Archipelago » qemu

/*

 * Copyright (c) 1995 Danny Gasparovski

 *

 * Please read the file COPYRIGHT for the

 * terms and conditions of the copyright.

 */

/*

 * mbuf's in SLiRP are much simpler than the real mbufs in

 * FreeBSD.  They are fixed size, determined by the MTU,

 * so that one whole packet can fit.  Mbuf's cannot be

 * chained together.  If there's more data than the mbuf

 * could hold, an external malloced buffer is pointed to

 * by m_ext (and the data pointers) and M_EXT is set in

 * the flags

 */

#include <slirp.h>

#define MBUF_THRESH 30

/*

 * Find a nice value for msize

 * XXX if_maxlinkhdr already in mtu

 */

#define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + sizeof(struct m_hdr ) + 6)

void

m_init(Slirp *slirp)

{

    slirp->m_freelist.m_next = slirp->m_freelist.m_prev = &slirp->m_freelist;

    slirp->m_usedlist.m_next = slirp->m_usedlist.m_prev = &slirp->m_usedlist;

}

/*

 * Get an mbuf from the free list, if there are none

 * malloc one

 *

 * Because fragmentation can occur if we alloc new mbufs and

 * free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE,

 * which tells m_free to actually free() it

 */

struct mbuf *

m_get(Slirp *slirp)

{

        register struct mbuf *m;

        int flags = 0;

        DEBUG_CALL("m_get");

        if (slirp->m_freelist.m_next == &slirp->m_freelist) {

                m = (struct mbuf *)malloc(SLIRP_MSIZE);

                if (m == NULL) goto end_error;

                slirp->mbuf_alloced++;

                if (slirp->mbuf_alloced > MBUF_THRESH)

                        flags = M_DOFREE;

                m->slirp = slirp;

        } else {

                m = slirp->m_freelist.m_next;

                remque(m);

        }

        /* Insert it in the used list */

        insque(m,&slirp->m_usedlist);

        m->m_flags = (flags | M_USEDLIST);

        /* Initialise it */

        m->m_size = SLIRP_MSIZE - sizeof(struct m_hdr);

        m->m_data = m->m_dat;

        m->m_len = 0;

        m->m_nextpkt = NULL;

        m->m_prevpkt = NULL;

end_error:

        DEBUG_ARG("m = %lx", (long )m);

        return m;

}

void

m_free(struct mbuf *m)

{

  DEBUG_CALL("m_free");

  DEBUG_ARG("m = %lx", (long )m);

  if(m) {

        /* Remove from m_usedlist */

        if (m->m_flags & M_USEDLIST)

           remque(m);

        /* If it's M_EXT, free() it */

        if (m->m_flags & M_EXT)

           free(m->m_ext);

        /*

         * Either free() it or put it on the free list

         */

        if (m->m_flags & M_DOFREE) {

                free(m);

                m->slirp->mbuf_alloced--;

        } else if ((m->m_flags & M_FREELIST) == 0) {

                insque(m,&m->slirp->m_freelist);

                m->m_flags = M_FREELIST; /* Clobber other flags */

        }

  } /* if(m) */

}

/*

 * Copy data from one mbuf to the end of

 * the other.. if result is too big for one mbuf, malloc()

 * an M_EXT data segment

 */

void

m_cat(struct mbuf *m, struct mbuf *n)

{

        /*

         * If there's no room, realloc

         */

        if (M_FREEROOM(m) < n->m_len)

                m_inc(m,m->m_size+MINCSIZE);

        memcpy(m->m_data+m->m_len, n->m_data, n->m_len);

        m->m_len += n->m_len;

        m_free(n);

}

/* make m size bytes large */

void

m_inc(struct mbuf *m, int size)

{

        int datasize;

        /* some compiles throw up on gotos.  This one we can fake. */

        if(m->m_size>size) return;

        if (m->m_flags & M_EXT) {

          datasize = m->m_data - m->m_ext;

          m->m_ext = (char *)realloc(m->m_ext,size);

          m->m_data = m->m_ext + datasize;

        } else {

          char *dat;

          datasize = m->m_data - m->m_dat;

          dat = (char *)malloc(size);

          memcpy(dat, m->m_dat, m->m_size);

          m->m_ext = dat;

          m->m_data = m->m_ext + datasize;

          m->m_flags |= M_EXT;

        }

        m->m_size = size;

}

void

m_adj(struct mbuf *m, int len)

{

        if (m == NULL)

                return;

        if (len >= 0) {

                /* Trim from head */

                m->m_data += len;

                m->m_len -= len;

        } else {

                /* Trim from tail */

                len = -len;

                m->m_len -= len;

        }

}

/*

 * Copy len bytes from m, starting off bytes into n

 */

int

m_copy(struct mbuf *n, struct mbuf *m, int off, int len)

{

        if (len > M_FREEROOM(n))

                return -1;

        memcpy((n->m_data + n->m_len), (m->m_data + off), len);

        n->m_len += len;

        return 0;

}

/*

 * Given a pointer into an mbuf, return the mbuf

 * XXX This is a kludge, I should eliminate the need for it

 * Fortunately, it's not used often

 */

struct mbuf *

dtom(Slirp *slirp, void *dat)

{

        struct mbuf *m;

        DEBUG_CALL("dtom");

        DEBUG_ARG("dat = %lx", (long )dat);

        /* bug corrected for M_EXT buffers */

        for (m = slirp->m_usedlist.m_next; m != &slirp->m_usedlist;

             m = m->m_next) {

          if (m->m_flags & M_EXT) {

            if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) )

              return m;

          } else {

            if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) )

              return m;

          }

        }

        DEBUG_ERROR((dfd, "dtom failed"));

        return (struct mbuf *)0;

}