| 1 | /*- |
| 2 | * Copyright (c) 1991 The Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * %sccs.include.redist.c% |
| 6 | * |
| 7 | * @(#)iso_chksum.c 7.6 (Berkeley) %G% |
| 8 | */ |
| 9 | |
| 10 | /*********************************************************** |
| 11 | Copyright IBM Corporation 1987 |
| 12 | |
| 13 | All Rights Reserved |
| 14 | |
| 15 | Permission to use, copy, modify, and distribute this software and its |
| 16 | documentation for any purpose and without fee is hereby granted, |
| 17 | provided that the above copyright notice appear in all copies and that |
| 18 | both that copyright notice and this permission notice appear in |
| 19 | supporting documentation, and that the name of IBM not be |
| 20 | used in advertising or publicity pertaining to distribution of the |
| 21 | software without specific, written prior permission. |
| 22 | |
| 23 | IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING |
| 24 | ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL |
| 25 | IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR |
| 26 | ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, |
| 27 | WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, |
| 28 | ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
| 29 | SOFTWARE. |
| 30 | |
| 31 | ******************************************************************/ |
| 32 | |
| 33 | /* |
| 34 | * ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison |
| 35 | */ |
| 36 | /* |
| 37 | * $Header: iso_chksum.c,v 4.7 88/07/29 15:31:26 nhall Exp $ |
| 38 | * $Source: /usr/argo/sys/netiso/RCS/iso_chksum.c,v $ |
| 39 | * |
| 40 | * ISO CHECKSUM |
| 41 | * |
| 42 | * The checksum generation and check routines are here. |
| 43 | * The checksum is 2 bytes such that the sum of all the bytes b(i) == 0 |
| 44 | * and the sum of i * b(i) == 0. |
| 45 | * The whole thing is complicated by the fact that the data are in mbuf |
| 46 | * chains. |
| 47 | * Furthermore, there is the possibility of wraparound in the running |
| 48 | * sums after adding up 4102 octets. In order to avoid doing a mod |
| 49 | * operation after EACH add, we have restricted this implementation to |
| 50 | * negotiating a maximum of 4096-octets per TPDU (for the transport layer). |
| 51 | * The routine iso_check_csum doesn't need to know where the checksum |
| 52 | * octets are. |
| 53 | * The routine iso_gen_csum takes a pointer to an mbuf chain (logically |
| 54 | * a chunk of data), an offset into the chunk at which the 2 octets are to |
| 55 | * be stuffed, and the length of the chunk. The 2 octets have to be |
| 56 | * logically adjacent, but may be physically located in separate mbufs. |
| 57 | */ |
| 58 | |
| 59 | #ifdef ISO |
| 60 | #include "argo_debug.h" |
| 61 | #include "param.h" |
| 62 | #include "mbuf.h" |
| 63 | #endif ISO |
| 64 | |
| 65 | #ifndef MNULL |
| 66 | #define MNULL (struct mbuf *)0 |
| 67 | #endif MNULL |
| 68 | |
| 69 | /* |
| 70 | * FUNCTION: iso_check_csum |
| 71 | * |
| 72 | * PURPOSE: To check the checksum of the packet in the mbuf chain (m). |
| 73 | * The total length of the packet is (len). |
| 74 | * Called from tp_input() and clnp_intr() |
| 75 | * |
| 76 | * RETURNS: TRUE (something non-zero) if there is a checksum error, |
| 77 | * FALSE if there was NO checksum error. |
| 78 | * |
| 79 | * SIDE EFFECTS: none |
| 80 | * |
| 81 | * NOTES: It might be possible to gain something by optimizing |
| 82 | * this routine (unrolling loops, etc). But it is such |
| 83 | * a horrible thing to fiddle with anyway, it probably |
| 84 | * isn't worth it. |
