/*
 * Copyright (c) 2005 Jeffrey M. Hsu.  All rights reserved.
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *      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. 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.
 *
 * @(#)uipc_socket2.c   8.1 (Berkeley) 6/10/93
 * $FreeBSD: src/sys/kern/uipc_socket2.c,v 1.55.2.17 2002/08/31 19:04:55 dwmalone Exp $
 */

#include "opt_param.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/domain.h>
#include <sys/file.h>   /* for maxfiles */
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/resourcevar.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/socketvar.h>

#include <sys/thread2.h>
#include <sys/msgport2.h>

/*
 * 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.  sbappendrecord() differs from
 * sbappend() in that data supplied is treated as the beginning of a new
 * record.  sbappend() only begins a new record if the last mbuf in the
 * sockbuf is marked M_EOR.
 *
 * To place a sender's address, optional access rights, and data in a
 * socket receive buffer, sbappendaddr() or sbappendcontrol() should be
 * used.   These functions also begin a new record.
 *
 * 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_copym 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.
 *
 * If M_EOR is set in the first or last mbuf of the last record, the
 * mbuf chain is appended as a new record.  M_EOR is usually just set
 * in the last mbuf of the last record's mbuf chain (see sbcompress()),
 * but this may be changed in the future since there is no real need
 * to propogate the flag any more.
 */
void
sbappend(struct sockbuf *sb, struct mbuf *m)
{
        struct mbuf *n;

        mbuftrackid(m, 16);

        if (m) {
                n = sb->sb_lastrecord;
                if (n) {
                        if (n->m_flags & M_EOR) {
                                sbappendrecord(sb, m);
                                return;
                        }
                }
                n = sb->sb_lastmbuf;
                if (n) {
                        if (n->m_flags & M_EOR) {
                                sbappendrecord(sb, m);
                                return;
                        }
                }
                sbcompress(sb, m, n);
        }
}

/*
 * sbappendstream() is an optimized form of sbappend() for protocols
 * such as TCP that only have one record in the socket buffer, are
 * not PR_ATOMIC, nor allow MT_CONTROL data.  A protocol that uses
 * sbappendstream() must use sbappendstream() exclusively.
 */
void
sbappendstream(struct sockbuf *sb, struct mbuf *m)
{
        mbuftrackid(m, 17);
        KKASSERT(m->m_nextpkt == NULL);
        sbcompress(sb, m, sb->sb_lastmbuf);
}

#ifdef SOCKBUF_DEBUG

void
_sbcheck(struct sockbuf *sb)
{
        struct mbuf *m;
        struct mbuf *n = NULL;
        u_long len = 0, mbcnt = 0;

        for (m = sb->sb_mb; m; m = n) {
            n = m->m_nextpkt;
            if (n == NULL && sb->sb_lastrecord != m) {
                    kprintf("sockbuf %p mismatched lastrecord %p vs %p\n", sb, sb->sb_lastrecord, m);
                    panic("sbcheck1");
            }
            for (; m; m = m->m_next) {
                len += m->m_len;
                mbcnt += MSIZE;
                if (m->m_flags & M_EXT) /*XXX*/ /* pretty sure this is bogus */
                        mbcnt += m->m_ext.ext_size;
                if (n == NULL && m->m_next == NULL) {
                        if (sb->sb_lastmbuf != m) {
                                kprintf("sockbuf %p mismatched lastmbuf %p vs %p\n", sb, sb->sb_lastmbuf, m);
                                panic("sbcheck2");
                        }
                }
            }
        }
        if (sb->sb_mb == NULL) {
            if (sb->sb_lastrecord != NULL) {
                kprintf("sockbuf %p is empty, lastrecord not NULL: %p\n",
                        sb, sb->sb_lastrecord);
                panic("sbcheck3");
            }
            if (sb->sb_lastmbuf != NULL) {
                kprintf("sockbuf %p is empty, lastmbuf not NULL: %p\n",
                        sb, sb->sb_lastmbuf);
                panic("sbcheck4");
            }
        }
        if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
                kprintf("sockbuf %p cc %ld != %ld || mbcnt %ld != %ld\n",
                    sb, len, sb->sb_cc, mbcnt, sb->sb_mbcnt);
                panic("sbcheck5");
        }
}

