/*
 * Send a single message to the TCP at address specified by
 * the given TCP/IP header.  If m == 0, then we make a copy
 * of the tcpiphdr at ti and send directly to the addressed host.
 * This is used to force keep alive messages out using the TCP
 * template for a connection tp->t_template.  If flags are given
 * then we send a message back to the TCP which originated the
 * segment ti, and discard the mbuf containing it and any other
 * attached mbufs.
 *
 * In any case the ack and sequence number of the transmitted
 * segment are as specified by the parameters.
 */
void
tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
            tcp_seq ack, tcp_seq seq, int flags, unsigned short af)
{
	register int tlen;
	int win = 0;

	DEBUG_CALL("tcp_respond");
	DEBUG_ARG("tp = %p", tp);
	DEBUG_ARG("ti = %p", ti);
	DEBUG_ARG("m = %p", m);
	DEBUG_ARG("ack = %u", ack);
	DEBUG_ARG("seq = %u", seq);
	DEBUG_ARG("flags = %x", flags);

	if (tp)
		win = sbspace(&tp->t_socket->so_rcv);
        if (m == NULL) {
		if (!tp || (m = m_get(tp->t_socket->slirp)) == NULL)
			return;
		tlen = 0;
		m->m_data += IF_MAXLINKHDR;
		*mtod(m, struct tcpiphdr *) = *ti;
		ti = mtod(m, struct tcpiphdr *);
		memset(&ti->ti, 0, sizeof(ti->ti));
		flags = TH_ACK;
	} else {

int
sbappendcontrol(struct sockbuf *sb, struct mbuf *m0, struct mbuf *control)
{
	struct mbuf *m, *mlast, *n;
	int space = 0;

	if (control == NULL)
		panic("sbappendcontrol");
	for (m = control; ; m = m->m_next) {
		space += m->m_len;
		if (m->m_next == NULL)
			break;
	}
	n = m;			/* save pointer to last control buffer */
	for (m = m0; m; m = m->m_next)
		space += m->m_len;
	if (space > sbspace(sb))
		return (0);
	n->m_next = m0;			/* concatenate data to control */

	SBLASTRECORDCHK(sb, "sbappendcontrol 1");

	for (m = control; m->m_next != NULL; m = m->m_next)
		sballoc(sb, m);
	sballoc(sb, m);
	mlast = m;
	SBLINKRECORD(sb, control);

	sb->sb_mbtail = mlast;
	SBLASTMBUFCHK(sb, "sbappendcontrol");

	SBLASTRECORDCHK(sb, "sbappendcontrol 2");

	return (1);
}

/*
 * Send a single message to the TCP at address specified by
 * the given TCP/IP header.  If m == 0, then we make a copy
 * of the tcpiphdr at ti and send directly to the addressed host.
 * This is used to force keep alive messages out using the TCP
 * template for a connection tp->t_template.  If flags are given
 * then we send a message back to the TCP which originated the
 * segment ti, and discard the mbuf containing it and any other
 * attached mbufs.
 *
 * In any case the ack and sequence number of the transmitted
 * segment are as specified by the parameters.
 */
void tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m, tcp_seq ack, tcp_seq seq, int flags)
{
	int tlen;
	int win = 0;

	DEBUG_CALL("tcp_respond");
	DEBUG_ARG("tp = %lx", (long)tp);
	DEBUG_ARG("ti = %lx", (long)ti);
	DEBUG_ARG("m = %lx", (long)m);
	DEBUG_ARG("ack = %u", ack);
	DEBUG_ARG("seq = %u", seq);
	DEBUG_ARG("flags = %x", flags);
	
	if (tp)
		win = sbspace(&tp->t_socket->so_rcv);
	if (m == 0) {
		if ((m = m_get()) == NULL)
			return;
#ifdef TCP_COMPAT_42
		tlen = 1;
#else
		tlen = 0;
#endif
		m->m_data += if_maxlinkhdr;
		*mtod(m, struct tcpiphdr *) = *ti;
		ti = mtod(m, struct tcpiphdr *);
		flags = TH_ACK;
	} else {

