conn_prepend_hdr
extern mblk_t *conn_prepend_hdr(ip_xmit_attr_t *, const ip_pkt_t *,
mp = conn_prepend_hdr(ixa, ipp, v6src, v6dst, connp->conn_proto,
mp = conn_prepend_hdr(ixa, ipp, v6src, v6dst, IPPROTO_UDP, flowinfo,