HESIOD(3)

NAME
hesiod, hesiod_init, hesiod_resolve, hesiod_free_list, hesiod_to_bind, hesiod_end - Hesiod name server interface library

LIBRARY
libc

SYNOPSIS
#include <hesiod.h>
int
hesiod_init(void **context);
char **
hesiod_resolve(void *context, const char *name, const char *type);
void
hesiod_free_list(void *context, char **list);
char *
hesiod_to_bind(void *context, const char *name, const char *type);
void
hesiod_end(void *context);

DESCRIPTION
This family of functions allows you to perform lookups of Hesiod information, which is stored as text records in the Domain Name Service. To perform lookups, you must first initialize a context, an opaque object which stores information used internally by the library between calls. The hesiod_init() function initializes a context, storing a pointer to the context in the location pointed to by the context argument. The hesiod_end() function frees the resources used by a context.

The hesiod_resolve() function is the primary interface to the library. If successful, it returns a list of one or more strings giving the records matching name and type. The last element of the list is followed by a NULL pointer. It is the caller's responsibility to call hesiod_free_list() to free the resources used by the returned list.

The hesiod_to_bind() function converts name and type into the DNS name used by hesiod_resolve(). It is the caller's responsibility to free the returned string using free().

RETURN VALUES
On failure, hesiod_resolve() and hesiod_to_bind() return NULL and set the global variable errno to indicate the error.

ENVIRONMENT

HES_DOMAIN
    If the environment variable HES_DOMAIN is set, it will override the domain in the Hesiod configuration file.

HESIOD_CONFIG
    If the environment variable HESIOD_CONFIG is set, it specifies the location of the Hesiod configuration file.

SEE ALSO
hesiod.conf(5), named(8) Hesiod - Project Athena Technical Plan -- Name Service.

ERRORS
Hesiod calls may fail because of:

[ENOMEM]
    Insufficient memory was available to carry out the requested operation.

[ENOEXEC]
    The hesiod_init() function failed because the Hesiod configuration file was invalid.

[ECONNREFUSED]
    The hesiod_resolve() function failed because no name server could be contacted to answer the query.

[EMSGSIZE]
    The hesiod_resolve() or hesiod_to_bind() function failed because the query or response was too big to fit into the packet buffers.

[ENOENT]
    The hesiod_resolve() function failed because the name server had no text records matching name and type, or hesiod_to_bind() failed because the name argument had a domain extension which could not be resolved with type “rhs-extension” in the local Hesiod domain.

AUTHORS
Steve Dyer, IBM/Project Athena Greg Hudson, MIT Team Athena

Copyright 1987, 1988, 1995, 1996 by the Massachusetts Institute of Technology.

BUGS
The strings corresponding to the errno values set by the Hesiod functions are not particularly indicative of what went wrong, especially for ENOEXEC and ENOENT.