Want digest checksum parsing
Fix problems in code that parse Want-Digest header that can be used either during file download (GET) or while client asks for file checksum (HEAD):
- split Wand-Digest value by comma
- parse checksum type and preference
- filter out unsupported checksum types
- sort checksums by preference
- query DPM database for requested checksum (only existing records)
- calculate most preferred checksum type in case nothing was found in database