[Windows only] Nginx does not decode the uri encoded bytes

[Giovanni]

For some reasons nginx or naxsi on the windows build does not decode correctly the bytes as we expect to see.

Logs:

2022-12-19T16:45:36.3777060Z rg: re.compile('^.*{\\"ip\\":\\"127\\.0\\.0\\.1\\",\\"server\\":\\"[a-z\\d.]+\\",\\"rid\\":\\"[a-f\\d]+\\",\\"uri\\":\\"\\/\\\\\\\\\\\\\\\\\\\\u00ff\\\\\\\\a\\",\\"id\\":20,\\"zone\\":\\"URL\\",\\"var_name\\":\\"\\")
2022-12-19T16:45:36.3777954Z fl:  2022/12/19 16:45:16 [error] 3516#6832: *1 {"ip":"127.0.0.1","server":"127.0.0.1","rid":"0c0f0000c5620000323a000091190000","uri":"/\u00ff/a","id":20,"zone":"URL","var_name":"","content":""}, client: 127.0.0.1, server: localhost, request: "GET /%5C%5C%ff%5Ca?b=<>%5C%5C HTTP/1.1", host: "127.0.0.1:8080"
2022-12-19T16:45:36.3778398Z 
2022-12-19T16:45:36.3778808Z fl:  2022/12/19 16:45:16 [error] 3516#6832: *1 {"ip":"127.0.0.1","server":"127.0.0.1","uri":"/%FF/a","config":"drop","rid":"0c0f0000c5620000323a000091190000","zone0":"URL","id0":"20","var_name0":""}, client: 127.0.0.1, server: localhost, request: "GET /%5C%5C%ff%5Ca?b=<>%5C%5C HTTP/1.1", host: "127.0.0.1:8080"

Reproducer test

=== TEST 1.9: JSON log + extended + FF byte
--- main_config
load_module $TEST_NGINX_NAXSI_MODULE_SO;
--- http_config
include $TEST_NGINX_NAXSI_RULES;
--- config
set $naxsi_json_log 1;
set $naxsi_extensive_log 1;
location / {
    SecRulesEnabled;
    DeniedUrl "/RequestDenied";
    CheckRule "$SQL >= 8" BLOCK;
    CheckRule "$RFI >= 8" BLOCK;
    CheckRule "$TRAVERSAL >= 4" BLOCK;
    CheckRule "$XSS >= 8" BLOCK;
    root $TEST_NGINX_SERVROOT/html/;
    index index.html index.htm;
}
location /RequestDenied {
     return 412;
    # return 412;
}
--- request eval
"GET /%5C%5C%ff%5Ca?b=<>%5C%5C"
--- error_code: 412
--- error_log eval
qr@{"ip":"127\.0\.0\.1","server":"[a-z\d.]+","rid":"[a-f\d]+","uri":"\/\\\\\\\\\\u00ff\\\\a","id":20,"zone":"URL","var_name":"","content":""}, client: 127\.0\.0\.1,@