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.\" $Whistle: netgraph.3,v 1.7 1999/01/25 07:14:06 archie Exp $ 35.\" 36.Dd May 15, 2020 37.Dt NETGRAPH 3 38.Os 39.Sh NAME 40.Nm NgMkSockNode , 41.Nm NgNameNode , 42.Nm NgSendMsg , 43.Nm NgSendAsciiMsg , 44.Nm NgSendReplyMsg , 45.Nm NgRecvMsg , 46.Nm NgAllocRecvMsg , 47.Nm NgRecvAsciiMsg , 48.Nm NgAllocRecvAsciiMsg , 49.Nm NgSendData , 50.Nm NgRecvData , 51.Nm NgAllocRecvData , 52.Nm NgSetDebug , 53.Nm NgSetErrLog 54.Nd netgraph user library 55.Sh LIBRARY 56.Lb libnetgraph 57.Sh SYNOPSIS 58.In netgraph.h 59.Ft int 60.Fn NgMkSockNode "const char *name" "int *csp" "int *dsp" 61.Ft int 62.Fn NgNameNode "int cs" "const char *path" "const char *fmt" ... 63.Ft int 64.Fo NgSendMsg 65.Fa "int cs" "const char *path" "int cookie" "int cmd" "const void *arg" 66.Fa "size_t arglen" 67.Fc 68.Ft int 69.Fn NgSendAsciiMsg "int cs" "const char *path" "const char *fmt" ... 70.Ft int 71.Fo NgSendReplyMsg 72.Fa "int cs" "const char *path" "struct ng_mesg *msg" "const void *arg" 73.Fa "size_t arglen" 74.Fc 75.Ft int 76.Fn NgRecvMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path" 77.Ft int 78.Fn NgAllocRecvMsg "int cs" "struct ng_mesg **rep" "char *path" 79.Ft int 80.Fn NgRecvAsciiMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path" 81.Ft int 82.Fn NgAllocRecvAsciiMsg "int cs" "struct ng_mesg **rep" "char *path" 83.Ft int 84.Fn NgSendData "int ds" "const char *hook" "const u_char *buf" "size_t len" 85.Ft int 86.Fn NgRecvData "int ds" "u_char *buf" "size_t len" "char *hook" 87.Ft int 88.Fn NgAllocRecvData "int ds" "u_char **buf" "char *hook" 89.Ft int 90.Fn NgSetDebug "int level" 91.Ft void 92.Fo NgSetErrLog 93.Fa "void \*[lp]*log\*[rp]\*[lp]const char *fmt, ...\*[rp]" 94.Fa "void \*[lp]*logx\*[rp]\*[lp]const char *fmt, ...\*[rp]" 95.Fc 96.Sh DESCRIPTION 97These functions facilitate user-mode program participation in the kernel 98.Xr netgraph 4 99graph-based networking system, by utilizing the netgraph 100.Vt socket 101node type (see 102.Xr ng_socket 4 ) . 103.Pp 104The 105.Fn NgMkSockNode 106function should be called first, to create a new 107.Vt socket 108type netgraph node with associated control and data sockets. 109If 110.Fa name 111is 112.No non- Ns Dv NULL , 113the node will have that global name assigned to it. 114The 115.Fa csp 116and 117.Fa dsp 118arguments will be set to the newly opened control and data sockets 119associated with the node; either 120.Fa csp 121or 122.Fa dsp 123may be 124.Dv NULL 125if only one socket is desired. 126The 127.Fn NgMkSockNode 128function loads the 129.Vt socket 130node type KLD if it is not already loaded. 131.Pp 132The 133.Fn NgNameNode 134function assigns a global name to the node addressed by 135.Fa path . 136.Pp 137The 138.Fn NgSendMsg 139function sends a binary control message from the 140.Vt socket 141node associated with control socket 142.Fa cs 143to the node addressed by 144.Fa path . 145The 146.Fa cookie 147indicates how to interpret 148.Fa cmd , 149which indicates a specific command. 150Extra argument data (if any) is specified by 151.Fa arg 152and 153.Fa arglen . 154The 155.Fa cookie , cmd , 156and argument data are defined by the header file corresponding 157to the type of the node being addressed. 158The unique, non-negative token value chosen for use in the message 159header is returned. 160This value is typically used to associate replies. 161.Pp 162Use 163.Fn NgSendReplyMsg 164to send reply to a previously received control message. 165The original message header should be pointed to by 166.Fa msg . 167.Pp 168The 169.Fn NgSendAsciiMsg 170function performs the same function as 171.Fn NgSendMsg , 172but adds support for 173.Tn ASCII 174encoding of control messages. 175The 176.Fn NgSendAsciiMsg 177function formats its input a la 178.Xr printf 3 179and then sends the resulting 180.Tn ASCII 181string to the node in a 182.Dv NGM_ASCII2BINARY 183control message. 184The node returns a binary version of the 185message, which is then sent back to the node just as with 186.Fn NgSendMsg . 187As with 188.Fn NgSendMsg , 189the message token value is returned. 190Note that 191.Tn ASCII 192conversion may not be supported by all node types. 193.Pp 194The 195.Fn NgRecvMsg 196function reads the next control message received by the node associated with 197control socket 198.Fa cs . 199The message and any extra argument data must fit in 200.Fa replen 201bytes. 202If 203.Fa path 204is 205.No non- Ns Dv NULL , 206it must point to a buffer of at least 207.Dv NG_PATHSIZ 208bytes, which will be filled in (and 209.Dv NUL 210terminated) with the path to 211the node from which the message was received. 212.Pp 213The length of the control message is returned. 214A return value of zero indicates that the socket was closed. 215.Pp 216The 217.Fn NgAllocRecvMsg 218function works exactly like 219.Fn NgRecvMsg , 220except that the buffer for a message is dynamically allocated 221to guarantee that a message is not truncated. 