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/* |
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* Copyright (c) 1995 Danny Gasparovski |
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* |
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* Please read the file COPYRIGHT for the |
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* terms and conditions of the copyright. |
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*/ |
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|
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/* |
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* mbuf's in SLiRP are much simpler than the real mbufs in |
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* FreeBSD. They are fixed size, determined by the MTU, |
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* so that one whole packet can fit. Mbuf's cannot be |
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* chained together. If there's more data than the mbuf |
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* could hold, an external malloced buffer is pointed to |
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* by m_ext (and the data pointers) and M_EXT is set in |
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* the flags |
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*/ |
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|
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#include <slirp.h> |
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|
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struct mbuf *mbutl; |
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char *mclrefcnt; |
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int mbuf_alloced = 0; |
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struct mbuf m_freelist, m_usedlist; |
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int mbuf_thresh = 30; |
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int mbuf_max = 0; |
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int msize; |
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|
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void |
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m_init() |
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{ |
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m_freelist.m_next = m_freelist.m_prev = &m_freelist; |
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m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist; |
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msize_init(); |
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} |
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|
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void |
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msize_init() |
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{ |
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/* |
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* Find a nice value for msize |
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* XXX if_maxlinkhdr already in mtu |
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*/ |
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msize = (if_mtu>if_mru?if_mtu:if_mru) + |
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if_maxlinkhdr + sizeof(struct m_hdr ) + 6; |
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} |
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|
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/* |
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* Get an mbuf from the free list, if there are none |
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* malloc one |
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* |
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* Because fragmentation can occur if we alloc new mbufs and |
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* free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE, |
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* which tells m_free to actually free() it |
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*/ |
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struct mbuf * |
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m_get() |
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{ |
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register struct mbuf *m; |
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int flags = 0; |
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|
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DEBUG_CALL("m_get"); |
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|
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if (m_freelist.m_next == &m_freelist) { |
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m = (struct mbuf *)malloc(msize); |
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if (m == NULL) goto end_error; |
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mbuf_alloced++; |
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if (mbuf_alloced > mbuf_thresh) |
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flags = M_DOFREE; |
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if (mbuf_alloced > mbuf_max) |
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mbuf_max = mbuf_alloced; |
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} else { |
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m = m_freelist.m_next; |
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remque(m); |
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} |
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|
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/* Insert it in the used list */ |
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insque(m,&m_usedlist); |
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m->m_flags = (flags | M_USEDLIST); |
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|
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/* Initialise it */ |
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m->m_size = msize - sizeof(struct m_hdr); |
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m->m_data = m->m_dat; |
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m->m_len = 0; |
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m->m_nextpkt = 0; |
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m->m_prevpkt = 0; |
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end_error: |
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DEBUG_ARG("m = %lx", (long )m); |
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return m; |
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} |
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|
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void |
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m_free(m) |
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struct mbuf *m; |
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{ |
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|
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DEBUG_CALL("m_free"); |
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DEBUG_ARG("m = %lx", (long )m); |
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|
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if(m) { |
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/* Remove from m_usedlist */ |
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if (m->m_flags & M_USEDLIST) |
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remque(m); |
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|
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/* If it's M_EXT, free() it */ |
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if (m->m_flags & M_EXT) |
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free(m->m_ext); |
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|
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/* |
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* Either free() it or put it on the free list |
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*/ |
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if (m->m_flags & M_DOFREE) { |
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free(m); |
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mbuf_alloced--; |
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} else if ((m->m_flags & M_FREELIST) == 0) { |
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insque(m,&m_freelist); |
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m->m_flags = M_FREELIST; /* Clobber other flags */ |
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} |
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} /* if(m) */ |
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} |
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|
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/* |
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* Copy data from one mbuf to the end of |
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* the other.. if result is too big for one mbuf, malloc() |
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* an M_EXT data segment |
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*/ |
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void |
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m_cat(m, n) |
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register struct mbuf *m, *n; |
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{ |
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/* |
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* If there's no room, realloc |
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*/ |
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if (M_FREEROOM(m) < n->m_len) |
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m_inc(m,m->m_size+MINCSIZE); |
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|
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memcpy(m->m_data+m->m_len, n->m_data, n->m_len); |
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m->m_len += n->m_len; |
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|
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m_free(n); |
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} |
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|
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|
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/* make m size bytes large */ |
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void |
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m_inc(m, size) |
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struct mbuf *m; |
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int size; |
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{ |
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/* some compiles throw up on gotos. This one we can fake. */ |
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if(m->m_size>size) return; |
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|
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if (m->m_flags & M_EXT) { |
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/* datasize = m->m_data - m->m_ext; */ |
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m->m_ext = (char *)realloc(m->m_ext,size); |
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/* if (m->m_ext == NULL) |
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* return (struct mbuf *)NULL; |
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*/ |
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/* m->m_data = m->m_ext + datasize; */ |
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} else { |
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int datasize; |
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char *dat; |
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datasize = m->m_data - m->m_dat; |
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dat = (char *)malloc(size); |
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/* if (dat == NULL) |
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* return (struct mbuf *)NULL; |
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*/ |
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memcpy(dat, m->m_dat, m->m_size); |
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|
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m->m_ext = dat; |
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m->m_data = m->m_ext + datasize; |
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m->m_flags |= M_EXT; |
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} |
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|
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m->m_size = size; |
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|
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} |
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|
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|
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|
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void |
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m_adj(m, len) |
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struct mbuf *m; |
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int len; |
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{ |
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if (m == NULL) |
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return; |
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if (len >= 0) { |
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/* Trim from head */ |
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m->m_data += len; |
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m->m_len -= len; |
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} else { |
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/* Trim from tail */ |
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len = -len; |
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m->m_len -= len; |
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} |
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} |
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|
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|
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/* |
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* Copy len bytes from m, starting off bytes into n |
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*/ |
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int |
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m_copy(n, m, off, len) |
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struct mbuf *n, *m; |
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int off, len; |
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{ |
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if (len > M_FREEROOM(n)) |
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return -1; |
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|
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memcpy((n->m_data + n->m_len), (m->m_data + off), len); |
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n->m_len += len; |
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return 0; |
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} |
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|
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|
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/* |
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* Given a pointer into an mbuf, return the mbuf |
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* XXX This is a kludge, I should eliminate the need for it |
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* Fortunately, it's not used often |
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*/ |
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struct mbuf * |
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dtom(dat) |
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void *dat; |
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{ |
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struct mbuf *m; |
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|
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DEBUG_CALL("dtom"); |
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DEBUG_ARG("dat = %lx", (long )dat); |
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|
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/* bug corrected for M_EXT buffers */ |
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for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) { |
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if (m->m_flags & M_EXT) { |
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if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) ) |
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return m; |
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} else { |
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if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) ) |
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return m; |
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} |
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} |
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|
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DEBUG_ERROR((dfd, "dtom failed")); |
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|
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return (struct mbuf *)0; |
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} |
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|
