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.Dd May 10, 2005
.Dt KRB5_KRBHST_INIT 3
.Os HEIMDAL
.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.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.