David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 1995 Danny Gasparovski |
| 3 | * |
| 4 | * Please read the file COPYRIGHT for the |
| 5 | * terms and conditions of the copyright. |
| 6 | */ |
| 7 | |
| 8 | /* |
| 9 | * mbuf's in SLiRP are much simpler than the real mbufs in |
| 10 | * FreeBSD. They are fixed size, determined by the MTU, |
| 11 | * so that one whole packet can fit. Mbuf's cannot be |
| 12 | * chained together. If there's more data than the mbuf |
| 13 | * could hold, an external malloced buffer is pointed to |
| 14 | * by m_ext (and the data pointers) and M_EXT is set in |
| 15 | * the flags |
| 16 | */ |
| 17 | |
| 18 | #include <slirp.h> |
| 19 | |
| 20 | int mbuf_alloced = 0; |
| 21 | struct mbuf m_freelist, m_usedlist; |
| 22 | #define MBUF_THRESH 30 |
| 23 | int mbuf_max = 0; |
| 24 | |
| 25 | /* |
| 26 | * Find a nice value for msize |
| 27 | * XXX if_maxlinkhdr already in mtu |
| 28 | */ |
| 29 | #define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + sizeof(struct m_hdr ) + 6) |
| 30 | |
| 31 | void |
| 32 | m_init(void) |
| 33 | { |
| 34 | m_freelist.m_next = m_freelist.m_prev = &m_freelist; |
| 35 | m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist; |
| 36 | } |
| 37 | |
| 38 | /* |
| 39 | * Get an mbuf from the free list, if there are none |
| 40 | * malloc one |
| 41 | * |
| 42 | * Because fragmentation can occur if we alloc new mbufs and |
| 43 | * free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE, |
| 44 | * which tells m_free to actually free() it |
| 45 | */ |
| 46 | struct mbuf * |
| 47 | m_get(void) |
| 48 | { |
| 49 | register struct mbuf *m; |
| 50 | int flags = 0; |
| 51 | |
| 52 | DEBUG_CALL("m_get"); |
| 53 | |
| 54 | if (m_freelist.m_next == &m_freelist) { |
| 55 | m = (struct mbuf *)malloc(SLIRP_MSIZE); |
| 56 | if (m == NULL) goto end_error; |
| 57 | mbuf_alloced++; |
| 58 | if (mbuf_alloced > MBUF_THRESH) |
| 59 | flags = M_DOFREE; |
| 60 | if (mbuf_alloced > mbuf_max) |
| 61 | mbuf_max = mbuf_alloced; |
| 62 | } else { |
| 63 | m = m_freelist.m_next; |
| 64 | remque(m); |
| 65 | } |
| 66 | |
| 67 | /* Insert it in the used list */ |
| 68 | insque(m,&m_usedlist); |
| 69 | m->m_flags = (flags | M_USEDLIST); |
| 70 | |
| 71 | /* Initialise it */ |
| 72 | m->m_size = SLIRP_MSIZE - sizeof(struct m_hdr); |
| 73 | m->m_data = m->m_dat; |
| 74 | m->m_len = 0; |
| 75 | m->m_nextpkt = NULL; |
| 76 | m->m_prevpkt = NULL; |
| 77 | end_error: |
| 78 | DEBUG_ARG("m = %lx", (long )m); |
| 79 | return m; |
| 80 | } |
| 81 | |
| 82 | void |
| 83 | m_free(struct mbuf *m) |
| 84 | { |
| 85 | |
| 86 | DEBUG_CALL("m_free"); |
| 87 | DEBUG_ARG("m = %lx", (long )m); |
| 88 | |
| 89 | if(m) { |
| 90 | /* Remove from m_usedlist */ |
| 91 | if (m->m_flags & M_USEDLIST) |
| 92 | remque(m); |
| 93 | |
| 94 | /* If it's M_EXT, free() it */ |
| 95 | if (m->m_flags & M_EXT) |
| 96 | free(m->m_ext); |
| 97 | |
| 98 | /* |
| 99 | * Either free() it or put it on the free list |
| 100 | */ |
| 101 | if (m->m_flags & M_DOFREE) { |
| 102 | free(m); |
| 103 | mbuf_alloced--; |
| 104 | } else if ((m->m_flags & M_FREELIST) == 0) { |
| 105 | insque(m,&m_freelist); |
| 106 | m->m_flags = M_FREELIST; /* Clobber other flags */ |
| 107 | } |
