TykTechnologies / tyk

Tyk Open Source API Gateway written in Go, supporting REST, GraphQL, TCP and gRPC protocols
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fix: correctly sync multi-value response headers with coprocess middl… #6394

Open sebkehr opened 1 month ago

sebkehr commented 1 month ago

Hi,

as this is my first PR to your project please let me know what further information you need for a review.

Description

When synchronizing single- and multi-valued header representations (of coprocess-based middleware responses) the list of values for any multi-valued header is currently replaced by a list containing only the value given by its single-value representation effectively dropping all but the first value. Instead synchronization should affect/replace only the first value and retain possibly remaining values.

Related Issue

fixes #6411

Motivation and Context

We like to employ Tyk Gateway with a coprocess-based response middleware attached to an upstream possibly responding with multiple Set-Cookie headers. We also require our middleware to modify other headers like Location. As is due to synchronization only the first Set-Cookie header passes our middleware.

How This Has Been Tested

This PR adds a test which should fail without proposed fix.

Types of changes

Checklist