437 lines
13 KiB
Groff
437 lines
13 KiB
Groff
.\"
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.\" Copyright (c) 2001-2003
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.\" Fraunhofer Institute for Open Communication Systems (FhG Fokus).
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.\" All rights reserved.
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.\"
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.\" Author: Harti Brandt <harti@freebsd.org>
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.\"
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.\" Redistribution of this software and documentation and use in source and
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.\" binary forms, with or without modification, are permitted provided that
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.\" the following conditions are met:
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.\"
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.\" 1. Redistributions of source code or documentation must retain the above
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.\" copyright notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE AND DOCUMENTATION IS PROVIDED BY FRAUNHOFER FOKUS
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.\" AND ITS CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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.\" FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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.\" FRAUNHOFER FOKUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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.\" OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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.\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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.\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 14, 2003
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.Dt snmp_netgraph 3
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.Os
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.Sh NAME
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.Nm snmp_netgraph ,
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.Nm snmp_node ,
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.Nm snmp_nodename ,
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.Nm ng_cookie_f ,
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.Nm ng_hook_f ,
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.Nm ng_register_cookie ,
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.Nm ng_unregister_cookie ,
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.Nm ng_register_hook ,
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.Nm ng_unregister_hook ,
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.Nm ng_unregister_module ,
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.Nm ng_output ,
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.Nm ng_output_node ,
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.Nm ng_output_id ,
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.Nm ng_dialog ,
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.Nm ng_dialog_node ,
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.Nm ng_dialog_id ,
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.Nm ng_send_data ,
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.Nm ng_mkpeer_id ,
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.Nm ng_connect_node ,
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.Nm ng_connect_id ,
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.Nm ng_connect2_id ,
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.Nm ng_connect2_tee_id ,
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.Nm ng_rmhook ,
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.Nm ng_rmhook_id ,
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.Nm ng_rmhook_tee_id ,
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.Nm ng_shutdown_id ,
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.Nm ng_next_node_id ,
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.Nm ng_node_id ,
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.Nm ng_node_id_node ,
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.Nm ng_node_name ,
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.Nm ng_node_type ,
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.Nm ng_peer_hook_id
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.Nd "netgraph module for snmpd.
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.Sh LIBRARY
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.Pq begemotSnmpdModulePath."netgraph" = "/usr/lib/snmp_netgraph.so"
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.Sh SYNOPSIS
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.In bsnmp/snmpmod.h
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.In bsnmp/snmp_netgraph.h
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.Vt extern ng_ID_t snmp_node ;
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.Vt extern u_char *snmp_nodename ;
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.Ft typedef void
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.Fn ng_cookie_f "const struct ng_mesg *mesg" "const char *path" "ng_ID_t id" "void *uarg"
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.Ft typedef void
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.Fn ng_hook_f "const char *hook" "const u_char *mesg" "size_t len" "void *uarg"
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.Ft void *
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.Fn ng_register_cookie "const struct lmodule *mod" "u_int32_t cookie" "ng_ID_t id" "ng_cookie_f *func" "void *uarg"
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.Ft void
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.Fn ng_unregister_cookie "void *reg"
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.Ft void *
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.Fn ng_register_hook "const struct lmodule *mod" "const char *hook" "ng_hook_f *func" "void *uarg"
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.Ft void
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.Fn ng_unregister_hook "void *reg"
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.Ft void
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.Fn ng_unregister_module "const struct lmodule *mod"
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.Ft int
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.Fn ng_output "const char *path" "u_int cookie" "u_int opcode" "const void *arg" "size_t arglen"
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.Ft int
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.Fn ng_output_node "const char *node" "u_int cookie" "u_int opcode" "const void *arg" "size_t arglen" "
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.Ft int
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.Fn ng_output_id "ng_ID_t node" "u_int cookie" "u_int opcode" "const void *arg" "size_t arglen" "
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.Ft struct ng_mesg *
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.Fn ng_dialog "const char *path" "u_int cookie" "u_int opcode" "const void *arg" "size_t arglen"
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.Ft struct ng_mesg *
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.Fn ng_dialog_node "const char *node" "u_int cookie" "u_int opcode" "const void *arg" "size_t arglen" "
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.Ft struct ng_mesg *
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.Fn ng_dialog_id "ng_ID_t id" "u_int cookie" "u_int opcode" "const void *arg" "size_t arglen" "
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.Ft int
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.Fn ng_send_data "const char *hook" "const void *sndbuf" "size_t sndlen"
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.Ft ng_ID_t
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.Fn ng_mkpeer_id "ng_ID_t id" "const char *name" "const char *type" "const char *hook" "const char *peerhook"
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.Ft int
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.Fn ng_connect_node "const char *node" "const char *ourhook" "const char *peerhook"
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.Ft int
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.Fn ng_connect_id "ng_ID_t id" "const char *ourhook" "const char *peerhook"
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.Ft int
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.Fn ng_connect2_id "ng_ID_t id" "ng_ID_t peer" "const char *ourhook" "const char *peerhook"
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.Ft int
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.Fn ng_connect2_tee_id "ng_ID_t id" "ng_ID_t peer" "const char *ourhook" "const char *peerhook"
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.Ft int
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.Fn ng_rmhook "const char *ourhook"
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.Ft int
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.Fn ng_rmhook_id "ng_ID_t id" "const char *hook"
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.Ft int
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.Fn ng_rmhook_tee_id "ng_ID_t id" "const char *hook"
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.Ft int
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.Fn ng_shutdown_id "ng_ID_t id"
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.Ft ng_ID_t
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.Fn ng_next_node_id "ng_ID_t node, const char *type, const char *hook);
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.Ft ng_ID_t
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.Fn ng_node_id "const char *path"
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.Ft ng_ID_t
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.Fn ng_node_id_node "const char *node"
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.Ft ng_ID_t
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.Fn ng_node_name "ng_ID_t id, char *name"
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.Ft ng_ID_t
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.Fn ng_node_type "ng_ID_t id, char *type"
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.Ft int
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.Fn ng_peer_hook_id "ng_ID_t id" "const char *hook" "char *peerhook"
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.Sh DESCRIPTION
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The
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.Nm snmp_netgraph
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module implements a number of tables and scalars that enable remote access to
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the netgraph subsystem.
