1.\" $NetBSD: mbuf.9,v 1.41 2006/03/29 19:36:55 riz Exp $ 2.\" 3.\" Copyright (c) 1997 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This documentation is derived from text contributed to The NetBSD Foundation 7.\" by S.P.Zeidler (aka stargazer). 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd March 29, 2006 38.Dt MBUF 9 39.Os 40.Sh NAME 41.Nm mbuf , 42.Nm m_get , 43.Nm m_getclr , 44.Nm m_gethdr , 45.Nm m_devget , 46.Nm m_copym , 47.Nm m_copypacket , 48.Nm m_copydata , 49.Nm m_copyback , 50.Nm m_copyback_cow , 51.Nm m_cat , 52.Nm m_dup , 53.Nm m_makewritable , 54.Nm m_prepend , 55.Nm m_pulldown , 56.Nm m_pullup , 57.Nm m_split , 58.Nm m_adj , 59.Nm m_apply , 60.Nm m_free , 61.Nm m_freem , 62.Nm mtod , 63.Nm MGET , 64.Nm MGETHDR , 65.Nm MEXTMALLOC , 66.Nm MEXTADD , 67.Nm MCLGET , 68.Nm M_COPY_PKTHDR , 69.Nm M_MOVE_PKTHDR , 70.Nm M_ALIGN , 71.Nm MH_ALIGN , 72.Nm M_LEADINGSPACE , 73.Nm M_TRAILINGSPACE , 74.Nm M_PREPEND , 75.Nm MCHTYPE , 76.Nm MEXTREMOVE , 77.Nm MFREE , 78.Nd "functions and macros for managing memory used by networking code" 79.Sh SYNOPSIS 80.In sys/mbuf.h 81.Ft struct mbuf * 82.Fn m_get "int nowait" "int type" 83.Ft struct mbuf * 84.Fn m_getclr "int nowait" "int type" 85.Ft struct mbuf * 86.Fn m_gethdr "int nowait" "int type" 87.Ft struct mbuf * 88.Fn m_devget "char *buf" "int totlen" "int off0" "struct ifnet *ifp" "void (*copy)(const void *, void *, size_t)" 89.Ft struct mbuf * 90.Fn m_copym "struct mbuf *m" "int off0" "int len" "int wait" 91.Ft struct mbuf * 92.Fn m_copypacket "struct mbuf *m" "int how" 93.Ft void 94.Fn m_copydata "struct mbuf *m" "int off" "int len" "caddr_t cp" 95.Ft void 96.Fn m_copyback "struct mbuf *m0" "int off" "int len" "caddr_t cp" 97.Ft struct mbuf * 98.Fn m_copyback_cow "struct mbuf *m0" "int off" "int len" "caddr_t cp" "int how" 99.Ft int 100.Fn m_makewritable "struct mbuf **mp" "int off" "int len" "int how" 101.Ft void 102.Fn m_cat "struct mbuf *m" "struct mbuf *n" 103.Ft struct mbuf * 104.Fn m_dup "struct mbuf *m" "int off0" "int len" "int wait" 105.Ft struct mbuf * 106.Fn m_prepend "struct mbuf *m" "int len" "int how" 107.Ft struct mbuf * 108.Fn m_pulldown "struct mbuf *m" "int off" "int len" "int *offp" 109.Ft struct mbuf * 110.Fn m_pullup "struct mbuf *n" "int len" 111.Ft struct mbuf * 112.Fn m_split "struct mbuf *m0" "int len0" "int wait" 113.Ft void 114.Fn m_adj "struct mbuf *mp" "int req_len" 115.Ft int 116.Fn m_apply "struct mbuf *m" "int off" "int len" "int *f(void *, caddr_t, unsigned int)" "void *arg" 117.Ft struct mbuf * 118.Fn m_free "struct mbuf *m" 119.Ft void 120.Fn m_freem "struct mbuf *m" 121.Ft datatype 122.Fn mtod "struct mbuf *m" "datatype" 123.Ft void 124.Fn MGET "struct mbuf *m" "int how" "int type" 125.Ft void 126.Fn MGETHDR "struct mbuf *m" "int how" "int type" 127.Ft void 128.Fn MEXTMALLOC "struct mbuf *m" "int len" "int how" 129.Ft void 130.Fn MEXTADD "struct mbuf *m" "caddr_t buf" "int size" "int type" "void (*free)(struct mbuf *, caddr_t, size_t, void *)" "void *arg" 131.Ft void 132.Fn MCLGET "struct mbuf *m" "int how" 133.Ft void 134.Fn M_COPY_PKTHDR "struct mbuf *to" "struct mbuf *from" 135.Ft void 136.Fn M_MOVE_PKTHDR "struct mbuf *to" "struct mbuf *from" 137.Ft void 138.Fn M_ALIGN "struct mbuf *m" "int len" 139.Ft void 140.Fn MH_ALIGN "struct mbuf *m" "int len" 141.Ft int 142.Fn M_LEADINGSPACE "struct mbuf *m" 143.Ft int 144.Fn M_TRAILINGSPACE "struct mbuf *m" 145.Ft void 146.Fn M_PREPEND "struct mbuf *m" "int plen" "int how" 147.Ft void 148.Fn MCHTYPE "struct mbuf *m" "int type" 149.Ft void 150.Fn MEXTREMOVE "struct mbuf *m" 151.Ft void 152.Fn MFREE "struct mbuf *m" "struct mbuf *n" 153.Sh DESCRIPTION 154The 155.Nm 156functions and macros provide an easy and consistent way to handle 157a networking stack's memory management needs. 