This commit tries to give the user a reason that their SLO manifest
was invalid instead of just saying "Invalid SLO Manifest File". It
doesn't get every error condition, but it's better than before.
Examples of things that now have real error messages include:
* bad keys in manifest (e.g. using "name" instead of "path")
* bogus range (e.g. "bytes=123-taco")
* multiple ranges (e.g. "bytes=10-20,30-40")
* bad JSON structure (i.e. not a list of objects)
* non-integer size_bytes
Also fixed an annoyance with unspecified-size segments that are too
small. Previously, if you uploaded a segment reference with
'{"size_bytes": null, ...}' in it and the referenced segment was less
than 1 MiB, you'd get a response that looked like this:
HTTP/1.1 400 Bad Request
Content-Length: 62
Content-Type: text/html; charset=UTF-8
X-Trans-Id: txd9ee3b25896642098e4d9-0055dd095a
Date: Wed, 26 Aug 2015 00:33:30 GMT
Each segment, except the last, must be at least 1048576 bytes.
This is true, but not particularly helpful, since it doesn't tell you
which of your segments violated the rule.
Now you get something more like this:
HTTP/1.1 400 Bad Request
Content-Length: 49
Content-Type: text/plain
X-Trans-Id: tx586e52580bac4956ad8e2-0055dd09c2
Date: Wed, 26 Aug 2015 00:35:14 GMT
Errors:
/segs/small, Too Small; each segment, except the last...
It's not exactly a tutorial on SLO manifests, but at least it names
the problematic segment.
This also changes the status code for a self-referential manifest from
409 to 400. The rest of the error machinery was using 400, and
special-casing self-reference would be really annoying. Besides, now
that we're showing more than one error message at a time, what would
the right status code be for a manifest with a self-referential
segment *and* a segment with a bad range? 400? 409? 404.5? It's much
more consistent to just say invalid manifest --> 400.
Change-Id: I2275683230b36bc273319254e37c16b9e9b9d69c
c0866ceaac