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It also exports a number of global variables and
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functions, that allow other modules to easily use the netgraph system.
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.Pp
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If upon start up of the module the variable
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.Va begemotNgControlNodeName
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is not empty the module opens a netgraph socket and names that socket node.
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If the variable is empty, the socket is created, as soon as the variable is
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written with a non-empty name.
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The socket can be closed by writing an empty
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string to the variable.
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The socket itself and its name are available in
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.Va snmp_node
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and
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.Va snmp_nodename .
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.Ss SENDING AND RECEIVING MESSAGES AND DATA
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There are three functions for sending control message:
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.Bl -tag -width ".It Fn ng_output_node"
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.It Fn ng_output
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sends a control message along the given
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.Fa path .
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.It Fn ng_output_node
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sends a control message to the node with name
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.Fa node
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and
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.It Fn ng_output_id
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sends a control message to the node with node id
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.Fa id .
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.El
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.Pp
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Each of these functions takes the following arguments:
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.Bl -tag -width ".It Fa cookie"
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.It Fa cookie
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is the node specific command cookie,
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.It Fa opcode
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is the node specific code for the operation to performa,
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.It Fa arg
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is a pointer to the message itself.
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This message must start with a
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.Vt struct ng_mesg .
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.It Fa arglen
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is the overall length of the message (header plus arguments).
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.El
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The functions return the message id that can be used to match incoming responses
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or -1 if an error occurs.
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.Pp
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Another class of functions is used to send a control message and to wait for
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a matching response.
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Note, that this operation blocks the daemon, so use it
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only if you are sure that the response will happen.
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There is a maximum timeout
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that is configurable in the MIB variable
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.Va begemotNgTimeout .
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Other messages arriving while the functions are waiting for the response are
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queued and delivered on the next call to the module's idle function.
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.Bl -tag -width ".It Fn ng_output_node"
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.It Fn ng_dialog
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sends a control message along the given
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.Fa path
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and waits for a matching response.
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.It Fn ng_dialog_node
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sends a control message to the node with name
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.Fa node
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and waits for a matching response.
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.It Fn ng_dialog_id
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sends a control message to the node with id
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.Fa id
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and waits for a matching response.
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.El
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.Pp
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All three functions take the same arguments as the
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.Fn ng_output*
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functions.
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The functions return the reponse message in a buffer allocated by
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.Xr malloc 3
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or NULL in case of an error.
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The maximum size of the response buffer can be
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configured in the variable
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.Va begemotNgResBufSiz .
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.Pp
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A data message can be send with the function
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.Fn ng_send_data .
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This function takes the name of the
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.Va snmp_node Ns 's
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hook through which to send the data, a pointer to the message buffer and
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the size of the message.
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It returns -1 if an error happens.
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.Ss ASYNCHRONOUS CONTROL AND DATA MESSAGES
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A module can register functions to asynchronuosly receive control and data
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message.
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.Pp
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The function
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.Fn ng_register_cookie
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registers a control message receive function.
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If a control message is
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received, that is not consumed by the dialog functions, the list of registerred
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control message receive functions is scanned.
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If the cookie in the received
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message is the same as the
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.Fa cookie
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argument to the
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.Fn ng_register_cookie
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call and the
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.Fn
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.Fa id
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argument to the
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.Fn ng_register_cookie
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call was either 0 or equals the node id which sent the control message, the
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handler function
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.Fa func
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is called with a pointer to the received message, the hook on which the
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message was received (or NULL if it was received not on a hook), the id
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of the sender's node and the
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.Fa uarg
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argument of the registration call.
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The handler function should not modify
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the contents of the message, because more than one function may be registered
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to the same cookie and node id.