#endif

/*
 * Same as sbappend(), except the mbuf chain begins a new record.
 */
void
sbappendrecord(struct sockbuf *sb, struct mbuf *m0)
{
        struct mbuf *firstmbuf;
        struct mbuf *secondmbuf;

        if (m0 == NULL)
                return;
        mbuftrackid(m0, 18);

        sbcheck(sb);

        /*
         * Break the first mbuf off from the rest of the mbuf chain.
         */
        firstmbuf = m0;
        secondmbuf = m0->m_next;
        m0->m_next = NULL;

        /*
         * Insert the first mbuf of the m0 mbuf chain as the last record of
         * the sockbuf.  Note this permits zero length records!  Keep the
         * sockbuf state consistent.
         */
        if (sb->sb_mb == NULL)
                sb->sb_mb = firstmbuf;
        else
                sb->sb_lastrecord->m_nextpkt = firstmbuf;
        sb->sb_lastrecord = firstmbuf;  /* update hint for new last record */
        sb->sb_lastmbuf = firstmbuf;    /* update hint for new last mbuf */

        /*
         * propagate the EOR flag so sbcompress() can pick it up
         */
        if ((firstmbuf->m_flags & M_EOR) && (secondmbuf != NULL)) {
                firstmbuf->m_flags &= ~M_EOR;
                secondmbuf->m_flags |= M_EOR;
        }

        /*
         * The succeeding call to sbcompress() omits accounting for
         * the first mbuf, so do it here.
         */
        sballoc(sb, firstmbuf);

        /* Compact the rest of the mbuf chain in after the first mbuf. */
        sbcompress(sb, secondmbuf, firstmbuf);
}

/*
 * 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 insufficient mbufs.
 */
int
sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa, struct mbuf *m0,
             struct mbuf *control)
{
        struct mbuf *m, *n;
        int eor;

        mbuftrackid(m0, 19);
        mbuftrackid(control, 20);
        if (m0 && (m0->m_flags & M_PKTHDR) == 0)
                panic("sbappendaddr");
        sbcheck(sb);

        for (n = control; n; n = n->m_next) {
                if (n->m_next == NULL)  /* keep pointer to last control buf */
                        break;
        }
        if (asa->sa_len > MLEN)
                return (0);
        MGET(m, M_NOWAIT, MT_SONAME);
        if (m == NULL)
                return (0);
        KKASSERT(m->m_nextpkt == NULL);
        m->m_len = asa->sa_len;
        bcopy(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 (sb->sb_mb == NULL)
                sb->sb_mb = m;
        else
                sb->sb_lastrecord->m_nextpkt = m;
        sb->sb_lastrecord = m;

        /*
         * Propogate M_EOR to the last mbuf and calculate sb_lastmbuf
         * so sbappend() can find it.
         */
        eor = m->m_flags;
        while (m->m_next) {
                m->m_flags &= ~M_EOR;
                m = m->m_next;
                eor |= m->m_flags;
        }
        m->m_flags |= eor & M_EOR;
        sb->sb_lastmbuf = m;

        return (1);
}

/*
 * Append control information followed by data. Both the control and data
 * must be non-null.
 */
int
sbappendcontrol(struct sockbuf *sb, struct mbuf *m0, struct mbuf *control)
{
        struct mbuf *n;
        u_int length, cmbcnt, m0mbcnt;
        int eor;

        KASSERT(control != NULL, ("sbappendcontrol"));
        KKASSERT(control->m_nextpkt == NULL);
        sbcheck(sb);

        mbuftrackid(m0, 21);
        mbuftrackid(control, 22);

        length = m_countm(control, &n, &cmbcnt) + m_countm(m0, NULL, &m0mbcnt);

        KKASSERT(m0 != NULL);

        n->m_next = m0;                 /* concatenate data to control */

        if (sb->sb_mb == NULL)
                sb->sb_mb = control;
        else
                sb->sb_lastrecord->m_nextpkt = control;
        sb->sb_lastrecord = control;

