1.\" Copyright (c) 1996-1999 Whistle Communications, Inc. 2.\" All rights reserved. 3.\" 4.\" Subject to the following obligations and disclaimer of warranty, use and 5.\" redistribution of this software, in source or object code forms, with or 6.\" without modifications are expressly permitted by Whistle Communications; 7.\" provided, however, that: 8.\" 1. Any and all reproductions of the source or object code must include the 9.\" copyright notice above and the following disclaimer of warranties; and 10.\" 2. No rights are granted, in any manner or form, to use Whistle 11.\" Communications, Inc. trademarks, including the mark "WHISTLE 12.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as 13.\" such appears in the above copyright notice or in the software. 14.\" 15.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 16.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 17.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 18.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 19.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 20.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 21.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 22.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 23.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 24.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 25.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 27.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 31.\" OF SUCH DAMAGE. 32.\" 33.\" Author: Archie Cobbs <archie@whistle.com> 34.\" 35.\" $FreeBSD: src/lib/libnetgraph/netgraph.3,v 1.4.2.10 2002/12/29 16:35:36 schweikh Exp $ 36.\" $Whistle: netgraph.3,v 1.7 1999/01/25 07:14:06 archie Exp $ 37.\" 38.Dd January 27, 2004 39.Dt NETGRAPH 3 40.Os 41.Sh NAME 42.Nm NgMkSockNode , 43.Nm NgNameNode , 44.Nm NgSendMsg , 45.Nm NgSendAsciiMsg , 46.Nm NgSendReplyMsg , 47.Nm NgRecvMsg , 48.Nm NgAllocRecvMsg , 49.Nm NgRecvAsciiMsg , 50.Nm NgAllocRecvAsciiMsg , 51.Nm NgSendData , 52.Nm NgRecvData , 53.Nm NgAllocRecvData , 54.Nm NgSetDebug , 55.Nm NgSetErrLog 56.Nd netgraph user library 57.Sh LIBRARY 58.Lb libnetgraph 59.Sh SYNOPSIS 60.In netgraph.h 61.Ft int 62.Fn NgMkSockNode "const char *name" "int *csp" "int *dsp" 63.Ft int 64.Fn NgNameNode "int cs" "const char *path" "const char *fmt" ... 65.Ft int 66.Fo NgSendMsg 67.Fa "int cs" "const char *path" "int cookie" "int cmd" "const void *arg" 68.Fa "size_t arglen" 69.Fc 70.Ft int 71.Fn NgSendAsciiMsg "int cs" "const char *path" "const char *fmt" ... 72.Ft int 73.Fo NgSendReplyMsg 74.Fa "int cs" "const char *path" "const struct ng_mesg *msg" "const void *arg" 75.Fa "size_t arglen" 76.Fc 77.Ft int 78.Fn NgRecvMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path" 79.Ft int 80.Fn NgAllocRecvMsg "int cs" "struct ng_mesg **rep" "char *path" 81.Ft int 82.Fn NgRecvAsciiMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path" 83.Ft int 84.Fn NgAllocRecvAsciiMsg "int cs" "struct ng_mesg **rep" "char *path" 85.Ft int 86.Fn NgSendData "int ds" "const char *hook" "const u_char *buf" "size_t len" 87.Ft int 88.Fn NgRecvData "int ds" "u_char *buf" "size_t len" "char *hook" 89.Ft int 90.Fn NgAllocRecvData "int ds" "u_char **buf" "char *hook" 91.Ft int 92.Fn NgSetDebug "int level" 93.Ft void 94.Fo NgSetErrLog 95.Fa "void (*log)(const char *fmt, ...)" 96.Fa "void (*logx)(const char *fmt, ...)" 97.Fc 98.Sh DESCRIPTION 99These functions facilitate user-mode program participation in the kernel 100.Xr netgraph 4 101graph-based networking system, by utilizing the netgraph 102.Vt socket 103node type (see 104.Xr ng_socket 4 ) . 105.Pp 106The 107.Fn NgMkSockNode 108function should be called first, to create a new 109.Vt socket 110type netgraph node with associated control and data sockets. 