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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94 30 */ 31#include <sys/kernel.h> 32#include <sys/malloc.h> 33#include <sys/mbuf.h> 34 35/* 36 * Copy data from an mbuf chain starting "off" bytes from the beginning, 37 * continuing for "len" bytes, into the indicated buffer. 38 */ 39void 40m_copydata(const struct mbuf *m, int off, int len, caddr_t cp) 41{ 42 u_int count; 43 44 KASSERT(off >= 0, ("m_copydata, negative off %d", off)); 45 KASSERT(len >= 0, ("m_copydata, negative len %d", len)); 46 while (off > 0) { 47 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain")); 48 if (off < m->m_len) 49 break; 50 off -= m->m_len; 51 m = m->m_next; 52 } 53 while (len > 0) { 54 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain")); 55 count = min(m->m_len - off, len); 56 bcopy(mtod(m, caddr_t) + off, cp, count); 57 len -= count; 58 cp += count; 59 off = 0; 60 m = m->m_next; 61 } 62} 63 64/* 65 * Concatenate mbuf chain n to m. 66 * Both chains must be of the same type (e.g. MT_DATA). 67 * Any m_pkthdr is not updated. 68 */ 69void 70m_cat(struct mbuf *m, struct mbuf *n) 71{ 72 while (m->m_next) 73 m = m->m_next; 74 while (n) { 75 if (m->m_flags & M_EXT || 76 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) { 77 /* just join the two chains */ 78 m->m_next = n; 79 return; 80 } 81 /* splat the data from one into the other */ 82 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 83 (u_int)n->m_len); 84 m->m_len += n->m_len; 85 n = m_free(n); 86 } 87} 88 89u_int 90m_length(struct mbuf *m0, struct mbuf **last) 91{ 92 struct mbuf *m; 93 u_int len; 94 95 len = 0; 96 for (m = m0; m != NULL; m = m->m_next) { 97 len += m->m_len; 98 if (m->m_next == NULL) 99 break; 100 } 101 if (last != NULL) 102 *last = m; 103 return (len); 104} 105 106u_int 107m_fixhdr(struct mbuf *m0) 108{ 109 u_int len; 110 111 len = m_length(m0, NULL); 112 m0->m_pkthdr.len = len; 113 return (len); 114} 115 116/* 117 * Duplicate "from"'s mbuf pkthdr in "to". 118 * "from" must have M_PKTHDR set, and "to" must be empty. 119 * In particular, this does a deep copy of the packet tags. 120 */ 121int 122m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how) 123{ 124 MBUF_CHECKSLEEP(how); 125 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 126 if ((to->m_flags & M_EXT) == 0) 127 to->m_data = to->m_pktdat; 128 to->m_pkthdr = from->m_pkthdr; 129 SLIST_INIT(&to->m_pkthdr.tags); 130 return (m_tag_copy_chain(to, from, MBTOM(how))); 131} 132 133/* 134 * Defragment a mbuf chain, returning the shortest possible 135 * chain of mbufs and clusters. If allocation fails and 136 * this cannot be completed, NULL will be returned, but 137 * the passed in chain will be unchanged. Upon success, 138 * the original chain will be freed, and the new chain 139 * will be returned. 140 * 141 * If a non-packet header is passed in, the original 142 * mbuf (chain?) will be returned unharmed. 143 */ 144struct mbuf * 145m_defrag(struct mbuf *m0, int how) 146{ 147 struct mbuf *m_new = NULL, *m_final = NULL; 148 int progress = 0, length; 149 150 MBUF_CHECKSLEEP(how); 151 if (!