uipc_sock2.c

VxWorks网络部分的源代码

 *    a data record, perhaps of zero length.
 *
 * Before using a new socket structure it is first necessary to reserve
 * buffer space to the socket, by calling sbreserve().  This should commit
 * some of the available buffer space in the system buffer pool for the
 * socket (currently, it does nothing but enforce limits).  The space
 * should be released by calling sbrelease() when the socket is destroyed.
 */

int
soreserve(so, sndcc, rcvcc)
	register struct socket *so;
	u_long sndcc, rcvcc;
{

	if (sbreserve(&so->so_snd, sndcc) == 0)
		goto bad;
	if (sbreserve(&so->so_rcv, rcvcc) == 0)
		goto bad2;
	if (so->so_rcv.sb_lowat == 0)
		so->so_rcv.sb_lowat = 1;
	if (so->so_snd.sb_lowat == 0)
		so->so_snd.sb_lowat = CL_SIZE_64;
	if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
		so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
	return (0);
bad2:
	sbrelease(&so->so_snd);
bad:
	return (ENOBUFS);
}

/*
 * Allot mbufs to a sockbuf.
 * Attempt to scale mbmax so that mbcnt doesn't become limiting
 * if buffering efficiency is near the normal case.
 */
int
sbreserve(sb, cc)
	struct sockbuf *sb;
	u_long cc;
{

	if (cc > sb_max * MCLBYTES / (MSIZE + MCLBYTES))
		return (0);
	sb->sb_hiwat = cc;
	sb->sb_mbmax = min(cc * 5, sb_max);
	if (sb->sb_lowat > sb->sb_hiwat)
		sb->sb_lowat = sb->sb_hiwat;
	return (1);
}

/*
 * Free mbufs held by a socket, and reserved mbuf space.
 */
void
sbrelease(sb)
	struct sockbuf *sb;
{

	sbflush(sb);
	sb->sb_hiwat = sb->sb_mbmax = 0;
}

/*
 * Routines to add and remove
 * data from an mbuf queue.
 *
 * The routines sbappend() or sbappendrecord() are normally called to
 * append new mbufs to a socket buffer, after checking that adequate
 * space is available, comparing the function sbspace() with the amount
 * of data to be added.  sbappendrecord() differs from sbappend() in
 * that data supplied is treated as the beginning of a new record.
 * To place a sender's address, optional access rights, and data in a
 * socket receive buffer, sbappendaddr() should be used.  To place
 * access rights and data in a socket receive buffer, sbappendrights()
 * should be used.  In either case, the new data begins a new record.
 * Note that unlike sbappend() and sbappendrecord(), these routines check
 * for the caller that there will be enough space to store the data.
 * Each fails if there is not enough space, or if it cannot find mbufs
 * to store additional information in.
 *
 * Reliable protocols may use the socket send buffer to hold data
 * awaiting acknowledgement.  Data is normally copied from a socket
 * send buffer in a protocol with m_copy for output to a peer,
 * and then removing the data from the socket buffer with sbdrop()
 * or sbdroprecord() when the data is acknowledged by the peer.
 */

/*
 * Append mbuf chain m to the last record in the
 * socket buffer sb.  The additional space associated
 * the mbuf chain is recorded in sb.  Empty mbufs are
 * discarded and mbufs are compacted where possible.
 */
void
sbappend(sb, m)
	struct sockbuf *sb;
	struct mbuf *m;
{
	register struct mbuf *n;

	if (m == 0)
		return;
	if (n = sb->sb_mb) {
		while (n->m_nextpkt)
			n = n->m_nextpkt;
		do {
			if (n->m_flags & M_EOR) {
				sbappendrecord(sb, m); /* XXXXXX!!!! */
				return;
			}
		} while (n->m_next && (n = n->m_next));
	}
	sbcompress(sb, m, n);
}

