tree b572452a9f02c6e4c80cbaa04cdee69942be8226
parent 817e8ca43ba600b8d633b8e7870e1ac7d69c6fca
author reubent <reubent@google.com> 1784231902 -0700
committer Copybara-Service <copybara-worker@google.com> 1784231939 -0700

Allow responses to HEAD requests to contain Content-Length or Transfer-Encoding

The failing prober sends curl requests with the [`-I` param](http://cs///depot/google3/net/fabric/monitoring/cloud_sdn_management/cep_workflows/csdnm_efg_probers/efg_control_plane_shard0_prober/efg_control_plane_shard0_prober.pb.txt;ws=reubent%2F418520;l=63), meaning it is sending a `HEAD` request.

Enforcement of `content_length_or_transfer_encoding_in_bodyless_response` was initially added to the same block where we check if the response should have a body or not. Responses to HEAD requests should not have a body. The logic error there is that, even though a response to a HEAD request cannot have a body, it is still permitted by the RFCs to return headers that describe the body it _would have_. RFC 9110, Section 9.3.2: "The server SHOULD send the same header fields in response to a HEAD request as it would have sent if the request method had been GET".

So this check has been moved to been moved to BalsaFrame::ProcessHeader and only limits TE/CL on 1xx and 204. New e2e and unit tests are added to confirm all RFC defined behavior:

> A server MAY send a Content-Length header field in a response to a HEAD request (Section 9.3.2);

`HEADResponseWithContentLengthAllowed`

> A server MAY send a Content-Length header field in a 304 (Not Modified) response

`304WithContentLengthAllowed`

> A server MUST NOT send a Content-Length header field in any response with a status code of 1xx (Informational) or 204 (No Content)

`1xxResponseWithContentLengthDisallowed and 204ResponseWithContentLengthDisallowed`

> Transfer-Encoding MAY be sent in a response to a HEAD request or in a 304 (Not Modified) response (Section 15.4.5 of [HTTP]) to a GET request, neither of which includes a message body

`304WithTransferEncodingAllowed` and `HEADResponseWithTransferEncodingAllowed`

> A server MUST NOT send a Transfer-Encoding header field in any response with a status code of 1xx (Informational) or 204 (No Content).

`204WithTransferEncodingDisallowed`

Protected by gfe2_reloadable_flag_use_zoll_balsa_http_validation_policy.

PiperOrigin-RevId: 949125790