Re-enable DSA, DSA_CERT, and RSA_CERT public key authentication.
DSA is discouraged for a long time already, but it might still be
way too disruptive to completely drop it. RSA is discouraged for
far less long, and dropping that would be really disruptive.

Adapt to the changed property handling. Remove work-arounds for
shortcomings of earlier sshd versions.

Use Orbit I20210203173513, which includes sshd 2.6.0. This also bumps
apache.httpclient to 4.5.13 and apache.httpcore to 4.4.14.

Change-Id: I2d24a1ce4cc9f616a94bb5c4bdaedbf20dc6638e
Signed-off-by: David Ostrovsky <david@ostrovsky.org>
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

Make all transports request protocol V2 when fetching. Depending on
the transport, set the GIT_PROTOCOL environment variable (file and
ssh), pass the Git-Protocol header (http), or set the hidden
"\0version=2\0" (git anon). We'll fall back to V0 if the server
doesn't reply with a version 2 answer.

A user can control which protocol the client requests via the git
config protocol.version; if not set, JGit requests protocol V2 for
fetching. Pushing always uses protocol V0 still.

In the API, there is only a new Transport.openFetch() version that
takes a collection of RefSpecs plus additional patterns to construct
the Ref prefixes for the "ls-refs" command in protocol V2. If none
are given, the server will still advertise all refs, even in protocol
V2.

BasePackConnection.readAdvertisedRefs() handles falling back to
protocol V0. It newly returns true if V0 was used and the advertised
refs were read, and false if V2 is used and an explicit "ls-refs" is
needed. (This can't be done transparently inside readAdvertisedRefs()
because a "stateless RPC" transport like TransportHttp may need to
open a new connection for writing.)

BasePackFetchConnection implements the changes needed for the protocol
V2 "fetch" command (stateless protocol, simplified ACK handling,
delimiters, section headers).

In TransportHttp, change readSmartHeaders() to also recognize the
"version 2" packet line as a valid smart server indication.

Adapt tests, and run all the HTTP tests not only with both HTTP
connection factories (JDK and Apache HttpClient) but also with both
protocol V0 and V2. The SSH tests are much slower and much more
focused on the SSH protocol and SSH key handling. Factor out two
very simple cloning and pulling tests and make those run with
protocol V2.

Bug: 553083
Change-Id: I357c7f5daa7efb2872f1c64ee6f6d54229031ae1
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Also mark the return value @Nullable to enable null analysis in Eclipse.

Change-Id: Ib954b231d743da6ea122adb2cc4880b5f99824cc
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

This is useful to access git repositories behind a bastion server
(jump host).

Add a constant for the config; rewrite the whole connection initiation
to parse the value and (recursively) set up the chain of hops. Add
tests for a single hop and two different ways to configure a two-hop
chain.

The connection timeout applies to each hop in the chain individually.

Change-Id: Idd25af95aa2ec5367404587e4e530b0663c03665
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

SshSupport.runSshCommand() had a comment that wait with time-out
could not be used because JSchProcess.exitValue() threw the wrong
unchecked exception when the process was still running.

Fix this and make JSchProcess.exitValue() throw the right exception,
then wait with a time-out in SshSupport.

The Apache sshd client's SshdExecProcess has always used the correct
IllegalThreadStateException.

Add tests for SshSupport.runCommand().

Change-Id: Id30893174ae8be3b9a16119674049337b0cf4381
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Improve the SshTestGitServer API for accessing the server properties.
Instead of returning the raw property map, return the proper sshd API
abstraction PropertyResolver.

This makes the interface more resilient against upstream changes.

Change-Id: Ie5b685bddc4e59f3eb6c121026d3658d57618ca4
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Use standard java.security to generate test keys, use sshd to write
public key files, and write PKCS#8 PEM files for our non-encrypted
test private keys. This is a format that both JSch and Apache MINA
sshd can read.

Change-Id: I6ec55cfd7346b672a7fb6139d51abfb06d81a394
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

SSHD-1028:[1] server doesn't close server-side sessions properly when
client disconnects.

[1] https://issues.apache.org/jira/projects/SSHD/issues/SSHD-1028

Change-Id: I0d67f49e35abe8375cb1370a494dc01d0fb2c9b1
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Motivation: JSch serves as 'default' implementations of the SSH
transport. If a client application does not use it then there is no need
to pull in this dependency.

Move the classes depending on JSch to an OSGi fragment extending the
org.eclipse.jgit bundle and keep them in the same package as before
since moving them to another package would break API. Defer moving them
to a separate package to the next major release.

Add a new feature org.eclipse.jgit.ssh.jsch feature to enable
installation. With that users can now decide which of the ssh client
integrations (JCraft JSch or Apache Mina SSHD) they want to install.
We will remove the JCraft JSch integration in a later step due to the
reasons discussed in bug 520927.

Bug: 553625
Change-Id: I5979c8a9dbbe878a2e8ac0fbfde7230059d74dc2
Also-by: Michael Dardis <git@md-5.net>
Signed-off-by: Michael Dardis <git@md-5.net>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: David Ostrovsky <david@ostrovsky.org>

Avoid using a key written to a file. This makes it clearer that
the test does not rely on files being present.

Change-Id: I31cf4f404aab5b891c32fc4bda906b7f8fe03777
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Change target platforms to Orbit I20200319180910 and regenerate them.
Change package imports to [2.4.0,2.5.0); adapt code to upstream API
changes.

Maven build: update version in root pom.

Bazel build: update version & hash in WORKSPACE file.

Proxy functionality verified manually using 3proxy (HTTP & SOCKS,
with basic authentication) and ssh -vvv -D7020 localhost (SOCKS, no
authentication).

Bug: 561078
Change-Id: I582f6b98055b013c006f2c749890fe6db801cbaa
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>

Change-Id: Ie2e207eb05e0f6da8018153f8a5dd636e8f35f4c
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>

Update target platforms, maven and bazel builds to use sshd 2.2.0.

Adapt internal classes to changed sshd interfaces and remove previous
work-arounds for asking repeatedly for key passwords and for loading
keys lazily; both are now done by sshd.

CQ: 19034
CQ: 19035
Bug: 541425
Change-Id: I85e1df6ebb8a94953a912d9b2b8a7b5bdfbd608a
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

Add tests for password and keyboard-interactive authentication.
Implement password authentication; the default provided by sshd
is non-interactive, which is not useful for JGit.

Make sure the CredentialsProvider gets reset on successive password
retrieval attempts. Otherwise it might always return the same non-
accepted password from a secure storage. (That one was discovered
by actually trying this via EGit; the JGit tests don't catch this.)

Change the default order of authentication mechanisms to prefer
password over keyboard-interactive. This is a mitigation for upstream
bug SSHD-866.[1]

Also include a fix for upstream bug SSHD-867.[2]

[1] https://issues.apache.org/jira/projects/SSHD/issues/SSHD-866
[2] https://issues.apache.org/jira/projects/SSHD/issues/SSHD-867

Bug: 520927
Change-Id: I423e548f06d3b51531016cf08938c8bd7acaa2a9
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Create the bundle and move the SshTestGitServer there. Verified that
the Eclipse build still works and ran JSchSshTest and ApacheSshTest as
junit tests inside Eclipse.

Update maven build and features to account for that. Verified by
running full maven build including packaging.

Update bazel build files to account for that. Verified by a
clean-slate bazel build :all, followed by running the JSchSshTest
and the ApacheSshTest via bazel.

Change-Id: Ia084942f4425b454529de148e00417e7da786a90
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>