/*
 * Send a single message to the TCP at address specified by
 * the given TCP/IP header.  If m == 0, then we make a copy
 * of the tcpiphdr at ti and send directly to the addressed host.
 * This is used to force keep alive messages out using the TCP
 * template for a connection tp->t_template.  If flags are given
 * then we send a message back to the TCP which originated the
 * segment ti, and discard the mbuf containing it and any other
 * attached mbufs.
 *
 * In any case the ack and sequence number of the transmitted
 * segment are as specified by the parameters.
 */
void
tcp_respond(PNATState pData, struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m, tcp_seq ack, tcp_seq seq, int flags)
{
    register int tlen;
    int win = 0;

    LogFlowFunc(("ENTER: tp = %R[tcpcb793], ti = %lx, m = %lx, ack = %u, seq = %u, flags = %x\n",
                 tp, (long)ti, (long)m, ack, seq, flags));

    if (tp)
        win = sbspace(&tp->t_socket->so_rcv);
    if (m == 0)
    {
        if ((m = m_gethdr(pData, M_DONTWAIT, MT_HEADER)) == NULL)
            return;
#ifdef TCP_COMPAT_42
        tlen = 1;
#else
        tlen = 0;
#endif
        m->m_data += if_maxlinkhdr;
        m->m_pkthdr.header = mtod(m, void *);
        *mtod(m, struct tcpiphdr *) = *ti;
        ti = mtod(m, struct tcpiphdr *);
        flags = TH_ACK;
    }
    else
    {

static int
rfcomm_attach(struct socket *so, int proto)
{
	int error;

	KASSERT(so->so_pcb == NULL);

	if (so->so_lock == NULL) {
		mutex_obj_hold(bt_lock);
		so->so_lock = bt_lock;
		solock(so);
	}
	KASSERT(solocked(so));

	/*
	 * Since we have nothing to add, we attach the DLC
	 * structure directly to our PCB pointer.
	 */
	error = soreserve(so, rfcomm_sendspace, rfcomm_recvspace);
	if (error)
		return error;

	error = rfcomm_attach_pcb((struct rfcomm_dlc **)&so->so_pcb,
				&rfcomm_proto, so);
	if (error)
		return error;

	error = rfcomm_rcvd_pcb(so->so_pcb, sbspace(&so->so_rcv));
	if (error) {
		rfcomm_detach_pcb((struct rfcomm_dlc **)&so->so_pcb);
		return error;
	}
	return 0;
}

int
sbappendcontrol_locked(struct sockbuf *sb, struct mbuf *m0,
    struct mbuf *control)
{
	struct mbuf *m, *n, *mlast;
	int space;

	SOCKBUF_LOCK_ASSERT(sb);

	if (control == 0)
		panic("sbappendcontrol_locked");
	space = m_length(control, &n) + m_length(m0, NULL);

	if (space > sbspace(sb))
		return (0);
	n->m_next = m0;			/* concatenate data to control */

	SBLASTRECORDCHK(sb);

	for (m = control; m->m_next; m = m->m_next)
		sballoc(sb, m);
	sballoc(sb, m);
	mlast = m;
	SBLINKRECORD(sb, control);

	sb->sb_mbtail = mlast;
	SBLASTMBUFCHK(sb);

	SBLASTRECORDCHK(sb);
	return (1);
}

/* You'd certainly better have an iocount on the vnode! */
int
fifo_freespace(struct vnode *vp, long *count) 
{
	struct socket *rsock;
	rsock = vp->v_fifoinfo->fi_readsock;
	socket_lock(rsock, 1);
	*count = sbspace(&rsock->so_rcv);
	socket_unlock(rsock, 1);
	return 0;
}

/*
 * natmintr: interrupt
 *
 * Note: we expect a socket pointer in rcvif rather than an interface
 * pointer.  We can get the interface pointer from the so's PCB if we really
 * need it.
 */
void
natmintr(struct mbuf *m)
{
	struct socket *so;
	struct natmpcb *npcb;

#ifdef DIAGNOSTIC
	M_ASSERTPKTHDR(m);
#endif

	NATM_LOCK();
	npcb = (struct natmpcb *)m->m_pkthdr.rcvif;	/* XXX: overloaded */
	so = npcb->npcb_socket;

	npcb->npcb_inq--;

	if (npcb->npcb_flags & NPCB_DRAIN) {
		if (npcb->npcb_inq == 0)
			free(npcb, M_PCB);			/* done! */
		NATM_UNLOCK();
		m_freem(m);
		return;
	}

	if (npcb->npcb_flags & NPCB_FREE) {
		NATM_UNLOCK();
		m_freem(m);					/* drop */
		return;
	}

