BSD 4_3_Net_2 release

[unix-history] / usr / src / sys / netimp / if_imphost.h

/*
* Copyright (c) 1982, 1986, 1988 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.
*
*      @(#)if_imphost.h        7.7 (Berkeley) 6/28/90
*/

/*
* Host structure used with IMP's.
* Used to hold outgoing packets which
* would exceed allowed RFNM count.
*
* These structures are packed into
* mbuf's and kept as small as possible.
*/
struct host {
       struct  mbuf *h_q;              /* holding queue */
       u_short h_timer;                /* used to stay off deletion */
       u_short h_imp;                  /* host's imp number */
       u_char  h_host;                 /* host's number on imp */
       u_char  h_qcnt;                 /* size of holding q */
       u_char  h_rfnm;                 /* # outstanding rfnm's */
       u_char  h_flags;                /* see below */
};

/*
* A host structure is kept around (even when there are no
* references to it) for a spell to avoid constant reallocation
* and also to reflect IMP status back to sites which aren't
* directly connected to the IMP.  When structures are marked
* idle, a timer is started; when the timer expires the structure
* is deallocated.  A structure may be reused before the timer expires.
* A structure holds a reference on the containing mbuf when it is marked
* HF_INUSE.
*/
#define HF_INUSE        0x1
#define HF_DEAD         (1<<IMPTYPE_HOSTDEAD)
#define HF_UNREACH      (1<<IMPTYPE_HOSTUNREACH)

#define HOSTTIMER       128             /* keep structure around awhile */

/*
* Mark a host structure free; used if host entry returned by hostlookup 
* isn't needed.  h_rfnm must be zero.
*/
#define hostfree(hp) { \
       if ((hp)->h_timer == 0 && (hp)->h_qcnt == 0 && \
           (hp)->h_flags & HF_INUSE) \
               hostrelease(hp); \
}

/*
* Release a host entry when last rfnm is received.
*/
#define hostidle(hp)    { (hp)->h_timer = HOSTTIMER; }

/*
* Host structures, as seen inside an mbuf.
* Hashing on the host and imp is used to
* select an index into the first mbuf.  Collisions
* are then resolved by searching successive
* mbuf's at the same index.  Reclamation is done
* automatically at the time a structure is freed.
*/
#define HPMBUF  ((MLEN - sizeof(int)) / sizeof(struct host))
/* don't need to swab as long as HPMBUF is odd */
#if defined(notdef) && BYTE_ORDER == BIG_ENDIAN
#define HOSTHASH(imp, host)     ((unsigned)(ntohs(imp)+(host)) % HPMBUF)
#else
#define HOSTHASH(imp, host)     ((unsigned)((imp)+(host)) % HPMBUF)
#endif

/*
* In-line expansions for queuing operations on
* host message holding queue.  Queue is maintained
* as circular list with the head pointing to the
* last message in the queue.
*/
#define HOST_ENQUE(hp, m) { \
       register struct mbuf *n; \
       (hp)->h_qcnt++; \
       if ((n = (hp)->h_q) == 0) \
               (hp)->h_q = (m)->m_act = (m); \
       else { \
               (m)->m_act = n->m_act; \
               (hp)->h_q = n->m_act = (m); \
       } \
}
#define HOST_DEQUE(hp, m) { \
       if ((m) = (hp)->h_q) { \
               if ((m)->m_act == (m)) \
                       (hp)->h_q = 0; \
               else { \
                       (m) = (m)->m_act; \
                       (hp)->h_q->m_act = (m)->m_act; \
               } \
               (hp)->h_qcnt--; \
               (m)->m_act = 0; \
       } \
}

struct hmbuf {
       int     hm_count;               /* # of struct's in use */
       struct  host hm_hosts[HPMBUF];  /* data structures proper */
};

#ifdef KERNEL
struct host *hostlookup();
struct host *hostenter();
#endif