(m0->m_flags & M_PKTHDR)) 152 return (m0); 153 154 m_fixhdr(m0); /* Needed sanity check */ 155 156 if (m0->m_pkthdr.len > MHLEN) 157 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 158 else 159 m_final = m_gethdr(how, MT_DATA); 160 161 if (m_final == NULL) 162 goto nospace; 163 164 if (m_dup_pkthdr(m_final, m0, how) == 0) 165 goto nospace; 166 167 m_new = m_final; 168 169 while (progress < m0->m_pkthdr.len) { 170 length = m0->m_pkthdr.len - progress; 171 if (length > MCLBYTES) 172 length = MCLBYTES; 173 174 if (m_new == NULL) { 175 if (length > MLEN) 176 m_new = m_getcl(how, MT_DATA, 0); 177 else 178 m_new = m_get(how, MT_DATA); 179 if (m_new == NULL) 180 goto nospace; 181 } 182 183 m_copydata(m0, progress, length, mtod(m_new, caddr_t)); 184 progress += length; 185 m_new->m_len = length; 186 if (m_new != m_final) 187 m_cat(m_final, m_new); 188 m_new = NULL; 189 } 190 191 m_freem(m0); 192 m0 = m_final; 193 return (m0); 194nospace: 195 if (m_final) 196 m_freem(m_final); 197 return (NULL); 198} 199 200void 201m_adj(struct mbuf *mp, int req_len) 202{ 203 int len = req_len; 204 struct mbuf *m; 205 int count; 206 207 if ((m = mp) == NULL) 208 return; 209 if (len >= 0) { 210 /* 211 * Trim from head. 212 */ 213 while (m != NULL && len > 0) { 214 if (m->m_len <= len) { 215 len -= m->m_len; 216 m->m_len = 0; 217 m = m->m_next; 218 } else { 219 m->m_len -= len; 220 m->m_data += len; 221 len = 0; 222 } 223 } 224 m = mp; 225 if (mp->m_flags & M_PKTHDR) 226 m->m_pkthdr.len -= (req_len - len); 227 } else { 228 /* 229 * Trim from tail. Scan the mbuf chain, 230 * calculating its length and finding the last mbuf. 231 * If the adjustment only affects this mbuf, then just 232 * adjust and return. Otherwise, rescan and truncate 233 * after the remaining size. 234 */ 235 len = -len; 236 count = 0; 237 for (;;) { 238 count += m->m_len; 239 if (m->m_next == (struct mbuf *)0) 240 break; 241 m = m->m_next; 242 } 243 if (m->m_len >= len) { 244 m->m_len -= len; 245 if (mp->m_flags & M_PKTHDR) 246 mp->m_pkthdr.len -= len; 247 return; 248 } 249 count -= len; 250 if (count < 0) 251 count = 0; 252 /* 253 * Correct length for chain is "count". 254 * Find the mbuf with last data, adjust its length, 255 * and toss data from remaining mbufs on chain. 256 */ 257 m = mp; 258 if (m->m_flags & M_PKTHDR) 259 m->m_pkthdr.len = count; 260 for (; m; m = m->m_next) { 261 if (m->m_len >= count) { 262 m->m_len = count; 263 if (m->m_next != NULL) { 264 m_freem(m->m_next); 265 m->m_next = NULL; 266 } 267 break; 268 } 269 count -= m->m_len; 270 } 271 } 272} 273 274/* 275 * Rearange an mbuf chain so that len bytes are contiguous 276 * and in the data area of an mbuf (so that mtod and dtom 277 * will work for a structure of size len). Returns the resulting 278 * mbuf chain on success, frees it and returns null on failure. 279 * If there is room, it will add up to max_protohdr-len extra bytes to the 280 * contiguous region in an attempt to avoid being called next time. 281 */ 282struct mbuf * 283m_pullup(struct mbuf *n, int len) 284{ 285 struct mbuf *m; 286 int count; 287 int space; 288 289 /* 290 * If first mbuf has no cluster, and has room for len bytes 291 * without shifting current data, pullup into it, 292 * otherwise allocate a new mbuf to prepend to the chain. 293 */ 294 if ((n->m_flags & M_EXT) == 0 && 295 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 296 if (n->m_len >= len) 297 return (n); 298 m = n; 299 n = n->m_next; 300 len -= m->m_len; 301 } else { 302 if (len > MHLEN) 303 goto bad; 304 MGET(m, M_DONTWAIT, n->m_type); 305 if (m == NULL) 306 goto bad; 307 m->m_len = 0; 308 if (n->m_flags & M_PKTHDR) 309 M_MOVE_PKTHDR(m, n); 310 } 311 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 312 do { 313 count = min(min(max(len, max_protohdr), space), n->m_len); 314 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 315 (u_int)count); 316 len -= count; 317 m->m_len += count; 318 n->m_len -= count; 319 space -= count; 320 if (n->m_len) 321 n->m_data += count; 322 else 323 n = m_free(n); 324 } while (len > 0 && n); 325 if (len > 0) { 326 (void) m_free(m); 327 goto bad; 328 } 329 m->m_next = n; 330 return (m); 331bad: 332 m_freem(n); 333 return (NULL); 334} 335 336/* 337 * Lesser-used path for M_PREPEND: 338 * allocate new mbuf to prepend to chain, 339 * copy junk along. 