.\" Copyright (c) 1996-1999 Whistle Communications, Inc. .\" All rights reserved. .\" .\" Subject to the following obligations and disclaimer of warranty, use and .\" redistribution of this software, in source or object code forms, with or .\" without modifications are expressly permitted by Whistle Communications; .\" provided, however, that: .\" 1. Any and all reproductions of the source or object code must include the .\" copyright notice above and the following disclaimer of warranties; and .\" 2. No rights are granted, in any manner or form, to use Whistle .\" Communications, Inc. trademarks, including the mark "WHISTLE .\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as .\" such appears in the above copyright notice or in the software. .\" .\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND .\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO .\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, .\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. .\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY .\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS .\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. .\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES .\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING .\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, .\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR .\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY .\" OF SUCH DAMAGE. .\" .\" Author: Archie Cobbs .\" .\" $FreeBSD: src/lib/libnetgraph/netgraph.3,v 1.4.2.10 2002/12/29 16:35:36 schweikh Exp $ .\" $DragonFly: src/lib/libnetgraph/netgraph.3,v 1.5 2007/06/03 23:41:25 swildner Exp $ .\" $Whistle: netgraph.3,v 1.7 1999/01/25 07:14:06 archie Exp $ .\" .Dd January 19, 1999 .Dt NETGRAPH 3 .Os .Sh NAME .Nm NgMkSockNode , .Nm NgNameNode , .Nm NgSendMsg , .Nm NgSendAsciiMsg , .Nm NgSendReplyMsg , .Nm NgRecvMsg , .Nm NgRecvAsciiMsg , .Nm NgSendData , .Nm NgRecvData , .Nm NgSetDebug , .Nm NgSetErrLog .Nd netgraph user library .Sh LIBRARY .Lb libnetgraph .Sh SYNOPSIS .In netgraph.h .Ft int .Fn NgMkSockNode "const char *name" "int *csp" "int *dsp" .Ft int .Fn NgNameNode "int cs" "const char *path" "const char *fmt" "..." .Ft int .Fn NgSendMsg "int cs" "const char *path" "int cookie" "int cmd" "const void *arg" "size_t arglen" .Ft int .Fn NgSendAsciiMsg "int cs" "const char *path" "const char *fmt" "..." .Ft int .Fn NgSendReplyMsg "int cs" "const char *path" "struct ng_mesg *msg" "const void *arg" "size_t arglen" .Ft int .Fn NgRecvMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path" .Ft int .Fn NgRecvAsciiMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path" .Ft int .Fn NgSendData "int ds" "const char *hook" "const u_char *buf" "size_t len" .Ft int .Fn NgRecvData "int ds" "u_char *buf" "size_t len" "char *hook" .Ft int .Fn NgSetDebug "int level" .Ft void .Fn NgSetErrLog "void (*log)(const char *fmt, ...)" "void (*logx)(const char *fmt, ...)" .Sh DESCRIPTION These functions facilitate user-mode program participation in the kernel .Xr netgraph 4 graph-based networking system, by utilizing the netgraph .Em socket node type (see .Xr ng_socket 4 ) . .Pp .Fn NgMkSockNode should be called first, to create a new .Em socket type netgraph node with associated control and data sockets. If .Fa name is non-NULL, the node will have that global name assigned to it. .Fa "*csp" and .Fa "*dsp" will be set to the newly opened control and data sockets associated with the node; either .Fa "csp" or .Fa "dsp" may be NULL if only one socket is desired. .Fn NgMkSockNode loads the socket node type KLD if it's not already loaded. .Pp .Fn NgNameNode assigns a global name to the node addressed by .Fa path . .Pp .Fn NgSendMsg sends a binary control message from the socket node associated with control socket .Fa cs to the node addressed by .Fa path . The .Fa cookie indicates how to interpret .Fa cmd , which indicates a specific command. Extra argument data (if any) is specified by .Fa arg and .Fa arglen . The .Fa cookie , .Fa cmd , and argument data are defined by the header file corresponding to the type of the node being addressed. The unique, non-negative token value chosen for use in the message header is returned. This value is typically used to associate replies. .Pp Use .Fn NgSendReplyMsg to send reply to a previously received control message. The original message header should be pointed to by .Fa msg . .Pp .Fn NgSendAsciiMsg performs the same function as .Fn NgSendMsg , but adds support for .Tn ASCII encoding of