| 85 | */ |
| 86 | int |
| 87 | iso_check_csum(m, len) |
| 88 | struct mbuf *m; |
| 89 | int len; |
| 90 | { |
| 91 | register u_char *p = mtod(m, u_char *); |
| 92 | register u_long c0=0, c1=0; |
| 93 | register int i=0; |
| 94 | int cum = 0; /* cumulative length */ |
| 95 | int l; |
| 96 | |
| 97 | l = len; |
| 98 | len = MIN(m->m_len, len); |
| 99 | i = 0; |
| 100 | |
| 101 | IFDEBUG(D_CHKSUM) |
| 102 | printf("iso_check_csum: m x%x, l x%x, m->m_len x%x\n", m, l, m->m_len); |
| 103 | ENDDEBUG |
| 104 | |
| 105 | while( i<l ) { |
| 106 | cum += len; |
| 107 | while (i<cum) { |
| 108 | c0 = c0 + *(p++); |
| 109 | c1 += c0; |
| 110 | i++; |
| 111 | } |
| 112 | if(i < l) { |
| 113 | m = m->m_next; |
| 114 | IFDEBUG(D_CHKSUM) |
| 115 | printf("iso_check_csum: new mbuf\n"); |
| 116 | if(l-i < m->m_len) |
| 117 | printf( |
| 118 | "bad mbuf chain in check csum l 0x%x i 0x%x m_data 0x%x", |
| 119 | l,i,m->m_data); |
| 120 | ENDDEBUG |
| 121 | ASSERT( m != MNULL); |
| 122 | len = MIN( m->m_len, l-i); |
| 123 | p = mtod(m, u_char *); |
| 124 | } |
| 125 | } |
| 126 | if ( ((int)c0 % 255) || ((int)c1 % 255) ) { |
| 127 | IFDEBUG(D_CHKSUM) |
| 128 | printf("BAD iso_check_csum l 0x%x cum 0x%x len 0x%x, i 0x%x", |
| 129 | l, cum, len, i); |
| 130 | ENDDEBUG |
| 131 | return ((int)c0 % 255)<<8 | ((int)c1 % 255); |
| 132 | } |
| 133 | return 0; |
| 134 | } |
| 135 | |
| 136 | /* |
| 137 | * FUNCTION: iso_gen_csum |
| 138 | * |
| 139 | * PURPOSE: To generate the checksum of the packet in the mbuf chain (m). |
| 140 | * The first of the 2 (logically) adjacent checksum bytes |
| 141 | * (x and y) go at offset (n). |
| 142 | * (n) is an offset relative to the beginning of the data, |
| 143 | * not the beginning of the mbuf. |
| 144 | * (l) is the length of the total mbuf chain's data. |
| 145 | * Called from tp_emit(), tp_error_emit() |
| 146 | * clnp_emit_er(), clnp_forward(), clnp_output(). |
| 147 | * |
| 148 | * RETURNS: Rien |
| 149 | * |
| 150 | * SIDE EFFECTS: Puts the 2 checksum bytes into the packet. |
| 151 | * |
| 152 | * NOTES: Ditto the note for iso_check_csum(). |
| 153 | */ |
| 154 | |
| 155 | void |
| 156 | iso_gen_csum(m,n,l) |
| 157 | struct mbuf *m; |
| 158 | int n; /* offset of 2 checksum bytes */ |
| 159 | int l; |
| 160 | { |
| 161 | register u_char *p = mtod(m, u_char *); |
| 162 | register int c0=0, c1=0; |
| 163 | register int i=0; |
| 164 | int loc = n++, len=0; /* n is position, loc is offset */ |
| 165 | u_char *xloc; |
| 166 | u_char *yloc; |
| 167 | int cum=0; /* cum == cumulative length */ |
| 168 | |
| 169 | IFDEBUG(D_CHKSUM) |
| 170 | printf("enter gen csum m 0x%x n 0x%x l 0x%x\n",m, n-1 ,l ); |
| 171 | ENDDEBUG |
| 172 | |
| 173 | while(i < l) { |
| 174 | len = MIN(m->m_len, CLBYTES); |
| 175 | /* RAH: don't cksum more than l bytes */ |
| 176 | len = MIN(len, l - i); |
| 177 | |
| 178 | cum +=len; |
| 179 | p = mtod(m, u_char *); |
| 180 | |
| 181 | if(loc>=0) { |
| 182 | if (loc < len) { |
| 183 | xloc = loc + mtod(m, u_char *); |
| 184 | IFDEBUG(D_CHKSUM) |
| 185 | printf("1: zeroing xloc 0x%x loc 0x%x\n",xloc, loc ); |
| 186 | ENDDEBUG |
| 187 | *xloc = (u_char)0; |
| 188 | if (loc+1 < len) { |
| 189 | /* both xloc and yloc are in same mbuf */ |
| 190 | yloc = 1 + xloc; |
| 191 | IFDEBUG(D_CHKSUM) |
| 192 | printf("2: zeroing yloc 0x%x loc 0x%x\n",yloc, loc ); |
| 193 | ENDDEBUG |
| 194 | *yloc = (u_char)0; |
| 195 | } else { |
| 196 | /* crosses boundary of mbufs */ |
| 197 | yloc = mtod(m->m_next, u_char *); |
| 198 | IFDEBUG(D_CHKSUM) |
| 199 | printf("3: zeroing yloc 0x%x \n",yloc ); |