        /*
         * Propogate M_EOR to the last mbuf and calculate sb_lastmbuf
         * so sbappend() can find it.
         */
        eor = m0->m_flags;
        while (m0->m_next) {
                m0->m_flags &= ~M_EOR;
                m0 = m0->m_next;
                eor |= m0->m_flags;
        }
        m0->m_flags |= eor & M_EOR;
        sb->sb_lastmbuf = m0;

        sb->sb_cc += length;
        sb->sb_mbcnt += cmbcnt + m0mbcnt;

        return (1);
}

/*
 * Compress mbuf chain m into the socket buffer sb following mbuf tailm.
 * If tailm is null, the buffer is presumed empty.  Also, as a side-effect,
 * increment the sockbuf counts for each mbuf in the chain.
 */
void
sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *tailm)
{
        int eor = 0;
        struct mbuf *free_chain = NULL;

        mbuftrackid(m, 23);

        sbcheck(sb);
        while (m) {
                struct mbuf *o;

                eor |= m->m_flags & M_EOR;
                /*
                 * Disregard empty mbufs as long as we don't encounter
                 * an end-of-record or there is a trailing mbuf of
                 * the same type to propagate the EOR flag to.
                 *
                 * Defer the m_free() call because it can block and break
                 * the atomicy of the sockbuf.
                 */
                if (m->m_len == 0 &&
                    (eor == 0 ||
                     (((o = m->m_next) || (o = tailm)) &&
                      o->m_type == m->m_type))) {
                        o = m->m_next;
                        m->m_next = free_chain;
                        free_chain = m;
                        m = o;
                        continue;
                }

                /*
                 * See if we can coalesce with preceding mbuf.  Never try
                 * to coalesce a mbuf representing an end-of-record or
                 * a mbuf locked by userland for reading.
                 */
                if (tailm && !(tailm->m_flags & (M_EOR | M_SOLOCKED)) &&
                    M_WRITABLE(tailm) &&
                    m->m_len <= MCLBYTES / 4 && /* XXX: Don't copy too much */
                    m->m_len <= M_TRAILINGSPACE(tailm) &&
                    tailm->m_type == m->m_type) {
                        u_long mbcnt_sz;

                        bcopy(mtod(m, caddr_t),
                              mtod(tailm, caddr_t) + tailm->m_len,
                              (unsigned)m->m_len);
                        tailm->m_len += m->m_len;

                        sb->sb_cc += m->m_len;          /* update sb counter */

                        /*
                         * Fix the wrongly updated mbcnt_prealloc
                         */
                        mbcnt_sz = MSIZE;
                        if (m->m_flags & M_EXT)
                                mbcnt_sz += m->m_ext.ext_size;
                        atomic_subtract_long(&sb->sb_mbcnt_prealloc, mbcnt_sz);

                        o = m->m_next;
                        m->m_next = free_chain;
                        free_chain = m;
                        m = o;
                        continue;
                }

                /* Insert whole mbuf. */
                if (tailm == NULL) {
                        KASSERT(sb->sb_mb == NULL,
                                ("sbcompress: sb_mb not NULL"));
                        sb->sb_mb = m;          /* only mbuf in sockbuf */
                        sb->sb_lastrecord = m;  /* new last record */
                } else {
                        tailm->m_next = m;      /* tack m on following tailm */
                }
                sb->sb_lastmbuf = m;    /* update last mbuf hint */

                tailm = m;      /* just inserted mbuf becomes the new tail */
                m = m->m_next;          /* advance to next mbuf */
                tailm->m_next = NULL;   /* split inserted mbuf off from chain */

                /* update sb counters for just added mbuf */
                sballoc(sb, tailm);

                /* clear EOR on intermediate mbufs */
                tailm->m_flags &= ~M_EOR;
        }

        /*
         * Propogate EOR to the last mbuf
         */
        if (eor) {
                if (tailm)
                        tailm->m_flags |= eor;
                else
                        kprintf("semi-panic: sbcompress");
        }

        /*
         * Clean up any defered frees.
         */
        while (free_chain)
                free_chain = m_free(free_chain);

        sbcheck(sb);
}

/*
 * Free all mbufs in a sockbuf.
 * Check that all resources are reclaimed.
 */
void
sbflush(struct sockbuf *sb)
{
        while (sb->sb_mbcnt) {
                /*
                 * Don't call sbdrop(sb, 0) if the leading mbuf is non-empty:
                 * we would loop forever. Panic instead.
                 */
                if (!sb->sb_cc && (sb->sb_mb == NULL || sb->sb_mb->m_len))
                        break;
                sbdrop(sb, (int)sb->sb_cc);
        }
        KASSERT(!(sb->sb_cc || sb->sb_mb || sb->sb_mbcnt || sb->sb_lastmbuf),
            ("sbflush: cc %ld || mb %p || mbcnt %ld || lastmbuf %p",
            sb->sb_cc, sb->sb_mb, sb->sb_mbcnt, sb->sb_lastmbuf));
}

