.\" -*- nroff -*-

.\"

.\" Project:      DHCP

.\" File:         dhcpctl.3

.\" RCSId:        $Id$

.\" 

.\" Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")

.\" Copyright (c) 2000-2003 by Internet Software Consortium

.\" Copyright (c) 2000 Nominum, Inc.

.\"

.\" Permission to use, copy, modify, and distribute this software for any

.\" purpose with or without fee is hereby granted, provided that the above

.\" copyright notice and this permission notice appear in all copies.

.\"

.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES

.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

.\" MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR

.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT

.\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

.\"

.\"   Internet Systems Consortium, Inc.

.\"   950 Charter Street

.\"   Redwood City, CA 94063

.\"   <info@isc.org>

.\"   http://www.isc.org/

.\"     

.\" Description:	dhcpctl man page.

.\" 

.\"

.Dd Nov 15, 2000

.Dt DHCPCTL 3

.Os DHCP 3

.ds vT DHCP Programmer's Manual

.\"

.\"

.\"

.Sh NAME

.Nm dhcpctl_initialize

.Nd dhcpctl library initialization.

.\"

.\"

.\"

.Sh SYNOPSIS

.Fd #include <dhcpctl.h>

.Ft dhcpctl_status

.Fo dhcpctl_initialize

.Fa void

.Fc

.\"

.Ft dhcpctl_status

.Fo dhcpctl_connect

.Fa "dhcpctl_handle *cxn"

.Fa "const char *host"

.Fa "int port"

.Fa "dhcpctl_handle auth"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_wait_for_completion

.Fa "dhcpctl_handle object"

.Fa "dhcpctl_status *status"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_get_value

.Fa "dhcpctl_data_string *value"

.Fa "dhcpctl_handle object"

.Fa "const char *name"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_get_boolean

.Fa "int *value"

.Fa "dhcpctl_handle object"

.Fa "const char *name"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_set_value

.Fa "dhcpctl_handle object"

.Fa "dhcpctl_data_string value"

.Fa "const char *name"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_set_string_value

.Fa "dhcpctl_handle object"

.Fa "const char *value"

.Fa "const char *name"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_set_boolean_value

.Fa "dhcpctl_handle object"

.Fa "int value"

.Fa "const char *name"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_set_int_value

.Fa "dhcpctl_handle object"

.Fa "int value"

.Fa "const char *name"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_object_update

.Fa "dhcpctl_handle connection"

.Fa "dhcpctl_handle object"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_object_refresh

.Fa "dhcpctl_handle connection"

.Fa "dhcpctl_handle object"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_object_remove

.Fa "dhcpctl_handle connection"

.Fa "dhcpctl_handle object"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_set_callback

.Fa "dhcpctl_handle object"

.Fa "void *data"

.Fa "void (*function) (dhcpctl_handle, dhcpctl_status, void *)"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_new_authenticator

.Fa "dhcpctl_handle *object"

.Fa "const char *name"

.Fa "const char *algorithm"

.Fa "const char *secret"

.Fa "unsigned secret_len"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_new_object

.Fa "dhcpctl_handle *object"

.Fa "dhcpctl_handle connection"

.Fa "const char *object_type"

.Fc

.\"

.\"

.\"

.Ft dhcpctl_status

.Fo dhcpctl_open_object

.Fa "dhcpctl_handle object"

.Fa "dhcpctl_handle connection"

.Fa "int flags"

.Fc

.\"

.\"

.\"

.Ft isc_result_t

.Fo omapi_data_string_new

.Fa dhcpctl_data_string *data

.Fa unsigned int length

.Fa const char *filename,

.Fa int lineno

.Fc

.\"

.\"

.\"

.Ft isc_result_t

.Fo dhcpctl_data_string_dereference

.Fa "dhcpctl_data_string *"

.Fa "const char *"

.Fa "int"

.Fc

.Sh DESCRIPTION

The dhcpctl set of functions provide an API that can be used to communicate

with and manipulate a running ISC DHCP server. All functions return a value of

.Dv isc_result_t .

The return values reflects the result of operations to local data

structures. If an operation fails on the server for any reason, then the error

result will be returned through the

second parameter of the 

.Fn dhcpctl_wait_for_completion 

call.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_initialize

sets up the data structures the library needs to do its work. This function

must be called once before any other.

.Pp

.Fn dhcpctl_connect

opens a connection to the DHCP server at the given host and port. If an

authenticator has been created for the connection, then it is given as the 4th

argument. On a successful return the address pointed at by the first

argument will have a new connection object assigned to it.

.Pp

For example:

.Bd -literal -offset indent

s = dhcpctl_connect(&cxn, "127.0.0.1", 7911, NULL);

.Ed

.Pp

connects to the DHCP server on the localhost via port 7911 (the standard

OMAPI port). No authentication is used for the connection.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_wait_for_completion

flushes a pending message to the server and waits for the response. The result

of the request as processed on the server is returned via the second

parameter.

.Bd -literal -offset indent

s = dhcpctl_wait_for_completion(cxn, &wv;;

if (s != ISC_R_SUCCESS) 

	local_failure(s);

else if (wv != ISC_R_SUCCESS)

	server_failure(wc);

.Ed

.Pp

The call to 

.Fn dhcpctl_wait_for_completion

won't return until the remote message processing completes or the connection

to the server is lost.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_get_value

extracts a value of an attribute from the handle. The value can be of any

length and is treated as a sequence of bytes.  The handle must have been

created first with

.Fn dhcpctl_new_object

and opened with

.Fn dhcpctl_open_object .

The value is returned via the parameter named

.Dq value .

The last parameter is the name of attribute to retrieve.

