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873N/A
0N/A<HTML
0N/A><HEAD
0N/A><TITLE
0N/A>lwres_resutil</TITLE
0N/A><META
5061N/ANAME="GENERATOR"
0N/ACONTENT="Modular DocBook HTML Stylesheet Version 1.73
0N/A"></HEAD
0N/A><BODY
0N/ACLASS="REFENTRY"
3000N/ABGCOLOR="#FFFFFF"
3000N/ATEXT="#000000"
3000N/ALINK="#0000FF"
3000N/AVLINK="#840084"
3000N/AALINK="#0000FF"
3000N/A><H1
801N/A><A
3000N/ANAME="AEN1"
801N/A>lwres_resutil</A
801N/A></H1
801N/A><DIV
801N/ACLASS="REFNAMEDIV"
0N/A><A
0N/ANAME="AEN8"
0N/A></A
0N/A><H2
0N/A>Name</H2
0N/A>lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr&nbsp;--&nbsp;lightweight resolver utility functions</DIV
0N/A><DIV
0N/ACLASS="REFSYNOPSISDIV"
0N/A><A
0N/ANAME="AEN14"
0N/A></A
0N/A><H2
801N/A>Synopsis</H2
3845N/A><DIV
801N/ACLASS="FUNCSYNOPSIS"
801N/A><A
3000N/ANAME="AEN15"
801N/A></A
801N/A><P
801N/A></P
801N/A><PRE
951N/ACLASS="FUNCSYNOPSISINFO"
3000N/A>#include &lt;lwres/lwres.h&gt;</PRE
3000N/A><P
3000N/A><CODE
3000N/A><CODE
3000N/ACLASS="FUNCDEF"
3000N/A>lwres_result_t
3000N/Alwres_string_parse</CODE
3000N/A>(lwres_buffer_t *b, char **c, lwres_uint16_t *len);</CODE
3000N/A></P
0N/A><P
0N/A><CODE
0N/A><CODE
0N/ACLASS="FUNCDEF"
0N/A>lwres_result_t
0N/Alwres_addr_parse</CODE
0N/A>(lwres_buffer_t *b, lwres_addr_t *addr);</CODE
0N/A></P
801N/A><P
0N/A><CODE
801N/A><CODE
801N/ACLASS="FUNCDEF"
0N/A>lwres_result_t
1309N/Alwres_getaddrsbyname</CODE
0N/A>(lwres_context_t *ctx, const char *name, lwres_uint32_t addrtypes, lwres_gabnresponse_t **structp);</CODE
3000N/A></P
3000N/A><P
3000N/A><CODE
3000N/A><CODE
3000N/ACLASS="FUNCDEF"
3000N/A>lwres_result_t
3291N/Alwres_getnamebyaddr</CODE
3000N/A>(lwres_context_t *ctx, lwres_uint32_t addrtype, lwres_uint16_t addrlen, const unsigned char *addr, lwres_gnbaresponse_t **structp);</CODE
3000N/A></P
3000N/A><P
3000N/A></P
3000N/A></DIV
3291N/A></DIV
3845N/A><DIV
0N/ACLASS="REFSECT1"
0N/A><A
0N/ANAME="AEN43"
3845N/A></A
0N/A><H2
3000N/A>DESCRIPTION</H2
3000N/A><P
3000N/A><TT
3000N/ACLASS="FUNCTION"
3291N/A>lwres_string_parse()</TT
0N/A> retrieves a DNS-encoded
801N/Astring starting the current pointer of lightweight resolver buffer
3291N/A<TT
0N/ACLASS="PARAMETER"
0N/A><I
0N/A>b</I
801N/A></TT
0N/A>: i.e. <TT
801N/ACLASS="CONSTANT"
801N/A>b-&gt;current</TT
0N/A>.