222The size of the buffer is equal to the socket's receive buffer size. 223The caller is responsible for freeing the buffer when it is no longer required. 224.Pp 225The 226.Fn NgRecvAsciiMsg 227function works exactly like 228.Fn NgRecvMsg , 229except that after the message is received, any binary arguments 230are converted to 231.Tn ASCII 232by sending a 233.Dv NGM_BINARY2ASCII 234request back to the originating node. 235The result is the same as 236.Fn NgRecvMsg , 237with the exception that the reply arguments field will contain a 238.Dv NUL Ns -terminated 239.Tn ASCII 240version of the arguments (and the reply 241header argument length field will be adjusted). 242.Pp 243The 244.Fn NgAllocRecvAsciiMsg 245function works exactly like 246.Fn NgRecvAsciiMsg , 247except that the buffer for a message is dynamically allocated 248to guarantee that a message is not truncated. 249The size of the buffer is equal to the socket's receive buffer size. 250The caller is responsible for freeing the buffer when it is no longer required. 251.Pp 252The 253.Fn NgSendData 254function writes a data packet out on the specified hook of the node 255corresponding to data socket 256.Fa ds . 257The node must already be connected to some other node via that hook. 258.Pp 259The 260.Fn NgRecvData 261function reads the next data packet (of up to 262.Fa len 263bytes) received by the node corresponding to data socket 264.Fa ds 265and stores it in 266.Fa buf , 267which must be large enough to hold the entire packet. 268If 269.Fa hook 270is 271.No non- Ns Dv NULL , 272it must point to a buffer of at least 273.Dv NG_HOOKSIZ 274bytes, which will be filled in (and 275.Dv NUL 276terminated) with the name of 277the hook on which the data was received. 278.Pp 279The length of the packet is returned. 280A return value of zero indicates that the socket was closed. 281.Pp 282The 283.Fn NgAllocRecvData 284function works exactly like 285.Fn NgRecvData , 286except that the buffer for a data packet is dynamically allocated 287to guarantee that a data packet is not truncated. 288The size of the buffer is equal to the socket's receive buffer size. 289The caller is responsible for freeing the buffer when it is no longer required. 290.Pp 291The 292.Fn NgSetDebug 293and 294.Fn NgSetErrLog 295functions are used for debugging. 296The 297.Fn NgSetDebug 298function sets the debug level (if non-negative), and returns the old setting. 299Higher debug levels result in more verbosity. 300The default is zero. 301All debug and error messages are logged via the functions 302specified in the most recent call to 303.Fn NgSetErrLog . 304The default logging functions are 305.Xr vwarn 3 306and 307.Xr vwarnx 3 . 308.Pp 309At debug level 3, the library attempts to display control message arguments 310in 311.Tn ASCII 312format; however, this results in additional messages being 313sent which may interfere with debugging. 314At even higher levels, 315even these additional messages will be displayed, etc. 316.Pp 317Note that 318.Xr select 2 319can be used on the data and the control sockets to detect the presence of 320incoming data and control messages, respectively. 321Data and control packets are always written and read atomically, i.e., 322in one whole piece. 323.Pp 324User mode programs must be linked with the 325.Fl l Ns Li netgraph 326flag to link in this library. 327.Sh INITIALIZATION 328To enable netgraph in your kernel, either your kernel must be 329compiled with 330.Cd "options NETGRAPH" 331in the kernel configuration 332file, or else the 333.Xr netgraph 4 334and 335.Xr ng_socket 4 336KLD modules must have been loaded via 337.Xr kldload 8 . 338.Sh RETURN VALUES 339The 340.Fn NgSetDebug 341function returns the previous debug setting. 342.Pp 343The 344.Fn NgSetErrLog 345function has no return value. 346.Pp 347All other functions return \-1 if there was an error and set 348.Va errno 349accordingly. 350.Pp 351A return value of zero from 352.Fn NgRecvMsg 353or 354.Fn NgRecvData 355indicates that the netgraph socket has been closed. 356.Pp 357For 358.Fn NgSendAsciiMsg 359and 360.Fn NgRecvAsciiMsg , 361the following additional errors are possible: 362.Bl -tag -width Er 363.It Bq Er ENOSYS 364The node type does not know how to encode or decode the control message. 365.It Bq Er ERANGE 366The encoded or decoded arguments were too long for the supplied buffer. 367.It Bq Er ENOENT 368An unknown structure field was seen in an 369.Tn ASCII 370control message. 371.It Bq Er EALREADY 372The same structure field was specified twice in an 373.Tn ASCII 374control message. 375.It Bq Er EINVAL 376.Tn ASCII 377control message parse error or illegal value. 378.It Bq Er E2BIG 379ASCII control message array or fixed width string buffer overflow. 380.El 381.Sh SEE ALSO 382.Xr select 2 , 383.Xr socket 2 , 384.Xr warnx 3 , 385.Xr kld 4 , 386.Xr netgraph 4 , 387.Xr ng_socket 4 388.Sh HISTORY 389The 390.Nm netgraph 391system was designed and first implemented at Whistle Communications, Inc.\& in 392a version of 393.Fx 2.2 394customized for the Whistle InterJet. 395.Sh AUTHORS 396.An Archie Cobbs Aq Mt archie@FreeBSD.org 397