158An 159.Nm 160consists of a header and a data area. 161It is of a fixed size, 162.Dv MSIZE 163.Pq defined in Aq Pa machine/param.h , 164which includes overhead. 165The header contains a pointer to the next 166.Nm 167in the 168.Sq "mbuf chain" , 169a pointer to the next 170.Sq "mbuf chain" , 171a pointer to the data area, the amount of data in this mbuf, its type 172and a 173.Dv flags 174field. 175.Pp 176The 177.Dv type 178variable can signify: 179.Bl -tag -compact -offset indent -width "XXXXXXXXXXX" 180.It Dv MT_FREE 181the mbuf should be on the ``free'' list 182.It Dv MT_DATA 183data was dynamically allocated 184.It Dv MT_HEADER 185data is a packet header 186.It Dv MT_SONAME 187data is a socket name 188.It Dv MT_SOOPTS 189data is socket options 190.It Dv MT_FTABLE 191data is the fragment reassembly header 192.It Dv MT_CONTROL 193mbuf contains ancillary \&(protocol control\&) data 194.It Dv MT_OOBDATA 195mbuf contains out-of-band data. 196.El 197.Pp 198The 199.Dv flags 200variable contains information describing the 201.Nm , 202notably: 203.Bl -tag -compact -offset indent -width "XXXXXXXXXXX" 204.It Dv M_EXT 205has external storage 206.It Dv M_PKTHDR 207is start of record 208.It Dv M_EOR 209is end of record 210.It Dv M_CLUSTER 211external storage is a cluster. 212.El 213.Pp 214If an 215.Nm 216designates the start of a record 217.Pq Dv M_PKTHDR , 218its 219.Dv flags 220field may contain additional information describing the content of 221the record: 222.Bl -tag -compact -offset indent -width "XXXXXXXXXXX" 223.It Dv M_BCAST 224sent/received as link-level broadcast 225.It Dv M_MCAST 226sent/received as link-level multicast 227.It Dv M_LINK0 , 228.It Dv M_LINK1 , 229.It Dv M_LINK2 230three link-level specific flags. 231.El 232.Pp 233An 234.Nm 235may add a single 236.Sq "mbuf cluster" 237of 238.Dv MCLBYTES 239bytes 240.Pq also defined in Aq Pa machine/param.h , 241which has no additional overhead 242and is used instead of the internal data area; this is done when at least 243.Dv MINCLSIZE 244bytes of data must be stored. 245.Pp 246When the 247.Dv M_EXT 248flag is raised for an mbuf, 249the external storage area could be shared among multiple mbufs. 250Be careful when you attempt to overwrite the data content of the mbuf. 251.Bl -tag -width compact 252.It Fn m_get "int nowait" "int type" 253Allocates an mbuf and initializes it to contain internal data. 254The 255.Fa nowait 256parameter is a choice of 257.Dv M_WAIT / M_DONTWAIT 258from caller. 259.Dv M_WAIT 260means the call cannot fail, but may take forever. 261The 262.Fa type 263parameter is an mbuf type. 264.It Fn m_getclr "int nowait" "int type" 265Allocates an mbuf and initializes it to contain internal data, then 266zeros the data area. 267The 268.Fa nowait 269parameter is a choice of 270.Dv M_WAIT / M_DONTWAIT 271from caller. 