.Bd -literal -offset indent

dhcpctl_data_string value = NULL;

dhcpctl_handle lease;

time_t thetime;

s = dhcpctl_get_value (&value, lease, "ends");

assert(s == ISC_R_SUCCESS && value->len == sizeof(thetime));

memcpy(&thetime, value->value, value->len);

.Ed

.\"

.\"

.\"

.Pp

.Fn dhcpctl_get_boolean

extracts a boolean valued attribute from the object handle.

.\"

.\"

.\"

.Pp

The

.Fn dhcpctl_set_value ,

.Fn dhcpctl_set_string_value ,

.Fn dhcpctl_set_boolean_value ,

and

.Fn dhcpctl_set_int_value

functions all set a value on the object handle. 

.\"

.\"

.\"

.Pp

.Fn dhcpctl_object_update

function queues a request for

all the changes made to the object handle be be sent to the remote

for processing. The changes made to the atributes on the handle will be

applied to remote object if permitted.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_object_refresh

queues up a request for a fresh copy of all the attribute values to be sent

from the remote to

refresh the values in the local object handle.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_object_remove

queues a request for the removal on the server of the object referenced by the

handle.

.\"

.\"

.\"

.Pp

The 

.Fn dhcpctl_set_callback

function sets up a user-defined function to be called when an event completes

on the given object handle. This is needed for asynchronous handling of

events, versus the synchronous handling given by

.Fn dhcpctl_wait_for_completion .

When the function is called the first parameter is the object the event

arrived for, the second is the status of the message that was processed, the

third is the same value as the second parameter given to 

.Fn dhcpctl_set_callback .

.\"

.\"

.\"

.Pp

The 

.Fn dhcpctl_new_authenticator

creates a new authenticator object to be used for signing the messages

that cross over the network. The 

.Dq name ,

.Dq algorithm ,

and 

.Dq secret

values must all match what the server uses and are defined in its

configuration file. The created object is returned through the first parameter

and must be used as the 4th parameter to 

.Fn dhcpctl_connect .

Note that the 'secret' value must not be base64 encoded, which is different

from how the value appears in the dhcpd.conf file.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_new_object

creates a local handle for an object on the the server. The 

.Dq object_type

parameter is the ascii name of the type of object being accessed. e.g. 

.Qq lease .

This function only sets up local data structures, it does not queue any 

messages

to be sent to the remote side,

.Fn dhcpctl_open_object

does that.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_open_object

builds and queues the request to the remote side. This function is used with

handle created via

.Fn dhcpctl_new_object .

The flags argument is a bit mask with the following values available for

setting:

.Bl -tag -offset indent -width 20

.It DHCPCTL_CREATE

if the object does not exist then the remote will create it

.It DHCPCTL_UPDATE

update the object on the remote side using the

attributes already set in the handle.

.It DHCPCTL_EXCL

return and error if the object exists and DHCPCTL_CREATE

was also specified

.El

.\"

.\"

.\"

.Pp

The 

.Fn omapi_data_string_new

function allocates a new

.Ft dhcpctl_data_string

object. The data string will be large enough to hold 

.Dq length

bytes of data. The

.Dq file 

and

.Dq lineno

arguments are the source file location the call is made from, typically by

using the 

.Dv __FILE__

and

.Dv __LINE__

macros or the 

.Dv MDL

macro defined in

.

.\"

.\"

.\"

.Pp

.Fn dhcpctl_data_string_dereference

deallocates a data string created by

.Fn omapi_data_string_new .

The memory for the object won't be freed until the last reference is

released.

.Sh EXAMPLES

.Pp 

The following program will connect to the DHCP server running on the local

host and will get the details of the existing lease for IP address

10.0.0.101. It will then print out the time the lease is due to expire. Note

that most error checking has been ommitted for brevity.

.Bd -literal -offset indent

#include <stdarg.h>

#include <sys/time.h>

#include <sys/socket.h>

#include <stdio.h>

#include <netinet/in.h>

#include <isc/result.h>

#include <dhcpctl.h>

int main (int argc, char **argv) {

	dhcpctl_data_string ipaddrstring = NULL;

	dhcpctl_data_string value = NULL;

	dhcpctl_handle connection = NULL;

	dhcpctl_handle lease = NULL;

	isc_result_t waitstatus;

	struct in_addr convaddr;

	time_t thetime;

        dhcpctl_initialize ();

        dhcpctl_connect (&connection, "127.0.0.1",

			 7911, 0);

        dhcpctl_new_object (&lease, connection,

			    "lease");

        memset (&ipaddrstring, 0, sizeof

		ipaddrstring);

        inet_pton(AF_INET, "10.0.0.101",

		  &convaddr);

	omapi_data_string_new (&ipaddrstring,

			       4, MDL);

	memcpy(ipaddrstring->value, &convaddr.s_addr, 4);

	dhcpctl_set_value (lease, ipaddrstring,

			   "ip-address");

	dhcpctl_open_object (lease, connection, 0);

	dhcpctl_wait_for_completion (lease,

				     &waitstatus);

        if (waitstatus != ISC_R_SUCCESS) {

		/* server not authoritative */

		exit (0);

        }

	dhcpctl_data_string_dereference(&ipaddrstring,

					MDL);

        dhcpctl_get_value (&value, lease, "ends");

	memcpy(&thetime, value->value, value->len);

	dhcpctl_data_string_dereference(&value, MDL);

	fprintf (stdout, "ending time is %s",

		 ctime(&thetime));

}

.Ed

.Sh SEE ALSO

omapi(3), omshell(3), dhcpd(8), dhclient(8), dhcpd.conf(5), dhclient.conf(5).

.Sh AUTHOR

.Em dhcpctl

was written by Ted Lemon of Nominum, Inc.

This preliminary documentation was written by James Brister of Nominum, Inc.