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IN NO EVENT SHALL - INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING - FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, - NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION - WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. --> <HTML ><HEAD ><TITLE >lwres_gnba</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.73 "></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><H1 ><A NAME="AEN1" >lwres_gnba</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN8" ></A ><H2 >Name</H2 >lwres_gnbarequest_render, lwres_gnbaresponse_render, lwres_gnbarequest_parse, lwres_gnbaresponse_parse, lwres_gnbaresponse_free, lwres_gnbarequest_free -- lightweight resolver getnamebyaddress message handling</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN16" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN17" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include <lwres/lwres.h></PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >lwres_result_t lwres_gnbarequest_render</CODE >(lwres_context_t *ctx, lwres_gnbarequest_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);</CODE ></P ><P ><CODE ><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 — <SPAN CLASS="TYPE" >lwres_gnbarequest_t</SPAN > — 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 — <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 ></BODY ></HTML >