/* * 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 + offsetof(struct mbuf, m_dat) + 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 - offsetof(struct mbuf, m_dat); 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) { m->slirp->mbuf_alloced--; free(m); } 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; }