Bug 423715 - Support multiple algorithms for artifact checksumsI20180301-2000

Developer of p2-based software should be able to check integrity of
artifact checksums using any MessageDigest implementation available,
at his own discretion, without ever touching p2 internals.

For the purpose of this bug, limit enabled checksum algorithms to:
- MD5 (legacy one, deprecated now, for backward compatibility only)
- SHA-256 (more collision-resistant than MD5)

See artifactChecksums.exsd for more details.

First, encode ID of the checksum algorithm into the name of the
property itself so that artifact descriptor now may look like:

    <artifact classifier='binary' id='testKeyId' version='1.2.3'>
      <properties size='6'>
        <property name='download.md5' value='b3788632488d48b850255acf68669651'/>
        <property name='artifact.md5' value='b3788632488d48b850255acf68669651'/>
        <property name='download.checksum.sha-256' value='d594816b995d1689c2dfc97dc244859abe6bdb9ebeb4b396e401afd85a97ee16'/>
        <property name='download.checksum.whirlpool' value='e4f3ece3d3f289cc2686a68f0b1b5a2d03da3a8ccdc3cd6d03209e4c789af724c8fa915bb890079e1abe78df44875cec132885dd6ae1176eed7938dfb3c7b551'/>
        <property name='artifact.checksum.sha-256' value='d594816b995d1689c2dfc97dc244859abe6bdb9ebeb4b396e401afd85a97ee16'/>
        <property name='artifact.checksum.tiger' value='462a72a1a593b9e2de8721b8d79335fd03e974f2e2e1f35a'/>
      </properties>
    </artifact>

Prefix helps to avoid conflicts with other, not checksum-related,
properties. To find checksums of specific type, we need all properties
with prefix 'artifact.checksum.', Extracting checksum id from the name
of the property is also trivial.

Store these prefixes in IArtifactDescriptor's DOWNLOAD_CHECKSUM and
ARTIFACT_CHECKSUM.

ChecksumUtilities provides internal API to deal with properties.

Second, map ID of checksum algorithm to the name of MessageDigest
implementation with a contribution to a new extension point
org.eclipse.equinox.p2.artifact.repository.artifactChecksums:

    <extension point="org.eclipse.equinox.p2.artifact.repository.artifactChecksums">
      <artifactChecksum algorithm="SHA-256"
                        id="sha-256"
			...
                        />
    </extension>

Number of actual checksums in artifact descriptor depends on the
configuration of the application that created such descriptor because
p2 will:
- handle MD5 checksums as usual, preserving backward compatibility
- calculate other checksums using extensions that contribute to
  artifactChecksums extension point

Last, we use id of specific checksum to get MessageDigest instance
with getInstance(String).

There is a number of standalone applications (like MirrorApplication)
and Ant tasks (like ValidateTask) that allow user to chose specific
comparator by id and ArtifactComparatorFactory is responsible for
instantiating it. Legacy MD5 comparator requires no special
configuration while the new ArtifactChecksumComparator is more generic
and needs some parameters to instantiate. ArtifactComparatorFactory
handles this by accepting fake comparator id - concatenated
ArtifactChecksumComparator's id and checksum algorithm id.

In other words, to compare artifacts using SHA-256 algorithm use
'org.eclipse.equinox.artifact.comparator.checksum.sha-256' as
comparator id.

We generate, consume and compare artifact checksums using all enabled
algorithms. Ideally, configuration options should provide more control
for both repository publisher and p2 client like:
- a priority (compare with SHA-512 first, then SHA-256 and, finally,
  MD5)
- skip specific checksum (do not use MD5 even if provided)
- mandatory checksum (require Whirlpool and it's an error if its not
  available)

While I have no good solution for this right now, there are some
configuration options provided. Also, number of new enabled checksum
algorithms is limited to SHA-256 only (more checksums = more reasons
to fail = more reasons to disable).

To turn checksum verification off completely:
- for p2 client, use property 'eclipse.p2.checksums.disable' (see
  SimpleArtifactRepository.CHECKSUMS_ENABLED constant).
- for p2 publisher, the old PublisherInfo's setArtifactOptions(int)
  and IPublisherInfo.A_NO_MD5 still could be used.

To disable MD5 checksums only, existing properties
'eclipse.p2.MD5Check' and 'eclipse.p2.MD5ArtifactCheck' still can be
used.

Change-Id: Iacd267e13d5d096694001d34cafbaea5451e7157
Signed-off-by: Mykola Nikishov <mn@mn.com.ua>

0 files changed, 0 insertions, 0 deletions