rgw: swift: configurable enforcement of container naming rules

[theanalyst]

This is a patchset addressing two issues

• rgw: allow buckets created with / to be useable

Previously we didn't restrict "/" in bucket names created via swift api
though swift client itself had a restriction, and cases like misconfigured
keystone urls would cause swift client also to prepend a
"/" before the bucket name. The problem is that create bucket succeeds such
a call and rgw_get_bucket_instance_info() and related functions would fail
because we replace the first encountered "/" with a ":" assuming that this
was a(n empty) tenant name. Make these buckets useable/ deleteable by
making sure that when we retreive the key back we replace the beginning /
with a colon as this was used in storing the bucket info. A non backwards
compatible cleaner change would be to make rgw_bucket_instance_key_to_oid not
replace slashes when 0 sized tenants were encountered. python-swiftclient/swift cli are
still broken when uploading objects etc. as they do not prepend the / in
PUT object requests whereas do in create bucket requests. However this
patch makes it possible to use/delete these created buckets when using the
rest api.

Note that however there is still an edge case which cannot be addressed,
which is, currently an object upload request of the form PUT /bucket/foo
would end up with another bucket with the name /bucket/foo being created.
With this patch however we ensure that a PUT /bucket/foo is indeed
considered as an object request, however this introduces the problem where
previously a bucket was created with such a name which would no longer be
accessible. There is no way to address this since object names are allowed
to contain slashes and we are now just allowing the case where a prefix
slash at bucket name is allowed (since we hadn't restricted that before), a
slash in the middle would end up with the part after being considered as an
object request, which is the convention.

Fixes: http://tracker.ceph.com/issues/21679

• rgw: add a configurable for enforcing swift bucket name validation

Swift containers are declared in the upstream documentation as 1-256 bytes
of UTF-8, and the only forbidden character is '/'.

We did not previously enforce the no-slash rule.

Adding a configurable rgw_swift_enforce_bucket_names which validates
according to swift container naming restrictions (which currently forbids
"/" in container names), also dropping the 0xff check that we previously
had since check_utf8 should already catch that

Making this as a configurable with the default that we enforce the swift
naming rules of no slash, the configurable is useful in cases where when
previously created buckets with slashes exists and need to be used

See-Also:
https://docs.openstack.org/developer/swift/api/object_api_v1_overview.html
Fixes: http://tracker.ceph.com/issues/19264

edit: formatting fixes

[theanalyst]

@rzarzynski @yehudasa I'm open to any other approaches if they can fix this as well

[mattbenjamin]

jenkins retest this please

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
If you are a maintainer or core committer, please follow-up on this issue to identify what steps should be taken by the author to move this proposed change forward.
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[mattbenjamin]

@mdw-at-linuxbox can you review this?

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
If you are a maintainer or core committer, please follow-up on this issue to identify what steps should be taken by the author to move this proposed change forward.
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