/* $NetBSD: tcp_usrreq.c,v 1.75 2003/02/26 06:31:16 matt Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /*- * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation * Facility, NASA Ames Research Center. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1982, 1986, 1988, 1993, 1995 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)tcp_usrreq.c 8.5 (Berkeley) 6/21/95 */ #include __KERNEL_RCSID(0, "$NetBSD: tcp_usrreq.c,v 1.75 2003/02/26 06:31:16 matt Exp $"); #include "opt_inet.h" #include "opt_ipsec.h" #include "opt_tcp_debug.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #ifndef INET #include #endif #include #include #include #endif #include #include #include #include #include #include #include #include "opt_tcp_space.h" #ifdef IPSEC #include #endif /*IPSEC*/ /* * TCP protocol interface to socket abstraction. */ extern char *tcpstates[]; /* * Process a TCP user request for TCP tb. If this is a send request * then m is the mbuf chain of send data. If this is a timer expiration * (called from the software clock routine), then timertype tells which timer. */ /*ARGSUSED*/ int tcp_usrreq(so, req, m, nam, control, p) struct socket *so; int req; struct mbuf *m, *nam, *control; struct proc *p; { struct inpcb *inp; #ifdef INET6 struct in6pcb *in6p; #endif struct tcpcb *tp = NULL; int s; int error = 0; #ifdef TCP_DEBUG int ostate = 0; #endif int family; /* family of the socket */ family = so->so_proto->pr_domain->dom_family; if (req == PRU_CONTROL) { switch (family) { #ifdef INET case PF_INET: return (in_control(so, (long)m, (caddr_t)nam, (struct ifnet *)control, p)); #endif #ifdef INET6 case PF_INET6: return (in6_control(so, (long)m, (caddr_t)nam, (struct ifnet *)control, p)); #endif default: return EAFNOSUPPORT; } } if (req == PRU_PURGEIF) { switch (family) { #ifdef INET case PF_INET: in_pcbpurgeif0(&tcbtable, (struct ifnet *)control); in_purgeif((struct ifnet *)control); in_pcbpurgeif(&tcbtable, (struct ifnet *)control); break; #endif #ifdef INET6 case PF_INET6: in6_pcbpurgeif0(&tcb6, (struct ifnet *)control); in6_purgeif((struct ifnet *)control); in6_pcbpurgeif(&tcb6, (struct ifnet *)control); break; #endif default: return (EAFNOSUPPORT); } return (0); } s = splsoftnet(); switch (family) { #ifdef INET case PF_INET: inp = sotoinpcb(so); #ifdef INET6 in6p = NULL; #endif break; #endif #ifdef INET6 case PF_INET6: inp = NULL; in6p = sotoin6pcb(so); break; #endif default: splx(s); return EAFNOSUPPORT; } #ifdef DIAGNOSTIC #ifdef INET6 if (inp && in6p) panic("tcp_usrreq: both inp and in6p set to non-NULL"); #endif if (req != PRU_SEND && req != PRU_SENDOOB && control) panic("tcp_usrreq: unexpected control mbuf"); #endif /* * When a TCP is attached to a socket, then there will be * a (struct inpcb) pointed at by the socket, and this * structure will point at a subsidary (struct tcpcb). */ #ifndef INET6 if (inp == 0 && req != PRU_ATTACH) #else if ((inp == 0 && in6p == 0) && req != PRU_ATTACH) #endif { error = EINVAL; goto release; } #ifdef INET if (inp) { tp = intotcpcb(inp); /* WHAT IF TP IS 0? */ #ifdef KPROF tcp_acounts[tp->t_state][req]++; #endif #ifdef TCP_DEBUG ostate = tp->t_state; #endif } #endif #ifdef INET6 if (in6p) { tp = in6totcpcb(in6p); /* WHAT IF TP IS 0? */ #ifdef KPROF tcp_acounts[tp->t_state][req]++; #endif #ifdef TCP_DEBUG ostate = tp->t_state; #endif } #endif switch (req) { /* * TCP attaches to socket via PRU_ATTACH, reserving space, * and an internet control block. */ case PRU_ATTACH: #ifndef INET6 if (inp != 0) #else if (inp != 0 || in6p != 0) #endif { error = EISCONN; break; } error = tcp_attach(so); if (error) break; if ((so->so_options & SO_LINGER) && so->so_linger == 0) so->so_linger = TCP_LINGERTIME; tp = sototcpcb(so); break; /* * PRU_DETACH detaches the TCP protocol from the socket. */ case PRU_DETACH: tp = tcp_disconnect(tp); break; /* * Give the socket an address. */ case PRU_BIND: switch (family) { #ifdef INET case PF_INET: error = in_pcbbind(inp, nam, p); break; #endif #ifdef INET6 case PF_INET6: error = in6_pcbbind(in6p, nam, p); if (!error) { /* mapped addr case */ if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_laddr)) tp->t_family = AF_INET; else tp->t_family = AF_INET6; } break; #endif } break; /* * Prepare to accept connections. */ case PRU_LISTEN: #ifdef INET if (inp && inp->inp_lport == 0) { error = in_pcbbind(inp, (struct mbuf *)0, (struct proc *)0); if (error) break; } #endif #ifdef INET6 if (in6p && in6p->in6p_lport == 0) { error = in6_pcbbind(in6p, (struct mbuf *)0, (struct proc *)0); if (error) break; } #endif tp->t_state = TCPS_LISTEN; break; /* * Initiate connection to peer. * Create a template for use in transmissions on this connection. * Enter SYN_SENT state, and mark socket as connecting. * Start keep-alive timer, and seed output sequence space. * Send initial segment on connection. */ case PRU_CONNECT: #ifdef INET if (inp) { if (inp->inp_lport == 0) { error = in_pcbbind(inp, (struct mbuf *)0, (struct proc *)0); if (error) break; } error = in_pcbconnect(inp, nam); } #endif #ifdef INET6 if (in6p) { if (in6p->in6p_lport == 0) { error = in6_pcbbind(in6p, (struct mbuf *)0, (struct proc *)0); if (error) break; } error = in6_pcbconnect(in6p, nam); if (!error) { /* mapped addr case */ if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) tp->t_family = AF_INET; else tp->t_family = AF_INET6; } } #endif if (error) break; tp->t_template = tcp_template(tp); if (tp->t_template == 0) { #ifdef INET if (inp) in_pcbdisconnect(inp); #endif #ifdef INET6 if (in6p) in6_pcbdisconnect(in6p); #endif error = ENOBUFS; break; } /* Compute window scaling to request. */ while (tp->request_r_scale < TCP_MAX_WINSHIFT && (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat) tp->request_r_scale++; soisconnecting(so); tcpstat.tcps_connattempt++; tp->t_state = TCPS_SYN_SENT; TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); tp->iss = tcp_new_iss(tp, 0); tcp_sendseqinit(tp); error = tcp_output(tp); break; /* * Create a TCP connection between two sockets. */ case PRU_CONNECT2: error = EOPNOTSUPP; break; /* * Initiate disconnect from peer. * If connection never passed embryonic stage, just drop; * else if don't need to let data drain, then can just drop anyways, * else have to begin TCP shutdown process: mark socket disconnecting, * drain unread data, state switch to reflect user close, and * send segment (e.g. FIN) to peer. Socket will be really disconnected * when peer sends FIN and acks ours. * * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB. */ case PRU_DISCONNECT: tp = tcp_disconnect(tp); break; /* * Accept a connection. Essentially all the work is * done at higher levels; just return the address * of the peer, storing through addr. */ case PRU_ACCEPT: #ifdef INET if (inp) in_setpeeraddr(inp, nam); #endif #ifdef INET6 if (in6p) in6_setpeeraddr(in6p, nam); #endif break; /* * Mark the connection as being incapable of further output. */ case PRU_SHUTDOWN: socantsendmore(so); tp = tcp_usrclosed(tp); if (tp) error = tcp_output(tp); break; /* * After a receive, possibly send window update to peer. */ case PRU_RCVD: /* * soreceive() calls this function when a user receives * ancillary data on a listening socket. We don't call * tcp_output in such a case, since there is no header * template for a listening socket and hence the kernel * will panic. */ if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) != 0) (void) tcp_output(tp); break; /* * Do a send by putting data in output queue and updating urgent * marker if URG set. Possibly send more data. */ case PRU_SEND: if (control && control->m_len) { m_freem(control); m_freem(m); error = EINVAL; break; } sbappendstream(&so->so_snd, m); error = tcp_output(tp); break; /* * Abort the TCP. */ case PRU_ABORT: tp = tcp_drop(tp, ECONNABORTED); break; case PRU_SENSE: /* * stat: don't bother with a blocksize. */ splx(s); return (0); case PRU_RCVOOB: if (control && control->m_len) { m_freem(control); m_freem(m); error = EINVAL; break; } if ((so->so_oobmark == 0 && (so->so_state & SS_RCVATMARK) == 0) || so->so_options & SO_OOBINLINE || tp->t_oobflags & TCPOOB_HADDATA) { error = EINVAL; break; } if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) { error = EWOULDBLOCK; break; } m->m_len = 1; *mtod(m, caddr_t) = tp->t_iobc; if (((long)nam & MSG_PEEK) == 0) tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA); break; case PRU_SENDOOB: if (sbspace(&so->so_snd) < -512) { m_freem(m); error = ENOBUFS; break; } /* * According to RFC961 (Assigned Protocols), * the urgent pointer points to the last octet * of urgent data. We continue, however, * to consider it to indicate the first octet * of data past the urgent section. * Otherwise, snd_up should be one lower. */ sbappendstream(&so->so_snd, m); tp->snd_up = tp->snd_una + so->so_snd.sb_cc; tp->t_force = 1; error = tcp_output(tp); tp->t_force = 0; break; case PRU_SOCKADDR: #ifdef INET if (inp) in_setsockaddr(inp, nam); #endif #ifdef INET6 if (in6p) in6_setsockaddr(in6p, nam); #endif break; case PRU_PEERADDR: #ifdef INET if (inp) in_setpeeraddr(inp, nam); #endif #ifdef INET6 if (in6p) in6_setpeeraddr(in6p, nam); #endif break; default: panic("tcp_usrreq"); } #ifdef TCP_DEBUG if (tp && (so->so_options & SO_DEBUG)) tcp_trace(TA_USER, ostate, tp, NULL, req); #endif release: splx(s); return (error); } int tcp_ctloutput(op, so, level, optname, mp) int op; struct socket *so; int level, optname; struct mbuf **mp; { int error = 0, s; struct inpcb *inp; #ifdef INET6 struct in6pcb *in6p; #endif struct tcpcb *tp; struct mbuf *m; int i; int family; /* family of the socket */ family = so->so_proto->pr_domain->dom_family; s = splsoftnet(); switch (family) { #ifdef INET case PF_INET: inp = sotoinpcb(so); #ifdef INET6 in6p = NULL; #endif break; #endif #ifdef INET6 case PF_INET6: inp = NULL; in6p = sotoin6pcb(so); break; #endif default: splx(s); return EAFNOSUPPORT; } #ifndef INET6 if (inp == NULL) #else if (inp == NULL && in6p == NULL) #endif { splx(s); if (op == PRCO_SETOPT && *mp) (void) m_free(*mp); return (ECONNRESET); } if (level != IPPROTO_TCP) { switch (family) { #ifdef INET case PF_INET: error = ip_ctloutput(op, so, level, optname, mp); break; #endif #ifdef INET6 case PF_INET6: error = ip6_ctloutput(op, so, level, optname, mp); break; #endif } splx(s); return (error); } if (inp) tp = intotcpcb(inp); #ifdef INET6 else if (in6p) tp = in6totcpcb(in6p); #endif else tp = NULL; switch (op) { case PRCO_SETOPT: m = *mp; switch (optname) { case TCP_NODELAY: if (m == NULL || m->m_len < sizeof (int)) error = EINVAL; else if (*mtod(m, int *)) tp->t_flags |= TF_NODELAY; else tp->t_flags &= ~TF_NODELAY; break; case TCP_MAXSEG: if (m && (i = *mtod(m, int *)) > 0 && i <= tp->t_peermss) tp->t_peermss = i; /* limit on send size */ else error = EINVAL; break; default: error = ENOPROTOOPT; break; } if (m) (void) m_free(m); break; case PRCO_GETOPT: *mp = m = m_get(M_WAIT, MT_SOOPTS); m->m_len = sizeof(int); MCLAIM(m, so->so_mowner); switch (optname) { case TCP_NODELAY: *mtod(m, int *) = tp->t_flags & TF_NODELAY; break; case TCP_MAXSEG: *mtod(m, int *) = tp->t_peermss; break; default: error = ENOPROTOOPT; break; } break; } splx(s); return (error); } #ifndef TCP_SENDSPACE #define TCP_SENDSPACE 1024*16 #endif int tcp_sendspace = TCP_SENDSPACE; #ifndef TCP_RECVSPACE #define TCP_RECVSPACE 1024*16 #endif int tcp_recvspace = TCP_RECVSPACE; /* * Attach TCP protocol to socket, allocating * internet protocol control block, tcp control block, * bufer space, and entering LISTEN state if to accept connections. */ int tcp_attach(so) struct socket *so; { struct tcpcb *tp; struct inpcb *inp; #ifdef INET6 struct in6pcb *in6p; #endif int error; int family; /* family of the socket */ family = so->so_proto->pr_domain->dom_family; #ifdef MBUFTRACE so->so_mowner = &tcp_mowner; so->so_rcv.sb_mowner = &tcp_rx_mowner; so->so_snd.sb_mowner = &tcp_tx_mowner; #endif if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { error = soreserve(so, tcp_sendspace, tcp_recvspace); if (error) return (error); } switch (family) { #ifdef INET case PF_INET: error = in_pcballoc(so, &tcbtable); if (error) return (error); inp = sotoinpcb(so); #ifdef INET6 in6p = NULL; #endif break; #endif #ifdef INET6 case PF_INET6: error = in6_pcballoc(so, &tcb6); if (error) return (error); inp = NULL; in6p = sotoin6pcb(so); break; #endif default: return EAFNOSUPPORT; } if (inp) tp = tcp_newtcpcb(family, (void *)inp); #ifdef INET6 else if (in6p) tp = tcp_newtcpcb(family, (void *)in6p); #endif else tp = NULL; if (tp == 0) { int nofd = so->so_state & SS_NOFDREF; /* XXX */ so->so_state &= ~SS_NOFDREF; /* don't free the socket yet */ #ifdef INET if (inp) in_pcbdetach(inp); #endif #ifdef INET6 if (in6p) in6_pcbdetach(in6p); #endif so->so_state |= nofd; return (ENOBUFS); } tp->t_state = TCPS_CLOSED; return (0); } /* * Initiate (or continue) disconnect. * If embryonic state, just send reset (once). * If in ``let data drain'' option and linger null, just drop. * Otherwise (hard), mark socket disconnecting and drop * current input data; switch states based on user close, and * send segment to peer (with FIN). */ struct tcpcb * tcp_disconnect(tp) struct tcpcb *tp; { struct socket *so; if (tp->t_inpcb) so = tp->t_inpcb->inp_socket; #ifdef INET6 else if (tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif else so = NULL; if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) tp = tcp_close(tp); else if ((so->so_options & SO_LINGER) && so->so_linger == 0) tp = tcp_drop(tp, 0); else { soisdisconnecting(so); sbflush(&so->so_rcv); tp = tcp_usrclosed(tp); if (tp) (void) tcp_output(tp); } return (tp); } /* * User issued close, and wish to trail through shutdown states: * if never received SYN, just forget it. If got a SYN from peer, * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN. * If already got a FIN from peer, then almost done; go to LAST_ACK * state. In all other cases, have already sent FIN to peer (e.g. * after PRU_SHUTDOWN), and just have to play tedious game waiting * for peer to send FIN or not respond to keep-alives, etc. * We can let the user exit from the close as soon as the FIN is acked. */ struct tcpcb * tcp_usrclosed(tp) struct tcpcb *tp; { switch (tp->t_state) { case TCPS_CLOSED: case TCPS_LISTEN: case TCPS_SYN_SENT: tp->t_state = TCPS_CLOSED; tp = tcp_close(tp); break; case TCPS_SYN_RECEIVED: case TCPS_ESTABLISHED: tp->t_state = TCPS_FIN_WAIT_1; break; case TCPS_CLOSE_WAIT: tp->t_state = TCPS_LAST_ACK; break; } if (tp && tp->t_state >= TCPS_FIN_WAIT_2) { struct socket *so; if (tp->t_inpcb) so = tp->t_inpcb->inp_socket; #ifdef INET6 else if (tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif else so = NULL; soisdisconnected(so); /* * If we are in FIN_WAIT_2, we arrived here because the * application did a shutdown of the send side. Like the * case of a transition from FIN_WAIT_1 to FIN_WAIT_2 after * a full close, we start a timer to make sure sockets are * not left in FIN_WAIT_2 forever. */ if ((tp->t_state == TCPS_FIN_WAIT_2) && (tcp_maxidle > 0)) TCP_TIMER_ARM(tp, TCPT_2MSL, tcp_maxidle); } return (tp); } static const struct { unsigned int valid : 1; unsigned int rdonly : 1; int *var; int val; } tcp_ctlvars[] = TCPCTL_VARIABLES; /* * Sysctl for tcp variables. */ int tcp_sysctl(name, namelen, oldp, oldlenp, newp, newlen) int *name; u_int namelen; void *oldp; size_t *oldlenp; void *newp; size_t newlen; { int error, saved_value = 0; /* All sysctl names at this level are terminal. */ if (namelen != 1) return (ENOTDIR); if (name[0] < sizeof(tcp_ctlvars)/sizeof(tcp_ctlvars[0]) && tcp_ctlvars[name[0]].valid) { if (tcp_ctlvars[name[0]].rdonly) { return (sysctl_rdint(oldp, oldlenp, newp, tcp_ctlvars[name[0]].val)); } else { switch (name[0]) { case TCPCTL_MSSDFLT: saved_value = tcp_mssdflt; break; } error = sysctl_int(oldp, oldlenp, newp, newlen, tcp_ctlvars[name[0]].var); if (error) return (error); switch (name[0]) { case TCPCTL_MSSDFLT: if (tcp_mssdflt < 32) { tcp_mssdflt = saved_value; return (EINVAL); } break; } return (0); } } return (ENOPROTOOPT); }