801N/AWhen the function returns, the address of the first byte of the
3291N/Aencoded string is returned via <TT
801N/ACLASS="PARAMETER"
801N/A><I
801N/A>*c</I
801N/A></TT
0N/A> and the
3845N/Alength of that string is given by <TT
5061N/ACLASS="PARAMETER"
5061N/A><I
3000N/A>*len</I
3845N/A></TT
3845N/A>. The
3845N/Abuffer's current pointer is advanced to point at the character
3845N/Afollowing the string length, the encoded string, and the trailing
3845N/A<SPAN
3845N/ACLASS="TYPE"
3845N/A>NULL</SPAN
3000N/A> character.</P
0N/A><P
0N/A><TT
0N/ACLASS="FUNCTION"
0N/A>lwres_addr_parse()</TT
0N/A> extracts an address from the
0N/Abuffer <TT
0N/ACLASS="PARAMETER"
3000N/A><I
3000N/A>b</I
0N/A></TT
801N/A>. The buffer's current pointer
0N/A<TT
0N/ACLASS="CONSTANT"
0N/A>b-&gt;current</TT
0N/A> is presumed to point at an encoded
3291N/Aaddress: the address preceded by a 32-bit protocol family identifier
0N/Aand a 16-bit length field. The encoded address is copied to
0N/A<TT
0N/ACLASS="CONSTANT"
0N/A>addr-&gt;address</TT
801N/A> and
801N/A<TT
801N/ACLASS="CONSTANT"
3000N/A>addr-&gt;length</TT
0N/A> indicates the size in bytes of
0N/Athe address that was copied. <TT
3000N/ACLASS="CONSTANT"
0N/A>b-&gt;current</TT
0N/A> is
3000N/Aadvanced to point at the next byte of available data in the buffer
3291N/Afollowing the encoded address.</P
3000N/A><P
3000N/A><TT
3000N/ACLASS="FUNCTION"
3000N/A>lwres_getaddrsbyname()</TT
3000N/A>
3000N/Aand
3000N/A<TT
3000N/ACLASS="FUNCTION"
0N/A>lwres_getnamebyaddr()</TT
3000N/A>
3000N/Ause the
3000N/A<SPAN
3000N/ACLASS="TYPE"
3000N/A>lwres_gnbaresponse_t</SPAN
3291N/A>
3000N/Astructure defined below:
3291N/A<PRE
3000N/ACLASS="PROGRAMLISTING"
3000N/A>typedef struct {
3000N/A lwres_uint32_t flags;
3000N/A lwres_uint16_t naliases;
3000N/A lwres_uint16_t naddrs;
3000N/A char *realname;
3000N/A char **aliases;
3000N/A lwres_uint16_t realnamelen;
3000N/A lwres_uint16_t *aliaslen;
3000N/A lwres_addrlist_t addrs;
3000N/A void *base;
3000N/A size_t baselen;
3000N/A} lwres_gabnresponse_t;</PRE
3000N/A>
801N/AThe contents of this structure are not manipulated directly but
3000N/Athey are controlled through the
3000N/A<SPAN
3000N/ACLASS="CITEREFENTRY"
3000N/A><SPAN
3000N/ACLASS="REFENTRYTITLE"
3000N/A>lwres_gabn</SPAN
3000N/A>(3)</SPAN
3000N/A>
3000N/Afunctions.</P
3000N/A><P
3000N/A>The lightweight resolver uses
0N/A<TT
0N/ACLASS="FUNCTION"
0N/A>lwres_getaddrsbyname()</TT
3000N/A> to perform foward lookups.
3000N/AHostname <TT
3000N/ACLASS="PARAMETER"
3000N/A><I
3000N/A>name</I
0N/A></TT
3000N/A> is looked up using the resolver
3000N/Acontext <TT
3000N/ACLASS="PARAMETER"
3000N/A><I
3000N/A>ctx</I
3000N/A></TT
3000N/A> for memory allocation.
3000N/A<TT
3000N/ACLASS="PARAMETER"
3000N/A><I
3000N/A>addrtypes</I
3000N/A></TT
3000N/A> is a bitmask indicating which type of
3000N/Aaddresses are to be looked up. Current values for this bitmask are
0N/A<SPAN
3000N/ACLASS="TYPE"
3000N/A>LWRES_ADDRTYPE_V4</SPAN
3000N/A> for IPv4 addresses and
3000N/A<SPAN
3000N/ACLASS="TYPE"
3000N/A>LWRES_ADDRTYPE_V6</SPAN
3000N/A> for IPv6 addresses. Results of the
3000N/Alookup are returned in <TT
3291N/ACLASS="PARAMETER"
3000N/A><I
3000N/A>*structp</I
3000N/A></TT
3000N/A>.</P
0N/A><P
3000N/A><TT
3000N/ACLASS="FUNCTION"
801N/A>lwres_getnamebyaddr()</TT
0N/A> performs reverse lookups.
