feature: add bypass_if_checks method to ngx.resp (#495)

I hereby granted the copyright of the changes in this pull request
to the authors of this lua-resty-core project.

Signed-off-by: tzssangglass <tzssangglass@gmail.com>

* apply comments

Signed-off-by: tzssangglass <tzssangglass@gmail.com>

---------

Signed-off-by: tzssangglass <tzssangglass@gmail.com>

Author: tzssangglass

lib/ngx/resp.lua

@@ -10,6 +10,7 @@ local FFI_BAD_CONTEXT = base.FFI_BAD_CONTEXT
 local core_response = require "resty.core.response"
 local set_resp_header = core_response.set_resp_header
 local get_request = base.get_request
+local bypass_if_checks = core_response.bypass_if_checks
 
 ffi.cdef[[
     int ngx_http_lua_ffi_set_resp_status_and_reason(ngx_http_request_t *r,
@@ -43,4 +44,9 @@ function _M.set_status(status, reason)
     end
 end
 
+
+function _M.bypass_if_checks()
+    return bypass_if_checks()
+end
+
 return _M

lib/ngx/resp.md

@@ -13,6 +13,7 @@ Table of Contents
 * [Methods](#methods)
     * [add_header](#add_header)
     * [set_status](#set_status)
+    * [bypass_if_checks](#bypass_if_checks)
 * [Community](#community)
     * [English Mailing List](#english-mailing-list)
     * [Chinese Mailing List](#chinese-mailing-list)
@@ -87,6 +88,23 @@ status with an optional reason. The `reason` should be a string.
 
 [Back to TOC](#table-of-contents)
 
+bypass_if_checks
+------------------
+**syntax:** *ngx_resp.bypass_if_checks()*
+
+Bypasses the conditional header checks as defined in RFC 9110 for the current request.
+This method is useful when you need to skip validation of headers such as `If-Modified-Since`,
+`If-None-Match`, `If-Range`, `If-Unmodified-Since`, and `If-Match`, allowing the response to 
+proceed without evaluating these conditions.
+
+When Nginx's validation of a conditional request fails, it has a specific response.
+It will return a 412 error, as per the provisions of Section 13 of RFC 9110. If `error_page 412` is configured,
+it will result in an internal redirect to the error handling process, making it impossible to customize the exit status code.
+
+This configuration, designed to bypass Nginx's built-in validation of conditional requests, serves a specific purpose.
+
+[Back to TOC](#table-of-contents)
+
 Community
 =========
 

lib/resty/core/response.lua

@@ -42,6 +42,8 @@ ffi.cdef[[
         const unsigned char *key, size_t key_len,
         unsigned char *key_buf, ngx_http_lua_ffi_str_t *values,
         int max_nvalues, char **errmsg);
+
+    int ngx_http_lua_ffi_bypass_if_checks(ngx_http_request_t *r);
 ]]
 
 
@@ -226,6 +228,18 @@ local function get_resp_header(tb, key)
 end
 
 
+local function bypass_if_checks()
+    local r = get_request()
+    if not r then
+        error("no request found")
+    end
+    C.ngx_http_lua_ffi_bypass_if_checks(r)
+end
+
+
+_M.bypass_if_checks = bypass_if_checks
+
+
 do
     local mt = new_tab(0, 2)
     mt.__newindex = set_resp_header