http: ocdavsvc - add If-Not-Match header on PUT

[DeepDiver1975]

If-Match is implemented - https://github.com/cernbox/reva/blob/a6be57bfedc01eddf38148bb7015c2fb8a7a0058/services/httpsvc/ocdavsvc/put.go#L151

To be capable to ensure that overwrite upon creating a new file is not possible the If-Not-Match header with the special value '*' should be implemented.

How does it work:
the client sends If-Not-Match: '*' with a request which shall create a new file. The server checks if the file does not exist otherwise 412 is returned.

[labkode]

@butonic is this still the case?

[DeepDiver1975]

there is still no if-not-match in https://github.com/cernbox/reva/blob/master/cmd/revad/svcs/httpsvcs/ocdavsvc/put.go - so I guess this is still the case ....

[butonic]

see https://tools.ietf.org/html/rfc2616#section-14.26

[labkode]

@DeepDiver1975 @butonic thanks for the pointers, does ownCloud uses the ETAG as the entity or only uses the * case?

[DeepDiver1975]

Both cases are used . If-None with * to make sure a new resource is created and If-Match 'etag' to make sure we do not overwrite by accident

[butonic]

see https://github.com/cs3org/reva/pull/674/files/4d072d0601acc9e21d5e774f1f714cf5ac9fc6f0#r413058259

[micbar]

@butonic if this fixed by #674 ?

[DeepDiver1975]

@butonic if this fixed by #674 ?

no - there is no If-Not-Match in the mentioned PR - also commented accordingly https://github.com/cs3org/reva/pull/674/files#r413058259