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diff --git a/static/openbsd/man9/mbuf.9 b/static/openbsd/man9/mbuf.9 new file mode 100644 index 00000000..73ef8064 --- /dev/null +++ b/static/openbsd/man9/mbuf.9 @@ -0,0 +1,826 @@ +.\" $OpenBSD: mbuf.9,v 1.127 2024/11/05 13:15:13 jsg Exp $ +.\" +.\" Copyright (c) 2001 Jean-Jacques Bernard-Gundol <jjbg@openbsd.org> +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. The name of the author may not be used to endorse or promote products +.\" derived from this software without specific prior written permission +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF +.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.Dd $Mdocdate: November 5 2024 $ +.Dt MGET 9 +.Os +.Sh NAME +.Nm m_copym , +.Nm m_free , +.Nm m_get , +.Nm MGET , +.Nm m_getclr , +.Nm m_gethdr , +.Nm m_removehdr , +.Nm m_resethdr , +.Nm m_calchdrlen , +.Nm MGETHDR , +.Nm m_prepend , +.Nm M_PREPEND , +.Nm m_pulldown , +.Nm m_pullup , +.Nm m_split , +.Nm m_makespace , +.Nm m_getptr , +.Nm m_adj , +.Nm m_copyback , +.Nm m_defrag , +.Nm m_freem , +.Nm m_freemp , +.Nm m_purge , +.Nm m_copydata , +.Nm m_cat , +.Nm m_devget , +.Nm m_apply , +.Nm MCLGET , +.Nm MCLGETL , +.Nm MEXTADD , +.Nm m_align , +.Nm M_READONLY , +.Nm m_leadingspace , +.Nm m_trailingspace , +.Nm mtod , +.Nm m_dup_pkt , +.Nm m_dup_pkthdr +.Nd kernel memory management for networking protocols +.Sh SYNOPSIS +.In sys/mbuf.h +.Ft struct mbuf * +.Fn m_copym "struct mbuf *m" "int off" "int len" "int wait" +.Ft struct mbuf * +.Fn m_free "struct mbuf *m" +.Ft struct mbuf * +.Fn m_get "int how" "int type" +.Fn MGET "struct mbuf *m" "int how" "int type" +.Ft struct mbuf * +.Fn m_getclr "int how" "int type" +.Ft void +.Fn m_removehdr "struct mbuf *m" +.Ft void +.Fn m_resethdr "struct mbuf *m" +.Ft void +.Fn m_calchdrlen "struct mbuf *m" +.Ft struct mbuf * +.Fn m_gethdr "int how" "int type" +.Fn MGETHDR "struct mbuf *m" "int how" "int type" +.Ft struct mbuf * +.Fn m_prepend "struct mbuf *m" "int len" "int how" +.Fn M_PREPEND "struct mbuf *m" "int plen" "int how" +.Ft struct mbuf * +.Fn m_pulldown "struct mbuf *m" "int off" "int len" "int *offp" +.Ft struct mbuf * +.Fn m_pullup "struct mbuf *n" "int len" +.Ft struct mbuf * +.Fn m_split "struct mbuf *m0" "int len0" "int wait" +.Ft struct mbuf * +.Fn m_makespace "struct mbuf *m0" "int skip" "int hlen" "int *off" +.Ft struct mbuf * +.Fn m_getptr "struct mbuf *m" "int loc" "int *off" +.Ft void +.Fn m_adj "struct mbuf *mp" "int req_len" +.Ft int +.Fn m_copyback "struct mbuf *m0" "int off" "int len" "const void *cp" "int wait" +.Ft int +.Fn m_defrag "struct mbuf *m" "int wait" +.Ft struct mbuf * +.Fn m_freem "struct mbuf *m" +.Ft struct mbuf * +.Fn m_freemp "struct mbuf **mp" +.Ft void +.Fn m_purge "struct mbuf *m" +.Ft void +.Fn m_copydata "struct mbuf *m" "int off" "int len" "void *cp" +.Ft void +.Fn m_cat "struct mbuf *m" "struct mbuf *n" +.Ft struct mbuf * +.Fn m_devget "char *buf" "int totlen" "int off" +.Ft int +.Fn m_apply "struct mbuf *m" "int off" "int len" \ +"int (*func)(caddr_t, caddr_t, unsigned int)" "caddr_t fstate" +.Fn MCLGET "struct mbuf *m" "int how" +.Ft struct mbuf * +.Fn MCLGETL "struct mbuf *m" "int how" "int len" +.Fn MEXTADD "struct mbuf *m" "caddr_t buf" "u_int size" "int flags" \ +"void (*free)(caddr_t, u_int, void *)" "void *arg" +.Ft void +.Fn m_align "struct mbuf *m" "int len" +.Fn M_READONLY "struct mbuf *m" +.Ft int +.Fn m_leadingspace "struct mbuf *m" +.Ft int +.Fn m_trailingspace "struct mbuf *m" +.Ft struct mbuf * +.Fn m_dup_pkt "struct mbuf *m" "u_int adj" "int how" +.Ft int +.Fn m_dup_pkthdr "struct mbuf *to" "struct mbuf *from" "int how" +.Bd -literal +#define MSIZE 256 + +#define MLEN (MSIZE - sizeof(struct m_hdr)) +#define MHLEN (MLEN - sizeof(struct pkthdr)) + +#define MAXMCLBYTES (64 * 1024) +#define MINCLSIZE (MHLEN + MLEN + 1) + +#define MCLSHIFT 11 + +#define MCLBYTES (1 << MCLSHIFT) + +#define mtod(m,t) ((t)((m)->m_data)) + +struct m_hdr { + struct mbuf *mh_next; + struct mbuf *mh_nextpkt; + caddr_t mh_data; + u_int mh_len; + short mh_type; + u_short mh_flags; +#ifndef __LP64__ + u_int mh_pad; +#endif +}; + +struct pkthdr { + void *ph_cookie; + SLIST_HEAD(, m_tag) ph_tags; + int64_t ph_timestamp; + int len; + u_int ph_rtableid; + u_int ph_ifidx; + u_int16_t ph_tagsset; + u_int16_t ph_flowid; + u_int16_t csum_flags; + u_int16_t ether_vtag; + u_int16_t ph_mss; + u_int8_t ph_loopcnt; + u_int8_t ph_family; + struct pkthdr_pf pf; +}; + +struct pkthdr_pf { + struct pf_state_key *statekey; + struct inpcb *inp; + u_int32_t qid; + u_int16_t tag; + u_int8_t flags; + u_int8_t routed; + u_int8_t prio; + u_int8_t pad[3]; +}; + +struct mbuf_ext { + caddr_t ext_buf; + void *ext_arg; + u_int ext_free_fn; + u_int ext_size; + struct mbuf *ext_nextref; + struct mbuf *ext_prevref; +}; + +struct mbuf { + struct m_hdr m_hdr; + union { + struct { + struct pkthdr MH_pkthdr; + union { + struct mbuf_ext MH_ext; + char MH_databuf[MHLEN]; + } MH_dat; + } MH; + char M_databuf[MLEN]; + } M_dat; +}; + +#define m_next m_hdr.mh_next +#define m_len m_hdr.mh_len +#define m_data m_hdr.mh_data +#define m_type m_hdr.mh_type +#define m_flags m_hdr.mh_flags +#define m_nextpkt m_hdr.mh_nextpkt +#define m_pkthdr M_dat.MH.MH_pkthdr +#define m_ext M_dat.MH.MH_dat.MH_ext +#define m_pktdat M_dat.MH.MH_dat.MH_databuf +#define m_dat M_dat.M_databuf +.Ed +.Sh DESCRIPTION +The +.Nm mbuf +functions provide a way to manage the memory buffers used by the kernel's +networking subsystem. +Several functions and macros are used to allocate and deallocate mbufs, +but also to get, inject, remove, copy, modify, prepend or append data +inside these mbufs. +The size of an +.Nm mbuf +is defined by MSIZE. +.Pp +An +.Nm mbuf +structure is defined as an +.Fa m_hdr +structure followed by a +union. +The header contains the following elements: +.Bl -tag -width foobarmoocow +.It Fa mh_next +A pointer to the next mbuf in the mbuf chain. +.It Fa mh_nextpkt +A pointer to the next mbuf chain (i.e., packet) in the queue. +.It Fa mh_data +Indicates the address of the beginning of data in the mbuf. +.It Fa mh_len +Indicates the amount of data in the mbuf. +.It Fa mh_type +Indicates the type of data contained in the mbuf (see below). +.It Fa mh_flags +Flags (see below). +.El +.Pp +The +.Fa mh_type +variable can take the following values: +.Pp +.Bl -tag -compact -offset indent -width XXXXXXXXXXXXXXXXXX +.It Dv MT_FREE +the mbuf should be on the free list. +.It Dv MT_DATA +the data in the mbuf was dynamically allocated. +.It Dv MT_HEADER +the data contains a packet header. +.It Dv MT_SONAME +the data is a socket name. +.It Dv MT_SOOPTS +the data are socket options. +.It Dv MT_FTABLE +the data is a fragment reassembly header. +.It Dv MT_CONTROL +the mbuf contains extra-data protocol message. +.It Dv MT_OOBDATA +the data consists of out-of-band data. +.El +.Pp +The +.Fa mh_flags +variable can take the following values: +.Pp +.Bl -tag -compact -offset indent -width XXXXXXXXXXXXXXXXXX +.It Dv M_EXT +mbuf has associated external storage. +.It Dv M_PKTHDR +the mbuf is the first that forms a packet. +.It Dv M_EOR +end of record. +.It Dv M_EXTWR +external storage is writable. +.It Dv M_PROTO1 +protocol-specific. +.It Dv M_VLANTAG +.Fa m_pkthdr.ether_vtag +variable is