Function send_ack

modules/tm/t_reply.c:303–343

* Build and send an ACK to a negative reply * On successful send: * - return 0 * - populate @ack_buf, for callback purposes, which *must* be SHM freed! */

 *   - populate @ack_buf, for callback purposes, which *must* be SHM freed!
 */
static int send_ack(struct sip_msg* rpl, struct cell *trans, int branch, str *ack_buf)
{
	str method = str_init(ACK);
	str to;
	struct usr_avp **backup_list;
	int rc;

	if(parse_headers(rpl,is_local(trans)?HDR_EOH_F:(HDR_TO_F|HDR_FROM_F),0)==-1
	|| !rpl->to || !rpl->from ) {
		LM_ERR("failed to generate a HBH ACK if key HFs in reply missing\n");
		goto error;
	}
	to.s=rpl->to->name.s;
	to.len=rpl->to->len;

	ack_buf->s = is_local(trans)?
		build_dlg_ack(rpl, trans, branch, &to, (unsigned int*)&ack_buf->len):
		build_local( trans, branch, &method, NULL, rpl, (unsigned int*)&ack_buf->len );
	if (ack_buf->s==0) {
		LM_ERR("failed to build ACK\n");
		goto error;
	}

	if (TM_BRANCH(trans,branch).br_flags & tcp_no_new_conn_bflag)
		tcp_no_new_conn = 1;

	set_bavp_list(&TM_BRANCH(trans,branch).user_avps);
	backup_list = set_avp_list( &trans->user_avps );

	rc = SEND_PR_BUFFER(&TM_BRANCH(trans,branch).request, ack_buf->s, ack_buf->len);

	set_avp_list(backup_list);
	reset_bavp_list();

	tcp_no_new_conn = 0;

	return rc;
error:
	memset(ack_buf, 0, sizeof *ack_buf);
	return -1;
}


static int _reply_light( struct cell *trans, char* buf, unsigned int len,