connection header needs to be excluded in sigv4a/sigv4

[shulin-sq]

Acknowledgements

• I have searched (https://github.com/aws/aws-sdk/issues?q=is%3Aissue) for past instances of this issue
• I have verified all of my SDK modules are up-to-date (you can perform a bulk update with go get -u github.com/aws/aws-sdk-go-v2/...)

Describe the bug

while using the sigv4a library (based on 9805a19) we were getting "IncompleteSignatureException: 'connection' is named as a SignedHeader, but it does not exist in the HTTP request." despite connection header being part of the http request.

Expected Behavior

for the signature to be accepted. I'm also curious why excluding the connection header as part of the signature seems to work?

Current Behavior

"IncompleteSignatureException: 'connection' is named as a SignedHeader, but it does not exist in the HTTP request."

Reproduction Steps

2024/04/02 23:05:22 [post-signing] Translated URL: REDACTED
2024/04/02 23:05:22 [post-signing] Translated Header: map[Accept:[*/*] Authorization:[AWS4-ECDSA-P256-SHA256 Credential=REDACTED/20240402/vpc-lattice-svcs/aws4_request, SignedHeaders=accept;connection;host;x-amz-content-sha256;x-amz-date;x-amz-region-set;x-amz-security-token;REDACTED, Signature=REDACTED] Connection:[Keep-Alive] User-Agent:[curl/7.29.0] X-Amz-Content-Sha256:[UNSIGNED-PAYLOAD] X-Amz-Date:[20240402T230522Z] X-Amz-Region-Set:[*] X-Amz-Security-Token:REDACTED] REDACTED]

as per this example connection is part of SignedHeaders and is part of the http request

Possible Solution

I noticed in the java sdk, connection is added as an ignored header https://github.com/aws/aws-sdk-java-v2/blob/dc695de6ab49ad03934e1b02e7263abbd2354be0/core/auth/src/main/java/software/amazon/awssdk/auth/signer/internal/AbstractAws4Signer.java#L59 adding it to this list

aws-sdk-go-v2/aws/signer/internal/v4/headers.go

Line 7 in 50d16cf

"Authorization": struct{}{},

seemed to resolve the issue. However I'd like to know more about why this header needs to be ignored.

Additional Information/Context

No response

AWS Go SDK V2 Module Versions Used

we're using an internal copy of 9805a19 where the sigv4a library is not in an internal package

Compiler and Version used

go 1.21.5

Operating System and version

Oracle Linux 8

[shulin-sq]

This ended up working for us, I submitted a PR to also contribute the fix upstream: #2606