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 * $FreeBSD$ 35 */ 36 37 #include "opt_mac.h" 38 #include "opt_param.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/kernel.h> 43 #include <sys/lock.h> 44 #include <sys/mac.h> 45 #include <sys/malloc.h> 46 #include <sys/mbuf.h> 47 #include <sys/sysctl.h> 48 #include <sys/domain.h> 49 #include <sys/protosw.h> 50 51 int max_linkhdr; 52 int max_protohdr; 53 int max_hdr; 54 int max_datalen; 55 int m_defragpackets; 56 int m_defragbytes; 57 int m_defraguseless; 58 int m_defragfailure; 59 60 /* 61 * sysctl(8) exported objects 62 */ 63 SYSCTL_DECL(_kern_ipc); 64 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW, 65 &max_linkhdr, 0, ""); 66 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW, 67 &max_protohdr, 0, ""); 68 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, ""); 69 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW, 70 &max_datalen, 0, ""); 71 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD, 72 &m_defragpackets, 0, ""); 73 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD, 74 &m_defragbytes, 0, ""); 75 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD, 76 &m_defraguseless, 0, ""); 77 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD, 78 &m_defragfailure, 0, ""); 79 80 /* 81 * "Move" mbuf pkthdr from "from" to "to". 82 * "from" must have M_PKTHDR set, and "to" must be empty. 83 */ 84 void 85 m_move_pkthdr(struct mbuf *to, struct mbuf *from) 86 { 87 88 #if 0 89 /* see below for why these are not enabled */ 90 KASSERT(to->m_flags & M_PKTHDR, 91 ("m_move_pkthdr: called on non-header")); 92 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), 93 ("m_move_pkthdr: to has tags")); 94 #endif 95 KASSERT((to->m_flags & M_EXT) == 0, ("m_move_pkthdr: to has cluster")); 96 #ifdef MAC 97 if (to->m_flags & M_PKTHDR) 98 mac_destroy_mbuf(to); 99 #endif 100 to->m_flags = from->m_flags & M_COPYFLAGS; 101 to->m_data = to->m_pktdat; 102 to->m_pkthdr = from->m_pkthdr; /* especially tags */ 103 #ifdef MAC 104 mac_init_mbuf(to, 1); /* XXXMAC no way to fail */ 105 mac_create_mbuf_from_mbuf(from, to); 106 #endif 107 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */ 108 from->m_flags &= ~M_PKTHDR; 109 } 110 111 /* 112 * Duplicate "from"'s mbuf pkthdr in "to". 113 * "from" must have M_PKTHDR set, and "to" must be empty. 114 * In particular, this does a deep copy of the packet tags. 115 */ 116 int 117 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how) 118 { 119 120 #if 0 121 /* 122 * The mbuf allocator only initializes the pkthdr 123 * when the mbuf is allocated with MGETHDR. Many users 124 * (e.g. m_copy*, m_prepend) use MGET and then 125 * smash the pkthdr as needed causing these 126 * assertions to trip. For now just disable them. 127 */ 128 KASSERT(to->m_flags & M_PKTHDR, ("m_dup_pkthdr: called on non-header")); 129 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags")); 130 #endif 131 #ifdef MAC 132 if (to->m_flags & M_PKTHDR) 133 mac_destroy_mbuf(to); 134 #endif 135 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 136 if ((to->m_flags & M_EXT) == 0) 137 to->m_data = to->m_pktdat; 138 to->m_pkthdr = from->m_pkthdr; 139 #ifdef MAC 140 mac_init_mbuf(to, 1); /* XXXMAC no way to fail */ 141 mac_create_mbuf_from_mbuf(from, to); 142 #endif 143 SLIST_INIT(&to->m_pkthdr.tags); 144 return (m_tag_copy_chain(to, from, (how & M_TRYWAIT) ? M_WAITOK : 145 M_NOWAIT)); 146 } 147 148 /* 149 * Lesser-used path for M_PREPEND: 150 * allocate new mbuf to prepend to chain, 151 * copy junk along. 