lwres/man/lwres_gnba.html

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d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence<!--
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ab023a65562e62b85a824509d829b6fad87e00b1Rob Austein>lwres_gnba</TITLE
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ab023a65562e62b85a824509d829b6fad87e00b1Rob Austein><H1
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><A
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David LawrenceNAME="AEN1"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence>lwres_gnba</A
ab023a65562e62b85a824509d829b6fad87e00b1Rob Austein></H1
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><DIV
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David LawrenceCLASS="REFNAMEDIV"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><A
ab023a65562e62b85a824509d829b6fad87e00b1Rob AusteinNAME="AEN8"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence></A
31707708c585c53b61ca1edb2e224e6bb1b985a5Evan Hunt><H2
31707708c585c53b61ca1edb2e224e6bb1b985a5Evan Hunt>Name</H2
31707708c585c53b61ca1edb2e224e6bb1b985a5Evan Hunt>lwres_gnbarequest_render, lwres_gnbaresponse_render, lwres_gnbarequest_parse, lwres_gnbaresponse_parse, lwres_gnbaresponse_free, lwres_gnbarequest_free&nbsp;--&nbsp;lightweight resolver getnamebyaddress message handling</DIV
31707708c585c53b61ca1edb2e224e6bb1b985a5Evan Hunt><DIV
31707708c585c53b61ca1edb2e224e6bb1b985a5Evan HuntCLASS="REFSYNOPSISDIV"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><A
ab023a65562e62b85a824509d829b6fad87e00b1Rob AusteinNAME="AEN16"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence></A
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><H2
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence>Synopsis</H2
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><DIV
ab023a65562e62b85a824509d829b6fad87e00b1Rob AusteinCLASS="FUNCSYNOPSIS"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><A
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David LawrenceNAME="AEN17"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence></A
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><P
ab023a65562e62b85a824509d829b6fad87e00b1Rob Austein></P
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><PRE
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David LawrenceCLASS="FUNCSYNOPSISINFO"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence>#include &lt;lwres/lwres.h&gt;</PRE
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><P
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence><CODE
ab023a65562e62b85a824509d829b6fad87e00b1Rob Austein><CODE
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David LawrenceCLASS="FUNCDEF"
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence>lwres_result_t
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrencelwres_gnbarequest_render</CODE
d8e34837cd6c88c42b3ecdb9107a43ecf8252e79David Lawrence>(lwres_context_t *ctx, lwres_gnbarequest_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);</CODE
ac9e556e494750eb6e454c337d6632fa395f24d8David Lawrence></P
ac9e556e494750eb6e454c337d6632fa395f24d8David Lawrence><P
ac9e556e494750eb6e454c337d6632fa395f24d8David Lawrence><CODE
ac9e556e494750eb6e454c337d6632fa395f24d8David Lawrence><CODE
CLASS="FUNCDEF"
>lwres_result_t
lwres_gnbaresponse_render</CODE
>(lwres_context_t *ctx, lwres_gnbaresponse_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>lwres_result_t
lwres_gnbarequest_parse</CODE
>(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gnbarequest_t **structp);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>lwres_result_t
lwres_gnbaresponse_parse</CODE
>(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gnbaresponse_t **structp);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void
lwres_gnbaresponse_free</CODE
>(lwres_context_t *ctx, lwres_gnbaresponse_t **structp);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void
lwres_gnbarequest_free</CODE
>(lwres_context_t *ctx, lwres_gnbarequest_t **structp);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN61"
></A
><H2
>DESCRIPTION</H2
><P
>These are low-level routines for creating and parsing
lightweight resolver address-to-name lookup request and
response messages.</P
><P
>There are four main functions for the getnamebyaddr opcode.
One render function converts a getnamebyaddr request structure &mdash;
<SPAN
CLASS="TYPE"
>lwres_gnbarequest_t</SPAN
> &mdash;
to the lightweight resolver's canonical format.
It is complemented by a parse function that converts a packet in this
canonical format to a getnamebyaddr request structure.
Another render function converts the getnamebyaddr response structure &mdash;
<SPAN
CLASS="TYPE"
>lwres_gnbaresponse_t</SPAN
>
to the canonical format.
This is complemented by a parse function which converts a packet in
canonical format to a getnamebyaddr response structure.</P
><P
>These structures are defined in
<TT
CLASS="FILENAME"
>lwres/lwres.h</TT
>.
They are shown below.
<PRE
CLASS="PROGRAMLISTING"
>#define LWRES_OPCODE_GETNAMEBYADDR 0x00010002U

typedef struct {
    lwres_uint32_t  flags;
    lwres_addr_t    addr;
} lwres_gnbarequest_t;

