Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf.c
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1 /* 2 * Copyright (c) 1982, 1986, 1988, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94 34 */ 35 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD: releng/5.2/sys/kern/uipc_mbuf.c 119644 2003-09-01 05:55:37Z silby $"); 38 39 #include "opt_mac.h" 40 #include "opt_param.h" 41 #include "opt_mbuf_stress_test.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/kernel.h> 46 #include <sys/lock.h> 47 #include <sys/mac.h> 48 #include <sys/malloc.h> 49 #include <sys/mbuf.h> 50 #include <sys/sysctl.h> 51 #include <sys/domain.h> 52 #include <sys/protosw.h> 53 54 int max_linkhdr; 55 int max_protohdr; 56 int max_hdr; 57 int max_datalen; 58 #ifdef MBUF_STRESS_TEST 59 int m_defragpackets; 60 int m_defragbytes; 61 int m_defraguseless; 62 int m_defragfailure; 63 int m_defragrandomfailures; 64 #endif 65 66 /* 67 * sysctl(8) exported objects 68 */ 69 SYSCTL_DECL(_kern_ipc); 70 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW, 71 &max_linkhdr, 0, ""); 72 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW, 73 &max_protohdr, 0, ""); 74 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, ""); 75 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW, 76 &max_datalen, 0, ""); 77 #ifdef MBUF_STRESS_TEST 78 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD, 79 &m_defragpackets, 0, ""); 80 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD, 81 &m_defragbytes, 0, ""); 82 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD, 83 &m_defraguseless, 0, ""); 84 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD, 85 &m_defragfailure, 0, ""); 86 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW, 87 &m_defragrandomfailures, 0, ""); 88 #endif 89 90 /* 91 * "Move" mbuf pkthdr from "from" to "to". 92 * "from" must have M_PKTHDR set, and "to" must be empty. 93 */ 94 void 95 m_move_pkthdr(struct mbuf *to, struct mbuf *from) 96 { 97 98 #if 0 99 /* see below for why these are not enabled */ 100 M_ASSERTPKTHDR(to); 101 /* Note: with MAC, this may not be a good assertion. */ 102 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), 103 ("m_move_pkthdr: to has tags")); 104 #endif 105 KASSERT((to->m_flags & M_EXT) == 0, ("m_move_pkthdr: to has cluster")); 106 #ifdef MAC 107 /* 108 * XXXMAC: It could be this should also occur for non-MAC? 109 */ 110 if (to->m_flags & M_PKTHDR) 111 m_tag_delete_chain(to, NULL); 112 #endif 113 to->m_flags = from->m_flags & M_COPYFLAGS; 114 to->m_data = to->m_pktdat; 115 to->m_pkthdr = from->m_pkthdr; /* especially tags */ 116 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */ 117 from->m_flags &= ~M_PKTHDR; 118 } 119 120 /* 121 * Duplicate "from"'s mbuf pkthdr in "to". 122 * "from" must have M_PKTHDR set, and "to" must be empty. 123 * In particular, this does a deep copy of the packet tags. 124 */ 125 int 126 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how) 127 { 128 129 #if 0 130 /* 131 * The mbuf allocator only initializes the pkthdr 132 * when the mbuf is allocated with MGETHDR. Many users 133 * (e.g. m_copy*, m_prepend) use MGET and then 134 * smash the pkthdr as needed causing these 135 * assertions to trip. For now just disable them. 136 */ 137 M_ASSERTPKTHDR(to); 138 /* Note: with MAC, this may not be a good assertion. */ 139 