#ifdef NEED_TO_RESTORE_IFP
	m->m_pkthdr.rcvif = npcb->npcb_ifp;
#else
#ifdef DIAGNOSTIC
	m->m_pkthdr.rcvif = NULL;	/* null it out to be safe */
#endif
#endif

	if (sbspace(&so->so_rcv) > m->m_pkthdr.len) {
#ifdef NATM_STAT
		natm_sookcnt++;
		natm_sookbytes += m->m_pkthdr.len;
#endif
		sbappendrecord(&so->so_rcv, m);
		sorwakeup(so);
		NATM_UNLOCK();
	} else {
#ifdef NATM_STAT
		natm_sodropcnt++;
		natm_sodropbytes += m->m_pkthdr.len;
#endif
		NATM_UNLOCK();
		m_freem(m);
	}
}

static int
rfcomm_rcvd(struct socket *so, int flags, struct lwp *l)
{
	struct rfcomm_dlc *pcb = so->so_pcb;

	KASSERT(solocked(so));

	if (pcb == NULL)
		return EINVAL;

	return rfcomm_rcvd_pcb(pcb, sbspace(&so->so_rcv));
}

int
filt_fifowrite(struct knote *kn, long hint)
{
	struct socket *so = (struct socket *)kn->kn_hook;

	kn->kn_data = sbspace(&so->so_snd);
	if (so->so_state & SS_CANTSENDMORE) {
		kn->kn_flags |= EV_EOF;
		return (1);
	}
	kn->kn_flags &= ~EV_EOF;
	return (kn->kn_data >= so->so_snd.sb_lowat);
}

/*
 * Append address and data, and optionally, control (ancillary) data
 * to the receive queue of a socket.  If present,
 * m0 must include a packet header with total length.
 * Returns 0 if no space in sockbuf or insufficient mbufs.
 */
int
sbappendaddr(struct sockbuf *sb, struct sockaddr *asa, struct mbuf *m0,
    struct mbuf *control)
{
	struct mbuf *m, *n, *nlast;
	int space = asa->sa_len;

	if (m0 && (m0->m_flags & M_PKTHDR) == 0)
		panic("sbappendaddr");
	if (m0)
		space += m0->m_pkthdr.len;
	for (n = control; n; n = n->m_next) {
		space += n->m_len;
		if (n->m_next == NULL)	/* keep pointer to last control buf */
			break;
	}
	if (space > sbspace(sb))
		return (0);
	if (asa->sa_len > MLEN)
		return (0);
	MGET(m, M_DONTWAIT, MT_SONAME);
	if (m == NULL)
		return (0);
	m->m_len = asa->sa_len;
	memcpy(mtod(m, caddr_t), asa, asa->sa_len);
	if (n)
		n->m_next = m0;		/* concatenate data to control */
	else
		control = m0;
	m->m_next = control;

	SBLASTRECORDCHK(sb, "sbappendaddr 1");

	for (n = m; n->m_next != NULL; n = n->m_next)
		sballoc(sb, n);
	sballoc(sb, n);
	nlast = n;
	SBLINKRECORD(sb, m);

	sb->sb_mbtail = nlast;
	SBLASTMBUFCHK(sb, "sbappendaddr");

	SBLASTRECORDCHK(sb, "sbappendaddr 2");

	return (1);
}

/*
 * Append address and data, and optionally, control (ancillary) data to the
 * receive queue of a socket.  If present, m0 must include a packet header
 * with total length.  Returns 0 if no space in sockbuf or insufficient
 * mbufs.
 */
int
sbappendaddr_locked(struct sockbuf *sb, const struct sockaddr *asa,
    struct mbuf *m0, struct mbuf *control)
{
	struct mbuf *m, *n, *nlast;
	int space = asa->sa_len;