111If 112.Fa name 113is 114.No non- Ns Dv NULL , 115the node will have that global name assigned to it. 116The 117.Fa csp 118and 119.Fa dsp 120arguments will be set to the newly opened control and data sockets 121associated with the node; either 122.Fa csp 123or 124.Fa dsp 125may be 126.Dv NULL 127if only one socket is desired. 128The 129.Fn NgMkSockNode 130function loads the 131.Vt socket 132node type KLD if it is not already loaded. 133.Pp 134The 135.Fn NgNameNode 136function assigns a global name to the node addressed by 137.Fa path . 138.Pp 139The 140.Fn NgSendMsg 141function sends a binary control message from the 142.Vt socket 143node associated with control socket 144.Fa cs 145to the node addressed by 146.Fa path . 147The 148.Fa cookie 149indicates how to interpret 150.Fa cmd , 151which indicates a specific command. 152Extra argument data (if any) is specified by 153.Fa arg 154and 155.Fa arglen . 156The 157.Fa cookie , cmd , 158and argument data are defined by the header file corresponding 159to the type of the node being addressed. 160The unique, non-negative token value chosen for use in the message 161header is returned. 162This value is typically used to associate replies. 163.Pp 164Use 165.Fn NgSendReplyMsg 166to send reply to a previously received control message. 167The original message header should be pointed to by 168.Fa msg . 169.Pp 170The 171.Fn NgSendAsciiMsg 172function performs the same function as 173.Fn NgSendMsg , 174but adds support for 175.Tn ASCII 176encoding of control messages. 177The 178.Fn NgSendAsciiMsg 179function formats its input a la 180.Xr printf 3 181and then sends the resulting 182.Tn ASCII 183string to the node in a 184.Dv NGM_ASCII2BINARY 185control message. 186The node returns a binary version of the 187message, which is then sent back to the node just as with 188.Fn NgSendMsg . 189As with 190.Fn NgSendMsg , 191the message token value is returned. 192Note that 193.Tn ASCII 194conversion may not be supported by all node types. 195.Pp 196The 197.Fn NgRecvMsg 198function reads the next control message received by the node associated with 199control socket 200.Fa cs . 201The message and any extra argument data must fit in 202.Fa replen 203bytes. 204If 205.Fa path 206is 207.No non- Ns Dv NULL , 208it must point to a buffer of at least 209.Dv NG_PATHSIZ 210bytes, which will be filled in (and 211.Dv NUL 212terminated) with the path to 213the node from which the message was received. 214.Pp 215The length of the control message is returned. 216A return value of zero indicates that the socket was closed. 217.Pp 218The 219.Fn NgAllocRecvMsg 220function works exactly like 221.Fn NgRecvMsg , 222except that the buffer for a message is dynamically allocated 223to guarantee that a message is not truncated. 224The size of the buffer is equal to the socket's receive buffer size. 225The caller is responsible for freeing the buffer when it is no longer required. 226.Pp 227The 228.Fn NgRecvAsciiMsg 229function works exactly like 230.Fn NgRecvMsg , 231except that after the message is received, any binary arguments 232are converted to 233.Tn ASCII 234by sending a 235.Dv NGM_BINARY2ASCII 236request back to the originating node. 237The result is the same as 238.Fn NgRecvMsg , 239with the exception that the reply arguments field will contain a 240.Dv NUL Ns -terminated 241.Tn ASCII 242version of the arguments (and the reply 243header argument length field will be adjusted). 244.Pp 245The 246.Fn NgAllocRecvAsciiMsg 247function works exactly like 248.Fn NgRecvAsciiMsg , 249except that the buffer for a message is dynamically allocated 250to guarantee that a message is not truncated. 251The size of the buffer is equal to the socket's receive buffer size. 252The caller is responsible for freeing the buffer when it is no longer required. 253.Pp 254The 255.Fn NgSendData 256function writes a data packet out on the specified hook of the node 257corresponding to data socket 258.Fa ds . 