340 */ 341struct mbuf * 342m_prepend(struct mbuf *m, int len, int how) 343{ 344 struct mbuf *mn; 345 346 if (m->m_flags & M_PKTHDR) 347 MGETHDR(mn, how, m->m_type); 348 else 349 MGET(mn, how, m->m_type); 350 if (mn == NULL) { 351 m_freem(m); 352 return (NULL); 353 } 354 if (m->m_flags & M_PKTHDR) 355 M_MOVE_PKTHDR(mn, m); 356 mn->m_next = m; 357 m = mn; 358 if (len < MHLEN) 359 MH_ALIGN(m, len); 360 m->m_len = len; 361 return (m); 362} 363 364/* 365 * "Move" mbuf pkthdr from "from" to "to". 366 * "from" must have M_PKTHDR set, and "to" must be empty. 367 */ 368void 369m_move_pkthdr(struct mbuf *to, struct mbuf *from) 370{ 371#ifdef MAC 372 /* 373 * XXXMAC: It could be this should also occur for non-MAC? 374 */ 375 if (to->m_flags & M_PKTHDR) 376 m_tag_delete_chain(to, NULL); 377#endif 378 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 379 if ((to->m_flags & M_EXT) == 0) 380 to->m_data = to->m_pktdat; 381 to->m_pkthdr = from->m_pkthdr; /* especially tags */ 382 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */ 383 from->m_flags &= ~M_PKTHDR; 384} 385 386/* 387 * Routine to copy from device local memory into mbufs. 388 * Note that `off' argument is offset into first mbuf of target chain from 389 * which to begin copying the data to. 390 */ 391struct mbuf * 392m_devget(char *buf, int totlen, int off, struct ifnet *ifp, 393 void (*copy)(char *from, caddr_t to, u_int len)) 394{ 395 struct mbuf *m; 396 struct mbuf *top = NULL, **mp = ⊤ 397 int len; 398 399 if (off < 0 || off > MHLEN) 400 return (NULL); 401 402 while (totlen > 0) { 403 if (top == NULL) { /* First one, must be PKTHDR */ 404 if (totlen + off >= MINCLSIZE) { 405 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 406 len = MCLBYTES; 407 } else { 408 m = m_gethdr(M_DONTWAIT, MT_DATA); 409 len = MHLEN; 410 411 /* Place initial small packet/header at end of mbuf */ 412 if (m && totlen + off + max_linkhdr <= MLEN) { 413 m->m_data += max_linkhdr; 414 len -= max_linkhdr; 415 } 416 } 417 if (m == NULL) 418 return NULL; 419 m->m_pkthdr.rcvif = ifp; 420 m->m_pkthdr.len = totlen; 421 } else { 422 if (totlen + off >= MINCLSIZE) { 423 m = m_getcl(M_DONTWAIT, MT_DATA, 0); 424 len = MCLBYTES; 425 } else { 426 m = m_get(M_DONTWAIT, MT_DATA); 427 len = MLEN; 428 } 429 if (m == NULL) { 430 m_freem(top); 431 return NULL; 432 } 433 } 434 if (off) { 435 m->m_data += off; 436 len -= off; 437 off = 0; 438 } 439 m->m_len = len = min(totlen, len); 440 if (copy) 441 copy(buf, mtod(m, caddr_t), (u_int)len); 442 else 443 bcopy(buf, mtod(m, caddr_t), (u_int)len); 444 buf += len; 445 *mp = m; 446 mp = &m->m_next; 447 totlen -= len; 448 } 449 return (top); 450} 451 452/* 453 * Copy data from a buffer back into the indicated mbuf chain, 454 * starting "off" bytes from the beginning, extending the mbuf 455 * chain if necessary. 456 */ 457void 458m_copyback(struct mbuf *m0, int off, int len, caddr_t cp) 459{ 460 int mlen; 461 struct mbuf *m = m0, *n; 462 int totlen = 0; 463 464 if (m0 == NULL) 465 return; 466 while (off > (mlen = m->m_len)) { 467 off -= mlen; 468 totlen += mlen; 469 if (m->m_next == NULL) { 470 n = m_get(M_DONTWAIT, m->m_type); 471 if (n == NULL) 472 goto out; 473 bzero(mtod(n, caddr_t), MLEN); 474 n->m_len = min(MLEN, len + off); 475 m->m_next = n; 476 } 477 m = m->m_next; 478 } 479 while (len > 0) { 480 mlen = min (m->m_len - off, len); 481 