152 */ 153 struct mbuf * 154 m_prepend(struct mbuf *m, int len, int how) 155 { 156 struct mbuf *mn; 157 158 MGET(mn, how, m->m_type); 159 if (mn == NULL) { 160 m_freem(m); 161 return (NULL); 162 } 163 if (m->m_flags & M_PKTHDR) { 164 M_MOVE_PKTHDR(mn, m); 165 #ifdef MAC 166 mac_destroy_mbuf(m); 167 #endif 168 } 169 mn->m_next = m; 170 m = mn; 171 if (len < MHLEN) 172 MH_ALIGN(m, len); 173 m->m_len = len; 174 return (m); 175 } 176 177 /* 178 * Make a copy of an mbuf chain starting "off0" bytes from the beginning, 179 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. 180 * The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller. 181 * Note that the copy is read-only, because clusters are not copied, 182 * only their reference counts are incremented. 183 */ 184 struct mbuf * 185 m_copym(struct mbuf *m, int off0, int len, int wait) 186 { 187 struct mbuf *n, **np; 188 int off = off0; 189 struct mbuf *top; 190 int copyhdr = 0; 191 192 KASSERT(off >= 0, ("m_copym, negative off %d", off)); 193 KASSERT(len >= 0, ("m_copym, negative len %d", len)); 194 if (off == 0 && m->m_flags & M_PKTHDR) 195 copyhdr = 1; 196 while (off > 0) { 197 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain")); 198 if (off < m->m_len) 199 break; 200 off -= m->m_len; 201 m = m->m_next; 202 } 203 np = ⊤ 204 top = 0; 205 while (len > 0) { 206 if (m == NULL) { 207 KASSERT(len == M_COPYALL, 208 ("m_copym, length > size of mbuf chain")); 209 break; 210 } 211 MGET(n, wait, m->m_type); 212 *np = n; 213 if (n == NULL) 214 goto nospace; 215 if (copyhdr) { 216 if (!m_dup_pkthdr(n, m, wait)) 217 goto nospace; 218 if (len == M_COPYALL) 219 n->m_pkthdr.len -= off0; 220 else 221 n->m_pkthdr.len = len; 222 copyhdr = 0; 223 } 224 n->m_len = min(len, m->m_len - off); 225 if (m->m_flags & M_EXT) { 226 n->m_data = m->m_data + off; 227 n->m_ext = m->m_ext; 228 n->m_flags |= M_EXT; 229 MEXT_ADD_REF(m); 230 } else 231 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 232 (u_int)n->m_len); 233 if (len != M_COPYALL) 234 len -= n->m_len; 235 off = 0; 236 m = m->m_next; 237 np = &n->m_next; 238 } 239 if (top == NULL) 240 mbstat.m_mcfail++; /* XXX: No consistency. */ 241 242 return (top); 243 nospace: 244 m_freem(top); 245 mbstat.m_mcfail++; /* XXX: No consistency. */ 246 return (NULL); 247 } 248 249 /* 250 * Copy an entire packet, including header (which must be present). 251 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 252 * Note that the copy is read-only, because clusters are not copied, 253 * only their reference counts are incremented. 254 * Preserve alignment of the first mbuf so if the creator has left 255 * some room at the beginning (e.g. for inserting protocol headers) 256 * the copies still have the room available. 257 */ 258 struct mbuf * 259 m_copypacket(struct mbuf *m, int how) 260 { 261 struct mbuf *top, *n, *o; 262 263 MGET(n, how, m->m_type); 264 top = n; 265 if (n == NULL) 266 goto nospace; 267 268 if (!m_dup_pkthdr(n, m, how)) 269 goto nospace; 270 n->m_len = m->m_len; 271 if (m->m_flags & M_EXT) { 272 n->m_data = m->m_data; 273 n->m_ext = m->m_ext; 274 n->m_flags |= M_EXT; 275 MEXT_ADD_REF(m); 276 } else { 277 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat ); 278 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 279 } 280 281 m = m->m_next; 282 while (m) { 283 MGET(o, how, m->m_type); 284 if (o == NULL) 285 goto