272The 273.Fa type 274parameter is an mbuf type. 275.It Fn m_gethdr "int nowait" "int type" 276Allocates an mbuf and initializes it to contain a packet header and internal 277data. 278The 279.Fa nowait 280parameter is a choice of 281.Dv M_WAIT / M_DONTWAIT 282from caller. 283The 284.Fa type 285parameter is an mbuf type. 286.It Fn m_devget "char *buf" "int totlen" "int off0" "struct ifnet *ifp" "void (*copy)(const void *, void *, size_t)" 287Copies 288.Fa len 289bytes from device local memory into mbufs using copy routine 290.Fa copy . 291If parameter 292.Fa off 293is non-zero, the packet is supposed to be trailer-encapsulated and 294.Fa off 295bytes plus the type and length fields will be skipped before copying. 296Returns the top of the mbuf chain it created. 297.It Fn m_copym "struct mbuf *m" "int off0" "int len" "int wait" 298Creates a copy of an mbuf chain starting 299.Fa off0 300bytes from the beginning, continuing for 301.Fa len 302bytes. 303If the 304.Fa len 305requested is 306.Dv M_COPYALL , 307the complete mbuf chain will be copied. 308The 309.Fa wait 310parameter is a choice of 311.Dv M_WAIT / M_DONTWAIT 312from caller. 313.It Fn m_copypacket "struct mbuf *m" "int how" 314Copies an entire packet, including header (which must be present). 315This function is an optimization of the common case 316.Li m_copym(m, 0, Dv M_COPYALL, Fa how ) . 317.It Fn m_copydata "struct mbuf *m" "int off" "int len" "caddr_t cp" 318Copies 319.Fa len 320bytes data from mbuf chain 321.Fa m 322into the buffer 323.Fa cp , 324starting 325.Fa off 326bytes from the beginning. 327.It Fn m_copyback "struct mbuf *m0" "int off" "int len" "caddr_t cp" 328Copies 329.Fa len 330bytes data from buffer 331.Fa cp 332back into the mbuf chain 333.Fa m0 , 334starting 335.Fa off 336bytes from the beginning of the chain, extending the mbuf chain if necessary. 337.Fn m_copyback 338can only fail when extending the chain. 339The caller should check for this kind of failure 340by checking the resulting length of the chain in that case. 341It is an error to use 342.Fn m_copyback 343on read-only mbufs. 344.It Fn m_copyback_cow "struct mbuf *m0" "int off" "int len" "caddr_t cp" \ 345"int how" 346Copies 347.Fa len 348bytes data from buffer 349.Fa cp 350back into the mbuf chain 351.Fa m0 352as 353.Fn m_copyback 354does. 355Unlike 356.Fn m_copyback , 357it is safe to use 358.Fn m_copyback_cow 359on read-only mbufs. 360If needed, 361.Fn m_copyback_cow 362automatically allocates new mbufs and adjusts the chain. 363On success, it returns a pointer to the resulting mbuf chain, 364and frees the original mbuf 365.Fa m0 . 366Otherwise, it returns 367.Dv NULL . 368The 369.Fa how 370parameter is a choice of 371.Dv M_WAIT / M_DONTWAIT 372from the caller. 373Unlike 374.Fn m_copyback , 375extending the mbuf chain isn't supported. 376It is an error to attempt to extend the mbuf chain using 377.Fn m_copyback_cow . 378.It Fn m_makewritable "struct mbuf **mp" "int off" "int len" "int how" 379Rearranges an mbuf chain so that 380.Fa len 381bytes from offset 382.Fa off 383are writable. 384When it meets read-only mbufs, it allocates new mbufs, adjusts the chain as 385.Fn m_copyback_cow 386does, and copies the original content into them. 387The 388.Fa how 389parameter is a choice of 390.Dv M_WAIT / M_DONTWAIT 391from the caller. 392.Fn m_makewritable 393preserves the contents of the mbuf chain even in the case of failure. 