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.TH "LWRES_RESUTIL" "3" "Jun 30, 2000" "BIND9" ""
.SH NAME
lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr \- lightweight resolver utility functions
.SH SYNOPSIS
\fB#include <lwres/lwres.h>
.sp
.na
lwres_result_t
lwres_string_parse(lwres_buffer_t *b, char **c, lwres_uint16_t *len);
.ad
.sp
.na
lwres_result_t
lwres_addr_parse(lwres_buffer_t *b, lwres_addr_t *addr);
.ad
.sp
.na
lwres_result_t
lwres_getaddrsbyname(lwres_context_t *ctx, const char *name, lwres_uint32_t addrtypes, lwres_gabnresponse_t **structp);
.ad
.sp
.na
lwres_result_t
lwres_getnamebyaddr(lwres_context_t *ctx, lwres_uint32_t addrtype, lwres_uint16_t addrlen, const unsigned char *addr, lwres_gnbaresponse_t **structp);
.ad
\fR
.SH "DESCRIPTION"
.PP
\fBlwres_string_parse()\fR retrieves a DNS-encoded
string starting the current pointer of lightweight resolver buffer
\fIb\fR: i.e. b->current.
When the function returns, the address of the first byte of the
encoded string is returned via \fI*c\fR and the
length of that string is given by \fI*len\fR. The
buffer's current pointer is advanced to point at the character
following the string length, the encoded string, and the trailing
\fBNULL\fR character.
.PP
\fBlwres_addr_parse()\fR extracts an address from the
buffer \fIb\fR. The buffer's current pointer
b->current is presumed to point at an encoded
address: the address preceded by a 32-bit protocol family identifier
and a 16-bit length field. The encoded address is copied to
addr->address and
addr->length indicates the size in bytes of
the address that was copied. b->current is
advanced to point at the next byte of available data in the buffer
following the encoded address.
.PP
\fBlwres_getaddrsbyname()\fR
and
\fBlwres_getnamebyaddr()\fR
use the
\fBlwres_gnbaresponse_t\fR
structure defined below:
.sp
.nf
typedef struct {
        lwres_uint32_t          flags;
        lwres_uint16_t          naliases;
        lwres_uint16_t          naddrs;
        char                   *realname;
        char                  **aliases;
        lwres_uint16_t          realnamelen;
        lwres_uint16_t         *aliaslen;
        lwres_addrlist_t        addrs;
        void                   *base;
        size_t                  baselen;
} lwres_gabnresponse_t;
.sp
.fi
The contents of this structure are not manipulated directly but
they are controlled through the
\fBlwres_gabn\fR(3)
functions.
.PP
The lightweight resolver uses
\fBlwres_getaddrsbyname()\fR to perform foward lookups.
Hostname \fIname\fR is looked up using the resolver
context \fIctx\fR for memory allocation.
\fIaddrtypes\fR is a bitmask indicating which type of
addresses are to be looked up. Current values for this bitmask are
\fBLWRES_ADDRTYPE_V4\fR for IPv4 addresses and
\fBLWRES_ADDRTYPE_V6\fR for IPv6 addresses. Results of the
lookup are returned in \fI*structp\fR.
.PP
\fBlwres_getnamebyaddr()\fR performs reverse lookups.
Resolver context \fIctx\fR is used for memory
allocation. The address type is indicated by
\fIaddrtype\fR: \fBLWRES_ADDRTYPE_V4\fR or
\fBLWRES_ADDRTYPE_V6\fR. The address to be looked up is given
by \fIaddr\fR and its length is
\fIaddrlen\fR bytes. The result of the function call
is made available through \fI*structp\fR.
.SH "RETURN VALUES"
.PP
Successful calls to
\fBlwres_string_parse()\fR
and
\fBlwres_addr_parse()\fR
return
LWRES_R_SUCCESS.
Both functions return
LWRES_R_FAILURE
if the buffer is corrupt or
LWRES_R_UNEXPECTEDEND
if the buffer has less space than expected for the components of the
encoded string or address.
.PP
\fBlwres_getaddrsbyname()\fR
returns
LWRES_R_SUCCESS
on success and it returns
LWRES_R_NOTFOUND
if the hostname
\fIname\fR
could not be found.
.PP
LWRES_R_SUCCESS
is returned by a successful call to
\fBlwres_getnamebyaddr()\fR.
.PP
Both
\fBlwres_getaddrsbyname()\fR
and
\fBlwres_getnamebyaddr()\fR
return
LWRES_R_NOMEMORY
when memory allocation requests fail and
LWRES_R_UNEXPECTEDEND
if the buffers used for sending queries and receiving replies are too
small.
.SH "SEE ALSO"
.PP
\fBlwres_buffer\fR(3),
\fBlwres_gabn\fR(3).