GETRRSETBYNAME(3) BSD Library Functions Manual GETRRSETBYNAME(3)
NAME
getrrsetbyname - retrieve DNS records
SYNOPSIS
#include <netdb.h>
int
getrrsetbyname(const char *hostname, unsigned int rdclass,
unsigned int rdtype, unsigned int flags, struct rrsetinfo **res);
int
freerrset(struct rrsetinfo **rrset);
DESCRIPTION
getrrsetbyname() gets a set of resource records associated with a
hostname, class and type. hostname is a pointer a to null-terminated
string. The flags field is currently unused and must be zero.
After a successful call to getrrsetbyname(), *res is a pointer to an
rrsetinfo structure, containing a list of one or more rdatainfo struc-
tures containing resource records and potentially another list of
rdatainfo structures containing SIG resource records associated with
those records. The members rri_rdclass and rri_rdtype are copied from
the parameters. rri_ttl and rri_name are properties of the obtained
rrset. The resource records contained in rri_rdatas and rri_sigs are in
uncompressed DNS wire format. Properties of the rdataset are represented
in the rri_flags bitfield. If the RRSET_VALIDATED bit is set, the data
has been DNSSEC validated and the signatures verified.
The following structures are used:
struct rdatainfo {
unsigned int rdi_length; /* length of data */
unsigned char *rdi_data; /* record data */
};
struct rrsetinfo {
unsigned int rri_flags; /* RRSET_VALIDATED ... */
unsigned int rri_rdclass; /* class number */
unsigned int rri_rdtype; /* RR type number */
unsigned int rri_ttl; /* time to live */
unsigned int rri_nrdatas; /* size of rdatas array */
unsigned int rri_nsigs; /* size of sigs array */
char *rri_name; /* canonical name */
struct rdatainfo *rri_rdatas; /* individual records */
struct rdatainfo *rri_sigs; /* individual signatures */
};
All of the information returned by getrrsetbyname() is dynamically allo-
cated: the rrsetinfo and rdatainfo structures, and the canonical host
name strings pointed to by the rrsetinfostructure. Memory allocated for
the dynamically allocated structures created by a successful call to
getrrsetbyname() is released by freerrset(). rrset is a pointer to a
struct rrset created by a call to getrrsetbyname().
If the EDNS0 option is activated in resolv.conf(3), getrrsetbyname() will
request DNSSEC authentication using the EDNS0 DNSSEC OK (DO) bit.
RETURN VALUES
getrrsetbyname() returns zero on success, and one of the following error
codes if an error occurred:
ERRSET_NONAME the name does not exist
ERRSET_NODATA the name exists, but does not have data of the desired
type
ERRSET_NOMEMORY memory could not be allocated
ERRSET_INVAL a parameter is invalid
ERRSET_FAIL other failure
SEE ALSO
resolver(3), resolv.conf(5), named(8)
AUTHORS
Jakob Schlyter <jakob@openbsd.org>
HISTORY
getrrsetbyname() first appeared in OpenBSD 3.0. The API first appeared
in ISC BIND version 9.
BUGS
The data in *rdi_data should be returned in uncompressed wire format.
Currently, the data is in compressed format and the caller can't uncom-
press since it doesn't have the full message.
CAVEATS
The RRSET_VALIDATED flag in rri_flags is set if the AD (autenticated
data) bit in the DNS answer is set. This flag should not be trusted
unless the transport between the nameserver and the resolver is secure
(e.g. IPsec, trusted network, loopback communication).
BSD Oct 18, 2000 BSD
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