May 10, 2005 KRB5_KRBHST_INIT 3

### 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

```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.