/*
 * Drop data from (the front of) a sockbuf.  If the current record is
 * exhausted this routine will move onto the next one and continue dropping
 * data.
 */
void
sbdrop(struct sockbuf *sb, int len)
{
        struct mbuf *m;
        struct mbuf *free_chain = NULL;

        sbcheck(sb);
        crit_enter();

        m = sb->sb_mb;
        while (m && len > 0) {
                if (m->m_len > len) {
                        m->m_len -= len;
                        m->m_data += len;
                        sb->sb_cc -= len;
                        atomic_subtract_long(&sb->sb_cc_prealloc, len);
                        break;
                }
                len -= m->m_len;
                m = sbunlinkmbuf(sb, m, &free_chain);
                if (m == NULL && len)
                        m = sb->sb_mb;
        }

        /*
         * Remove any trailing 0-length mbufs in the current record.  If
         * the last record for which data was removed is now empty, m will be
         * NULL.
         */
        while (m && m->m_len == 0) {
                m = sbunlinkmbuf(sb, m, &free_chain);
        }
        crit_exit();
        if (free_chain)
                m_freem(free_chain);
        sbcheck(sb);
}

/*
 * Drop a record off the front of a sockbuf and move the next record
 * to the front.
 *
 * Must be called while holding a critical section.
 */
void
sbdroprecord(struct sockbuf *sb)
{
        struct mbuf *m;
        struct mbuf *n;

        sbcheck(sb);
        m = sb->sb_mb;
        if (m) {
                if ((sb->sb_mb = m->m_nextpkt) == NULL) {
                        sb->sb_lastrecord = NULL;
                        sb->sb_lastmbuf = NULL;
                }
                m->m_nextpkt = NULL;
                for (n = m; n; n = n->m_next)
                        sbfree(sb, n);
                m_freem(m);
                sbcheck(sb);
        }
}

/*
 * Drop the first mbuf off the sockbuf and move the next mbuf to the front.
 * Currently only the head mbuf of the sockbuf may be dropped this way.
 *
 * The next mbuf in the same record as the mbuf being removed is returned
 * or NULL if the record is exhausted.  Note that other records may remain
 * in the sockbuf when NULL is returned.
 *
 * Must be called while holding a critical section.
 */
struct mbuf *
sbunlinkmbuf(struct sockbuf *sb, struct mbuf *m, struct mbuf **free_chain)
{
        struct mbuf *n;

        KKASSERT(sb->sb_mb == m);
        sbfree(sb, m);
        n = m->m_next;
        if (n) {
                sb->sb_mb = n;
                if (sb->sb_lastrecord == m)
                        sb->sb_lastrecord = n;
                KKASSERT(sb->sb_lastmbuf != m);
                n->m_nextpkt = m->m_nextpkt;
        } else {
                sb->sb_mb = m->m_nextpkt;
                if (sb->sb_lastrecord == m) {
                        KKASSERT(sb->sb_mb == NULL);
                        sb->sb_lastrecord = NULL;
                }
                if (sb->sb_mb == NULL)
                        sb->sb_lastmbuf = NULL;
        }
        m->m_nextpkt = NULL;
        if (free_chain) {
                m->m_next = *free_chain;
                *free_chain = m;
        } else {
                m->m_next = NULL;
        }
        return(n);
}

/*
 * Create a "control" mbuf containing the specified data
 * with the specified type for presentation on a socket buffer.
 */
struct mbuf *
sbcreatecontrol(const void *p, size_t size, int type, int level)
{
        struct cmsghdr *cp;
        struct mbuf *m;

        if (CMSG_SPACE(size) > MCLBYTES)
                return (NULL);
        m = m_getl(CMSG_SPACE(size), M_NOWAIT, MT_CONTROL, 0, NULL);
        if (m == NULL)
                return (NULL);
        m->m_len = CMSG_SPACE(size);
        cp = mtod(m, struct cmsghdr *);
        if (p != NULL)
                memcpy(CMSG_DATA(cp), p, size);
        cp->cmsg_len = CMSG_LEN(size);
        cp->cmsg_level = level;
        cp->cmsg_type = type;
        mbuftrackid(m, 24);
        return (m);
}