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags")); 140 #endif 141 #ifdef MAC 142 if (to->m_flags & M_PKTHDR) 143 m_tag_delete_chain(to, NULL); 144 #endif 145 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 146 if ((to->m_flags & M_EXT) == 0) 147 to->m_data = to->m_pktdat; 148 to->m_pkthdr = from->m_pkthdr; 149 SLIST_INIT(&to->m_pkthdr.tags); 150 return (m_tag_copy_chain(to, from, MBTOM(how))); 151 } 152 153 /* 154 * Lesser-used path for M_PREPEND: 155 * allocate new mbuf to prepend to chain, 156 * copy junk along. 157 */ 158 struct mbuf * 159 m_prepend(struct mbuf *m, int len, int how) 160 { 161 struct mbuf *mn; 162 163 if (m->m_flags & M_PKTHDR) 164 MGETHDR(mn, how, m->m_type); 165 else 166 MGET(mn, how, m->m_type); 167 if (mn == NULL) { 168 m_freem(m); 169 return (NULL); 170 } 171 if (m->m_flags & M_PKTHDR) 172 M_MOVE_PKTHDR(mn, m); 173 mn->m_next = m; 174 m = mn; 175 if (len < MHLEN) 176 MH_ALIGN(m, len); 177 m->m_len = len; 178 return (m); 179 } 180 181 /* 182 * Make a copy of an mbuf chain starting "off0" bytes from the beginning, 183 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. 184 * The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller. 185 * Note that the copy is read-only, because clusters are not copied, 186 * only their reference counts are incremented. 187 */ 188 struct mbuf * 189 m_copym(struct mbuf *m, int off0, int len, int wait) 190 { 191 struct mbuf *n, **np; 192 int off = off0; 193 struct mbuf *top; 194 int copyhdr = 0; 195 196 KASSERT(off >= 0, ("m_copym, negative off %d", off)); 197 KASSERT(len >= 0, ("m_copym, negative len %d", len)); 198 if (off == 0 && m->m_flags & M_PKTHDR) 199 copyhdr = 1; 200 while (off > 0) { 201 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain")); 202 if (off < m->m_len) 203 break; 204 off -= m->m_len; 205 m = m->m_next; 206 } 207 np = ⊤ 208 top = 0; 209 while (len > 0) { 210 if (m == NULL) { 211 KASSERT(len == M_COPYALL, 212 ("m_copym, length > size of mbuf chain")); 213 break; 214 } 215 if (copyhdr) 216 MGETHDR(n, wait, m->m_type); 217 else 218 MGET(n, wait, m->m_type); 219 *np = n; 220 if (n == NULL) 221 goto nospace; 222 if (copyhdr) { 223 if (!m_dup_pkthdr(n, m, wait)) 224 goto nospace; 225 if (len == M_COPYALL) 226 n->m_pkthdr.len -= off0; 227 else 228 n->m_pkthdr.len = len; 229 copyhdr = 0; 230 } 231 n->m_len = min(len, m->m_len - off); 232 if (m->m_flags & M_EXT) { 233 n->m_data = m->m_data + off; 234 n->m_ext = m->m_ext; 235 n->m_flags |= M_EXT; 236 MEXT_ADD_REF(m); 237 } else 238 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 239 (u_int)n->m_len); 240 if (len != M_COPYALL) 241 len -= n->m_len; 242 off = 0; 243 m = m->m_next; 244 np = &n->m_next; 245 } 246 if (top == NULL) 247 mbstat.m_mcfail++; /* XXX: No consistency. */ 248 249 return (top); 250 nospace: 251 m_freem(top); 252 mbstat.m_mcfail++; /* XXX: No consistency. */ 253 return (NULL); 254 } 255 256 /* 257 * Copy an entire packet, including header (which must be present). 258 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 259 * Note that the copy is read-only, because clusters are not copied, 260 * only their reference counts are incremented. 261 * Preserve alignment of the first mbuf so if the creator has left 262 * some room at the beginning (e.g. for inserting protocol headers) 263 * the copies still have the room available. 