typedef struct {
    lwres_uint32_t  flags;
    lwres_uint16_t  naliases;
    char           *realname;
    char          **aliases;
    lwres_uint16_t  realnamelen;
    lwres_uint16_t *aliaslen;
    void           *base;
    size_t      baselen;
} lwres_gnbaresponse_t;</PRE
></P
><P
><TT
CLASS="FUNCTION"
>lwres_gnbarequest_render()</TT
>
uses resolver context
<TT
CLASS="VARNAME"
>ctx</TT
>
to convert getnamebyaddr request structure
<TT
CLASS="VARNAME"
>req</TT
>
to canonical format.
The packet header structure
<TT
CLASS="VARNAME"
>pkt</TT
>
is initialised and transferred to
buffer
<TT
CLASS="VARNAME"
>b</TT
>.
The contents of
<TT
CLASS="VARNAME"
>*req</TT
>
are then appended to the buffer in canonical format.
<TT
CLASS="FUNCTION"
>lwres_gnbaresponse_render()</TT
>
performs the same task, except it converts a getnamebyaddr response structure
<SPAN
CLASS="TYPE"
>lwres_gnbaresponse_t</SPAN
>
to the lightweight resolver's canonical format.</P
><P
><TT
CLASS="FUNCTION"
>lwres_gnbarequest_parse()</TT
>
uses context
<TT
CLASS="VARNAME"
>ctx</TT
>
to convert the contents of packet
<TT
CLASS="VARNAME"
>pkt</TT
>
to a
<SPAN
CLASS="TYPE"
>lwres_gnbarequest_t</SPAN
>
structure.
Buffer
<TT
CLASS="VARNAME"
>b</TT
>
provides space to be used for storing this structure.
When the function succeeds, the resulting
<SPAN
CLASS="TYPE"
>lwres_gnbarequest_t</SPAN
>
is made available through
<TT
CLASS="VARNAME"
>*structp</TT
>.
<TT
CLASS="FUNCTION"
>lwres_gnbaresponse_parse()</TT
>
offers the same semantics as
<TT
CLASS="FUNCTION"
>lwres_gnbarequest_parse()</TT
>
except it yields a
<SPAN
CLASS="TYPE"
>lwres_gnbaresponse_t</SPAN
>
structure.</P
><P
><TT
CLASS="FUNCTION"
>lwres_gnbaresponse_free()</TT
>
and
<TT
CLASS="FUNCTION"
>lwres_gnbarequest_free()</TT
>
release the memory in resolver context
<TT
CLASS="VARNAME"
>ctx</TT
>
that was allocated to the
<SPAN
CLASS="TYPE"
>lwres_gnbaresponse_t</SPAN
>
or
<SPAN
CLASS="TYPE"
>lwres_gnbarequest_t</SPAN
>
structures referenced via
<TT
CLASS="VARNAME"
>structp</TT
>.
Any memory associated with ancillary buffers and strings for those
structures is also discarded.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN97"
></A
><H2
>RETURN VALUES</H2
><P
>The getnamebyaddr opcode functions
<TT
CLASS="FUNCTION"
>lwres_gnbarequest_render()</TT
>,
<TT
CLASS="FUNCTION"
>lwres_gnbaresponse_render()</TT
>
<TT
CLASS="FUNCTION"
>lwres_gnbarequest_parse()</TT
>
and
<TT
CLASS="FUNCTION"
>lwres_gnbaresponse_parse()</TT
>
all return
<SPAN
CLASS="ERRORCODE"
>LWRES_R_SUCCESS</SPAN
>
on success.
They return
<SPAN
CLASS="ERRORCODE"
>LWRES_R_NOMEMORY</SPAN
>
if memory allocation fails.
<SPAN
CLASS="ERRORCODE"
>LWRES_R_UNEXPECTEDEND</SPAN
>
is returned if the available space in the buffer
<TT
CLASS="VARNAME"
>b</TT
>
is too small to accommodate the packet header or the
<SPAN
CLASS="TYPE"
>lwres_gnbarequest_t</SPAN
>
and
<SPAN
CLASS="TYPE"
>lwres_gnbaresponse_t</SPAN
>
structures.
<TT
CLASS="FUNCTION"
>lwres_gnbarequest_parse()</TT
>
and
<TT
CLASS="FUNCTION"
>lwres_gnbaresponse_parse()</TT
>
will return
<SPAN
CLASS="ERRORCODE"
>LWRES_R_UNEXPECTEDEND</SPAN
>
if the buffer is not empty after decoding the received packet.
These functions will return
<SPAN
CLASS="ERRORCODE"
>LWRES_R_FAILURE</SPAN
>
if
<TT
CLASS="STRUCTFIELD"
><I
>pktflags</I
></TT
>
in the packet header structure
<SPAN
CLASS="TYPE"
>lwres_lwpacket_t</SPAN
>
indicate that the packet is not a response to an earlier query.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN116"
></A
><H2
>SEE ALSO</H2
><P
><SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres_packet</SPAN
>(3)</SPAN
>.</P
></DIV
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>