and pass descriptor to the
worker who will be responsible for waiting for the connection to finish.

MFC after: 1 week

Allow to specify connection timeout by the caller.

MFC after: 1 week

Do not set socket send and receive buffer. It will be auto-tuned.

Confirmed by: rwatson
MFC after: 1 week

- Use pjdlog for assertions and aborts as this will log assert/abort message
to syslog if we run in background.
- Asserts in proto.c that method we want to call is implemented and remove
dummy methods from protocols implementation that are only there to abort
the program with nice message.

MFC after: 1 week

Make comment more readable.

MFC after: 2 weeks
Obtained from: Wheel Systems Sp. z o.o. http://www.wheelsystems.com

The 'size' variable is there to limit how many bytes we want to copy from
'addr'. It is very likely that size of 'addr' is larger than 'size', so checking
strlcpy() return value is bogus.

MFC after: 3 weeks

Assert that various buffers we are large enough.

MFC after: 1 month

Now that TCP will be checked last we don't need any knowledge about other
protocols.

MFC after: 1 month

Add an argument to the proto_register() function which allows protocol to
declare it is the default and be placed at the end of the queue so it is
checked last.

MFC after: 1 month

Default connection timeout is way too long. To make it shorter we have to
make socket non-blocking, connect() and if we get EINPROGRESS, we have to
wait using select(). Very complex, but I know no other way to define
connection timeout for a given socket.

Reported by: hiroshi@soupacific.com
MFC after: 3 days

Please welcome HAST - Highly Avalable Storage.

HAST allows to transparently store data on two physically separated machines
connected over the TCP/IP network. HAST works in Primary-Secondary
(Master-Backup, Master-Slave) configuration, which means that only one of the
cluster nodes can be active at any given time. Only Primary node is able to
handle I/O requests to HAST-managed devices. Currently HAST is limited to two
cluster nodes in total.

HAST operates on block level - it provides disk-like devices in /dev/hast/
directory for use by file systems and/or applications. Working on block level
makes it transparent for file systems and applications. There in no difference
between using HAST-provided device and raw disk, partition, etc. All of them
are just regular GEOM providers in FreeBSD.

For more information please consult hastd(8), hastctl(8) and hast.conf(5)
manual pages, as well as http://wiki.FreeBSD.org/HAST.

Sponsored by: FreeBSD Foundation
Sponsored by: OMCnet Internet Service GmbH
Sponsored by: TransIP BV