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
.