getrrsetbyname

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
    
2017-02-09
Documentation license for this page: Open Publication License