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen); 482 cp += mlen; 483 len -= mlen; 484 mlen += off; 485 off = 0; 486 totlen += mlen; 487 if (len == 0) 488 break; 489 if (m->m_next == NULL) { 490 n = m_get(M_DONTWAIT, m->m_type); 491 if (n == NULL) 492 break; 493 n->m_len = min(MLEN, len); 494 m->m_next = n; 495 } 496 m = m->m_next; 497 } 498out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 499 m->m_pkthdr.len = totlen; 500} 501 502/* 503 * Append the specified data to the indicated mbuf chain, 504 * Extend the mbuf chain if the new data does not fit in 505 * existing space. 506 * 507 * Return 1 if able to complete the job; otherwise 0. 508 */ 509int 510m_append(struct mbuf *m0, int len, c_caddr_t cp) 511{ 512 struct mbuf *m, *n; 513 int remainder, space; 514 515 for (m = m0; m->m_next != NULL; m = m->m_next) 516 ; 517 remainder = len; 518 space = M_TRAILINGSPACE(m); 519 if (space > 0) { 520 /* 521 * Copy into available space. 522 */ 523 if (space > remainder) 524 space = remainder; 525 bcopy(cp, mtod(m, caddr_t) + m->m_len, space); 526 m->m_len += space; 527 cp += space, remainder -= space; 528 } 529 while (remainder > 0) { 530 /* 531 * Allocate a new mbuf; could check space 532 * and allocate a cluster instead. 533 */ 534 n = m_get(M_DONTWAIT, m->m_type); 535 if (n == NULL) 536 break; 537 n->m_len = min(MLEN, remainder); 538 bcopy(cp, mtod(n, caddr_t), n->m_len); 539 cp += n->m_len, remainder -= n->m_len; 540 m->m_next = n; 541 m = n; 542 } 543 if (m0->m_flags & M_PKTHDR) 544 m0->m_pkthdr.len += len - remainder; 545 return (remainder == 0); 546} 547 548/* 549 * Defragment an mbuf chain, returning at most maxfrags separate 550 * mbufs+clusters. If this is not possible NULL is returned and 551 * the original mbuf chain is left in it's present (potentially 552 * modified) state. We use two techniques: collapsing consecutive 553 * mbufs and replacing consecutive mbufs by a cluster. 554 * 555 * NB: this should really be named m_defrag but that name is taken 556 */ 557struct mbuf * 558m_collapse(struct mbuf *m0, int how, int maxfrags) 559{ 560 struct mbuf *m, *n, *n2, **prev; 561 u_int curfrags; 562 563 /* 564 * Calculate the current number of frags. 565 */ 566 curfrags = 0; 567 for (m = m0; m != NULL; m = m->m_next) 568 curfrags++; 569 /* 570 * First, try to collapse mbufs. Note that we always collapse 571 * towards the front so we don't need to deal with moving the 572 * pkthdr. This may be suboptimal if the first mbuf has much 573 * less data than the following. 574 */ 575 m = m0; 576again: 577 for (;;) { 578 n = m->m_next; 579 if (n == NULL) 580 break; 581 if ((m->m_flags & M_RDONLY) == 0 && 582 n->m_len < M_TRAILINGSPACE(m)) { 583 bcopy(mtod(n, void *), mtod(m, char *) + m->m_len, 584 n->m_len); 585 m->m_len += n->m_len; 586 m->m_next = n->m_next; 587 m_free(n); 588 if (--curfrags <= maxfrags) 589 return m0; 590 } else 591 m = n; 592 } 593 KASSERT(maxfrags > 1, 594 ("maxfrags %u, but normal collapse failed", maxfrags)); 595 /* 596 * Collapse consecutive mbufs to a cluster. 597 */ 598 prev = &m0->m_next; /* NB: not the first mbuf */ 599 while ((n = *prev) != NULL) { 600 if ((n2 = n->m_next) != NULL && 601 n->m_len + n2->m_len < MCLBYTES) { 602 m = m_getcl(how, MT_DATA, 0); 603 if (m == NULL) 604 goto bad; 605 bcopy(mtod(n, void *), mtod(m, void *), n->m_len); 606 bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len, 607 n2->m_len); 608 m->m_len = n->m_len + n2->m_len; 609 m->m_next = n2->m_next; 610 *prev = m; 611 m_free(n); 612 m_free(n2); 613 if (--curfrags <= maxfrags) /* +1 cl -2 mbufs */ 614 return m0; 615 /* 616 * Still not there, try the normal collapse 617 * again before we allocate another cluster. 