nospace; 286 287 n->m_next = o; 288 n = n->m_next; 289 290 n->m_len = m->m_len; 291 if (m->m_flags & M_EXT) { 292 n->m_data = m->m_data; 293 n->m_ext = m->m_ext; 294 n->m_flags |= M_EXT; 295 MEXT_ADD_REF(m); 296 } else { 297 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 298 } 299 300 m = m->m_next; 301 } 302 return top; 303 nospace: 304 m_freem(top); 305 mbstat.m_mcfail++; /* XXX: No consistency. */ 306 return (NULL); 307 } 308 309 /* 310 * Copy data from an mbuf chain starting "off" bytes from the beginning, 311 * continuing for "len" bytes, into the indicated buffer. 312 */ 313 void 314 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp) 315 { 316 u_int count; 317 318 KASSERT(off >= 0, ("m_copydata, negative off %d", off)); 319 KASSERT(len >= 0, ("m_copydata, negative len %d", len)); 320 while (off > 0) { 321 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain")); 322 if (off < m->m_len) 323 break; 324 off -= m->m_len; 325 m = m->m_next; 326 } 327 while (len > 0) { 328 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain")); 329 count = min(m->m_len - off, len); 330 bcopy(mtod(m, caddr_t) + off, cp, count); 331 len -= count; 332 cp += count; 333 off = 0; 334 m = m->m_next; 335 } 336 } 337 338 /* 339 * Copy a packet header mbuf chain into a completely new chain, including 340 * copying any mbuf clusters. Use this instead of m_copypacket() when 341 * you need a writable copy of an mbuf chain. 342 */ 343 struct mbuf * 344 m_dup(struct mbuf *m, int how) 345 { 346 struct mbuf **p, *top = NULL; 347 int remain, moff, nsize; 348 349 /* Sanity check */ 350 if (m == NULL) 351 return (NULL); 352 KASSERT((m->m_flags & M_PKTHDR) != 0, ("%s: !PKTHDR", __func__)); 353 354 /* While there's more data, get a new mbuf, tack it on, and fill it */ 355 remain = m->m_pkthdr.len; 356 moff = 0; 357 p = ⊤ 358 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ 359 struct mbuf *n; 360 361 /* Get the next new mbuf */ 362 MGET(n, how, m->m_type); 363 if (n == NULL) 364 goto nospace; 365 if (top == NULL) { /* first one, must be PKTHDR */ 366 if (!m_dup_pkthdr(n, m, how)) 367 goto nospace; 368 nsize = MHLEN; 369 } else /* not the first one */ 370 nsize = MLEN; 371 if (remain >= MINCLSIZE) { 372 MCLGET(n, how); 373 if ((n->m_flags & M_EXT) == 0) { 374 (void)m_free(n); 375 goto nospace; 376 } 377 nsize = MCLBYTES; 378 } 379 n->m_len = 0; 380 381 /* Link it into the new chain */ 382 *p = n; 383 p = &n->m_next; 384 385 /* Copy data from original mbuf(s) into new mbuf */ 386 while (n->m_len < nsize && m != NULL) { 387 int chunk = min(nsize - n->m_len, m->m_len - moff); 388 389 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); 390 moff += chunk; 391 n->m_len += chunk; 392 remain -= chunk; 393 if (moff == m->m_len) { 394 m = m->m_next; 395 moff = 0; 396 } 397 } 398 399 /* Check correct total mbuf length */ 400 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), 401 ("%s: bogus m_pkthdr.len", __func__)); 402 } 403 return (top); 404 405 nospace: 406 m_freem(top); 407 mbstat.m_mcfail++; /* XXX: No consistency. */ 408 return (NULL); 409 } 410 411 /* 412 * Concatenate mbuf chain n to m. 413 * Both chains must be of the same type (e.g. MT_DATA). 414 * Any m_pkthdr is not updated. 