264 */ 265 struct mbuf * 266 m_copypacket(struct mbuf *m, int how) 267 { 268 struct mbuf *top, *n, *o; 269 270 MGET(n, how, m->m_type); 271 top = n; 272 if (n == NULL) 273 goto nospace; 274 275 if (!m_dup_pkthdr(n, m, how)) 276 goto nospace; 277 n->m_len = m->m_len; 278 if (m->m_flags & M_EXT) { 279 n->m_data = m->m_data; 280 n->m_ext = m->m_ext; 281 n->m_flags |= M_EXT; 282 MEXT_ADD_REF(m); 283 } else { 284 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat ); 285 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 286 } 287 288 m = m->m_next; 289 while (m) { 290 MGET(o, how, m->m_type); 291 if (o == NULL) 292 goto nospace; 293 294 n->m_next = o; 295 n = n->m_next; 296 297 n->m_len = m->m_len; 298 if (m->m_flags & M_EXT) { 299 n->m_data = m->m_data; 300 n->m_ext = m->m_ext; 301 n->m_flags |= M_EXT; 302 MEXT_ADD_REF(m); 303 } else { 304 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 305 } 306 307 m = m->m_next; 308 } 309 return top; 310 nospace: 311 m_freem(top); 312 mbstat.m_mcfail++; /* XXX: No consistency. */ 313 return (NULL); 314 } 315 316 /* 317 * Copy data from an mbuf chain starting "off" bytes from the beginning, 318 * continuing for "len" bytes, into the indicated buffer. 319 */ 320 void 321 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp) 322 { 323 u_int count; 324 325 KASSERT(off >= 0, ("m_copydata, negative off %d", off)); 326 KASSERT(len >= 0, ("m_copydata, negative len %d", len)); 327 while (off > 0) { 328 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain")); 329 if (off < m->m_len) 330 break; 331 off -= m->m_len; 332 m = m->m_next; 333 } 334 while (len > 0) { 335 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain")); 336 count = min(m->m_len - off, len); 337 bcopy(mtod(m, caddr_t) + off, cp, count); 338 len -= count; 339 cp += count; 340 off = 0; 341 m = m->m_next; 342 } 343 } 344 345 /* 346 * Copy a packet header mbuf chain into a completely new chain, including 347 * copying any mbuf clusters. Use this instead of m_copypacket() when 348 * you need a writable copy of an mbuf chain. 349 */ 350 struct mbuf * 351 m_dup(struct mbuf *m, int how) 352 { 353 struct mbuf **p, *top = NULL; 354 int remain, moff, nsize; 355 356 /* Sanity check */ 357 if (m == NULL) 358 return (NULL); 359 M_ASSERTPKTHDR(m); 360 361 /* While there's more data, get a new mbuf, tack it on, and fill it */ 362 remain = m->m_pkthdr.len; 363 moff = 0; 364 p = ⊤ 365 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ 366 struct mbuf *n; 367 368 /* Get the next new mbuf */ 369 MGET(n, how, m->m_type); 370 if (n == NULL) 371 goto nospace; 372 if (top == NULL) { /* first one, must be PKTHDR */ 373 if (!m_dup_pkthdr(n, m, how)) 374 goto nospace; 375 nsize = MHLEN; 376 } else /* not the first one */ 377 nsize = MLEN; 378 if (remain >= MINCLSIZE) { 379 MCLGET(n, how); 380 if ((n->m_flags & M_EXT) == 0) { 381 (void)m_free(n); 382 goto nospace; 383 } 384 nsize = MCLBYTES; 385 } 386 n->m_len = 0; 387 388 /* Link it into the new chain */ 389 *p = n; 390 p = &n->m_next; 391 392 /* Copy data from original mbuf(s) into new mbuf */ 393 while (n->m_len < nsize && m != NULL) { 394 int chunk = min(nsize - n->m_len, m->m_len - moff); 395 396 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); 397 moff += chunk; 398 n->m_len += chunk; 399 remain -= chunk; 400 if (moff == m->m_len) { 401 m = m->m_next; 402 moff = 0; 403 } 404 } 405 406 /* Check correct total mbuf length */ 407 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), 408 ("%s: bogus m_pkthdr.len", __func__)); 409 } 410 return (top); 411 412 nospace: 413 m_freem(top); 414 mbstat.m_mcfail++; /* XXX: No consistency. */ 415 return (NULL); 416 } 417 418 /* 419 * Concatenate mbuf chain n to m. 420 * Both chains must be of the same type (e.g. MT_DATA). 