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.Pp
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A control message registration can be undone by calling
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.Fn ng_unregister_cookie
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with the return value of the registration call.
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If an error occures while registering,
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.Fn ng_register_cookie
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returns NULL.
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.Pp
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A module can call
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.Fn ng_register_hook
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to register a callback for data messages on one of the
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.Va snmp_node Ns 's
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hooks.
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If a data message is received on that hook, the callback function
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.Fa func
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is called with the hook name, a pointer to the data message, the size of
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the message and the argument
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.Fa uarg
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to the registration function.
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The message should be treated as read-only.
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A data message registration can be undone by calling
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.Fn ng_unregister_hook
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with the return value of the registration call.
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If an error occures while registering,
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.Fn ng_register_hook
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returns NULL.
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.Pp
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The function
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.Fn ng_unregister_module
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removes all control and data registrations for that module.
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.Ss FINDING NODES AND NODE CHARACTERISTICS
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.Pp
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The function
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.Fn ng_node_id
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returns the id of the node addressed by
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.Fa path
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or 0 if the node does not exists.
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.Pp
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The function
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.Fn ng_node_id_node
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returns the id of the node with name
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.Fa node
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or 0 if the node does not exist.
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.Pp
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The function
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.Fn ng_node_node
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retrieves the name of the node with id
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.Fa id
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and writes it to the buffer pointed to by
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.Fa name .
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This buffer should be at least
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.Li NG_NODESIZ
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bytes long.
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The function returns the node id or 0 if the
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node is not found
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.Pp
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The function
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.Fn ng_node_type
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retrieves the name of the node with id
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.Fa id
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and writes it to the buffer pointed to by
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.Fa type .
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This buffer should be at least
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.Li NG_TYPESIZ
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bytes long.
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The function returns the node id or 0 if the
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node is not found.
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.Pp
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The function
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.Fn ng_peer_hook_id
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writes the name of the peer hook of the hook
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.Fa hook
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on the node with
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.Fa id
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to the buffer pointed to by
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.Fa peer_hook .
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The buffer should be at least
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.Li NG_HOOKSIZ
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bytes long.
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The function returns 0 if the node and the hook is found, -1
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otherwise.
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The function skips intermediate tee nodes (see
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.Xr ng_tee 4 ).
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.Pp
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The function
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.Fn ng_next_node_id
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returns the node id of the peer node that is on the other side of hook
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.Fa hook
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of node
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.Fa id .
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If
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.Fa type
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is not NULL, the function checks, that the peer node's type is
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.Fa type .
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The function skips intermediate tee nodes (see
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.Xr ng_tee 4 ).
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It returns the node id of the peer node or 0 if an error occurres or the
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types do not match.
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.Ss CHANGING THE GRAPH
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A number of functions can be used to create or destroy nodes and hooks.
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.Pp
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The function
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.Fn ng_mkpeer_id
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creates a new node of type
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.Fa type
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who's hook
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.Fa peerhook
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will be connected to
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.Fa hook
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of node
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.Fa id .
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If
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.Fa name
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is not NULL the new node is named with this name.
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The function returns
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The node id of the new node or 0 if an error happens.
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.Pp
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The functions
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.Fn ng_connect_node
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and
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.Fn ng_connect_id
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make a new hook connecting
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.Fa ourhook
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of the modules socket node
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.Va snmp_node
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to
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.Fa peerhook
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of the node identified by id
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.Fa id
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or name
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.Fa node .
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The functions return 0 on success or -1 otherwise.
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.Pp
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The function
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.Fn ng_connect2_id
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connects hook
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.Fa ourhook
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of the node with id
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.Fa id
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to hook
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.Fa peerhook
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of the node with id
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.Fa peer .
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The functions return 0 on success or -1 otherwise.
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The function
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.Fn ng_connect2_tee_id does the same as
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.Fn ng_connect2_id
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except, that it puts an unnamed tee node between the two nodes.
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.Pp
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The function
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.Fn ng_rmhook
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removes hook
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.Fa hook
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on the module's
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.Va snmp_node .
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The function
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.Fn ng_rmhook_id
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removes hook
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.Fa hook
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on the node with id
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.Fa id .
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The function
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.Fn ng_rmhook_tee_id
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additionally shuts down all tee nodes between the node and the first non-tee
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peer.
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.Pp
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The function
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.Fn ng_shutdown_id
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destroys the given node.
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.Sh FILES
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.Bl -tag -width "XXXXXXXXX"
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.It Pa /usr/share/bsnmp/defs/netgraph_tree.def
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The description of the MIB tree implemented by
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.Nm .
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.It Pa /usr/share/bsnmp/mibs/BEGEMOT-NETGRAPH.txt
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This is the MIB that is implemented by this module.
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.Sh SEE ALSO
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.Xr gensnmptree 1 ,
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.Xr snmpmod 3
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.Sh AUTHORS
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.An Hartmut Brandt Aq harti@freebsd.org
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