| 108 | } /* if(m) */ |
| 109 | } |
| 110 | |
| 111 | /* |
| 112 | * Copy data from one mbuf to the end of |
| 113 | * the other.. if result is too big for one mbuf, malloc() |
| 114 | * an M_EXT data segment |
| 115 | */ |
| 116 | void |
| 117 | m_cat(struct mbuf *m, struct mbuf *n) |
| 118 | { |
| 119 | /* |
| 120 | * If there's no room, realloc |
| 121 | */ |
| 122 | if (M_FREEROOM(m) < n->m_len) |
| 123 | m_inc(m,m->m_size+MINCSIZE); |
| 124 | |
| 125 | memcpy(m->m_data+m->m_len, n->m_data, n->m_len); |
| 126 | m->m_len += n->m_len; |
| 127 | |
| 128 | m_free(n); |
| 129 | } |
| 130 | |
| 131 | |
| 132 | /* make m size bytes large */ |
| 133 | void |
| 134 | m_inc(struct mbuf *m, int size) |
| 135 | { |
| 136 | int datasize; |
| 137 | |
| 138 | /* some compiles throw up on gotos. This one we can fake. */ |
| 139 | if(m->m_size>size) return; |
| 140 | |
| 141 | if (m->m_flags & M_EXT) { |
| 142 | datasize = m->m_data - m->m_ext; |
| 143 | m->m_ext = (char *)realloc(m->m_ext,size); |
| 144 | /* if (m->m_ext == NULL) |
| 145 | * return (struct mbuf *)NULL; |
| 146 | */ |
| 147 | m->m_data = m->m_ext + datasize; |
| 148 | } else { |
| 149 | char *dat; |
| 150 | datasize = m->m_data - m->m_dat; |
| 151 | dat = (char *)malloc(size); |
| 152 | /* if (dat == NULL) |
| 153 | * return (struct mbuf *)NULL; |
| 154 | */ |
| 155 | memcpy(dat, m->m_dat, m->m_size); |
| 156 | |
| 157 | m->m_ext = dat; |
| 158 | m->m_data = m->m_ext + datasize; |
| 159 | m->m_flags |= M_EXT; |
| 160 | } |
| 161 | |
| 162 | m->m_size = size; |
| 163 | |
| 164 | } |
| 165 | |
| 166 | |
| 167 | |
| 168 | void |
| 169 | m_adj(struct mbuf *m, int len) |
| 170 | { |
| 171 | if (m == NULL) |
| 172 | return; |
| 173 | if (len >= 0) { |
| 174 | /* Trim from head */ |
| 175 | m->m_data += len; |
| 176 | m->m_len -= len; |
| 177 | } else { |
| 178 | /* Trim from tail */ |
| 179 | len = -len; |
| 180 | m->m_len -= len; |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | |
| 185 | /* |
| 186 | * Copy len bytes from m, starting off bytes into n |
| 187 | */ |
| 188 | int |
| 189 | m_copy(struct mbuf *n, struct mbuf *m, int off, int len) |
| 190 | { |
| 191 | if (len > M_FREEROOM(n)) |
| 192 | return -1; |
| 193 | |
| 194 | memcpy((n->m_data + n->m_len), (m->m_data + off), len); |
| 195 | n->m_len += len; |
| 196 | return 0; |
| 197 | } |
| 198 | |
| 199 | |
| 200 | /* |
| 201 | * Given a pointer into an mbuf, return the mbuf |
| 202 | * XXX This is a kludge, I should eliminate the need for it |
| 203 | * Fortunately, it's not used often |
| 204 | */ |
| 205 | struct mbuf * |
| 206 | dtom(void *dat) |
| 207 | { |
| 208 | struct mbuf *m; |
| 209 | |
| 210 | DEBUG_CALL("dtom"); |
| 211 | DEBUG_ARG("dat = %lx", (long )dat); |
| 212 | |
| 213 | /* bug corrected for M_EXT buffers */ |
| 214 | for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) { |
| 215 | if (m->m_flags & M_EXT) { |
| 216 | if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) ) |
| 217 | return m; |
| 218 | } else { |
| 219 | if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) ) |
| 220 | return m; |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | DEBUG_ERROR((dfd, "dtom failed")); |
| 225 | |
| 226 | return (struct mbuf *)0; |
| 227 | } |