When request is sent to http://localhost:8080/ipfs/$cid response has
HTTP 301 status code and "Location" header with redirect destination at
$cid.ipfs.localhost:8080
Redirect is followed by browsersi, but not by commandline tools.
Status 301 is ignored by curl in default mode: it will print response
and won't follow redirect, user needs to add -L for that.
To fix curl, we return correct payload in body of HTTP 301 response,
but set Clear-Site-Data header to ensure Origin sandbox can't be abused.
This requires a surgical workaround:
If Location header is present in ResponseWriter's Header map,
we ensure http.ServeContent() returns HTTP 301
Context: https://github.com/ipfs/go-ipfs/pull/6982
License: MIT
Signed-off-by: Marcin Rataj <lidel@lidel.org>
