"400 bad request" is returned for non-existing objects instead of 404

[roman-khimov]

$ LANG=C wget http://localhost:8082/get/Dxhf4PNprrJHWWTG5RGLdfLkJiSQ3AQqit1MSnEPRkDZ/Dinq6fbQR9Ry1NQvp4YzmTgDXCQ5SYQ9FR7koyTFjb2a
--2021-04-30 00:19:35--  http://localhost:8082/get/Dxhf4PNprrJHWWTG5RGLdfLkJiSQ3AQqit1MSnEPRkDZ/Dinq6fbQR9Ry1NQvp4YzmTgDXCQ5SYQ9FR7koyTFjb2a
Resolving localhost (localhost)... ::1, 127.0.0.1
Connecting to localhost (localhost)|::1|:8082... failed: Connection refused.
Connecting to localhost (localhost)|127.0.0.1|:8082... connected.
HTTP request sent, awaiting response... 400 Bad Request
2021-04-30 00:19:35 ERROR 400: Bad Request.

Gate log:

2021-04-30T00:19:35.457+0300    error   downloader/download.go:104      could not receive object        {"cid": "Dxhf4PNprrJHWWTG5RGLdfLkJiSQ3AQqit1MSnEPRkDZ", "oid": "Dinq6fbQR9Ry1NQvp4YzmTgDXCQ5SYQ9FR7koyTFjb2a", "elapsed": "63.078586ms", "error": "reading the response failed: rpc error: code = Unknown desc = object not found", "errorVerbose": "rpc error: code = Unknown desc = object not found\nreading the response failed\ngithub.com/nspcc-dev/neofs-api-go/pkg/client.(*clientImpl).GetObject\n\tgithub.com/nspcc-dev/[email protected]/pkg/client/object.go:542\ngithub.com/nspcc-dev/neofs-http-gate/neofs.(*neofsObjectClient).Get\n\tgithub.com/nspcc-dev/neofs-http-gate/neofs/client-plant.go:128\ngithub.com/nspcc-dev/neofs-http-gate/downloader.(*request).receiveFile\n\tgithub.com/nspcc-dev/neofs-http-gate/downloader/download.go:102\ngithub.com/nspcc-dev/neofs-http-gate/downloader.(*Downloader).DownloadByAddress\n\tgithub.com/nspcc-dev/neofs-http-gate/downloader/download.go:214\ngithub.com/fasthttp/router.(*Router).Handler\n\tgithub.com/fasthttp/[email protected]/router.go:414\ngithub.com/valyala/fasthttp.(*Server).serveConn\n\tgithub.com/valyala/[email protected]/server.go:2219\ngithub.com/valyala/fasthttp.(*workerPool).workerFunc\n\tgithub.com/valyala/[email protected]/workerpool.go:223\ngithub.com/valyala/fasthttp.(*workerPool).getCh.func1\n\tgithub.com/valyala/[email protected]/workerpool.go:195\nruntime.goexit\n\truntime/asm_amd64.s:1371"}

The problem is that even though desc has proper object not found string the code is Unknown and thus we return this generic error 400 instead of more appropriate 404. I'm not sure this happens and it doesn't seem to be critical, but maybe @alexvanin knows something about it (we're doing a GetObject call here (WithAddress/WithSession/WithBearer)).

[roman-khimov]

Bad container ID is handled similarly:

2021-04-30T09:43:31.315+0300    error   downloader/download.go:104      could not receive object        {"cid": "Dxhf4PNprrJHWWTG5RGLdfLkJiSQ3AQqit1MSnEPRkDD", "oid": "Dinq6fbQR9Ry1NQvp4YzmTgDXCQ5SYQ9FR7koyTFjb2a", "elapsed": "3.750129ms", "error": "reading the response failed: rpc error: code = Unknown desc = can't fetch container info", "errorVerbose": "rpc error: code = Unknown desc = can't fetch container info\nreading the response failed\ngithub.com/nspcc-dev/neofs-api-go/pkg/client.(*clientImpl).GetObject\n\tgithub.com/nspcc-dev/[email protected]/pkg/client/object.go:542\ngithub.com/nspcc-dev/neofs-http-gate/neofs.(*neofsObjectClient).Get\n\tgithub.com/nspcc-dev/neofs-http-gate/neofs/client-plant.go:128\ngithub.com/nspcc-dev/neofs-http-gate/downloader.(*request).receiveFile\n\tgithub.com/nspcc-dev/neofs-http-gate/downloader/download.go:102\ngithub.com/nspcc-dev/neofs-http-gate/downloader.(*Downloader).DownloadByAddress\n\tgithub.com/nspcc-dev/neofs-http-gate/downloader/download.go:214\ngithub.com/fasthttp/router.(*Router).Handler\n\tgithub.com/fasthttp/[email protected]/router.go:414\ngithub.com/valyala/fasthttp.(*Server).serveConn\n\tgithub.com/valyala/[email protected]/server.go:2219\ngithub.com/valyala/fasthttp.(*workerPool).workerFunc\n\tgithub.com/valyala/[email protected]/workerpool.go:223\ngithub.com/valyala/fasthttp.(*workerPool).getCh.func1\n\tgithub.com/valyala/[email protected]/workerpool.go:195\nruntime.goexit\n\truntime/asm_amd64.s:1371"}

[alexvanin]

NeoFS is doing poor job of error handling right now. While details (string messages) are somewhat useful, error codes are mostly ignored. This happened because error codes and error handling in general are tightly coupled with transport implementation. We want to break that coupling by defining error handling mechanism directly in NeoFS API in the future (nspcc-dev/neofs-api#150).

If it will be necessary, we can handle and return sensible gRPC error codes for some number of cases. Otherwise it is better to wait for transport independent NeoFS errors.