421 * Any m_pkthdr is not updated. 422 */ 423 void 424 m_cat(struct mbuf *m, struct mbuf *n) 425 { 426 while (m->m_next) 427 m = m->m_next; 428 while (n) { 429 if (m->m_flags & M_EXT || 430 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) { 431 /* just join the two chains */ 432 m->m_next = n; 433 return; 434 } 435 /* splat the data from one into the other */ 436 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 437 (u_int)n->m_len); 438 m->m_len += n->m_len; 439 n = m_free(n); 440 } 441 } 442 443 void 444 m_adj(struct mbuf *mp, int req_len) 445 { 446 int len = req_len; 447 struct mbuf *m; 448 int count; 449 450 if ((m = mp) == NULL) 451 return; 452 if (len >= 0) { 453 /* 454 * Trim from head. 455 */ 456 while (m != NULL && len > 0) { 457 if (m->m_len <= len) { 458 len -= m->m_len; 459 m->m_len = 0; 460 m = m->m_next; 461 } else { 462 m->m_len -= len; 463 m->m_data += len; 464 len = 0; 465 } 466 } 467 m = mp; 468 if (mp->m_flags & M_PKTHDR) 469 m->m_pkthdr.len -= (req_len - len); 470 } else { 471 /* 472 * Trim from tail. Scan the mbuf chain, 473 * calculating its length and finding the last mbuf. 474 * If the adjustment only affects this mbuf, then just 475 * adjust and return. Otherwise, rescan and truncate 476 * after the remaining size. 477 */ 478 len = -len; 479 count = 0; 480 for (;;) { 481 count += m->m_len; 482 if (m->m_next == (struct mbuf *)0) 483 break; 484 m = m->m_next; 485 } 486 if (m->m_len >= len) { 487 m->m_len -= len; 488 if (mp->m_flags & M_PKTHDR) 489 mp->m_pkthdr.len -= len; 490 return; 491 } 492 count -= len; 493 if (count < 0) 494 count = 0; 495 /* 496 * Correct length for chain is "count". 497 * Find the mbuf with last data, adjust its length, 498 * and toss data from remaining mbufs on chain. 499 */ 500 m = mp; 501 if (m->m_flags & M_PKTHDR) 502 m->m_pkthdr.len = count; 503 for (; m; m = m->m_next) { 504 if (m->m_len >= count) { 505 m->m_len = count; 506 break; 507 } 508 count -= m->m_len; 509 } 510 while (m->m_next) 511 (m = m->m_next) ->m_len = 0; 512 } 513 } 514 515 /* 516 * Rearange an mbuf chain so that len bytes are contiguous 517 * and in the data area of an mbuf (so that mtod and dtom 518 * will work for a structure of size len). Returns the resulting 519 * mbuf chain on success, frees it and returns null on failure. 520 * If there is room, it will add up to max_protohdr-len extra bytes to the 521 * contiguous region in an attempt to avoid being called next time. 522 */ 523 struct mbuf * 524 m_pullup(struct mbuf *n, int len) 525 { 526 struct mbuf *m; 527 int count; 528 int space; 529 530 /* 531 * If first mbuf has no cluster, and has room for len bytes 532 * without shifting current data, pullup into it, 533 * otherwise allocate a new mbuf to prepend to the chain. 