	SOCKBUF_LOCK_ASSERT(sb);

	if (m0 && (m0->m_flags & M_PKTHDR) == 0)
		panic("sbappendaddr_locked");
	if (m0)
		space += m0->m_pkthdr.len;
	space += m_length(control, &n);

	if (space > sbspace(sb))
		return (0);
#if MSIZE <= 256
	if (asa->sa_len > MLEN)
		return (0);
#endif
	MGET(m, M_DONTWAIT, MT_SONAME);
	if (m == 0)
		return (0);
	m->m_len = asa->sa_len;
	bcopy(asa, mtod(m, caddr_t), asa->sa_len);
	if (n){
		CHECK_ADD_LINKCNT(n, m0, NULL, "sbappendaddr_locked");
		n->m_next = m0;		/* concatenate data to control */
	}else
		control = m0;
	CHECK_ADD_LINKCNT(m, control, NULL, "sbappendaddr_locked");	
	m->m_next = control;
	for (n = m; n->m_next != NULL; n = n->m_next)
		sballoc(sb, n);
	sballoc(sb, n);
	nlast = n;
	SBLINKRECORD(sb, m);

	sb->sb_mbtail = nlast;
	SBLASTMBUFCHK(sb);

	SBLASTRECORDCHK(sb);
	return (1);
}

key_receive(struct socket *so, struct mbuf **paddr, struct uio *uio,
	struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
#endif
{
	struct rawcb *rp = sotorawcb(so);
	struct keycb *kp = (struct keycb *)rp;
	int error;

#ifndef __FreeBSD__
	error = (*kp->kp_receive)(so, paddr, uio, mp0, controlp, flagsp);
#else
	error = soreceive(so, paddr, uio, mp0, controlp, flagsp);
#endif
	if (kp->kp_queue &&
	    sbspace(&rp->rcb_socket->so_rcv) > kp->kp_queue->m_pkthdr.len)
		sorwakeup(so);

	return error;
}

/*
 * Append address and data, and optionally, control (ancillary) data to the
 * receive queue of a socket.  If present, m0 must include a packet header
 * with total length.  Returns 0 if no space in sockbuf or insufficient
 * mbufs.
 */
int
sbappendaddr_locked(struct sockbuf *sb, const struct sockaddr *asa,
    struct mbuf *m0, struct mbuf *control)
{
	struct mbuf *ctrl_last;
	int space = asa->sa_len;

	SOCKBUF_LOCK_ASSERT(sb);

	if (m0 && (m0->m_flags & M_PKTHDR) == 0)
		panic("sbappendaddr_locked");
	if (m0)
		space += m0->m_pkthdr.len;
	space += m_length(control, &ctrl_last);

	if (space > sbspace(sb))
		return (0);
	return (sbappendaddr_locked_internal(sb, asa, m0, control, ctrl_last));
}

//.........这里部分代码省略.........
				    SEQ_GT(ti->ti_ack, tp->t_rtseq))
					tcp_xmit_timer(tp, tp->t_rtt);
				acked = ti->ti_ack - tp->snd_una;
				sbdrop(&so->so_snd, acked);
				tp->snd_una = ti->ti_ack;
				m_free(m);

				/*
				 * If all outstanding data are acked, stop
				 * retransmit timer, otherwise restart timer
				 * using current (possibly backed-off) value.
				 * If process is waiting for space,
				 * wakeup/selwakeup/signal.  If data
				 * are ready to send, let tcp_output
				 * decide between more output or persist.
				 */
				if (tp->snd_una == tp->snd_max)
					tp->t_timer[TCPT_REXMT] = 0;
				else if (tp->t_timer[TCPT_PERSIST] == 0)
					tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;

				/*
				 * This is called because sowwakeup might have
				 * put data into so_snd.  Since we don't so sowwakeup,
				 * we don't need this.. XXX???
				 */
				if (so->so_snd.sb_cc)
					(void) tcp_output(tp);

				return;
			}
		} else if (ti->ti_ack == tp->snd_una &&
		    tcpfrag_list_empty(tp) &&
		    ti->ti_len <= sbspace(&so->so_rcv)) {
			/*
			 * this is a pure, in-sequence data packet
			 * with nothing on the reassembly queue and
			 * we have enough buffer space to take it.
			 */
			tp->rcv_nxt += ti->ti_len;
			/*
			 * Add data to socket buffer.
			 */
			if (so->so_emu) {
				if (tcp_emu(so,m)) sbappend(so, m);
			} else
				sbappend(so, m);

			/*
			 * If this is a short packet, then ACK now - with Nagel
			 *	congestion avoidance sender won't send more until
			 *	he gets an ACK.
			 *
			 * It is better to not delay acks at all to maximize
			 * TCP throughput.  See RFC 2581.
			 */
			tp->t_flags |= TF_ACKNOW;
			tcp_output(tp);
			return;
		}
	} /* header prediction */
	/*
	 * Calculate amount of space in receive window,
	 * and then do TCP input processing.
	 * Receive window is amount of space in rcv queue,
	 * but not less than advertised window.