valid. +.It Dv M_LOOP +packet has been sent from local machine. +.It Dv M_BCAST +packet sent/received as link-level broadcast. +.It Dv M_MCAST +packet sent/received as link-level multicast. +.It Dv M_CONF +packet was encrypted (ESP-transport). +.It Dv M_AUTH +packet was authenticated (AH or ESP). +.It Dv M_TUNNEL +header was IP-in-IP encapsulated by tunnel mode IPsec. +.It Dv M_ZEROIZE +Zero the data part of the mbufs in the mbuf chain pointed to by +.Nm m_free . +.It Dv M_COMP +header was decompressed. +.It Dv M_LINK0 +link layer specific flag. +.El +.Pp +An external cluster is used when the data to hold in the mbuf is +large. +The size of an external cluster is between MCLBYTES and MAXMCLBYTES. +A cluster should be used when the size of the data reach MINCLSIZE +(the minimum size to be held by an external cluster). +.Pp +The combination of the M_EXT and M_PKTHDR flags give four types of +mbuf. +When none of these constants are in use, the mbuf is a "normal" +one, where the data part of the mbuf has the following elements: +.Bl -tag -width foobarmoocow +.It Fa m_dat +buffer holding the data (size MLEN). +.El +.Pp +When only M_PKTHDR is set, the data contained in the mbuf is a packet header. +The data itself is contained in the mbuf (just like the previous case), +but part of the mbuf is used to store a packet header. +The data part has then the following elements: +.Bl -tag -width foobarmoocow +.It Fa m_pkthdr +packet header, containing the length of the data, a pointer to the +interface on which the data was received, checksum information +and list of +.Xr mbuf_tags 9 . +.It Fa m_pktdat +buffer holding the data (size MHLEN). +.El +.Pp +The +.Fa m_pkthdr.csum_flags +variable can take the following values: +.Pp +.Bl -tag -compact -offset indent -width XXXXXXXXXXXXXXXXXX +.It Dv M_IPV4_CSUM_OUT +IPv4 checksum needed. +.It Dv M_TCP_CSUM_OUT +TCP checksum needed. +.It Dv M_UDP_CSUM_OUT +UDP checksum needed. +.It Dv M_ICMP_CSUM_OUT +ICMP/ICMPv6 checksum needed. +.It Dv M_IPV4_CSUM_IN_OK +IPv4 checksum verified. +.It Dv M_IPV4_CSUM_IN_BAD +IPv4 checksum bad. +.It Dv M_TCP_CSUM_IN_OK +TCP checksum verified. +.It Dv M_TCP_CSUM_IN_BAD +TCP checksum bad. +.It Dv M_UDP_CSUM_IN_OK +UDP checksum verified. +.It Dv M_UDP_CSUM_IN_BAD +UDP checksum bad. +.It Dv M_ICMP_CSUM_IN_OK +ICMP/ICMPv6 checksum verified. +.It Dv M_ICMP_CSUM_IN_BAD +ICMP/ICMPv6 checksum bad. +.It Dv M_IPV6_DF_OUT +Do not fragment IPv6 on output. +.It M_TIMESTAMP +.Fa m_pkthdr.ph_timestamp +is valid. +.It M_FLOWID +.Fa m_pkthdr.ph_flowid +is valid. +.It M_TCP_TSO +TCP Segmentation Offload needed and +.Fa m_pkthdr.ph_mss +is valid. +.El +.Pp +The +.Fa m_pkthdr.flowid +variable can contain a low resolution (15-bit) classification of a +flow or connection that the current mbuf is part of. +If the flowid is valid, it may be used as an alternative to hashing +the packets content to pick between different paths for the traffic. +The following masks can be ORed with the flowid: +.Pp +.Bl -tag -compact -offset indent -width XXXXXXXXXXXXXXXXXX +.It Dv M_FLOWID_VALID +The flow ID has been set. +.It Dv M_FLOWID_MASK +The flow ID. +.El +.Pp +When only M_EXT flag is set, an external storage buffer is being used to +hold the data, which is no longer stored in the mbuf. +The data part of the mbuf has now the following elements: +.Bl -tag -width foobarmoocow +.It Fa m_pkthdr +a packet header, just like the previous case, but it is empty. +No information is stored here. +.It Fa m_ext +a structure containing information about the external storage +buffer. +The information consists of the address of the external buffer, +a pointer to