A builder API provides a more convenient way to define a customized
SshdSessionFactory by hiding the subclassing.

Also provide a new interface SshConfigStore to abstract away the
specifics of reading a ssh config file, and provide a way to customize
the concrete ssh config implementation to be used. This facilitates
using an alternate ssh config implementation that may or may not be
based on files.

Change-Id: Ib9038e8ff2a4eb3a9ce7b3554d1450befec8e1e1
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

This is the format given by the Eclipse legal doc generator [1].

[1] https://www.eclipse.org/projects/tools/documentation.php?id=technology.jgit

Bug: 548298
Change-Id: I8d8cabc998ba1b083e3f0906a8d558d391ffb6c4
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

Add the constant, and implement hashing of known host names in
OpenSshServerKeyDatabase. Add a test verifying that the hashing
works.

Bug: 548492
Change-Id: Iabe82b666da627bd7f4d82519a366d166aa9ddd4
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Provide a wrapper interface and change the implementation such that
a client can substitute its own database of known hosts keys instead
of the default file-based mechanism.

Bug: 547619
Change-Id: Ifc25a4519fa5bcf7bb8541b9f3e2de15215e3d66
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

RFC 4253 section 4.2 allows an ssh server to send additional lines
before its server identification string. Apache MINA sshd enforces
for these lines the constraints specified for the server identification
line, too: no NUL characters and not longer than 255 characters. That
is too strict. RFC 4253 doesn't mandate this, and it also doesn't
make sense given the rationale for these lines in RFC 4253: a TCP
wrapper may not be aware of SSH restrictions, and may not adhere to
these constraints.

Be more lenient when parsing the server's protocol version. Allow
NULs and longer lines in the preamble, and also handle line endings
more leniently. Only enforce the restrictions for the actual server
identification line.

Bug: 545939
Change-Id: I75955e9d8a8daef7c04fc0f39539c2ee93514e1c
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Include the net.i2p.crypto.eddsa bundle via a hard dependency.

Add tests for dealing with ed25519 host keys and user key files.

Manual tests: fetching from git.eclipse.org with an ed25519 user key,
and pushing this change itself using the same ed25519 key.

Note that sshd 2.0.0 does not yet support encrypted ed25519 private
keys.

Bug: 541272
Change-Id: I7072f4014d9eca755b4a2412e19c086235e5eae9
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

This is not about the ssh config ProxyCommand but about programmatic
support for HTTP and SOCKS5 proxies. Eclipse allows the user to
specify such proxies, and JSch at least contains code to connect
through proxies. So our Apache MINA sshd client also should be able
to do this.

Add interfaces and provide two implementations for HTTP and SOCKS5
proxies. Adapt the core code to be able to deal with proxy connections
at all. The built-in client-side support for this in sshd 2.0.0 is
woefully inadequate.

Tested manually by running proxies and then fetching various real-
world repositories via these proxies from different servers. Proxies
tested: ssh -D (SOCKS, anonymous), tinyproxy (HTTP, anonymous), and
3proxy (SOCKS & HTTP, username-password authentication). The GSS-API
authentication is untested since I have no Kerberos setup.

Bug: 520927
Change-Id: I1a5c34687d439b3ef8373c5d58e24004f93e63ae
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Add a new ssh client implementation based on Apach MINA sshd 2.0.0.

This implementation uses JGit's own config file parser and host entry
resolver. Code inspection of the Apache MINA implementation revealed
a few bugs or idiosyncrasies that immediately would re-introduce bugs
already fixed in the past in JGit.

Apache MINA sshd is not without quirks either, and I had to configure
and override more than I had expected. But at least it was all doable
in clean ways.

Apache MINA boasts support for Bouncy Castle, so in theory this should
open the way to using more ssh key algorithms, such as ed25519.

The implementation is in a separate bundle and is still not used in
the core org.eclipse.jgit bundle. The tests re-use the ssh tests from
the core test bundle.

Bug: 520927
Change-Id: Ib35e73c35799140fe050d1ff4fb18d0d3596580e
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>