//.........这里部分代码省略.........
      len = 0;
      if (win == 0) 
      {
         tp->t_timer[TCPT_REXMT] = 0;
         tp->snd_nxt = tp->snd_una;
      }
   }

   if (len > (int)tp->t_maxseg)
   {
      len = tp->t_maxseg;
      sendalot = 1;
   }

#ifdef IP_V4
#ifdef IP_PMTU
   {
      int pmtu = tp->t_inpcb->inp_pmtu - 40;

      if (len > pmtu)
      {
         len = pmtu - 40;
         sendalot = 1;
      }
   }
#endif /* IP_PMTU */
   /* We don't need a pmtu test for IPv6. V6 code limits t_maxseg to
    * the Path MTU, so the test above the v4 ifdef above covers us.
    */
#endif /* IP_V4 */

   if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + so->so_snd.sb_cc))
      flags &= ~TH_FIN;
   win = (long)(sbspace(&so->so_rcv));

   /*
    * If our state indicates that FIN should be sent
    * and we have not yet done so, or we're retransmitting the FIN,
    * then we need to send.
    */
   if ((flags & TH_FIN) &&
       (so->so_snd.sb_cc == 0) &&
       ((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una))
   {
      goto send;
   }
   /*
    * Send if we owe peer an ACK.
    */
   if (tp->t_flags & TF_ACKNOW)
      goto send;
   if (flags & (TH_SYN|TH_RST))
      goto send;
   if (SEQ_GT(tp->snd_up, tp->snd_una))
      goto send;

   /*
    * Sender silly window avoidance.  If connection is idle
    * and can send all data, a maximum segment,
    * at least a maximum default-size segment do it,
    * or are forced, do it; otherwise don't bother.
    * If peer's buffer is tiny, then send
    * when window is at least half open.
    * If retransmitting (possibly after persist timer forced us
    * to send into a small window), then must resend.
    */

void
natmintr()

{
  int s;
  struct mbuf *m;
  struct socket *so;
  struct natmpcb *npcb;

next:
  s = splnet();
  IF_DEQUEUE(&natmintrq, m);
  splx(s);
  if (m == NULL)
    return;

#ifdef DIAGNOSTIC
  if ((m->m_flags & M_PKTHDR) == 0)
    panic("natmintr no HDR");
#endif

  npcb = (struct natmpcb *) m->m_pkthdr.rcvif; /* XXX: overloaded */
  so = npcb->npcb_socket;

  s = splnet();			/* could have atm devs @ different levels */
  npcb->npcb_inq--;
  splx(s);

  if (npcb->npcb_flags & NPCB_DRAIN) {
    m_freem(m);
    if (npcb->npcb_inq == 0)
      free(npcb, M_PCB);			/* done! */
    goto next;
  }

  if (npcb->npcb_flags & NPCB_FREE) {
    m_freem(m);					/* drop */
    goto next;
  }

#ifdef NEED_TO_RESTORE_IFP
  m->m_pkthdr.rcvif = npcb->npcb_ifp;
#else
#ifdef DIAGNOSTIC
m->m_pkthdr.rcvif = NULL;	/* null it out to be safe */
#endif
#endif

  if (sbspace(&so->so_rcv) > m->m_pkthdr.len ||
     ((npcb->npcb_flags & NPCB_RAW) != 0 && so->so_rcv.sb_cc < NPCB_RAWCC) ) {
#ifdef NATM_STAT
    natm_sookcnt++;
    natm_sookbytes += m->m_pkthdr.len;
#endif
    sbappendrecord(&so->so_rcv, m);
    sorwakeup(so);
  } else {
#ifdef NATM_STAT
    natm_sodropcnt++;
    natm_sodropbytes += m->m_pkthdr.len;
#endif
    m_freem(m);
  }

  goto next;
}

/*
 * Append address and data, and optionally, control (ancillary) data
 * to the receive queue of a socket.  If present,
 * m0 must include a packet header with total length.
 * Returns 0 if no space in sockbuf or insufficient mbufs.
 */
int
sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa, struct mbuf *m0,
	struct mbuf *control)
{
	struct mbuf	*m, *n, *nlast;
	int		space, len;

