bugfix: exec should return 200 if client doesn't upgrade proto

[fuweid]

Signed-off-by: Wei Fu [email protected]

1.Describe what this PR did

If user calls /exec/execid/start without upgrade header, the pouchd should return 200 status.
But now, the pouchd always return 101 switch protocol. This PR is to fix this bug.

2.Does this pull request fix one issue?

fixes #494

3.Describe how you did it

For the AttachConfig, the Upgrade field should check header from request.

4.Describe how to verify it

I have added the test for this.

5.Special notes for reviews

In this PR, I upgrades the request.Hijack function and add more comments here:

For hijack request, the server can return 200 status or 101 switch proto.

If http-client doesn't switch proto, the Do function will return error caused by ErrPersistEOF.

As the RFC 2616, section 4.4 mentioned, if there is no Content-Length or chunked Transfer-Encoding on a *Response and the status is not 1xx, 204 or 304, then the body is unbounded. And the response is always terminated by the first empty line after the header fields.

In our case, the 200 response is like:

HTTP/1.1 200 OK
Content-Type: application/vnd.docker.raw-stream
<= first empty line
[raw-data]

The golang http client does follow the RFC 2616. More detail is here:

• https://github.com/golang/go/blob/release-branch.go1.9/src/net/http/response.go#L190
• https://github.com/golang/go/blob/release-branch.go1.9/src/net/http/transfer.go#L486:L518

For this case, both status and header has been read into response. And the [raw-data] will be read from hijack.reader. So we can ignore the ErrPersistEOF here.

cc @allencloud and @Letty5411

[codecov-io]

Codecov Report

Merging #515 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #515   +/-   ##
=======================================
  Coverage   18.04%   18.04%           
=======================================
  Files          35       35           
  Lines        1790     1790           
=======================================
  Hits          323      323           
  Misses       1432     1432           
  Partials       35       35

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[Letty5411]

LGTM