cors.hpp

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#pragma once
 
#include <boost/beast/http/field.hpp>
#include <boost/beast/http/verb.hpp>
 
#include <string>
#include <vector>
#include <cctype>
#include <optional>
 
namespace Roar
{
    struct CorsSettings
    {
        std::function<std::string(std::string const&)> allowedOrigin{[](std::string const& origin) {
            // Requests with credentials CANNOT use a wildcard for any Allow-* header.
            return origin.empty() ? std::string("*") : origin;
        }};
 
        std::function<std::vector<std::string>(std::vector<std::string> const&)> methodAllowSelection{
            [](std::vector<std::string> const& requestedMethods) {
                return requestedMethods;
            }};
 
        std::function<std::vector<std::string>(std::vector<std::string> const&)> headerAllowSelection{
            [](std::vector<std::string> const& requestedHeaders) {
                return requestedHeaders;
            }};
 
        std::vector<boost::beast::http::field> exposeHeaders{};
 
        std::optional<bool> allowCredentials{std::nullopt};
 
        bool generatePreflightOptionsRoute = true;
    };
 
    inline CorsSettings makePermissiveCorsSettings(std::string method)
    {
        CorsSettings cors;
        std::transform(begin(method), end(method), begin(method), [](auto character) {
            return std::toupper(character);
        });
        cors.methodAllowSelection =
            [method = std::move(method)](std::vector<std::string> const&) -> std::vector<std::string> {
            return std::vector<std::string>{method};
        };
        cors.allowCredentials = true;
        return cors;
    }
 
    inline CorsSettings makePermissiveCorsSettings(boost::beast::http::verb method)
    {
        return makePermissiveCorsSettings(std::string{boost::beast::http::to_string(method)});
    }
}