415 */ 416 void 417 m_cat(struct mbuf *m, struct mbuf *n) 418 { 419 while (m->m_next) 420 m = m->m_next; 421 while (n) { 422 if (m->m_flags & M_EXT || 423 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) { 424 /* just join the two chains */ 425 m->m_next = n; 426 return; 427 } 428 /* splat the data from one into the other */ 429 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 430 (u_int)n->m_len); 431 m->m_len += n->m_len; 432 n = m_free(n); 433 } 434 } 435 436 void 437 m_adj(struct mbuf *mp, int req_len) 438 { 439 int len = req_len; 440 struct mbuf *m; 441 int count; 442 443 if ((m = mp) == NULL) 444 return; 445 if (len >= 0) { 446 /* 447 * Trim from head. 448 */ 449 while (m != NULL && len > 0) { 450 if (m->m_len <= len) { 451 len -= m->m_len; 452 m->m_len = 0; 453 m = m->m_next; 454 } else { 455 m->m_len -= len; 456 m->m_data += len; 457 len = 0; 458 } 459 } 460 m = mp; 461 if (mp->m_flags & M_PKTHDR) 462 m->m_pkthdr.len -= (req_len - len); 463 } else { 464 /* 465 * Trim from tail. Scan the mbuf chain, 466 * calculating its length and finding the last mbuf. 467 * If the adjustment only affects this mbuf, then just 468 * adjust and return. Otherwise, rescan and truncate 469 * after the remaining size. 470 */ 471 len = -len; 472 count = 0; 473 for (;;) { 474 count += m->m_len; 475 if (m->m_next == (struct mbuf *)0) 476 break; 477 m = m->m_next; 478 } 479 if (m->m_len >= len) { 480 m->m_len -= len; 481 if (mp->m_flags & M_PKTHDR) 482 mp->m_pkthdr.len -= len; 483 return; 484 } 485 count -= len; 486 if (count < 0) 487 count = 0; 488 /* 489 * Correct length for chain is "count". 490 * Find the mbuf with last data, adjust its length, 491 * and toss data from remaining mbufs on chain. 492 */ 493 m = mp; 494 if (m->m_flags & M_PKTHDR) 495 m->m_pkthdr.len = count; 496 for (; m; m = m->m_next) { 497 if (m->m_len >= count) { 498 m->m_len = count; 499 break; 500 } 501 count -= m->m_len; 502 } 503 while (m->m_next) 504 (m = m->m_next) ->m_len = 0; 505 } 506 } 507 508 /* 509 * Rearange an mbuf chain so that len bytes are contiguous 510 * and in the data area of an mbuf (so that mtod and dtom 511 * will work for a structure of size len). Returns the resulting 512 * mbuf chain on success, frees it and returns null on failure. 513 * If there is room, it will add up to max_protohdr-len extra bytes to the 514 * contiguous region in an attempt to avoid being called next time. 515 */ 516 struct mbuf * 517 m_pullup(struct mbuf *n, int len) 518 { 519 struct mbuf *m; 520 int count; 521 int space; 522 523 /* 524 * If first mbuf has no cluster, and has room for len bytes 525 * without shifting current data, pullup into it, 526 * otherwise allocate a new mbuf to prepend to the chain. 527 */ 528 if ((n->m_flags & M_EXT) == 0 && 529 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 530 if (n->m_len >= len) 531 return (n); 532 m = n; 533 n = n->m_next; 534 len -= m->m_len; 535 } else { 536 if (len > MHLEN) 537 goto bad; 538 MGET(m, M_DONTWAIT, n->m_type); 539 if (m == NULL) 540 goto bad; 541 m->m_len = 0; 542 if (n->m_flags & M_PKTHDR) 543 M_MOVE_PKTHDR(m, n); 544 } 545 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 546 do { 547 count = min(min(max(len, max_protohdr), space), n->m_len); 548 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 549 (u_int)count); 550 len -= count; 551 m->m_len += count; 552 n->m_len -= count; 553 space -= count; 554 if (n->m_len) 555 n->m_data += count; 556 else 557 n = m_free(n); 558 } while (len > 0 && n); 559 if (len > 0) { 560 (void) m_free(m); 561 goto bad; 562 } 563 m->m_next = n; 564 return (m); 565 bad: 566 m_freem(n); 567 mbstat.m_mpfail++; /* XXX: No consistency. */ 568 return (NULL); 569 } 570 571 /* 572 * Partition an mbuf chain in two pieces, returning the tail -- 573 * all but the first len0 bytes. In case of failure, it returns NULL and 574 * attempts to restore the chain to its original state. 