This commit refactors the code in `cmd/crypto`
and separates SSE-S3, SSE-C and SSE-KMS.
This commit should not cause any behavior change
except for:
- `IsRequested(http.Header)`
which now returns the requested type {SSE-C, SSE-S3,
SSE-KMS} and does not consider SSE-C copy headers.
However, SSE-C copy headers alone are anyway not valid.
x-amz-content-sha256 can be optional for any AWS signature v4
requests, make sure to skip sha256 calculation when payload
checksum is not set.
Here is the overall expected behavior
** Signed request **
- X-Amz-Content-Sha256 is set to 'empty' or some 'value' or its
not 'UNSIGNED-PAYLOAD'- use it to validate the incoming payload.
- X-Amz-Content-Sha256 is set to 'UNSIGNED-PAYLOAD' - skip checksum verification
- X-Amz-Content-Sha256 is not set we use emptySHA256
** Presigned request **
- X-Amz-Content-Sha256 is set to 'empty' or some 'value' or its
not 'UNSIGNED-PAYLOAD'- use it to validate the incoming payload
- X-Amz-Content-Sha256 is set to 'UNSIGNED-PAYLOAD' - skip checksum verification
- X-Amz-Content-Sha256 is not set we use 'UNSIGNED-PAYLOAD'
Fixes#5339
This is a consolidation effort, avoiding usage
of naked strings in codebase. Whenever possible
use constants which can be repurposed elsewhere.
This also fixes `goconst ./...` reported issues.
Andreas Auernhammer