control messages. .Fn NgSendAsciiMsg formats its input a la .Xr printf 3 and then sends the resulting .Tn ASCII string to the node in a .Dv NGM_ASCII2BINARY control message. The node returns a binary version of the message, which is then sent back to the node just as with .Fn NgSendMsg . As with .Fn NgSendMsg , the message token value is returned. Note that .Tn ASCII conversion may not be supported by all node types. .Pp .Fn NgRecvMsg reads the next control message received by the node associated with control socket .Fa cs . The message and any extra argument data must fit in .Fa replen bytes. If .Fa "path" is non-NULL, it must point to a buffer of at least .Dv "NG_PATHSIZ" bytes, which will be filled in (and NUL terminated) with the path to the node from which the message was received. .Pp The length of the control message is returned. A return value of zero indicates that the socket was closed. .Pp .Fn NgRecvAsciiMsg works exactly like .Fn NgRecvMsg , except that after the message is received, any binary arguments are converted to .Tn ASCII by sending a .Dv NGM_BINARY2ASCII request back to the originating node. The result is the same as .Fn NgRecvAsciiMsg , with the exception that the reply arguments field will contain a NUL-terminated .Tn ASCII version of the arguments (and the reply header argument length field will be adjusted). .Pp .Fn NgSendData writes a data packet out on the specified hook of the node corresponding to data socket .Fa ds . The node must already be connected to some other node via that hook. .Pp .Fn NgRecvData reads the next data packet (of up to .Fa len bytes) received by the node corresponding to data socket .Fa ds and stores it in .Fa buf , which must be large enough to hold the entire packet. If .Fa "hook" is non-NULL, it must point to a buffer of at least .Dv "NG_HOOKSIZ" bytes, which will be filled in (and NUL terminated) with the name of the hook on which the data was received. .Pp The length of the packet is returned. A return value of zero indicates that the socket was closed. .Pp .Fn NgSetDebug and .Fn NgSetErrLog are used for debugging. .Fn NgSetDebug sets the debug level (if non-negative), and returns the old setting. Higher debug levels result in more verbosity. The default is zero. All debug and error messages are logged via the functions specified in the most recent call to .Fn NgSetErrLog . The default logging functions are .Xr vwarn 3 and .Xr vwarnx 3 . .Pp At debug level 3, the library attempts to display control message arguments in .Tn ASCII format; however, this results in additional messages being sent which may interfere with debugging. At even higher levels, even these additional messages will be displayed, etc. .Pp Note that .Xr select 2 can be used on the data and the control sockets to detect the presence of incoming data and control messages, respectively. Data and control packets are always written and read atomically, i.e., in one whole piece. .Pp User mode programs must be linked with the .Dv -lnetgraph flag to link in this library. .Sh INITIALIZATION To enable Netgraph in your kernel, either your kernel must be compiled with .Cd options NETGRAPH in the kernel configuration file, or else the .Xr netgraph 4 and .Xr ng_socket 4 KLD modules must have been loaded via .Xr kldload 8 . .Sh RETURN VALUES .Fn NgSetDebug returns the previous debug setting. .Fn NgSetErrLog has no return value. All other functions return \-1 if there was an error and set .Va errno accordingly. A return value of zero from .Fn NgRecvMsg or .Fn NgRecvData indicates that the netgraph socket has been closed. .Pp For .Fn NgSendAsciiMsg and .Fn NgRecvAsciiMsg , the following additional errors are possible: .Bl -tag -width Er .It Bq Er ENOSYS The node type does not know how to encode or decode the control message. .It Bq Er ERANGE The encoded or decoded arguments were too long for the supplied buffer. .It Bq Er ENOENT An unknown structure field was seen in an .Tn ASCII control message. .It Bq Er EALREADY The same structure field was specified twice in an .Tn ASCII control message. .It Bq Er EINVAL .Tn ASCII control message parse error or illegal value. .It Bq Er E2BIG ASCII control message array or fixed width string buffer overflow. .El .Sh SEE ALSO .Xr select 2 , .Xr socket 2 , .Xr warnx 3 , .Xr kld 4 , .Xr netgraph 4 , .Xr ng_socket 4 .Sh HISTORY The .Nm netgraph system was designed and first implemented at Whistle Communications, Inc. in a version of .Fx 2.2 customized for the Whistle InterJet. .Sh AUTHORS .An Archie Cobbs Aq archie@whistle.com