the function used to free the buffer, a pointer to the +arguments of the function, the size of the buffer, the type of the +buffer, and pointers to the previous and next mbufs using this +cluster. +.El +.Pp +When both the M_EXT and M_PKTHDR flags are set, an external storage buffer +is being used to store the data and this data contains a packet header. +The structure used is the same as the previous one except that the +.Fa m_pkthdr +element is not empty, it contains the same information as when +M_PKTHDR is used alone. +.Bl -tag -width Ds +.It Fn m_copym "struct mbuf *m" "int off" "int len" "int wait" +Copy an mbuf chain starting at +.Fa off +bytes from the beginning +and continuing for +.Fa len +bytes. +If +.Fa off +is zero and +.Fa m +has the M_PKTHDR flag set, +the header is copied. +If +.Fa len +is M_COPYALL, +the whole mbuf is copied. +The +.Fa wait +parameter can be M_WAIT or +M_DONTWAIT. +It does not copy clusters, it just increases their reference count. +.It Fn m_free "struct mbuf *m" +Free the mbuf pointed to by +.Fa m . +A pointer to the successor of the mbuf, +if it exists, is returned by the function. +If +.Fa m +is a +.Dv NULL +pointer, no action occurs and +.Dv NULL +is returned. +.It Fn m_get "int how" "int type" +Return a pointer to an mbuf of the type specified. +If the +.Fa how +argument is +.Fa M_WAITOK , +the function may call +.Xr tsleep 9 +to await resources. +If +.Fa how +is +.Fa M_DONTWAIT +and resources are not available, +.Fn m_get +returns NULL. +.It Fn MGET "struct mbuf *m" "int how" "int type" +Return a pointer to an mbuf in +.Fa m +of the type specified. +See +.Fn m_get +for a description of +.Fa how . +.It Fn m_getclr "int how" "int type" +Return a pointer to an mbuf of the type specified, and clear the data +area of the mbuf. +See +.Fn m_get +for a description of +.Fa how . +.It Fn m_removehdr "struct mbuf *m" +Convert an mbuf with packet header to one without. +Delete all +.Xr pf 4 +data and all tags attached to an +.Fa mbuf . +Keep the data and mbuf chain, clear the packet header. +.It Fn m_resethdr "struct mbuf *m" +Delete all +.Xr pf 4 +data and all tags attached to an +.Fa mbuf . +Keep the data and mbuf chain, initialize the packet header. +.It Fn m_calchdrlen "struct mbuf *m" +Set the packet header length to the sum of all length values in the +mbuf chain. +.It Fn m_gethdr "int how" "int type" +Return a pointer to an mbuf of the type specified after initializing +it to contain a packet header. +See +.Fn m_get +for a description of +.Fa how . +.It Fn MGETHDR "struct mbuf *m" "int how" "int type" +Return a pointer to an mbuf of the type specified after initializing +it to contain a packet header. +See +.Fn m_get +for a description of +.Fa how . +.It Fn m_prepend "struct mbuf *m" "int len" "int how" +Prepend space of size +.Fa plen +to the mbuf pointed to by +.Fa m . +If necessary, allocate a new mbuf and prepend it to the mbuf chain pointed to by +.Fa m . +If +.Fa m +points to an mbuf with a packet header, it is moved to the new +mbuf that has been prepended. +The return value is a pointer on the new mbuf chain. +If this function fails to allocate a new mbuf, +.Fa m +is freed. +See +.Fn m_get +for a description of +.Fa how . +.It Fn M_PREPEND "struct mbuf *m" "int plen" "int how" +Prepend space of size +.Fa plen +to the mbuf pointed to by +.Fa m . +If a new mbuf must be allocated, +.Fa how +specifies whether to wait or not. +If this function fails to allocate a new mbuf, +.Fa m +is freed. +.It Fn m_pulldown "struct mbuf *m" "int off" "int len" "int *offp" +Ensure that the data in the mbuf chain starting at +.Fa off +and ending at +.Fa off+len +will be put in a continuous memory region. +If memory must be allocated, then it will fail if the +.Fa len +argument is greater than MAXMCLBYTES. +The pointer returned points to an mbuf in the chain and the new offset +for data in this mbuf is +.Fa *offp . +If this function fails, +.Fa m +is freed. +.It Fn m_pullup "struct mbuf *n" "int len" +Ensure that the data in the mbuf chain starting at the beginning of +the chain and ending at +.Fa len +will be put in continuous memory region. +If memory must be allocated, then it will fail if the +.Fa len +argument is greater than MAXMCLBYTES. +If this function fails, +.Fa n +is freed. +.It Fn m_split "struct mbuf *m0" "int len0" "int wait" +Split an mbuf chain in two pieces, returning a pointer to +the tail (which is made of the previous mbuf chain except the first +.Fa len0 +bytes). +.It Fn m_makespace "struct mbuf *m0" "int skip" "int hlen" "int *off" +Make space for a continuous memory region of length +.Fa hlen +at +.Fa skip +bytes into the mbuf chain. +On success, the mbuf of the continuous memory is returned +together with an offset +.Fa off +into the mbuf. +On failure, NULL is returned and the mbuf chain may have been modified. +The caller is assumed to always free the chain. +.It Fn m_getptr "struct mbuf *m" "int loc" "int *off" +Returns a pointer to the mbuf containing the data located at +.Fa loc +bytes of the beginning. +The offset in the new mbuf is pointed to by +.Fa off . +.It Fn m_adj "struct mbuf *mp" "int req_len" +Trims +.Fa req_len +bytes of data from the mbuf chain pointed to by +.Fa mp . +If +.Fa req_len +is positive, the data will be trimmed from the head of the mbuf chain +and if it is negative, it will be trimmed from the tail of the mbuf +chain. +.It Fn m_copyback "struct mbuf *m0" "int off" "int len" "const void *cp" "int wait" +Copy data from a buffer pointed to by +.Fa cp +back into the mbuf chain pointed to by +.Fa m0 +starting at +.Fa off +bytes from the beginning, extending the mbuf chain if +necessary, sleeping for mbufs if +.Fa wait +is +.Fa M_WAIT . +If +.Fa M_NOWAIT +is set and no mbufs are available, +.Fn m_copyback +returns +.Er ENOBUFS . +The mbuf chain must be initialized properly, including setting +.Fa m_len . +.It Fn m_defrag "struct mbuf *m" "int wait" +Defragment the data mbufs referenced by +.Fa m +by replacing the chain with a copy of their contents made into a +single mbuf or cluster. +.Fa wait +specifies whether it can wait or not for the replacement storage. +.Fn m_defrag +returns 0 on success or +.Er ENOBUFS +on failure. +The mbuf pointer +.Fa m +remains in existence and unchanged on failure. +.It Fn m_freem "struct mbuf *m" +Free the mbuf chain pointed to by +.Fa m . +A pointer to the next mbuf in the list linked by m_nextpkt, +if it exists, is returned by the function. +If +.Fa m +is a +.Dv NULL +pointer, no action occurs and +.Dv NULL +is returned. +.It Fn m_freemp "struct mbuf **mp" +Set the input mbuf pointer to +.Dv NULL +and call +.Fn m_freem . +.It Fn m_purge "struct mbuf *m" +Free the list of mbufs linked by m_nextpkt that is pointed to by +.Fa m . +Each mbuf is freed by a call to +.Fn m_freem . +If +.Fa m +is a +.Dv NULL +pointer, no action occurs. +.It Fn m_copydata "struct mbuf *m" "int off" "int len" "void *cp" +Copy data from the mbuf chain pointed to by +.Fa m +starting at +.Fa off +bytes from the beginning and continuing for +.Fa len +bytes into the buffer pointed to by +.Fa cp . +.It Fn m_cat "struct mbuf *m" "struct mbuf *n" +Concatenate the mbuf chain pointed to by +.Fa n +to the mbuf chain pointed to by +.Fa m . +The mbuf chains must be of the same