575 * 576 * Note that the resulting mbufs might be read-only, because the new 577 * mbuf can end up sharing an mbuf cluster with the original mbuf if 578 * the "breaking point" happens to lie within a cluster mbuf. Use the 579 * M_WRITABLE() macro to check for this case. 580 */ 581 struct mbuf * 582 m_split(struct mbuf *m0, int len0, int wait) 583 { 584 struct mbuf *m, *n; 585 u_int len = len0, remain; 586 587 for (m = m0; m && len > m->m_len; m = m->m_next) 588 len -= m->m_len; 589 if (m == NULL) 590 return (NULL); 591 remain = m->m_len - len; 592 if (m0->m_flags & M_PKTHDR) { 593 MGETHDR(n, wait, m0->m_type); 594 if (n == NULL) 595 return (NULL); 596 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 597 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 598 m0->m_pkthdr.len = len0; 599 if (m->m_flags & M_EXT) 600 goto extpacket; 601 if (remain > MHLEN) { 602 /* m can't be the lead packet */ 603 MH_ALIGN(n, 0); 604 n->m_next = m_split(m, len, wait); 605 if (n->m_next == NULL) { 606 (void) m_free(n); 607 return (NULL); 608 } else { 609 n->m_len = 0; 610 return (n); 611 } 612 } else 613 MH_ALIGN(n, remain); 614 } else if (remain == 0) { 615 n = m->m_next; 616 m->m_next = NULL; 617 return (n); 618 } else { 619 MGET(n, wait, m->m_type); 620 if (n == NULL) 621 return (NULL); 622 M_ALIGN(n, remain); 623 } 624 extpacket: 625 if (m->m_flags & M_EXT) { 626 n->m_flags |= M_EXT; 627 n->m_ext = m->m_ext; 628 MEXT_ADD_REF(m); 629 n->m_data = m->m_data + len; 630 } else { 631 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 632 } 633 n->m_len = remain; 634 m->m_len = len; 635 n->m_next = m->m_next; 636 m->m_next = NULL; 637 return (n); 638 } 639 /* 640 * Routine to copy from device local memory into mbufs. 641 * Note that `off' argument is offset into first mbuf of target chain from 642 * which to begin copying the data to. 643 */ 644 struct mbuf * 645 m_devget(char *buf, int totlen, int off, struct ifnet *ifp, 646 void (*copy)(char *from, caddr_t to, u_int len)) 647 { 648 struct mbuf *m; 649 struct mbuf *top = 0, **mp = ⊤ 650 int len; 651 652 if (off < 0 || off > MHLEN) 653 return (NULL); 654 655 MGETHDR(m, M_DONTWAIT, MT_DATA); 656 if (m == NULL) 657 return (NULL); 658 m->m_pkthdr.rcvif = ifp; 659 m->m_pkthdr.len = totlen; 660 len = MHLEN; 661 662 while (totlen > 0) { 663 if (top) { 664 MGET(m, M_DONTWAIT, MT_DATA); 665 if (m == NULL) { 666 m_freem(top); 667 return (NULL); 668 } 669 len = MLEN; 670 } 671 if (totlen + off >= MINCLSIZE) { 672 MCLGET(m, M_DONTWAIT); 673 if (m->m_flags & M_EXT) 674 len = MCLBYTES; 675 } else { 676 /* 677 * Place initial small packet/header at end of mbuf. 678 */ 679 if (top == NULL && totlen + off + max_linkhdr <= len) { 680 m->m_data += max_linkhdr; 681 len -= max_linkhdr; 682 } 683 } 684 if (off) { 685 m->m_data += off; 686 len -= off; 687 off = 0; 688 } 689 m->m_len = len = min(totlen, len); 690 if (copy) 691 copy(buf, mtod(m, caddr_t), (u_int)len); 692 else 693 bcopy(buf, mtod(m, caddr_t), (u_int)len); 694 buf += len; 695 *mp = m; 696 mp = &m->m_next; 697 totlen -= len; 698 } 699 return (top); 700 } 701 702 /* 703 * Copy data from a buffer back into the indicated mbuf chain, 704 * starting "off" bytes from the beginning, extending the mbuf 705 * chain if necessary. 