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 (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. Do the same for the SSH transport tests.

Bug: 553083
Change-Id: Ice9866aa78020f5ca8f397cde84dc224bf5d41b4
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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>

Factor out the test parameterization to use both connection factories
into a common super class and use it in more tests.

This made HttpClientTests.testV2HttpSubsequentResponse() fail for
Apache HTTP. The test used the pattern

  - create POST connection
  - setDoOutput(true)
  - connect()
  - write output stream
  - get & read input stream

This pattern is never used in JGit, which actually calls connect() only
in one case in LFS, and that's on a HEAD request.

The above pattern works on JDK, but fails on Apache HTTP because with
Apache HTTP a connect() actually executes the full request including
writing the entity. To work with Apache HTTP, the pattern would need
to be

  - create POST connection
  - setDoOutput(true)
  - write output stream
  - connect()
  - get & read input stream

which is fine for both. JDK connects implicitly in getOutputStream()
and treats the later explicit connect() as a no-op, and Apache works
because the entity is written when connect() is called.

Because JDK connects implicitly on getOutputStream(), the following
pattern also works with JDK:

  - create POST connection
  - setDoOutput(true)
  - write output stream
  - get & read input stream

Support this with Apache HTTP too: let getInputStream() execute
the request if it wasn't executed already.

Remove explicit connect() calls from test code, since JGit doesn't do
those either.

Change-Id: Ica038c00a7b8edcc01d5660d18e961146305b87f
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Its implementation contains

		} catch (IOException e) {
			// Legacy API, assume error means "no"
			return false;
		}

Better to use ObjectDatabase#has, which throws IOException to report
errors.

Change-Id: I7de02f7ceb8f57b2a8ebdb16d2aa4376775ff933
Signed-off-by: Jonathan Nieder <jrn@google.com>

When a https connection could not be established because the SSL
handshake was unsuccessful, TransportHttp would unconditionally
throw a TransportException.

Other https clients like web browsers or also some SVN clients
handle this more gracefully. If there's a problem with the server
certificate, they inform the user and give him a possibility to
connect to the server all the same.

In git, this would correspond to dynamically setting http.sslVerify
to false for the server.

Implement this using the CredentialsProvider to inform and ask the
user. We offer three choices:

1. skip SSL verification for the current git operation, or
2. skip SSL verification for the server always from now on for
   requests originating from the current repository, or
3. always skip SSL verification for the server from now on.

For (1), we just suppress SSL verification for the current instance of
TransportHttp.

For (2), we store a http.<uri>.sslVerify = false setting for the
original URI in the repo config.

For (3), we store the http.<uri>.sslVerify setting in the git user
config.

Adapt the SmartClientSmartServerSslTest such that it uses this
mechanism instead of setting http.sslVerify up front.

Improve SimpleHttpServer to enable setting it up also with HTTPS
support in anticipation of an EGit SWTbot UI test verifying that
cloning via HTTPS from a server that has a certificate that doesn't
validate pops up the correct dialog, and that cloning subsequently
proceeds successfully if the user decides to skip SSL verification.

Bug: 374703
Change-Id: Ie1abada9a3d389ad4d8d52c2d5265d2764e3fb0e
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

Git has a rather elaborate mechanism to specify HTTP configuration
options per URL, based on pattern matching the URL against "http"
subsection names.[1] The URLs used for this matching are always the
original URLs; redirected URLs do not participate.

* Scheme and host must match exactly case-insensitively.
* An optional user name must match exactly.
* Ports must match exactly after default ports have been filled in.
* The path of a subsection, if any, must match a segment prefix of
  the path of the URL.
* Matches with user name take precedence over equal-length path
  matches without, but longer path matches are preferred over
  shorter matches with user name.

Implement this for JGit. Factor out the HttpConfig from TransportHttp
and implement the matching and override mechanism.

The set of supported settings is still the same; JGit currently
supports only followRedirects, postBuffer, and sslVerify, plus the
JGit-specific maxRedirects key.

Add tests for path normalization and prefix matching only on segment
separators, and use the new mechanism in SmartClientSmartServerSslTest
to disable sslVerify selectively for only the test server URLs.

Compare also bug 374703 and bug 465492. With this commit it would be
possible to set sslVerify to false for only the git server using a
self-signed certificate instead of having to switch it off globally
via http.sslVerify.

[1] https://git-scm.com/docs/git-config

Change-Id: I42a3c2399cb937cd7884116a2a32fcaa7a418fcb
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

git-core follows HTTP redirects so JGit should also provide this.

Implement config setting http.followRedirects with possible values
"false" (= never), "true" (= always), and "initial" (only on GET, but
not on POST).[1]

We must do our own redirect handling and cannot rely on the support
that the underlying real connection may offer. At least the JDK's
HttpURLConnection has two features that get in the way:

* it does not allow cross-protocol redirects and thus fails on
  http->https redirects (for instance, on Github).
* it translates a redirect after a POST to a GET unless the system
  property "http.strictPostRedirect" is set to true. We don't want
  to manipulate that system setting nor require it.

Additionally, git has its own rules about what redirects it accepts;[2]
for instance, it does not allow a redirect that adds query arguments.

We handle response codes 301, 302, 303, and 307 as per RFC 2616.[3]
On POST we do not handle 303, and we follow redirects only if
http.followRedirects == true.

Redirects are followed only a certain number of times. There are two
ways to control that limit:

* by default, the limit is given by the http.maxRedirects system
  property that is also used by the JDK. If the system property is
  not set, the default is 5. (This is much lower than the JDK default
  of 20, but I don't see the value of following so many redirects.)
* this can be overwritten by a http.maxRedirects git config setting.

The JGit http.* git config settings are currently all global; JGit has
no support yet for URI-specific settings "http.<pattern>.name". Adding
support for that is well beyond the scope of this change.

Like git-core, we log every redirect attempt (LOG.info) so that users
may know about the redirection having occurred.

Extends the test framework to configure an AppServer with HTTPS support
so that we can test cloning via HTTPS and redirections involving HTTPS.

[1] https://git-scm.com/docs/git-config
[2] 6628eb41db
[3] https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html

CQ: 13987
Bug: 465167
Change-Id: I86518cb76842f7d326b51f8715e3bbf8ada89859
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>