.\"	$NetBSD: krb5_krbhst_init.3,v 1.2 2017/01/28 21:31:49 christos Exp $
.\"
.\" Copyright (c) 2001-2005 Kungliga Tekniska Högskolan
.\" (Royal Institute of Technology, Stockholm, Sweden).
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" 3. Neither the name of the Institute nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON 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 ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" Id
.\"
.Dd May 10, 2005
.Dt KRB5_KRBHST_INIT 3
.Os
.Sh NAME
.Nm krb5_krbhst_init ,
.Nm krb5_krbhst_init_flags ,
.Nm krb5_krbhst_next ,
.Nm krb5_krbhst_next_as_string ,
.Nm krb5_krbhst_reset ,
.Nm krb5_krbhst_free ,
.Nm krb5_krbhst_format_string ,
.Nm krb5_krbhst_get_addrinfo
.Nd lookup Kerberos KDC hosts
.Sh LIBRARY
Kerberos 5 Library (libkrb5, -lkrb5)
.Sh SYNOPSIS
.In krb5/krb5.h
.Ft krb5_error_code
.Fn krb5_krbhst_init "krb5_context context" "const char *realm" "unsigned int type" "krb5_krbhst_handle *handle"
.Ft krb5_error_code
.Fn krb5_krbhst_init_flags "krb5_context context" "const char *realm" "unsigned int type" "int flags" "krb5_krbhst_handle *handle"
.Ft krb5_error_code
.Fn "krb5_krbhst_next" "krb5_context context" "krb5_krbhst_handle handle" "krb5_krbhst_info **host"
.Ft krb5_error_code
.Fn krb5_krbhst_next_as_string "krb5_context context" "krb5_krbhst_handle handle" "char *hostname" "size_t hostlen"
.Ft void
.Fn krb5_krbhst_reset "krb5_context context" "krb5_krbhst_handle handle"
.Ft void
.Fn krb5_krbhst_free "krb5_context context" "krb5_krbhst_handle handle"
.Ft krb5_error_code
.Fn krb5_krbhst_format_string "krb5_context context" "const krb5_krbhst_info *host" "char *hostname" "size_t hostlen"
.Ft krb5_error_code
.Fn krb5_krbhst_get_addrinfo "krb5_context context" "krb5_krbhst_info *host" "struct addrinfo **ai"
.Sh DESCRIPTION
These functions are used to sequence through all Kerberos hosts of a
particular realm and service. The service type can be the KDCs, the
administrative servers, the password changing servers, or the servers
for Kerberos 4 ticket conversion.
.Pp
First a handle to a particular service is obtained by calling
.Fn krb5_krbhst_init
(or
.Fn krb5_krbhst_init_flags )
with the
.Fa realm
of interest and the type of service to lookup. The
.Fa type
can be one of:
.Pp
.Bl -tag -width Ds -compact -offset indent
.It KRB5_KRBHST_KDC
.It KRB5_KRBHST_ADMIN
.It KRB5_KRBHST_CHANGEPW
.It KRB5_KRBHST_KRB524
.El
.Pp
The
.Fa handle
is returned to the caller, and should be passed to the other
functions.
.Pp
The
.Fa flag
argument to
.Nm krb5_krbhst_init_flags
is the same flags as
.Fn krb5_send_to_kdc_flags
uses.
Possible values are:
.Pp
.Bl -tag -width KRB5_KRBHST_FLAGS_LARGE_MSG -compact -offset indent
.It KRB5_KRBHST_FLAGS_MASTER
only talk to master (readwrite) KDC
.It KRB5_KRBHST_FLAGS_LARGE_MSG
this is a large message, so use transport that can handle that.
.El
.Pp
For each call to
.Fn krb5_krbhst_next
information on a new host is returned. The former function returns in
.Fa host
a pointer to a structure containing information about the host, such
as protocol, hostname, and port:
.Bd -literal -offset indent
typedef struct krb5_krbhst_info {
    enum { KRB5_KRBHST_UDP,
	   KRB5_KRBHST_TCP,
	   KRB5_KRBHST_HTTP } proto;
    unsigned short port;
    struct addrinfo *ai;
    struct krb5_krbhst_info *next;
    char hostname[1];
} krb5_krbhst_info;
.Ed
.Pp
The related function,
.Fn krb5_krbhst_next_as_string ,
return the same information as a URL-like string.
.Pp
When there are no more hosts, these functions return
.Dv KRB5_KDC_UNREACH .
.Pp
To re-iterate over all hosts, call
.Fn krb5_krbhst_reset
and the next call to
.Fn krb5_krbhst_next
will return the first host.
.Pp
When done with the handle,
.Fn krb5_krbhst_free
should be called.
.Pp
To use a
.Va krb5_krbhst_info ,
there are two functions:
.Fn krb5_krbhst_format_string
that will return a printable representation of that struct
and
.Fn krb5_krbhst_get_addrinfo
that will return a
.Va struct addrinfo
that can then be used for communicating with the server mentioned.
.Sh EXAMPLES
The following code will print the KDCs of the realm
.Dq MY.REALM :
.Bd -literal -offset indent
krb5_krbhst_handle handle;
char host[MAXHOSTNAMELEN];
krb5_krbhst_init(context, "MY.REALM", KRB5_KRBHST_KDC, &handle);
while(krb5_krbhst_next_as_string(context, handle,
				 host, sizeof(host)) == 0)
    printf("%s\\n", host);
krb5_krbhst_free(context, handle);
.Ed
.\" .Sh BUGS
.Sh SEE ALSO
.Xr getaddrinfo 3 ,
.Xr krb5_get_krbhst 3 ,
.Xr krb5_send_to_kdc_flags 3
.Sh HISTORY
These functions first appeared in Heimdal 0.3g.