#ifdef SOCKBUF_DEBUG
void
sbcheck(sb)
	register struct sockbuf *sb;
{
	register struct mbuf *m;
	register int len = 0, mbcnt = 0;

	for (m = sb->sb_mb; m; m = m->m_next) {
		len += m->m_len;
		mbcnt += MSIZE;
		if (m->m_flags & M_EXT)
			mbcnt += m->m_extSize;
		if (m->m_nextpkt)
			panic("sbcheck nextpkt");
	}
	if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
		printf("cc %d != %d || mbcnt %d != %d\n", len, sb->sb_cc,
		    mbcnt, sb->sb_mbcnt);
		panic("sbcheck");
	}
}
#endif

/*
 * As above, except the mbuf chain
 * begins a new record.
 */
void
sbappendrecord(sb, m0)
	register struct sockbuf *sb;
	register struct mbuf *m0;
{
	register struct mbuf *m;

	if (m0 == 0)
		return;
	if (m = sb->sb_mb)
		while (m->m_nextpkt)
			m = m->m_nextpkt;
	/*
	 * Put the first mbuf on the queue.
	 * Note this permits zero length records.
	 */
	sballoc(sb, m0);
	if (m)
		m->m_nextpkt = m0;
	else
		sb->sb_mb = m0;
	m = m0->m_next;
	m0->m_next = 0;
	if (m && (m0->m_flags & M_EOR)) {
		m0->m_flags &= ~M_EOR;
		m->m_flags |= M_EOR;
	}
	sbcompress(sb, m, m0);
}

/*
 * As above except that OOB data
 * is inserted at the beginning of the sockbuf,
 * but after any other OOB data.
 */
void
sbinsertoob(sb, m0)
	register struct sockbuf *sb;
	register struct mbuf *m0;
{
	register struct mbuf *m;
	register struct mbuf **mp;

	if (m0 == 0)
		return;
	for (mp = &sb->sb_mb; m = *mp; mp = &((*mp)->m_nextpkt)) {
	    again:
		switch (m->m_type) {

		case MT_OOBDATA:
			continue;		/* WANT next train */

		case MT_CONTROL:
			if (m = m->m_next)
				goto again;	/* inspect THIS train further */
		}
		break;
	}
	/*
	 * Put the first mbuf on the queue.
	 * Note this permits zero length records.
	 */
	sballoc(sb, m0);
	m0->m_nextpkt = *mp;
	*mp = m0;
	m = m0->m_next;
	m0->m_next = 0;
	if (m && (m0->m_flags & M_EOR)) {
		m0->m_flags &= ~M_EOR;
		m->m_flags |= M_EOR;
	}
	sbcompress(sb, m, m0);
}

/*
 * 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(sb, asa, m0, control)
	register struct sockbuf *sb;
	struct sockaddr *asa;
	struct mbuf *m0, *control;
{
	register struct mbuf *m, *n;
	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 == 0)	/* keep pointer to last control buf */
			break;
	}
	if (space > sbspace(sb))
		return (0);
	if (asa->sa_len > CL_SIZE_128)
		return (0);
	m = mBufClGet(M_DONTWAIT, MT_SONAME, CL_SIZE_128, TRUE);
	if (m == 0)
		return (0);
	m->m_len = asa->sa_len;
	bcopy((caddr_t)asa, mtod(m, caddr_t), asa->sa_len);
	if (n)
		n->m_next = m0;		/* concatenate data to control */
	else
		control = m0;
	m->m_next = control;
	for (n = m; n; n = n->m_next)
		sballoc(sb, n);
	if (n = sb->sb_mb) {
		while (n->m_nextpkt)
			n = n->m_nextpkt;
		n->m_nextpkt = m;
	} else
		sb->sb_mb = m;
	return (1);
}

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

	if (control == 0)
		panic("sbappendcontrol");
	for (m = control; ; m = m->m_next) {
		space += m->m_len;
		if (m->m_next == 0)
			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 */
	for (m = control; m; m = m->m_next)
		sballoc(sb, m);
	if (n = sb->sb_mb) {
		while (n->m_nextpkt)
			n = n->m_nextpkt;
		n->m_nextpkt = control;
	} else
		sb->sb_mb = control;
	return (1);
}

