NAME
hesiod,
hesiod_init, hesiod_resolve,
hesiod_free_list,
hesiod_to_bind, hesiod_end
— Hesiod name server interface
library
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.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.
ENOEXEChesiod_init() failed because the Hesiod configuration file was invalid.ECONNREFUSEDhesiod_resolve() failed because no name server could be contacted to answer the query.EMSGSIZEhesiod_resolve() orhesiod_to_bind() failed because the query or response was too big to fit into the packet buffers.ENOENThesiod_resolve() failed because the name server had no text records matching name and type, orhesiod_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 - 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.