394It updates a pointer to the mbuf chain pointed to by 395.Fa mp . 396It returns 0 on success. 397Otherwise, it returns an error code, typically 398.Er ENOBUFS . 399.It Fn m_cat "struct mbuf *m" "struct mbuf *n" 400Concatenates mbuf chain 401.Fa n 402to 403.Fa m . 404Both chains must be of the same type; packet headers will 405.Em not 406be updated if present. 407.It Fn m_dup "struct mbuf *m" "int off0" "int len" "int wait" 408Similarly to 409.Fn m_copym , 410the function creates a copy of an mbuf chain starting 411.Fa off0 412bytes from the beginning, continuing for 413.Fa len 414bytes. 415While 416.Fn m_copym 417tries to share external storage for mbufs with 418.Dv M_EXT 419flag, 420.Fn m_dup 421will deep-copy the whole data content into new mbuf chain 422and avoids shared external storage. 423.It Fn m_prepend "struct mbuf *m" "int len" "int how" 424Lesser-used path for 425.Fn M_PREPEND : 426allocates new mbuf 427.Fa m 428of size 429.Fa len 430to prepend to the chain, copying junk along. 431The 432.Fa how 433parameter is a choice of 434.Dv M_WAIT / M_DONTWAIT 435from caller. 436.It Fn m_pulldown "struct mbuf *m" "int off" "int len" "int *offp" 437Rearranges an mbuf chain so that 438.Fa len 439bytes from offset 440.Fa off 441are contiguous and in the data area of an mbuf. 442The return value points to an mbuf in the middle of the mbuf chain 443.Fa m . 444If we call the return value 445.Fa n , 446the contiguous data region is available at 447.Li "mtod(n, caddr_t) + *offp" , 448or 449.Li "mtod(n, caddr_t)" 450if 451.Fa offp 452is 453.Dv NULL . 454The top of the mbuf chain 455.Fa m , 456and mbufs up to 457.Fa off , 458will not be modified. 459On successful return, it is guaranteed that the mbuf pointed to by 460.Fa n 461does not have a shared external storage, 462therefore it is safe to update the contiguous region. 463Returns 464.Dv NULL 465and frees the mbuf chain on failure. 466.Fa len 467must be smaller or equal than 468.Dv MCLBYTES . 469.It Fn m_pullup "struct mbuf *m" "int len" 470Rearranges an mbuf chain so that 471.Fa len 472bytes are contiguous 473and in the data area of an mbuf (so that 474.Fn mtod 475will work for a structure of size 476.Fa len ) . 477Returns the resulting 478mbuf chain on success, frees it and returns 479.Dv NULL 480on failure. 481If there is room, it will add up to 482.Dv max_protohdr 483- 484.Fa len 485extra bytes to the 486contiguous region to possibly avoid being called again. 487.Fa len 488must be smaller or equal than 489.Dv MHLEN . 490.It Fn m_split "struct mbuf *m0" "int len0" "int wait" 491Partitions an mbuf chain in two pieces, returning the tail, 492which is all but the first 493.Fa len0 494bytes. 495In case of failure, it returns 496.Dv NULL 497and attempts to 498restore the chain to its original state. 499.It Fn m_adj "struct mbuf *mp" "int req_len" 500Shaves off 501.Fa req_len 502bytes from head or tail of the (valid) data area. 503If 504.Fa req_len 505is greater than zero, front bytes are being shaved off, if it's smaller, 506from the back (and if it is zero, the mbuf will stay bearded). 507This function does not move data in any way, but is used to manipulate the 508data area pointer and data length variable of the mbuf in a non-clobbering 509way. 510.It Fn m_apply "struct mbuf *m" "int off" "int len" "int (*f)(void *, caddr_t, unsigned int)" "void *arg" 511Apply function 512.Fa f 513to the data in an mbuf chain starting 514.Fa off 515bytes from the beginning, continuing for 516.Fa len 517bytes. 