534 */ 535 if ((n->m_flags & M_EXT) == 0 && 536 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 537 if (n->m_len >= len) 538 return (n); 539 m = n; 540 n = n->m_next; 541 len -= m->m_len; 542 } else { 543 if (len > MHLEN) 544 goto bad; 545 MGET(m, M_DONTWAIT, n->m_type); 546 if (m == NULL) 547 goto bad; 548 m->m_len = 0; 549 if (n->m_flags & M_PKTHDR) 550 M_MOVE_PKTHDR(m, n); 551 } 552 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 553 do { 554 count = min(min(max(len, max_protohdr), space), n->m_len); 555 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 556 (u_int)count); 557 len -= count; 558 m->m_len += count; 559 n->m_len -= count; 560 space -= count; 561 if (n->m_len) 562 n->m_data += count; 563 else 564 n = m_free(n); 565 } while (len > 0 && n); 566 if (len > 0) { 567 (void) m_free(m); 568 goto bad; 569 } 570 m->m_next = n; 571 return (m); 572 bad: 573 m_freem(n); 574 mbstat.m_mpfail++; /* XXX: No consistency. */ 575 return (NULL); 576 } 577 578 /* 579 * Partition an mbuf chain in two pieces, returning the tail -- 580 * all but the first len0 bytes. In case of failure, it returns NULL and 581 * attempts to restore the chain to its original state. 582 * 583 * Note that the resulting mbufs might be read-only, because the new 584 * mbuf can end up sharing an mbuf cluster with the original mbuf if 585 * the "breaking point" happens to lie within a cluster mbuf. Use the 586 * M_WRITABLE() macro to check for this case. 587 */ 588 struct mbuf * 589 m_split(struct mbuf *m0, int len0, int wait) 590 { 591 struct mbuf *m, *n; 592 u_int len = len0, remain; 593 594 for (m = m0; m && len > m->m_len; m = m->m_next) 595 len -= m->m_len; 596 if (m == NULL) 597 return (NULL); 598 remain = m->m_len - len; 599 if (m0->m_flags & M_PKTHDR) { 600 MGETHDR(n, wait, m0->m_type); 601 if (n == NULL) 602 return (NULL); 603 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 604 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 605 m0->m_pkthdr.len = len0; 606 if (m->m_flags & M_EXT) 607 goto extpacket; 608 if (remain > MHLEN) { 609 /* m can't be the lead packet */ 610 MH_ALIGN(n, 0); 611 n->m_next = m_split(m, len, wait); 612 if (n->m_next == NULL) { 613 (void) m_free(n); 614 return (NULL); 615 } else { 616 n->m_len = 0; 617 return (n); 618 } 619 } else 620 MH_ALIGN(n, remain); 621 } else if (remain == 0) { 622 n = m->m_next; 623 m->m_next = NULL; 624 return (n); 625 } else { 626 MGET(n, wait, m->m_type); 627 if (n == NULL) 628 return (NULL); 629 M_ALIGN(n, remain); 630 } 631 extpacket: 632 if (m->m_flags & M_EXT) { 633 n->m_flags |= M_EXT; 634 n->m_ext = m->m_ext; 635 MEXT_ADD_REF(m); 636 n->m_data = m->m_data + len; 637 } else { 638 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 639 } 640 n->m_len = remain; 641 m->m_len = len; 642 n->m_next = m->m_next; 643 m->m_next = NULL; 644 return (n); 645 } 646 /* 647 * Routine to copy from device local memory into mbufs. 648 * Note that `off' argument is offset into first mbuf of target chain from 649 * which to begin copying the data to. 650 */ 651 struct mbuf * 652 m_devget(char *buf, int totlen, int off, struct ifnet *ifp, 653 void (*copy)(char *from, caddr_t to, u_int len)) 654 { 655 struct mbuf *m; 656 struct mbuf *top = 0, **mp = ⊤ 657 int len; 658 659 if (off < 0 || off > MHLEN) 660 return (NULL); 661 662 MGETHDR(m, M_DONTWAIT, MT_DATA); 663 if (m == NULL) 664 return (NULL); 665 m->m_pkthdr.rcvif = ifp; 666 m->m_pkthdr.len = totlen; 667 len = MHLEN; 668 669 while (totlen > 0) { 670 if (top) { 671 MGET(m, M_DONTWAIT, MT_DATA); 672 if (m == NULL) { 673 m_freem(top); 