soreceive_stream
so2->so_proto->pr_soreceive == soreceive_stream,
tcp_protosw.pr_soreceive = soreceive_stream;
tcp6_protosw.pr_soreceive = soreceive_stream;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, soreceive_stream, CTLFLAG_RDTUN,
int soreceive_stream(struct socket *so, struct sockaddr **paddr,