618 */ 619 goto again; 620 } 621 prev = &n->m_next; 622 } 623 /* 624 * No place where we can collapse to a cluster; punt. 625 * This can occur if, for example, you request 2 frags 626 * but the packet requires that both be clusters (we 627 * never reallocate the first mbuf to avoid moving the 628 * packet header). 629 */ 630bad: 631 return NULL; 632} 633 634/* 635 * Attach the the cluster from *m to *n, set up m_ext in *n 636 * and bump the refcount of the cluster. 637 */ 638static void 639mb_dupcl(struct mbuf *n, struct mbuf *m) 640{ 641 KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__)); 642 KASSERT((n->m_flags & M_EXT) == 0, ("%s: M_EXT set", __func__)); 643 644 n->m_ext.ext_buf = m->m_ext.ext_buf; 645 n->m_ext.ext_size = m->m_ext.ext_size; 646 n->m_ext.ext_type = m->m_ext.ext_type; 647 n->m_flags |= M_EXT; 648} 649 650/* 651 * Partition an mbuf chain in two pieces, returning the tail -- 652 * all but the first len0 bytes. In case of failure, it returns NULL and 653 * attempts to restore the chain to its original state. 654 * 655 * Note that the resulting mbufs might be read-only, because the new 656 * mbuf can end up sharing an mbuf cluster with the original mbuf if 657 * the "breaking point" happens to lie within a cluster mbuf. Use the 658 * M_WRITABLE() macro to check for this case. 659 */ 660struct mbuf * 661m_split(struct mbuf *m0, int len0, int wait) 662{ 663 struct mbuf *m, *n; 664 u_int len = len0, remain; 665 666 MBUF_CHECKSLEEP(wait); 667 for (m = m0; m && len > m->m_len; m = m->m_next) 668 len -= m->m_len; 669 if (m == NULL) 670 return (NULL); 671 remain = m->m_len - len; 672 if (m0->m_flags & M_PKTHDR) { 673 MGETHDR(n, wait, m0->m_type); 674 if (n == NULL) 675 return (NULL); 676 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 677 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 678 m0->m_pkthdr.len = len0; 679 if (m->m_flags & M_EXT) 680 goto extpacket; 681 if (remain > MHLEN) { 682 /* m can't be the lead packet */ 683 MH_ALIGN(n, 0); 684 n->m_next = m_split(m, len, wait); 685 if (n->m_next == NULL) { 686 (void) m_free(n); 687 return (NULL); 688 } else { 689 n->m_len = 0; 690 return (n); 691 } 692 } else 693 MH_ALIGN(n, remain); 694 } else if (remain == 0) { 695 n = m->m_next; 696 m->m_next = NULL; 697 return (n); 698 } else { 699 MGET(n, wait, m->m_type); 700 if (n == NULL) 701 return (NULL); 702 M_ALIGN(n, remain); 703 } 704extpacket: 705 if (m->m_flags & M_EXT) { 706 n->m_data = m->m_data + len; 707 mb_dupcl(n, m); 708 } else { 709 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 710 } 711 n->m_len = remain; 712 m->m_len = len; 713 n->m_next = m->m_next; 714 m->m_next = NULL; 715 return (n); 716} 717 718/* 719 * Copy a packet header mbuf chain into a completely new chain, including 720 * copying any mbuf clusters. Use this instead of m_copypacket() when 721 * you need a writable copy of an mbuf chain. 722 */ 723struct mbuf * 724m_dup(struct mbuf *m, int how) 725{ 726 struct mbuf **p, *top = NULL; 727 int remain, moff, nsize; 728 729 MBUF_CHECKSLEEP(how); 730 /* Sanity check */ 731 if (m == NULL) 732 return (NULL); 733 M_ASSERTPKTHDR(m); 734 735 /* While there's more data, get a new mbuf, tack it on, and fill it */ 736 remain = m->m_pkthdr.len; 737 moff = 0; 738 p = ⊤ 739 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ 740 struct mbuf *n; 741 742 /* Get the next new mbuf */ 743 if (remain >= MINCLSIZE) { 744 n = m_getcl(how, m->m_type, 0); 745 nsize = MCLBYTES; 746 } else { 747 n = m_get(how, m->m_type); 748 nsize = MLEN; 