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$FreeBSD: src/lib/libutil/realhostname.3,v 1.10 2005/02/13 22:25:14 ru Exp $
.Dd April 6, 1999 .Os .Dt REALHOSTNAME 3 .Sh NAME .Nm realhostname .Nd "convert an IP number to the real host name" .Sh LIBRARY .Lb libutil .Sh SYNOPSIS n sys/types.h n netinet/in.h n libutil.h .Ft int .Fn realhostname "char *host" "size_t hsize" "const struct in_addr *ip" .Sh DESCRIPTION The function .Fn realhostname converts .Ar ip to the corresponding host name. This is done by resolving .Ar ip to a host name and then ensuring that the host name resolves back to .Ar ip .
p .Ar host must point to a buffer of at least .Ar hsize bytes, and will always be written to by this function.
p If the name resolution does not work both ways or if the host name is longer than .Ar hsize bytes, .Xr inet_ntoa 3 is used to convert .Ar ip to an ASCII form.
p If the string written to .Ar host is .Ar hsize bytes long, .Ar host will not be NUL terminated. .Sh RETURN VALUES The .Fn realhostname function will return one of the following constants which are defined in n libutil.h :
p l -tag -width XXX -offset XXX t Li HOSTNAME_FOUND A valid host name was found. t Li HOSTNAME_INCORRECTNAME A host name was found, but it did not resolve back to the passed .Ar ip . .Ar host now contains the numeric value of .Ar ip . t Li HOSTNAME_INVALIDADDR .Ar ip could not be resolved. .Ar host now contains the numeric value of .Ar ip . t Li HOSTNAME_INVALIDNAME A host name was found, but it could not be resolved back to any ip number. .Ar host now contains the numeric value of .Ar ip . .El .Sh SEE ALSO .Xr gethostbyaddr 3 , .Xr gethostbyname 3 , .Xr inet_ntoa 3 , .Xr realhostname_sa 3