Potential denial of service attack by rogue servers

[itamarst]

• Malicious server SN joins grid G
• Client C begins to upload shares R[1..N] to storage servers S[1..N]
• SN sees upload of share RN to storage index I
• SN immediately calls allocate_buckets on S[1..N-1] for shares R[1..N] (but doesn't bother to upload anything)
• For any server/share combination where SN gets there first, C is denied the ability to perform an upload. Also, to C, it looks like the share has already been uploaded so no further work is required on its part.