NAME

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

LIBRARY

Standard C Library (libc, -lc)

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. hesiod_init() initializes a context, storing a pointer to the context in the location pointed to by the context argument. hesiod_end() frees the resources used by a context.

hesiod_resolve() 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.

hesiod_to_bind() 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(3).

RETURN VALUES

If successful, hesiod_init() returns 0; otherwise it returns -1 and sets errno to indicate the error. On failure, hesiod_resolve() and hesiod_to_bind() return NULL and set the global variable errno to indicate the error.

ENVIRONMENT

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

ERRORS

Hesiod calls may fail because of:

ENOMEM

Insufficient memory was available to carry out the requested operation.

ENOEXEC

hesiod_init() failed because the Hesiod configuration file was invalid.

ECONNREFUSED

hesiod_resolve() failed because no name server could be contacted to answer the query.

EMSGSIZE

hesiod_resolve() or hesiod_to_bind() failed because the query or response was too big to fit into the packet buffers.

ENOENT

hesiod_resolve() 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.

SEE ALSO

hesiod.conf(5), named(8)

Hesiod - Project Athena Technical Plan -- Name Service.

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.