518Neither 519.Fa off 520nor 521.Fa len 522may be negative. 523.Fa arg 524will be supplied as first argument for 525.Fa f , 526the second argument will be the pointer to the data buffer of a 527packet (starting after 528.Fa off 529bytes in the stream), and the third argument is the amount 530of data in bytes in this call. 531If 532.Fa f 533returns something not equal to zero 534.Fn m_apply 535will bail out, returning the return code of 536.Fa f . 537Upon successful completion it will return zero. 538.It Fn m_free "struct mbuf *m" 539Frees mbuf 540.Fa m . 541.It Fn m_freem "struct mbuf *m" 542Frees the mbuf chain beginning with 543.Fa m . 544This function contains the elementary sanity check for a 545.Dv NULL 546pointer. 547.It Fn mtod "struct mbuf *m" "datatype" 548Returns a pointer to the data contained in the specified mbuf 549.Fa m , 550type-casted to the specified data type 551.Fa datatype . 552Implemented as a macro. 553.It Fn MGET "struct mbuf *m" "int how" "int type" 554Allocates mbuf 555.Fa m 556and initializes it to contain internal data. 557See 558.Fn m_get . 559Implemented as a macro. 560.It Fn MGETHDR "struct mbuf *m" "int how" "int type" 561Allocates mbuf 562.Fa m 563and initializes it to contain a packet header. 564See 565.Fn m_gethdr . 566Implemented as a macro. 567.It Fn MEXTMALLOC "struct mbuf *m" "int len" "int how" 568Allocates external storage of size 569.Fa len 570for mbuf 571.Fa m . 572The 573.Fa how 574parameter is a choice of 575.Dv M_WAIT / M_DONTWAIT 576from caller. 577The flag 578.Dv M_EXT 579is set upon success. 580Implemented as a macro. 581.It Fn MEXTADD "struct mbuf *m" "caddr_t buf" "int size" "int type" "void (*free)(struct mbuf *, caddr_t, size_t, void *)" "void *arg" 582Adds pre-allocated external storage 583.Fa buf 584to a normal mbuf 585.Fa m ; 586the parameters 587.Fa size , 588.Fa type , 589.Fa free 590and 591.Fa arg 592describe the external storage. 593.Fa size 594is the size of the storage, 595.Fa type 596describes its 597.Xr malloc 9 598type, 599.Fa free 600is a free routine (if not the usual one), and 601.Fa arg 602is a possible argument to the free routine. 603The flag 604.Dv M_EXT 605is set upon success. 606Implemented as a macro. 607If a free routine is specified, it will be called when the mbuf is freed or 608when MEXTREMOVE is called for the mbuf. 609In the case of former, the first argument for a free routine is the mbuf 610.Fa m 611and the routine is expected to free it in addition to the external storage 612pointed by second argument. 613In the case of latter, the first argument for the routine is NULL. 614.It Fn MCLGET "struct mbuf *m" "int how" 615Allocates and adds an mbuf cluster to a normal mbuf 616.Fa m . 617The 618.Fa how 619parameter is a choice of 620.Dv M_WAIT / M_DONTWAIT 621from caller. 622The flag 623.Dv M_EXT 624is set upon success. 625Implemented as a macro. 626.It Fn M_COPY_PKTHDR "struct mbuf *to" "struct mbuf *from" 627Copies the mbuf pkthdr from mbuf 628.Fa from 629to mbuf 630.Fa to . 631.Fa from 632must have the type flag 633.Dv M_PKTHDR 634set, and 635.Fa to 636must be empty. 637Implemented as a macro. 