panic inside WithGetResponseHeader

[minaevmike]

Confirm by changing [ ] to [x] below to ensure that it's a bug:

• I've gone though Developer Guide and API reference
• I've checked AWS Forums and StackOverflow for answers
• I've searched for previous similar issues and didn't find any solution

Describe the bug
We are using S3 API to manipulate files inside our S3 storage.
In some rare cases, WithGetResponseHeader may panic. If the request builds failed, before it was sent, request.HTTPResponse would be nil. But the complete callback would be called anyway.

Version of AWS SDK for Go?
Example: v1.41.0

Version of Go (go version)?
go 1.17.5
To Reproduce (observed behavior)
Steps to reproduce the behavior (please share code or minimal repo)

      opts1 := []func(downloader *s3manager.Downloader){
		s3manager.WithDownloaderRequestOptions(
			func(r *request.Request) {
				r.Handlers.Build.PushBackNamed(request.NamedHandler{Name: "my bad handler", Fn: func(r *request.Request) {
					r.Error = io.EOF
				}})
			}),
	}
	err := d.DownloadWithContext(ctx, buf, &r, opts1...)

Expected behavior
no panic occurs

[KaibaLopez]

Hi @minaevmike ,
Could you provide a sample I can run and reproduce? From what I've tried I don't see the bug, but I might be doing something different.

[davidmerwin]

🔆

[eitankatznelson]

We've run into this issue at our company, the issue here is that the Send method will always execute the Complete handlers, but if the request is canceled before the response object is initialized we get a nil pointer dereference causing a panic.

To reproduce, I would initiate the call in one go routine, and cancel the context in a second go routine right after a call to Send.

[jasdel]

Thanks for reporting this issue, and providing reproduction example. I put together #4256 that fixes this bug and ensures that HTTPResponse will not be nil when Complete handlers are called returns.

[github-actions]

⚠️COMMENT VISIBILITY WARNING⚠️

Comments on closed issues are hard for our team to see.
If you need more assistance, please either tag a team member or open a new issue that references this one.
If you wish to keep having a conversation with other community members under this issue feel free to do so.