674 return (NULL); 675 } 676 len = MLEN; 677 } 678 if (totlen + off >= MINCLSIZE) { 679 MCLGET(m, M_DONTWAIT); 680 if (m->m_flags & M_EXT) 681 len = MCLBYTES; 682 } else { 683 /* 684 * Place initial small packet/header at end of mbuf. 685 */ 686 if (top == NULL && totlen + off + max_linkhdr <= len) { 687 m->m_data += max_linkhdr; 688 len -= max_linkhdr; 689 } 690 } 691 if (off) { 692 m->m_data += off; 693 len -= off; 694 off = 0; 695 } 696 m->m_len = len = min(totlen, len); 697 if (copy) 698 copy(buf, mtod(m, caddr_t), (u_int)len); 699 else 700 bcopy(buf, mtod(m, caddr_t), (u_int)len); 701 buf += len; 702 *mp = m; 703 mp = &m->m_next; 704 totlen -= len; 705 } 706 return (top); 707 } 708 709 /* 710 * Copy data from a buffer back into the indicated mbuf chain, 711 * starting "off" bytes from the beginning, extending the mbuf 712 * chain if necessary. 713 */ 714 void 715 m_copyback(struct mbuf *m0, int off, int len, caddr_t cp) 716 { 717 int mlen; 718 struct mbuf *m = m0, *n; 719 int totlen = 0; 720 721 if (m0 == NULL) 722 return; 723 while (off > (mlen = m->m_len)) { 724 off -= mlen; 725 totlen += mlen; 726 if (m->m_next == NULL) { 727 n = m_get_clrd(M_DONTWAIT, m->m_type); 728 if (n == NULL) 729 goto out; 730 n->m_len = min(MLEN, len + off); 731 m->m_next = n; 732 } 733 m = m->m_next; 734 } 735 while (len > 0) { 736 mlen = min (m->m_len - off, len); 737 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen); 738 cp += mlen; 739 len -= mlen; 740 mlen += off; 741 off = 0; 742 totlen += mlen; 743 if (len == 0) 744 break; 745 if (m->m_next == NULL) { 746 n = m_get(M_DONTWAIT, m->m_type); 747 if (n == NULL) 748 break; 749 n->m_len = min(MLEN, len); 750 m->m_next = n; 751 } 752 m = m->m_next; 753 } 754 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 755 m->m_pkthdr.len = totlen; 756 } 757 758 void 759 m_print(const struct mbuf *m) 760 { 761 int len; 762 const struct mbuf *m2; 763 764 len = m->m_pkthdr.len; 765 m2 = m; 766 while (len) { 767 printf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-"); 768 len -= m2->m_len; 769 m2 = m2->m_next; 770 } 771 return; 772 } 773 774 u_int 775 m_fixhdr(struct mbuf *m0) 776 { 777 u_int len; 778 779 len = m_length(m0, NULL); 780 m0->m_pkthdr.len = len; 781 return (len); 782 } 783 784 u_int 785 m_length(struct mbuf *m0, struct mbuf **last) 786 { 787 struct mbuf *m; 788 u_int len; 789 790 len = 0; 791 for (m = m0; m != NULL; m = m->m_next) { 792 len += m->m_len; 793 if (m->m_next == NULL) 794 break; 795 } 796 if (last != NULL) 797 *last = m; 798 return (len); 799 } 800 801 /* 802 * Defragment a mbuf chain, returning the shortest possible 803 * chain of mbufs and clusters. If allocation fails and 804 * this cannot be completed, NULL will be returned, but 805 * the passed in chain will be unchanged. Upon success, 806 * the original chain will be freed, and the new chain 807 * will be returned. 808 * 809 * If a non-packet header is passed in, the original 810 * mbuf (chain?) will be returned unharmed. 811 */ 812 struct mbuf * 813 m_defrag(struct mbuf *m0, int how) 814 { 815 struct mbuf *m_new = NULL, *m_final = NULL; 816 int progress = 0, length; 817 818 if (!