NAME¶
hesiod, hesiod_init, hesiod_resolve, hesiod_free_list, hesiod_to_bind,
hesiod_free_string, hesiod_end - Hesiod name server interface library
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_free_string(void *context, char *str);
char **hesiod_parse_result(void *context,
unsigned const char *result, int rlen)
void hesiod_end(void *context)
cc file.c -lhesiod
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
hesiod_free_string.
hesiod_parse_result parses the result of a name server query into text
records. It is the caller's responsibility to call
hesiod_free_list to
free the resources used by the returned list.
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.
SEE ALSO¶
`Hesiod - Project Athena Technical Plan -- Name Service',
named(8),
hesiod.conf(5)
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.
- EINVAL
- hesiod_to_bind failed to convert the resulting domain name from
UTF-8 to an internationalized domain name.
AUTHOR¶
Steve Dyer, IBM/Project Athena
Greg Hudson, MIT Team Athena
Copyright 1987, 1988, 1995, 1996, 2000 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.