749 } 750 if (n == NULL) 751 goto nospace; 752 753 if (top == NULL) { /* First one, must be PKTHDR */ 754 if (!m_dup_pkthdr(n, m, how)) { 755 m_free(n); 756 goto nospace; 757 } 758 if ((n->m_flags & M_EXT) == 0) 759 nsize = MHLEN; 760 } 761 n->m_len = 0; 762 763 /* Link it into the new chain */ 764 *p = n; 765 p = &n->m_next; 766 767 /* Copy data from original mbuf(s) into new mbuf */ 768 while (n->m_len < nsize && m != NULL) { 769 int chunk = min(nsize - n->m_len, m->m_len - moff); 770 771 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); 772 moff += chunk; 773 n->m_len += chunk; 774 remain -= chunk; 775 if (moff == m->m_len) { 776 m = m->m_next; 777 moff = 0; 778 } 779 } 780 781 /* Check correct total mbuf length */ 782 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), 783 ("%s: bogus m_pkthdr.len", __func__)); 784 } 785 return (top); 786 787nospace: 788 m_freem(top); 789 return (NULL); 790} 791 792/* 793 * Create a writable copy of the mbuf chain. While doing this 794 * we compact the chain with a goal of producing a chain with 795 * at most two mbufs. The second mbuf in this chain is likely 796 * to be a cluster. The primary purpose of this work is to create 797 * a writable packet for encryption, compression, etc. The 798 * secondary goal is to linearize the data so the data can be 799 * passed to crypto hardware in the most efficient manner possible. 800 */ 801struct mbuf * 802m_unshare(struct mbuf *m0, int how) 803{ 804 struct mbuf *m, *mprev; 805 struct mbuf *n, *mfirst, *mlast; 806 int len, off; 807 808 mprev = NULL; 809 for (m = m0; m != NULL; m = mprev->m_next) { 810 /* 811 * Regular mbufs are ignored unless there's a cluster 812 * in front of it that we can use to coalesce. We do 813 * the latter mainly so later clusters can be coalesced 814 * also w/o having to handle them specially (i.e. convert 815 * mbuf+cluster -> cluster). This optimization is heavily 816 * influenced by the assumption that we're running over 817 * Ethernet where MCLBYTES is large enough that the max 818 * packet size will permit lots of coalescing into a 819 * single cluster. This in turn permits efficient 820 * crypto operations, especially when using hardware. 821 */ 822 if ((m->m_flags & M_EXT) == 0) { 823 if (mprev && (mprev->m_flags & M_EXT) && 824 m->m_len <= M_TRAILINGSPACE(mprev)) { 825 /* XXX: this ignores mbuf types */ 826 memcpy(mtod(mprev, caddr_t) + mprev->m_len, 827 mtod(m, caddr_t), m->m_len); 828 mprev->m_len += m->m_len; 829 mprev->m_next = m->m_next; /* unlink from chain */ 830 m_free(m); /* reclaim mbuf */ 831#if 0 832 newipsecstat.ips_mbcoalesced++; 833#endif 834 } else { 835 mprev = m; 836 } 837 continue; 838 } 839 /* 840 * Writable mbufs are left alone (for now). 841 */ 842 if (M_WRITABLE(m)) { 843 mprev = m; 844 continue; 845 } 846 847 /* 848 * Not writable, replace with a copy or coalesce with 849 * the previous mbuf if possible (since we have to copy 850 * it anyway, we try to reduce the number of mbufs and 851 * clusters so that future work is easier). 852 */ 853 KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags)); 854 /* NB: we only coalesce into a cluster or larger */ 855 if (mprev != NULL && (mprev->m_flags & M_EXT) && 856 m->m_len <= M_TRAILINGSPACE(mprev)) { 857 /* XXX: this ignores mbuf types */ 858 memcpy(mtod(mprev, caddr_t) + mprev->m_len, 859 mtod(m, caddr_t), m->m_len); 860 mprev->m_len += m->m_len; 861 mprev->m_next = m->m_next; /* unlink from chain */ 862 m_free(m); /* reclaim mbuf */ 863#if 0 864 newipsecstat.ips_clcoalesced++; 865#endif 866 continue; 867 } 868 869 /* 870 * Allocate new space to hold the copy... 871 */ 872 /* XXX why can M_PKTHDR be set past the first mbuf? */ 873 if (mprev == NULL && (m->m_flags & M_PKTHDR)) { 874 /* 875 * NB: if a packet header is present we must 876 * allocate the mbuf separately from any cluster 877 * because M_MOVE_PKTHDR will smash the data 878 * pointer and drop the M_EXT marker. 