	KASSERT(solocked(sb->sb_so));

	space = asa->sa_len;

	if (m0 != NULL) {
		if ((m0->m_flags & M_PKTHDR) == 0)
			panic("sbappendaddr");
		space += m0->m_pkthdr.len;
#ifdef MBUFTRACE
		m_claimm(m0, sb->sb_mowner);
#endif
	}
	for (n = control; n; n = n->m_next) {
		space += n->m_len;
		MCLAIM(n, sb->sb_mowner);
		if (n->m_next == 0)	/* keep pointer to last control buf */
			break;
	}
	if (space > sbspace(sb))
		return (0);
	MGET(m, M_DONTWAIT, MT_SONAME);
	if (m == 0)
		return (0);
	MCLAIM(m, sb->sb_mowner);
	/*
	 * XXX avoid 'comparison always true' warning which isn't easily
	 * avoided.
	 */
	len = asa->sa_len;
	if (len > MLEN) {
		MEXTMALLOC(m, asa->sa_len, M_NOWAIT);
		if ((m->m_flags & M_EXT) == 0) {
			m_free(m);
			return (0);
		}
	}
	m->m_len = asa->sa_len;
	memcpy(mtod(m, void *), asa, asa->sa_len);
	if (n)
		n->m_next = m0;		/* concatenate data to control */
	else
		control = m0;
	m->m_next = control;

	SBLASTRECORDCHK(sb, "sbappendaddr 1");

	for (n = m; n->m_next != NULL; n = n->m_next)
		sballoc(sb, n);
	sballoc(sb, n);
	nlast = n;
	SBLINKRECORD(sb, m);

	sb->sb_mbtail = nlast;
	SBLASTMBUFCHK(sb, "sbappendaddr");
	SBLASTRECORDCHK(sb, "sbappendaddr 2");

	return (1);
}

int
sbappendaddrchain(struct sockbuf *sb, const struct sockaddr *asa,
		  struct mbuf *m0, int sbprio)
{
	int space;
	struct mbuf *m, *n, *n0, *nlast;
	int error;

	KASSERT(solocked(sb->sb_so));

	/*
	 * XXX sbprio reserved for encoding priority of this* request:
	 *  SB_PRIO_NONE --> honour normal sb limits
	 *  SB_PRIO_ONESHOT_OVERFLOW --> if socket has any space,
	 *	take whole chain. Intended for large requests
	 *      that should be delivered atomically (all, or none).
	 * SB_PRIO_OVERDRAFT -- allow a small (2*MLEN) overflow
	 *       over normal socket limits, for messages indicating
	 *       buffer overflow in earlier normal/lower-priority messages
	 * SB_PRIO_BESTEFFORT -->  ignore limits entirely.
	 *       Intended for  kernel-generated messages only.
	 *        Up to generator to avoid total mbuf resource exhaustion.
	 */
	(void)sbprio;

	if (m0 && (m0->m_flags & M_PKTHDR) == 0)
		panic("sbappendaddrchain");

	space = sbspace(sb);

#ifdef notyet
	/*
	 * Enforce SB_PRIO_* limits as described above.
	 */
#endif

	n0 = NULL;
	nlast = NULL;
	for (m = m0; m; m = m->m_nextpkt) {
		struct mbuf *np;

#ifdef MBUFTRACE
		m_claimm(m, sb->sb_mowner);
#endif

		/* Prepend sockaddr to this record (m) of input chain m0 */
	  	n = m_prepend_sockaddr(sb, m, asa);
		if (n == NULL) {
			error = ENOBUFS;
			goto bad;
		}

		/* Append record (asa+m) to end of new chain n0 */
		if (n0 == NULL) {
			n0 = n;
		} else {
			nlast->m_nextpkt = n;
		}
		/* Keep track of last record on new chain */
		nlast = n;

		for (np = n; np; np = np->m_next)
			sballoc(sb, np);
	}

	SBLASTRECORDCHK(sb, "sbappendaddrchain 1");