(m0->m_flags & M_PKTHDR)) 819 return (m0); 820 821 m_fixhdr(m0); /* Needed sanity check */ 822 823 #ifdef MBUF_STRESS_TEST 824 if (m_defragrandomfailures) { 825 int temp = arc4random() & 0xff; 826 if (temp == 0xba) 827 goto nospace; 828 } 829 #endif 830 831 if (m0->m_pkthdr.len > MHLEN) 832 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 833 else 834 m_final = m_gethdr(how, MT_DATA); 835 836 if (m_final == NULL) 837 goto nospace; 838 839 if (m_dup_pkthdr(m_final, m0, how) == NULL) 840 goto nospace; 841 842 m_new = m_final; 843 844 while (progress < m0->m_pkthdr.len) { 845 length = m0->m_pkthdr.len - progress; 846 if (length > MCLBYTES) 847 length = MCLBYTES; 848 849 if (m_new == NULL) { 850 if (length > MLEN) 851 m_new = m_getcl(how, MT_DATA, 0); 852 else 853 m_new = m_get(how, MT_DATA); 854 if (m_new == NULL) 855 goto nospace; 856 } 857 858 m_copydata(m0, progress, length, mtod(m_new, caddr_t)); 859 progress += length; 860 m_new->m_len = length; 861 if (m_new != m_final) 862 m_cat(m_final, m_new); 863 m_new = NULL; 864 } 865 #ifdef MBUF_STRESS_TEST 866 if (m0->m_next == NULL) 867 m_defraguseless++; 868 #endif 869 m_freem(m0); 870 m0 = m_final; 871 #ifdef MBUF_STRESS_TEST 872 m_defragpackets++; 873 m_defragbytes += m0->m_pkthdr.len; 874 #endif 875 return (m0); 876 nospace: 877 #ifdef MBUF_STRESS_TEST 878 m_defragfailure++; 879 #endif 880 if (m_new) 881 m_free(m_new); 882 if (m_final) 883 m_freem(m_final); 884 return (NULL); 885 } 886 887 #ifdef MBUF_STRESS_TEST 888 889 /* 890 * Fragment an mbuf chain. There's no reason you'd ever want to do 891 * this in normal usage, but it's great for stress testing various 892 * mbuf consumers. 893 * 894 * If fragmentation is not possible, the original chain will be 895 * returned. 896 * 897 * Possible length values: 898 * 0 no fragmentation will occur 899 * > 0 each fragment will be of the specified length 900 * -1 each fragment will be the same random value in length 901 * -2 each fragment's length will be entirely random 902 * (Random values range from 1 to 256) 903 */ 904 struct mbuf * 905 m_fragment(struct mbuf *m0, int how, int length) 906 { 907 struct mbuf *m_new = NULL, *m_final = NULL; 908 int progress = 0; 909 910 if (!(m0->m_flags & M_PKTHDR)) 911 return (m0); 912 913 if ((length == 0) || (length < -2)) 914 return (m0); 915 916 m_fixhdr(m0); /* Needed sanity check */ 917 918 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 919 920 if (m_final == NULL) 921 goto nospace; 922 923 if (m_dup_pkthdr(m_final, m0, how) == NULL) 924 goto nospace; 925 926 m_new = m_final; 927 928 if (length == -1) 929 length = 1 + (arc4random() & 255); 930 931 while (progress < m0->m_pkthdr.len) { 932 int fraglen; 933 934 if (length > 0) 935 fraglen = length; 936 else 937 fraglen = 1 + (arc4random() & 255); 938 if (fraglen > m0->m_pkthdr.len - progress) 939 fraglen = m0->m_pkthdr.len - progress; 940 941 if (fraglen > MCLBYTES) 942 fraglen = MCLBYTES; 943 944 if (m_new == NULL) { 945 m_new = m_getcl(how, MT_DATA, 0); 946 if (m_new == NULL) 947 goto nospace; 948 } 949 950 m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t)); 951 progress += fraglen; 952 m_new->m_len = fraglen; 953 if (m_new != m_final) 954 m_cat(m_final, m_new); 955 m_new = NULL; 956 } 957 m_freem(m0); 958 m0 = m_final; 959 return (m0); 960 nospace: 961 if (m_new) 962 m_free(m_new); 963 if (m_final) 964 m_freem(m_final); 965 /* Return the original chain on failure */ 966 return (m0); 967 } 968 969 #endif
Cache object: 24e115151873417cea5874d4fc1dfad3
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