A template for the callback function. Don't forget to include <stdarg.h>

bagent-cb.c

/*
**  DESCRIPTION: A template for the callback function. Don't forget to include <stdarg.h>
**
**  INPUT:
**	ctx:	a callback context argument has been passed into the bagent_init()
**	what:	see BP$K_* constants:
**	sd:	is an optional argument is passed if what==BP$K_PROTSD
**
**  OUTPUT:
**	NONE
**
**  RETURN:
**	NONE
*/

void	callback ( void *ctx, int what, ...)
{
#if	ANDROID
/* Globals for callback function */
JavaVM* javaVM = NULL;
jclass bagentClass;
jobject bagentObj;
JNIEnv *env;
#endif	/* ANDROID */

	switch (what)
		{
		case	BP$K_BAGUP:
		case	BP$K_BAGDOWN:
		case	BP$K_BAGCTLUP:
		case	BP$K_BAGCTLDOWN:
			$LOG(STS$K_INFO, "BAGENT Sent notification #%d", what);
			break;

		case	BP$K_PROTSD:
			{
			int	*p;
			int	sd = -1;
			va_list ap;

			/* ‘sd’ (to be protected from VPN routing)  is coming as third argument,
			** Point pointer to next after 'what' argument in stack
			*/
			va_start(ap, what);
			sd  = (int) va_arg(ap, int);
			va_end(ap);

			$IFTRACE(g_trace, "Got sd=%d", sd);
#if	ANDROID
			/* Prepare jvm and call Java method */
			(*javaVM)->AttachCurrentThread(javaVM, &env, NULL);
			jmethodID method = (*env)->GetMethodID(env, bagentClass, "protectBagentSocketCallback", "(I)V");
			(*env)->CallVoidMethod(env, bagentObj, method, sd);

#endif	/* ANDROID */

			} /* case BP$K_PROTSD */
			break;
		default:
			$LOG(STS$K_ERROR, "Uhandled function code %#x", what);
		}

	return;
}