proxy_execute.md

proxy_execute

Executes a Proxy Auto-Configuration (PAC) script containing the JavasScript function FindProxyForURL for a particular URL to determine its proxies. Support varies depending on the operating system and the libraries available.

The script execution process is blocking.

Script Engine Support by Operating System

OS	Engine	Info
Linux	JavaScriptCoreGTK	Dynamically loaded at run-time.
macOS	JavaScriptCore	Dynamically loaded at run-time.
Windows	Windows Script Host	Uses IActiveScript COM interfaces.

API

• proxy_execute_get_proxies_for_url
• proxy_execute_get_list
• proxy_execute_get_error
• proxy_execute_create
• proxy_execute_delete
• proxy_execute_global_init
• proxy_execute_global_cleanup

proxy_execute_get_proxies_for_url

Executes a PAC script for a particular URL.

Arguments

Type	Name	Description
void *	ctx	Proxy execute instance.
const char *	script	PAC JavaScript null-terminated string.
const char *	url	URL to evaluate.

Return

Type	Description
bool	true if successful, false otherwise.

proxy_execute_get_list

Get the list of proxies returned by the call to FindProxyForURL.

Arguments

Type	Name	Description
void *	ctx	Proxy execute instance.

Return

Type	Description
const char *	List of proxies returned by script.

proxy_execute_get_error

Error code for script execution. Value varies depending upon script engine and platform.

Arguments

Type	Name	Description
void *	ctx	Proxy execute instance.

Return

Type	Description
int32_t	Error code.

proxy_execute_create

Create new PAC script execution instance.

Return

Type	Description
void *	Pointer to new instance or NULL upon failure.

proxy_execute_delete

Delete a PAC script execution instance.

Arguments

Type	Name	Description
void **	ctx	Pointer to instance.

Return

Type	Description
bool	true if successful, false otherwise.

proxy_execute_global_init

Initialization function for PAC script execution. Must be called before any proxy_execute instances are created.

Return

Type	Description
bool	true if successful, false otherwise.

proxy_execute_global_cleanup

Uninitialization function for PAC script execution. Must be called after all proxy_execute instances have been deleted.

Return

Type	Description
bool	true if successful, false otherwise.

Example

static const char *pac_script = R"(
function FindProxyForURL(url, host) {
  if (host == "simple.com") {
    return "PROXY no-such-proxy:80";
  }
  return "DIRECT";
})";
static const char *url = "https://simple.com/hello-world";

bool execute_simple(void) {
    bool is_ok = false
    void *proxy_execute = proxy_execute_create();
    if (proxy_execute) {
        if (!proxy_execute_get_proxies_for_url(proxy_execute, pac_script, url)) {
            printf("Failed to execute PAC script for url %s (%d)\n", url,
                proxy_execute_get_error(proxy_execute));
        } else {
            const char *list = proxy_execute_get_list(proxy_execute);
            if (list) {
                printf("FindProxyForURL for %s = %s\n", url, list);
                is_ok = true;
            }
            free(list);
        }
        proxy_execute_delete(&proxy_execute);
    }
    return is_ok;
}