706 */ 707 void 708 m_copyback(struct mbuf *m0, int off, int len, caddr_t cp) 709 { 710 int mlen; 711 struct mbuf *m = m0, *n; 712 int totlen = 0; 713 714 if (m0 == NULL) 715 return; 716 while (off > (mlen = m->m_len)) { 717 off -= mlen; 718 totlen += mlen; 719 if (m->m_next == NULL) { 720 n = m_get_clrd(M_DONTWAIT, m->m_type); 721 if (n == NULL) 722 goto out; 723 n->m_len = min(MLEN, len + off); 724 m->m_next = n; 725 } 726 m = m->m_next; 727 } 728 while (len > 0) { 729 mlen = min (m->m_len - off, len); 730 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen); 731 cp += mlen; 732 len -= mlen; 733 mlen += off; 734 off = 0; 735 totlen += mlen; 736 if (len == 0) 737 break; 738 if (m->m_next == NULL) { 739 n = m_get(M_DONTWAIT, m->m_type); 740 if (n == NULL) 741 break; 742 n->m_len = min(MLEN, len); 743 m->m_next = n; 744 } 745 m = m->m_next; 746 } 747 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 748 m->m_pkthdr.len = totlen; 749 } 750 751 void 752 m_print(const struct mbuf *m) 753 { 754 int len; 755 const struct mbuf *m2; 756 757 len = m->m_pkthdr.len; 758 m2 = m; 759 while (len) { 760 printf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-"); 761 len -= m2->m_len; 762 m2 = m2->m_next; 763 } 764 return; 765 } 766 767 u_int 768 m_fixhdr(struct mbuf *m0) 769 { 770 u_int len; 771 772 len = m_length(m0, NULL); 773 m0->m_pkthdr.len = len; 774 return (len); 775 } 776 777 u_int 778 m_length(struct mbuf *m0, struct mbuf **last) 779 { 780 struct mbuf *m; 781 u_int len; 782 783 len = 0; 784 for (m = m0; m != NULL; m = m->m_next) { 785 len += m->m_len; 786 if (m->m_next == NULL) 787 break; 788 } 789 if (last != NULL) 790 *last = m; 791 return (len); 792 } 793 794 /* 795 * Defragment a mbuf chain, returning the shortest possible 796 * chain of mbufs and clusters. If allocation fails and 797 * this cannot be completed, NULL will be returned, but 798 * the passed in chain will be unchanged. Upon success, 799 * the original chain will be freed, and the new chain 800 * will be returned. 801 * 802 * If a non-packet header is passed in, the original 803 * mbuf (chain?) will be returned unharmed. 804 */ 805 struct mbuf * 806 m_defrag(struct mbuf *m0, int how) 807 { 808 struct mbuf *m_new = NULL, *m_final = NULL; 809 int progress = 0, length; 810 811 if (!(m0->m_flags & M_PKTHDR)) 812 return (m0); 813 814 815 if (m0->m_pkthdr.len > MHLEN) 816 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 817 else 818 m_final = m_gethdr(how, MT_DATA); 819 820 if (m_final == NULL) 821 goto nospace; 822 823 if (m_dup_pkthdr(m_final, m0, how) == NULL) 824 goto nospace; 825 826 m_new = m_final; 827 828 while (progress < m0->m_pkthdr.len) { 829 length = m0->m_pkthdr.len - progress; 830 if (length > MCLBYTES) 831 length = MCLBYTES; 832 833 if (m_new == NULL) { 834 if (length > MLEN) 835 m_new = m_getcl(how, MT_DATA, 0); 836 else 837 m_new = m_get(how, MT_DATA); 838 if (m_new == NULL) 839 goto nospace; 840 } 841 842 m_copydata(m0, progress, length, mtod(m_new, caddr_t)); 843 progress += length; 844 m_new->m_len = length; 845 if (m_new != m_final) 846 m_cat(m_final, m_new); 847 m_new = NULL; 848 } 849 if (m0->m_next == NULL) 850 m_defraguseless++; 851 m_freem(m0); 852 m0 = m_final; 853 m_defragpackets++; 854 m_defragbytes += m0->m_pkthdr.len; 855 return (m0); 856 nospace: 857 m_defragfailure++; 858 if (m_new) 859 m_free(m_new); 860 if (m_final) 861 m_freem(m_final); 862 return (NULL); 863 } 864