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HESIOD(3) Library Functions Manual HESIOD(3)


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


#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


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.


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.


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.


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


Hesiod calls may fail because of:

Insufficient memory was available to carry out the requested operation.
hesiod_init failed because the Hesiod configuration file was invalid.
hesiod_resolve failed because no name server could be contacted to answer the query.
hesiod_resolve or hesiod_to_bind failed because the query or response was too big to fit into the packet buffers.
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.
hesiod_to_bind failed to convert the resulting domain name from UTF-8 to an internationalized domain name.


Steve Dyer, IBM/Project Athena
Greg Hudson, MIT Team Athena
Copyright 1987, 1988, 1995, 1996, 2000 by the Massachusetts Institute of Technology.


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.

30 November 1996