/*
 * Compress mbuf chain m into the socket
 * buffer sb following mbuf n.  If n
 * is null, the buffer is presumed empty.
 */
void
sbcompress(sb, m, n)
	register struct sockbuf *sb;
	register struct mbuf *m, *n;
{
	register int eor = 0;
	register struct mbuf *o;

	while (m) {
		eor |= m->m_flags & M_EOR;
		if (m->m_len == 0 &&
		    (eor == 0 ||
		     (((o = m->m_next) || (o = n)) &&
		      o->m_type == m->m_type))) {
			m = m_free(m);
			continue;
		}

		/*
		 * This test determines whether or not the data in <m> will
		 * be copied to the cluster referenced by <n>.  The conditions
		 * which are required for compression are:
		 *     1) <n> is non-NULL
		 *     2) <n> is not the end of a record.  M_EOR is set for
		 *        datagram protocols (UDP, raw IP) but not stream
		 *        protocols (TCP)
		 *     3) length of data in <m> is less than CL_SIZE_MIN.  This
		 *        condition optimizes buffer usage for small clusters
		 *        and optimizes speed for large clusters, by not 
		 *        copying data in those cases.
		 *     4) The data in <m> must fit in the remaining space in 
		 *        the cluster referenced by <n>
		 *     5) <m> and <n> must contain the same type of data
		 */

		if (n && 
		    (n->m_flags & M_EOR) == 0 && 
		    m->m_len < CL_SIZE_MIN &&
		    (n->m_data + n->m_len + m->m_len) < 
		    (n->m_extBuf + n->m_extSize) &&
		    n->m_type == m->m_type) 
		    {
		    bcopy(mtod(m, caddr_t), mtod(n, caddr_t) + n->m_len,
			  (unsigned)m->m_len);
		    n->m_len += m->m_len;
		    sb->sb_cc += m->m_len;
		    m = m_free(m);
		    continue;
		    }
		if (n)
			n->m_next = m;
		else
			sb->sb_mb = m;
		sballoc(sb, m);
		n = m;
		m->m_flags &= ~M_EOR;
		m = m->m_next;
		n->m_next = 0;
	}
	if (eor) {
		if (n)
			n->m_flags |= eor;
		else
			printf("semi-panic: sbcompress\n");
	}
}

/*
 * Free all mbufs in a sockbuf.
 * Check that all resources are reclaimed.
 */
void
sbflush(sb)
	register struct sockbuf *sb;
{

	if (sb->sb_flags & SB_LOCK)
		panic("sbflush");
	while (sb->sb_mbcnt)
		sbdrop(sb, (int)sb->sb_cc);
	if (sb->sb_cc || sb->sb_mb)
		panic("sbflush 2");
}

/*
 * Drop data from (the front of) a sockbuf.
 */
void
sbdrop(sb, len)
	register struct sockbuf *sb;
	register int len;
{
	register struct mbuf *m, *mn;
	struct mbuf *next;

	next = (m = sb->sb_mb) ? m->m_nextpkt : 0;
	while (len > 0) {
		if (m == 0) {
			if (next == 0)
				panic("sbdrop");
			m = next;
			next = m->m_nextpkt;
			continue;
		}
		if (m->m_len > len) {
			m->m_len -= len;
			m->m_data += len;
			sb->sb_cc -= len;
			break;
		}
		len -= m->m_len;
		sbfree(sb, m);
		mn = m_free(m);
		m = mn;
	}
	while (m && m->m_len == 0) {
		sbfree(sb, m);
		mn = m_free(m);
		m = mn;
	}
	if (m) {
		sb->sb_mb = m;
		m->m_nextpkt = next;
	} else
		sb->sb_mb = next;
}

/*
 * Drop a record off the front of a sockbuf
 * and move the next record to the front.
 */
void
sbdroprecord(sb)
	register struct sockbuf *sb;
{
	register struct mbuf *m, *mn;

	m = sb->sb_mb;
	if (m) {
		sb->sb_mb = m->m_nextpkt;
		do {
			sbfree(sb, m);
			mn = m_free(m);
		} while ((m = mn));
	}
}