type. +.It Fn m_devget "char *buf" "int totlen" "int off" +Copy +.Fa totlen +bytes of data from device local memory pointed to by +.Fa buf . +The data is copied into an mbuf chain at offset +.Fa off +and a pointer to the head of the chain is returned. +Returns NULL on failure. +.It Fn m_apply "struct mbuf *m" "int off" "int len" \ +"int (*func)(caddr_t, caddr_t, unsigned int)" "caddr_t fstate" +Apply the function +.Fa func +to the data in the mbuf chain pointed to by +.Fa m +starting at +.Fa off +bytes from the beginning and continuing for +.Fa len +bytes. +.It Fn mtod "struct mbuf *m" "datatype" +Return a pointer to the data contained in the specified mbuf +.Fa m +cast to +.Fa datatype . +.It Fn MCLGET "struct mbuf *m" "int how" +Allocate and add an mbuf cluster to the mbuf pointed to by +.Fa m . +On success, the flag M_EXT is set in the mbuf. +See +.Fn m_get +for a description of +.Fa how . +.It Fn MCLGETL "struct mbuf *m" "int how" "int len" +If +.Fa m +is NULL, allocate it. +Then allocate and add an mbuf cluster of length +.Fa len +to the mbuf pointed to by +.Fa m . +Returns either the mbuf +.Fa m +that was passed in, or the newly allocated one which was allocated; in +either case the flag M_EXT is set in the mbuf. +See +.Fn m_get +for a description of +.Fa how . +.It Fn MEXTADD "struct mbuf *m" "caddr_t buf" "u_int size" "int flags" \ +"void (*free)(caddr_t, u_int, void *)" "void *arg" +Add pre-allocated storage to the mbuf pointed to by +.Fa m . +On success, the flag M_EXT is set in the mbuf, and M_EXTWR is specified in +.Fa flags . +.It Fn m_align "struct mbuf *m" "int len" +Set the +.Fa m_data +pointer of the newly allocated mbuf +.Fa m +to an object of the specified size +.Fa len +at the end of this mbuf data area, longword aligned. +.It Fn M_READONLY "struct mbuf *m" +Check if the data of the mbuf pointed to by +.Fa m +is read-only. +This is true for non-cluster external storage and for clusters that +are being referenced by more than one mbuf. +.It Fn m_leadingspace "struct mbuf *m" +Compute the amount of space available before the current start of data +in the mbuf pointed to by +.Fa m . +If the data of the mbuf pointed to by +.Fa m +is read-only then 0 is returned. +.It Fn m_trailingspace "struct mbuf *m" +Compute the amount of space available after the end of data in the +mbuf pointed to by +.Fa m . +If the data of the mbuf pointed to by +.Fa m +is read-only then 0 is returned. +.It Fn m_dup_pkt "struct mbuf *m" "u_int adj" "int how" +Allocate a new mbuf and storage and copy the packet data and header, +including mbuf tags, from +.Fa m . +The data in the new mbuf will be offset from the start of the storage by +.Fa adj +bytes. +See +.Fn m_get +for a description of +.Fa how . +.It Fn m_dup_pkthdr "struct mbuf *to" "struct mbuf *from" "int how" +Copy mbuf packet header, including mbuf tags, from +.Fa from +to +.Fa to . +See +.Fn m_get +for a description of +.Fa how . +.El +.Sh CODE REFERENCES +The mbuf management functions are implemented in the files +.Pa sys/kern/uipc_mbuf.c +and +.Pa sys/kern/uipc_mbuf2.c . +The function prototypes and the macros are located in +.Pa sys/sys/mbuf.h . +.Sh SEE ALSO +.Xr netstat 1 , +.Xr mbuf_tags 9 , +.Xr mutex 9 , +.Xr spl 9 +.Rs +.\" 4.4BSD SMM:18 +.%A S. J. Leffler +.%A W. N. Joy +.%A R. S. Fabry +.%A M. J. Karels +.%T Networking Implementation Notes +.%B 4.4BSD System Manager's Manual (SMM) +.Re +.Rs +.%A Jun-Ichiro Hagino +.%T "Mbuf issues in 4.4BSD IPv6/IPsec support (experiences from KAME IPv6/IPsec implementation)" +.%B "Proceedings of the Freenix Track: 2000 USENIX Annual Technical Conference" +.%D June 2000 +.Re |