	/* Drop the entire chain of (asa+m) records onto the socket */
	SBLINKRECORDCHAIN(sb, n0, nlast);

	SBLASTRECORDCHK(sb, "sbappendaddrchain 2");

	for (m = nlast; m->m_next; m = m->m_next)
		;
	sb->sb_mbtail = m;
	SBLASTMBUFCHK(sb, "sbappendaddrchain");

	return (1);

bad:
	/*
	 * On error, free the prepended addreseses. For consistency
	 * with sbappendaddr(), leave it to our caller to free
	 * the input record chain passed to us as m0.
	 */
	while ((n = n0) != NULL) {
	  	struct mbuf *np;

		/* Undo the sballoc() of this record */
		for (np = n; np; np = np->m_next)
			sbfree(sb, np);

		n0 = n->m_nextpkt;	/* iterate at next prepended address */
		MFREE(n, np);		/* free prepended address (not data) */
	}
	return 0;
}

int
sosend(struct socket *so, 
       struct mbuf *nam,      /* sockaddr, if UDP socket, NULL if TCP */
       char  *data,           /* data to send */
       int   *data_length,    /* IN/OUT  length of (remaining) data */
       int   flags)
{
   struct mbuf *head = (struct mbuf *)NULL;
   struct mbuf *m;
   int   space;
   int   resid;
   int   len;
   int   error = 0;
   int   dontroute;
   int   first = 1;

   resid = *data_length;

   /*
    * In theory resid should be unsigned.
    * However, space must be signed, as it might be less than 0
    * if we over-committed, and we must use a signed comparison
    * of space and resid.  On the other hand, a negative resid
    * causes us to loop sending 0-length segments to the protocol.
    */
   if (resid < 0)
      return (EINVAL);

   INET_TRACE (INETM_IO, ("INET:sosend: so %lx resid %d sb_hiwat %d so_state %x\n",
               so, resid, so->so_snd.sb_hiwat, so->so_state));

   if (sosendallatonce(so) && (resid > (int)so->so_snd.sb_hiwat))
      return (EMSGSIZE);

   dontroute = (flags & MSG_DONTROUTE) &&
               ((so->so_options & SO_DONTROUTE) == 0) &&
               (so->so_proto->pr_flags & PR_ATOMIC);

#define     snderr(errno)     {  error =  errno;   goto  release; }

restart:
   sblock(&so->so_snd);
   do 
   {
      if (so->so_error) 
      {
         error = so->so_error;
         so->so_error = 0;          /* ??? */
         goto release;
      }
      if (so->so_state & SS_CANTSENDMORE)
         snderr(EPIPE);
      if ((so->so_state & SS_ISCONNECTED) == 0) 
      {
         if (so->so_proto->pr_flags & PR_CONNREQUIRED)
            snderr(ENOTCONN);
         if (nam == 0)
            snderr(EDESTADDRREQ);
      }
      if (flags & MSG_OOB)
         space = 1024;
      else 
      {
         space = (int)sbspace(&so->so_snd);
         if ((sosendallatonce(so) && (space < resid)) ||
             ((resid >= CLBYTES) && (space < CLBYTES) &&
              (so->so_snd.sb_cc >= CLBYTES) &&
              ((so->so_state & SS_NBIO) == 0) &&
              ((flags & MSG_DONTWAIT) == 0)))
         {
            if ((so->so_state & SS_NBIO) || (flags & MSG_DONTWAIT))
            {
               if (first)
                  error = EWOULDBLOCK;
               goto release;
            }
            sbunlock(&so->so_snd);
            sbwait(&so->so_snd);
            goto restart;
         }
      }
      if ( space <= 0 ) 
      {
         /* no space in socket send buffer - see if we can wait */
         if ((so->so_state & SS_NBIO) || (flags & MSG_DONTWAIT))
         {
            if (first)     /* report first error */
               error = EWOULDBLOCK;
            goto release;
         }
         /* If blocking socket, let someone else run */
         sbunlock(&so->so_snd);
         sbwait(&so->so_snd);
         goto restart;
      }

      while (space > 0) 
      {
         len = resid;
         if ( so->so_type == SOCK_STREAM )
//.........这里部分代码省略.........