Commits on Nov 3, 2024

1. fix(pdk): service.response.get_headers behavior …

   This commit attempts to fix several issues in the
   `kong.service.response.get_headers()` module.
   
   Issues
   ======
   
   1. Said method must only return response headers set by the upstream
      service. However, since its introcution, it is broken; in the
      original implementation, it added an `__index` metamethod to the full headers
      table (both Kong and upstream headers) to ensure a given header being indexed
      was found in a `ngx.var.upstream_http_<header_name> variable (ie, it was
      set by the upstream). However, it responded with the table itself, which
      contained the headers, so the `__index` metamethod would never be called.
      Summarizing, since its introduction, the method has been returning
      both Kong and upstream headers. Tests were also broken due to a
      case-sensitiveness issue (implementation described above bypased the
      original headers table metatable, effectively breaking
      case-insensitiveness implemented by the `ngx.resp.get_headers` API).
   
   2. Buffered proxying, later added, introduced new logic to handle
      buffered headers. This logic corretly implemented the metamethod by
      using a so-called "proxy table"; this is an empty table to which the
      `__index` metamethod is added. Since it's empty, `__index` is
      correctly invoked and ensures only upstream headers are accessible
      (as described by 1.). However, being empty it does not allow the
      headers table to be iterated on, leading to inconsistent and
      unexpected behavior -- a source of bug reports (e.g., #11546, KAG-4866,
      to name two).
   
   What does it change?
   ====================
   
   1. Standardize the interface: both buffered and unbuffered respond
      with an iterable table.
   2. Add more tests, for both buffered and unbuffered modes
       - test that returned table is indeed iterable
       - test that returned table only has upstream headers
   
   Caveats
   =======
   
   - Buffered proxying already reads all headers; adding additional logic
     to limit by `max_headers` arguably does not make sense.
   - Calls to this method will always respond with less than `max_headers`,
     as the call to `ngx.resp.get_headers` includes both Kong and upstream
     headers and we filter out non-upstream headers after said call. The
     ideal solution would use a native API that reads upstream only headers
     directly, and has a similar interface as `ngx.resp.get_headers`,
     taking a `max_headers` argument.

   

   gszr committed Nov 3, 2024
   Configuration menu

   • View commit details
   • Copy full SHA for 659bb66
   • Browse repository at this point

   Copy the full SHA

   659bb66 View commit details

   Browse the repository at this point in the history