638.It Fn M_MOVE_PKTHDR "struct mbuf *to" "struct mbuf *from" 639Moves the mbuf pkthdr from mbuf 640.Fa from 641to mbuf 642.Fa to . 643.Fa from 644must have the type flag 645.Dv M_PKTHDR 646set, and 647.Fa to 648must be empty. 649The flag 650.Dv M_PKTHDR 651in mbuf 652.Fa from 653will be cleared. 654.It Fn M_ALIGN "struct mbuf *m" "int len" 655Sets the data pointer of a newly allocated mbuf 656.Fa m 657to 658.Fa len 659bytes from the end of the mbuf data area, so that 660.Fa len 661bytes of data written to the mbuf 662.Fa m , 663starting at the data pointer, will be aligned to the end of the data area. 664Implemented as a macro. 665.It Fn MH_ALIGN "struct mbuf *m" "int len" 666Sets the data pointer of a newly allocated packetheader mbuf 667.Fa m 668to 669.Fa len 670bytes from the end of the mbuf data area, so that 671.Fa len 672bytes of data written to the mbuf 673.Fa m , 674starting at the data pointer, will be aligned to the end of the data area. 675Implemented as a macro. 676.It Fn M_LEADINGSPACE "struct mbuf *m" 677Returns the amount of space available before the current start of valid 678data in mbuf 679.Fa m . 680Returns 0 if the mbuf data part is shared across multiple mbufs 681.Pq i.e. not writable . 682Implemented as a macro. 683.It Fn M_TRAILINGSPACE "struct mbuf *m" 684Returns the amount of space available after the current end of valid 685data in mbuf 686.Fa m . 687Returns 0 if the mbuf data part is shared across multiple mbufs 688.Pq i.e. not writable . 689Implemented as a macro. 690.It Fn M_PREPEND "struct mbuf *m" "int plen" "int how" 691Prepends space of size 692.Fa plen 693to mbuf 694.Fa m . 695If a new mbuf must be allocated, 696.Fa how 697specifies whether to wait. 698If 699.Fa how 700is 701.Dv M_DONTWAIT 702and allocation fails, the original mbuf chain is freed and 703.Fa m 704is set to 705.Dv NULL . 706Implemented as a macro. 707.It Fn MCHTYPE "struct mbuf *m" "int type" 708Change mbuf 709.Fa m 710to new type 711.Fa type . 712Implemented as a macro. 713.It Fn MEXTREMOVE "struct mbuf *m" 714Removes external storage from mbuf 715.Fa m . 716The flag 717.Dv M_EXT 718is removed. 719Implemented as a macro. 720.It Fn MFREE "struct mbuf *m" "struct mbuf *n" 721Frees a single mbuf 722.Fa m 723and places the successor, if any, in mbuf 724.Fa n . 725Implemented as a macro. 726.El 727.Sh FILES 728The 729.Nm 730management functions are implemented within the file 731.Pa sys/kern/uipc_mbuf.c . 732Function prototypes, and the functions implemented as macros 733are located in 734.Pa sys/sys/mbuf.h . 735Both pathnames are relative to the root of the 736.Nx 737source tree, 738.Pa /usr/src . 739.Sh SEE ALSO 740.Pa /usr/share/doc/smm/18.net , 741.Xr netstat 1 , 742.Xr m_tag 9 , 743.Xr malloc 9 744.Rs 745.%A Jun-ichiro Hagino 746.%T "Mbuf issues in 4.4BSD IPv6/IPsec support (experiences from KAME IPv6/IPsec implementation)" 747.%B "Proceedings of the freenix track: 2000 USENIX annual technical conference" 748.%D June 2000 749.Re 750.Sh AUTHORS 751.An -nosplit 752The original mbuf data structures were designed by Rob Gurwitz 753when he did the initial TCP/IP implementation at BBN. 754.br 755Further extensions and enhancements were made by Bill Joy, Sam Leffler, 756and Mike Karels at CSRG. 757.br 758Current implementation of external storage by 759.An Matt Thomas 760.Aq matt@3am-software.com 761and 762.An Jason R. Thorpe 763.Aq thorpej@NetBSD.org . 764