| 200 | ENDDEBUG |
| 201 | *yloc = (u_char)0; |
| 202 | } |
| 203 | } |
| 204 | loc -= len; |
| 205 | } |
| 206 | |
| 207 | while(i < cum) { |
| 208 | c0 = (c0 + *p); |
| 209 | c1 += c0 ; |
| 210 | i++; |
| 211 | p++; |
| 212 | } |
| 213 | m = m->m_next; |
| 214 | } |
| 215 | IFDEBUG(D_CHKSUM) |
| 216 | printf("gen csum final xloc 0x%x yloc 0x%x\n",xloc, yloc ); |
| 217 | ENDDEBUG |
| 218 | |
| 219 | c1 = (((c0 * (l-n))-c1)%255) ; |
| 220 | *xloc = (u_char) ((c1 < 0)? c1+255 : c1); |
| 221 | |
| 222 | c1 = (-(int)(c1+c0))%255; |
| 223 | *yloc = (u_char) (c1 < 0? c1 + 255 : c1); |
| 224 | |
| 225 | IFDEBUG(D_CHKSUM) |
| 226 | printf("gen csum end \n"); |
| 227 | ENDDEBUG |
| 228 | } |
| 229 | |
| 230 | /* |
| 231 | * FUNCTION: m_datalen |
| 232 | * |
| 233 | * PURPOSE: returns length of the mbuf chain. |
| 234 | * used all over the iso code. |
| 235 | * |
| 236 | * RETURNS: integer |
| 237 | * |
| 238 | * SIDE EFFECTS: none |
| 239 | * |
| 240 | * NOTES: |
| 241 | */ |
| 242 | |
| 243 | int |
| 244 | m_datalen (m) |
| 245 | register struct mbuf *m; |
| 246 | { |
| 247 | register int datalen; |
| 248 | |
| 249 | for (datalen = 0; m; m = m->m_next) |
| 250 | datalen += m->m_len; |
| 251 | return datalen; |
| 252 | } |
| 253 | |
| 254 | int |
| 255 | m_compress(in, out) |
| 256 | register struct mbuf *in, **out; |
| 257 | { |
| 258 | register int datalen = 0; |
| 259 | int s = splimp(); |
| 260 | |
| 261 | if( in->m_next == MNULL ) { |
| 262 | *out = in; |
| 263 | IFDEBUG(D_REQUEST) |
| 264 | printf("m_compress returning 0x%x: A\n", in->m_len); |
| 265 | ENDDEBUG |
| 266 | splx(s); |
| 267 | return in->m_len; |
| 268 | } |
| 269 | MGET((*out), M_DONTWAIT, MT_DATA); |
| 270 | if((*out) == MNULL) { |
| 271 | *out = in; |
| 272 | IFDEBUG(D_REQUEST) |
| 273 | printf("m_compress returning -1: B\n"); |
| 274 | ENDDEBUG |
| 275 | splx(s); |
| 276 | return -1; |
| 277 | } |
| 278 | (*out)->m_len = 0; |
| 279 | (*out)->m_act = MNULL; |
| 280 | |
| 281 | while (in) { |
| 282 | IFDEBUG(D_REQUEST) |
| 283 | printf("m_compress in 0x%x *out 0x%x\n", in, *out); |
| 284 | printf("m_compress in: len 0x%x, off 0x%x\n", in->m_len, in->m_data); |
| 285 | printf("m_compress *out: len 0x%x, off 0x%x\n", (*out)->m_len, |
| 286 | (*out)->m_data); |
| 287 | ENDDEBUG |
| 288 | if (in->m_flags & M_EXT) { |
| 289 | ASSERT(in->m_len == 0); |
| 290 | } |
| 291 | if ( in->m_len == 0) { |
| 292 | in = in->m_next; |
| 293 | continue; |
| 294 | } |
| 295 | if (((*out)->m_flags & M_EXT) == 0) { |
| 296 | int len; |
| 297 | |
| 298 | len = M_TRAILINGSPACE(*out); |
| 299 | len = MIN(len, in->m_len); |
| 300 | datalen += len; |
| 301 | |
| 302 | IFDEBUG(D_REQUEST) |
| 303 | printf("m_compress copying len %d\n", len); |
| 304 | ENDDEBUG |
| 305 | bcopy(mtod(in, caddr_t), mtod((*out), caddr_t) + (*out)->m_len, |
| 306 | (unsigned)len); |
| 307 | |
| 308 | (*out)->m_len += len; |
| 309 | in->m_len -= len; |
| 310 | continue; |
| 311 | } else { |
| 312 | /* (*out) is full */ |
| 313 | if(( (*out)->m_next = m_get(M_DONTWAIT, MT_DATA) ) == MNULL) { |
| 314 | m_freem(*out); |
| 315 | *out = in; |
| 316 | IFDEBUG(D_REQUEST) |
| 317 | printf("m_compress returning -1: B\n"); |
| 318 | ENDDEBUG |
| 319 | splx(s); |
| 320 | return -1; |
| 321 | } |
| 322 | (*out)->m_len = 0; |
| 323 | (*out)->m_act = MNULL; |
| 324 | *out = (*out)->m_next; |
| 325 | } |
| 326 | } |
| 327 | m_freem(in); |
| 328 | IFDEBUG(D_REQUEST) |
| 329 | printf("m_compress returning 0x%x: A\n", datalen); |
| 330 | ENDDEBUG |
| 331 | splx(s); |
| 332 | return datalen; |
| 333 | } |