879 */ 880 MGETHDR(n, how, m->m_type); 881 if (n == NULL) { 882 m_freem(m0); 883 return (NULL); 884 } 885 M_MOVE_PKTHDR(n, m); 886 MCLGET(n, how); 887 if ((n->m_flags & M_EXT) == 0) { 888 m_free(n); 889 m_freem(m0); 890 return (NULL); 891 } 892 } else { 893 n = m_getcl(how, m->m_type, m->m_flags); 894 if (n == NULL) { 895 m_freem(m0); 896 return (NULL); 897 } 898 } 899 /* 900 * ... and copy the data. We deal with jumbo mbufs 901 * (i.e. m_len > MCLBYTES) by splitting them into 902 * clusters. We could just malloc a buffer and make 903 * it external but too many device drivers don't know 904 * how to break up the non-contiguous memory when 905 * doing DMA. 906 */ 907 len = m->m_len; 908 off = 0; 909 mfirst = n; 910 mlast = NULL; 911 for (;;) { 912 int cc = min(len, MCLBYTES); 913 memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc); 914 n->m_len = cc; 915 if (mlast != NULL) 916 mlast->m_next = n; 917 mlast = n; 918#if 0 919 newipsecstat.ips_clcopied++; 920#endif 921 922 len -= cc; 923 if (len <= 0) 924 break; 925 off += cc; 926 927 n = m_getcl(how, m->m_type, m->m_flags); 928 if (n == NULL) { 929 m_freem(mfirst); 930 m_freem(m0); 931 return (NULL); 932 } 933 } 934 n->m_next = m->m_next; 935 if (mprev == NULL) 936 m0 = mfirst; /* new head of chain */ 937 else 938 mprev->m_next = mfirst; /* replace old mbuf */ 939 m_free(m); /* release old mbuf */ 940 mprev = mfirst; 941 } 942 return (m0); 943} 944 945/* 946 * Set the m_data pointer of a newly-allocated mbuf 947 * to place an object of the specified size at the 948 * end of the mbuf, longword aligned. 949 */ 950void 951m_align(struct mbuf *m, int len) 952{ 953 int adjust; 954 955 if (m->m_flags & M_EXT) 956 adjust = m->m_ext.ext_size - len; 957 else if (m->m_flags & M_PKTHDR) 958 adjust = MHLEN - len; 959 else 960 adjust = MLEN - len; 961 m->m_data += adjust &~ (sizeof(long)-1); 962} 963 964/* 965 * Copy an entire packet, including header (which must be present). 966 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 967 * Note that the copy is read-only, because clusters are not copied, 968 * only their reference counts are incremented. 969 * Preserve alignment of the first mbuf so if the creator has left 970 * some room at the beginning (e.g. for inserting protocol headers) 971 * the copies still have the room available. 972 */ 973struct mbuf * 974m_copypacket(struct mbuf *m, int how) 975{ 976 struct mbuf *top, *n, *o; 977 978 MBUF_CHECKSLEEP(how); 979 MGET(n, how, m->m_type); 980 top = n; 981 if (n == NULL) 982 goto nospace; 983 984 if (!m_dup_pkthdr(n, m, how)) 985 goto nospace; 986 n->m_len = m->m_len; 987 if (m->m_flags & M_EXT) { 988 n->m_data = m->m_data; 989 mb_dupcl(n, m); 990 } else { 991 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat ); 992 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 993 } 994 995 m = m->m_next; 996 while (m) { 997 MGET(o, how, m->m_type); 998 if (o == NULL) 999 goto nospace; 1000 1001 n->m_next = o; 1002 n = n->m_next; 1003 1004 n->m_len = m->m_len; 1005 if (m->m_flags & M_EXT) { 1006 n->m_data = m->m_data; 1007 mb_dupcl(n, m); 1008 } else { 1009 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 1010 } 1011 1012 m = m->m_next; 1013 } 1014 return top; 1015nospace: 1016 m_freem(top); 1017 return (NULL); 1018} 1019