Fix Amazon response when cover is not found

[taskula]

By using provider "aws" in Coce, a result in JSON response is always returned whether cover image is found or not.

It seems Amazon is returning a 1x1 pixel gif when cover is not found. Looking at your aws fetcher I imagine it previously returned HTTP 404 or something similar, but now it returns a HTTP 200 and this 1x1 image when no cover is found.

To reproduce:

Make a request to Coce server:

http://coce.server/cover?id=0000000000&provider=aws

Observe response:

{"0000000000":"https://images-na.ssl-images-amazon.com/images/P/0000000000.01.MZZZZZZZZZ.jpg"}

Open the returned URL in your browser and observe 1x1 gif.

Expected response:

{}

As we use a HEAD request for aws I propose we examine Content-Length response header for 43 bytes that is the size of this 1x1 gif. If Content-Length is something else then we expect a cover was found and return URL in our response.

[fredericd]

Thanks. Very intersting perspective. I've tested with your example: id=0000000000. And I get the strange result you describe. Your patch is a solution. I've then tested with other values, and I find other results, and even more strange. For example, with id=0000000001, or id=0000000002, the returned value is:

https://images-na.ssl-images-amazon.com/images/P/0000000001.01.MZZZZZZZZZ.jpg
https://images-na.ssl-images-amazon.com/images/P/0000000002.01.MZZZZZZZZZ.jpg

What game is Amazon playing?

[taskula]

Another question, what is the case for accepting a HTTP 403 response code? Do they really provide an image together with 403 response code?

(referring to)

coce/coce.js

Line 67 in 8c7f96e

if (res.statusCode === 200 || res.statusCode === 403) repo.addurl('aws', id, url);