259The node must already be connected to some other node via that hook. 260.Pp 261The 262.Fn NgRecvData 263function reads the next data packet (of up to 264.Fa len 265bytes) received by the node corresponding to data socket 266.Fa ds 267and stores it in 268.Fa buf , 269which must be large enough to hold the entire packet. 270If 271.Fa hook 272is 273.No non- Ns Dv NULL , 274it must point to a buffer of at least 275.Dv NG_HOOKSIZ 276bytes, which will be filled in (and 277.Dv NUL 278terminated) with the name of 279the hook on which the data was received. 280.Pp 281The length of the packet is returned. 282A return value of zero indicates that the socket was closed. 283.Pp 284The 285.Fn NgAllocRecvData 286function works exactly like 287.Fn NgRecvData , 288except that the buffer for a data packet is dynamically allocated 289to guarantee that a data packet is not truncated. 290The size of the buffer is equal to the socket's receive buffer size. 291The caller is responsible for freeing the buffer when it is no longer required. 292.Pp 293The 294.Fn NgSetDebug 295and 296.Fn NgSetErrLog 297functions are used for debugging. 298The 299.Fn NgSetDebug 300function sets the debug level (if non-negative), and returns the old setting. 301Higher debug levels result in more verbosity. 302The default is zero. 303All debug and error messages are logged via the functions 304specified in the most recent call to 305.Fn NgSetErrLog . 306The default logging functions are 307.Xr vwarn 3 308and 309.Xr vwarnx 3 . 310.Pp 311At debug level 3, the library attempts to display control message arguments 312in 313.Tn ASCII 314format; however, this results in additional messages being 315sent which may interfere with debugging. 316At even higher levels, 317even these additional messages will be displayed, etc. 318.Pp 319Note that 320.Xr select 2 321can be used on the data and the control sockets to detect the presence of 322incoming data and control messages, respectively. 323Data and control packets are always written and read atomically, i.e., 324in one whole piece. 325.Pp 326User mode programs must be linked with the 327.Fl l Ns Li netgraph 328flag to link in this library. 329.Sh INITIALIZATION 330To enable netgraph in your kernel, either your kernel must be 331compiled with 332.Cd "options NETGRAPH" 333in the kernel configuration 334file, or else the 335.Xr netgraph 4 336and 337.Xr ng_socket 4 338KLD modules must have been loaded via 339.Xr kldload 8 . 340.Sh RETURN VALUES 341The 342.Fn NgSetDebug 343function returns the previous debug setting. 344.Pp 345The 346.Fn NgSetErrLog 347function has no return value. 348.Pp 349All other functions return \-1 if there was an error and set 350.Va errno 351accordingly. 352.Pp 353A return value of zero from 354.Fn NgRecvMsg 355or 356.Fn NgRecvData 357indicates that the netgraph socket has been closed. 358.Pp 359For 360.Fn NgSendAsciiMsg 361and 362.Fn NgRecvAsciiMsg , 363the following additional errors are possible: 364.Bl -tag -width Er 365.It Bq Er ENOSYS 366The node type does not know how to encode or decode the control message. 367.It Bq Er ERANGE 368The encoded or decoded arguments were too long for the supplied buffer. 369.It Bq Er ENOENT 370An unknown structure field was seen in an 371.Tn ASCII 372control message. 373.It Bq Er EALREADY 374The same structure field was specified twice in an 375.Tn ASCII 376control message. 377.It Bq Er EINVAL 378.Tn ASCII 379control message parse error or illegal value. 380.It Bq Er E2BIG 381ASCII control message array or fixed width string buffer overflow. 382.El 383.Sh SEE ALSO 384.Xr select 2 , 385.Xr socket 2 , 386.Xr warnx 3 , 387.Xr kld 4 , 388.Xr netgraph 4 , 389.Xr ng_socket 4 390.Sh HISTORY 391The 392.Nm netgraph 393system was designed and first implemented at Whistle Communications, Inc.\& in 394a version of 395.Fx 2.2 396customized for the Whistle InterJet. 397.Sh AUTHORS 398.An Archie Cobbs Aq Mt archie@FreeBSD.org 399