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$Id: lwres_getnameinfo.3,v 1.4 2000/08/01 01:21:28 tale Exp $
.Dd Jun 30, 2000 .Dt LWRES_GETNAMEINFO 3 .Os BIND9 9 .Sh NAME .Nm lwres_getnameinfo .Nd lightweight resolver socket address structure to hostname and service name .Sh SYNOPSIS .Fd #include <lwres/lwres.h> .Fd .Ft int .Fo lwres_getnameinfo .Fa "const struct sockaddr *sa" .Fa "size_t salen" .Fa "char *host" .Fa "size_t hostlen" .Fa "char *serv" .Fa "size_t servlen" .Fa "int flags" .Fc .Sh DESCRIPTION
p This function is equivalent to the .Xr getnameinfo 3 function defined in RFC2133. .Fn lwres_getnameinfo returns the hostname for the .Dv "struct sockaddr" .Fa sa which is .Fa salen bytes long. The hostname is of length .Fa hostlen and is returned via .Fa *host. The maximum length of the hostname is 1025 bytes: .Li NI_MAXHOST .
p The name of the service associated with the port number in .Fa sa is returned in .Fa *serv. It is .Fa servlen bytes long. The maximum length of the service name is .Li NI_MAXSERV - 32 - bytes.
p The .Fa flags argument sets the following bits: l -tag -width NI_NUMERICSERV t Li NI_NOFQDN a fully qualified domain name is not required for local hosts. The local part of the fully qualified domain name is returned instead. t Li NI_NUMERICHOST the address in the .Dv sockaddr structure is presented as a dotted-decimal string for an IPv4 address or an IPv6 hex address if the hostname is not found in the DNS. t Li NI_NAMEREQD a name is required. If the hostname cannot be found in the DNS and this flag is set, a non-zero error code is returned. t Li NI_NUMERICSERV service name is returned as a digit string representing the port number. t Li NI_DGRAM the service uses a datagram transport protocol .El
p
When a numeric host address string is needed,
.Fn lwres_getnameinfo
calls
.Fn lwres_net_ntop
to generate an IPv6 hex address or a dotted decimal IPv4 address.
If required,
.Fn lwres_getnameinfo
will create a resolver context by calling
.Fn lwres_context_create
and then using
.Fn lwres_getnamebyaddr
to perform the reverse lookup.
Any memory allocated during that reverse lookup will be
freed by calling
.Fn lwres_gnbaresponse_free .
.Fn lwres_context_destroy
is called immediately before
.Fn lwres_getnameinfo
returns so that the created resolver context gets discarded.
.Sh RETURN VALUES
.Fn lwres_getnameinfo
returns 0 on success or a non-zero error code if an error occurs.
The error codes below were invented by the ISC/Nominum. They
should be defined in RFC2133 before getting documented here.
XXXJR 28/6/00
The error codes are:
Bl -tag -width ENI_NOSERVNAME
It Li ENI_NOSOCKET
there was no socket in
Fa sa
It Li ENI_NOSERVNAME
no service name was found
It Li ENI_NOHOSTNAME
no hostname was found
It Li ENI_MEMORY
memory could not be allocated
It Li ENI_SYSTEM
a system error occurred
It Li ENI_FAMILY
an unsupported protocol family was requested
It Li ENI_SALEN
Fa salen
is the wrong number of bytes for the address in
Fa sa .
.Sh SEE ALSO
.Xr getnameinfo 3 ,
.Xr RFC2133 ,
.Xr getservbyport 3 ,
.Xr lwres_res_net_ntop 3 ,
.Xr lwres_res_context_create 3,
.Xr lwres_res_getnamebyaddr 3,
.Xr lwres_res_gnbaresponse_free 3 ,
.Xr lwres_res_context_destroy 3 ,
.Xr lwres_res_net_ntop 3 .