object

http_cors

Transport-neutral CORS request classification, preflight response generation, and response decoration helpers for normalized HTTP messages.

Availability:
logtalk_load(http_cors(loader))
Author: Paulo Moura
Version: 1:0:0
Date: 2026-06-26
Compilation flags:
static, context_switching_calls
Imports:
public options
public http_origin_site_helpers
Uses:
atom
http_core
list
Remarks:
(none)
Inherited public predicates:
 check_option/1  check_options/1  default_option/1  default_options/1  option/2  option/3  valid_option/1  valid_options/1

Public predicates

request_origin/2

Returns the single request Origin header value when present.

Compilation flags:
static
Template:
request_origin(Request,Origin)
Mode and number of proofs:
request_origin(+compound,-atom) - zero_or_one

is_cors_request/1

Succeeds when the request carries a single Origin header value.

Compilation flags:
static
Template:
is_cors_request(Request)
Mode and number of proofs:
is_cors_request(+compound) - zero_or_one

is_preflight_request/1

Succeeds when the request is a CORS preflight request with method options and a single Access-Control-Request-Method header value.

Compilation flags:
static
Template:
is_preflight_request(Request)
Mode and number of proofs:
is_preflight_request(+compound) - zero_or_one

preflight_response/3

Builds a normalized CORS preflight response using the given policy options. Allowed preflight requests return 200 OK with the relevant Access-Control-* headers and denied requests return 403 Forbidden. Non-preflight requests raise an error.

Compilation flags:
static
Template:
preflight_response(Request,Response,Options)
Mode and number of proofs:
preflight_response(+compound,-compound,+list(compound)) - one_or_error
Exceptions:
Request is not a CORS preflight request:
domain_error(http_cors_preflight_request,Request)
Options is a variable or a partial list:
instantiation_error
Options is neither a variable nor a list:
type_error(list,Options)
An element Option of the list Options is neither a variable nor a compound term:
type_error(compound,Option)
An element Option of the list Options is a compound term but not a valid option:
domain_error(option,Option)
Options contains an invalid CORS option combination:
domain_error(http_cors_options,Options)
The generated response violates normalized HTTP response semantics:
domain_error(http_header_semantics,Header)

add_response_headers/4

Decorates a normalized response with the relevant CORS response headers when the request matches and the policy allows it. Denied requests preserve or add cache-relevant Vary metadata but do not add permission headers.

Compilation flags:
static
Template:
add_response_headers(Request,Response0,Response,Options)
Mode and number of proofs:
add_response_headers(+compound,+compound,-compound,+list(compound)) - one_or_error
Exceptions:
Options is a variable or a partial list:
instantiation_error
Options is neither a variable nor a list:
type_error(list,Options)
An element Option of the list Options is neither a variable nor a compound term:
type_error(compound,Option)
An element Option of the list Options is a compound term but not a valid option:
domain_error(option,Option)
Options contains an invalid CORS option combination:
domain_error(http_cors_options,Options)
Response0 is not a valid normalized HTTP response term:
domain_error(http_response,Response0)
The decorated response violates normalized HTTP response semantics:
domain_error(http_header_semantics,Header)

Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

(no local declarations; see entity ancestors if any)

Operators

(none)