LWRES_GETRRSETBYNAME(3)LWRES_GETRRSETBYNAME(3)NAME
lwres_getrrsetbyname, lwres_freerrset - retrieve DNS records
SYNOPSIS
#include <lwres/netdb.h>
int lwres_getrrsetbyname(const char *hostname, unsigned int rdclass, unsigned int rdtype, unsigned int flags, struct rrsetinfo **res);
void lwres_freerrset(struct rrsetinfo *rrset); .PP 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 */
};
DESCRIPTION
lwres_getrrsetbyname() gets a set of resource records associated with a hostname, class, and type. hostname is a pointer a to null-termi-
nated string. The flags field is currently unused and must be zero.
After a successful call to lwres_getrrsetbyname(), *res is a pointer to an rrsetinfo structure, containing a list of one or more rdatainfo
structures 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 rep-
resented in the rri_flags bitfield. If the RRSET_VALIDATED bit is set, the data has been DNSSEC validated and the signatures verified.
All of the information returned by lwres_getrrsetbyname() is dynamically allocated: the rrsetinfo and rdatainfo structures, and the canoni-
cal host name strings pointed to by the rrsetinfostructure. Memory allocated for the dynamically allocated structures created by a suc-
cessful call to lwres_getrrsetbyname() is released by lwres_freerrset(). rrset is a pointer to a struct rrset created by a call to
lwres_getrrsetbyname().
RETURN VALUES
lwres_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 lwres(3).
BIND9 Oct 18, 2000 LWRES_GETRRSETBYNAME(3)
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LWRES_GETADDRINFO(3) BIND9 LWRES_GETADDRINFO(3)NAME
lwres_getaddrinfo, lwres_freeaddrinfo - socket address structure to host and service name
SYNOPSIS
#include <lwres/netdb.h>
int lwres_getaddrinfo(const char *hostname, const char *servname, const struct addrinfo *hints, struct addrinfo **res);
void lwres_freeaddrinfo(struct addrinfo *ai);
If the operating system does not provide a struct addrinfo, the following structure is used:
struct addrinfo {
int ai_flags; /* AI_PASSIVE, AI_CANONNAME */
int ai_family; /* PF_xxx */
int ai_socktype; /* SOCK_xxx */
int ai_protocol; /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
size_t ai_addrlen; /* length of ai_addr */
char *ai_canonname; /* canonical name for hostname */
struct sockaddr *ai_addr; /* binary address */
struct addrinfo *ai_next; /* next structure in linked list */
};
DESCRIPTION
lwres_getaddrinfo() is used to get a list of IP addresses and port numbers for host hostname and service servname. The function is the
lightweight resolver's implementation of getaddrinfo() as defined in RFC2133. hostname and servname are pointers to null-terminated
strings or NULL. hostname is either a host name or a numeric host address string: a dotted decimal IPv4 address or an IPv6 address.
servname is either a decimal port number or a service name as listed in /etc/services.
hints is an optional pointer to a struct addrinfo. This structure can be used to provide hints concerning the type of socket that the
caller supports or wishes to use. The caller can supply the following structure elements in *hints:
ai_family
The protocol family that should be used. When ai_family is set to PF_UNSPEC, it means the caller will accept any protocol family
supported by the operating system.
ai_socktype
denotes the type of socket -- SOCK_STREAM, SOCK_DGRAM or SOCK_RAW -- that is wanted. When ai_socktype is zero the caller will accept
any socket type.
ai_protocol
indicates which transport protocol is wanted: IPPROTO_UDP or IPPROTO_TCP. If ai_protocol is zero the caller will accept any protocol.
ai_flags
Flag bits. If the AI_CANONNAME bit is set, a successful call to lwres_getaddrinfo() will return a null-terminated string containing the
canonical name of the specified hostname in ai_canonname of the first addrinfo structure returned. Setting the AI_PASSIVE bit indicates
that the returned socket address structure is intended for used in a call to bind(2). In this case, if the hostname argument is a NULL
pointer, then the IP address portion of the socket address structure will be set to INADDR_ANY for an IPv4 address or IN6ADDR_ANY_INIT
for an IPv6 address.
When ai_flags does not set the AI_PASSIVE bit, the returned socket address structure will be ready for use in a call to connect(2) for
a connection-oriented protocol or connect(2), sendto(2), or sendmsg(2) if a connectionless protocol was chosen. The IP address portion
of the socket address structure will be set to the loopback address if hostname is a NULL pointer and AI_PASSIVE is not set in
ai_flags.
If ai_flags is set to AI_NUMERICHOST it indicates that hostname should be treated as a numeric string defining an IPv4 or IPv6 address
and no name resolution should be attempted.
All other elements of the struct addrinfo passed via hints must be zero.
A hints of NULL is treated as if the caller provided a struct addrinfo initialized to zero with ai_familyset to PF_UNSPEC.
After a successful call to lwres_getaddrinfo(), *res is a pointer to a linked list of one or more addrinfo structures. Each struct addrinfo
in this list cn be processed by following the ai_next pointer, until a NULL pointer is encountered. The three members ai_family,
ai_socktype, and ai_protocol in each returned addrinfo structure contain the corresponding arguments for a call to socket(2). For each
addrinfo structure in the list, the ai_addr member points to a filled-in socket address structure of length ai_addrlen.
All of the information returned by lwres_getaddrinfo() is dynamically allocated: the addrinfo structures, and the socket address structures
and canonical host name strings pointed to by the addrinfostructures. Memory allocated for the dynamically allocated structures created by
a successful call to lwres_getaddrinfo() is released by lwres_freeaddrinfo(). ai is a pointer to a struct addrinfo created by a call to
lwres_getaddrinfo().
RETURN VALUES
lwres_getaddrinfo() returns zero on success or one of the error codes listed in gai_strerror(3) if an error occurs. If both hostname and
servname are NULL lwres_getaddrinfo() returns EAI_NONAME.
SEE ALSO lwres(3), lwres_getaddrinfo(3), lwres_freeaddrinfo(3), lwres_gai_strerror(3), RFC2133(), getservbyname(3), bind(2), connect(2), sendto(2),
sendmsg(2), socket(2).
COPYRIGHT
Copyright (C) 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
Copyright (C) 2000, 2001, 2003 Internet Software Consortium.
BIND9 Jun 30, 2000 LWRES_GETADDRINFO(3)