fix: handle malformed location header when using next/navigation redirect API #3332
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Description
There is Next.js quirk where it sets or appends
locationheader multiple times. In specific cases it first set it and then append it, which results inlocationheader being twice in response. When usingnext startthis doesn't seem to cause actual problems, however you can seelocationheader twice:Despite the weirdness browsers work fine with it.
We however adapt NF's Fetch API
RequestandResponseto(req: http.IncomingMessage, res: http.ServerResponse)pair used under the hood by Next.js.Fetch API
Headershave different behavior - it will create single header with,delimeter ( https://github.com/nodejs/undici/blob/59fd5f4ee6b2da75cf5365c06c7a409f7ba3b206/lib/web/fetch/headers.js#L246-L250 )which result in reponses like so:
which breaks browser's behavior.
This adds a workaround to
res.appendHeaderthat we pass to Next.js to disallow appending same location againDocumentation
Tests
Added test case for the scenario in first commit (failing without code changes)