NAME

krb5_krbhst_init, krb5_krbhst_init_flags, krb5_krbhst_next, krb5_krbhst_next_as_string, krb5_krbhst_reset, krb5_krbhst_free, krb5_krbhst_format_string, krb5_krbhst_get_addrinfo — lookup Kerberos KDC hosts

LIBRARY

Kerberos 5 Library (libkrb5, -lkrb5)

SYNOPSIS

#include <krb5/krb5.h>

krb5_error_code
krb5_krbhst_init(krb5_context context, const char *realm, unsigned int type, krb5_krbhst_handle *handle);

krb5_error_code
krb5_krbhst_init_flags(krb5_context context, const char *realm, unsigned int type, int flags, krb5_krbhst_handle *handle);

krb5_error_code
krb5_krbhst_next(krb5_context context, krb5_krbhst_handle handle, krb5_krbhst_info **host);

krb5_error_code
krb5_krbhst_next_as_string(krb5_context context, krb5_krbhst_handle handle, char *hostname, size_t hostlen);

void
krb5_krbhst_reset(krb5_context context, krb5_krbhst_handle handle);

void
krb5_krbhst_free(krb5_context context, krb5_krbhst_handle handle);

krb5_error_code
krb5_krbhst_format_string(krb5_context context, const krb5_krbhst_info *host, char *hostname, size_t hostlen);

krb5_error_code
krb5_krbhst_get_addrinfo(krb5_context context, krb5_krbhst_info *host, struct addrinfo **ai);

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.

First a handle to a particular service is obtained by calling krb5_krbhst_init() (or krb5_krbhst_init_flags()) with the realm of interest and the type of service to lookup. The type can be one of:

KRB5_KRBHST_KDC

KRB5_KRBHST_ADMIN

KRB5_KRBHST_CHANGEPW

KRB5_KRBHST_KRB524

The handle is returned to the caller, and should be passed to the other functions.

The flag argument to krb5_krbhst_init_flags is the same flags as krb5_send_to_kdc_flags() uses. Possible values are:

KRB5_KRBHST_FLAGS_MASTER

only talk to master (readwrite) KDC

KRB5_KRBHST_FLAGS_LARGE_MSG

this is a large message, so use transport that can handle that.

For each call to krb5_krbhst_next() information on a new host is returned. The former function returns in host a pointer to a structure containing information about the host, such as protocol, hostname, and port:

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;

The related function, krb5_krbhst_next_as_string(), return the same information as a URL-like string.

When there are no more hosts, these functions return KRB5_KDC_UNREACH.

To re-iterate over all hosts, call krb5_krbhst_reset() and the next call to krb5_krbhst_next() will return the first host.

When done with the handle, krb5_krbhst_free() should be called.

To use a krb5_krbhst_info, there are two functions: krb5_krbhst_format_string() that will return a printable representation of that struct and krb5_krbhst_get_addrinfo() that will return a struct addrinfo that can then be used for communicating with the server mentioned.

EXAMPLES

The following code will print the KDCs of the realm “MY.REALM”:

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);

SEE ALSO

getaddrinfo(3), krb5_get_krbhst(3), krb5_send_to_kdc_flags(3)

HISTORY

These functions first appeared in Heimdal 0.3g.