801N/AResolver context <TT
0N/ACLASS="PARAMETER"
0N/A><I
0N/A>ctx</I
3000N/A></TT
3000N/A> is used for memory
3845N/Aallocation. The address type is indicated by
3845N/A<TT
3000N/ACLASS="PARAMETER"
3000N/A><I
3000N/A>addrtype</I
3000N/A></TT
3000N/A>: <SPAN
3000N/ACLASS="TYPE"
3000N/A>LWRES_ADDRTYPE_V4</SPAN
3000N/A> or
3000N/A<SPAN
3291N/ACLASS="TYPE"
3000N/A>LWRES_ADDRTYPE_V6</SPAN
3000N/A>. The address to be looked up is given
3291N/Aby <TT
3000N/ACLASS="PARAMETER"
3000N/A><I
0N/A>addr</I
3000N/A></TT
3000N/A> and its length is
3000N/A<TT
3000N/ACLASS="PARAMETER"
3000N/A><I
3000N/A>addrlen</I
3000N/A></TT
3000N/A> bytes. The result of the function call
3000N/Ais made available through <TT
3000N/ACLASS="PARAMETER"
3291N/A><I
3000N/A>*structp</I
3000N/A></TT
3000N/A>.</P
3000N/A></DIV
3000N/A><DIV
3000N/ACLASS="REFSECT1"
3000N/A><A
3000N/ANAME="AEN84"
3000N/A></A
3000N/A><H2
3000N/A>RETURN VALUES</H2
3000N/A><P
3000N/A>Successful calls to
3000N/A<TT
3000N/ACLASS="FUNCTION"
3000N/A>lwres_string_parse()</TT
3000N/A>
3000N/Aand
3000N/A<TT
3000N/ACLASS="FUNCTION"
3000N/A>lwres_addr_parse()</TT
3000N/A>
3000N/Areturn
3000N/A<SPAN
3000N/ACLASS="ERRORCODE"
3000N/A>LWRES_R_SUCCESS.</SPAN
3000N/A>
0N/ABoth functions return
0N/A<SPAN
0N/ACLASS="ERRORCODE"
0N/A>LWRES_R_FAILURE</SPAN
3000N/A>
3845N/Aif the buffer is corrupt or
3000N/A<SPAN
3000N/ACLASS="ERRORCODE"
3000N/A>LWRES_R_UNEXPECTEDEND</SPAN
3000N/A>
3000N/Aif the buffer has less space than expected for the components of the
3000N/Aencoded string or address.</P
3000N/A><P
3000N/A><TT
3000N/ACLASS="FUNCTION"
3000N/A>lwres_getaddrsbyname()</TT
3000N/A>
3000N/Areturns
3000N/A<SPAN
3000N/ACLASS="ERRORCODE"
3000N/A>LWRES_R_SUCCESS</SPAN
3000N/A>
3000N/Aon success and it returns
3000N/A<SPAN
3000N/ACLASS="ERRORCODE"
3000N/A>LWRES_R_NOTFOUND</SPAN
3000N/A>
3000N/Aif the hostname
3000N/A<TT
3000N/ACLASS="PARAMETER"
3291N/A><I
3000N/A>name</I
3000N/A></TT
3000N/A>
3000N/Acould not be found.</P
3000N/A><P
3000N/A><SPAN
3000N/ACLASS="ERRORCODE"
3291N/A>LWRES_R_SUCCESS</SPAN
3000N/A>
3000N/Ais returned by a successful call to
3000N/A<TT
3000N/ACLASS="FUNCTION"
3000N/A>lwres_getnamebyaddr()</TT
3000N/A>.</P
3000N/A><P
3000N/A>Both
3291N/A<TT
3000N/ACLASS="FUNCTION"
3291N/A>lwres_getaddrsbyname()</TT
3000N/A>
0N/Aand
0N/A<TT
0N/ACLASS="FUNCTION"
3000N/A>lwres_getnamebyaddr()</TT
3000N/A>
3000N/Areturn
3000N/A<SPAN
3000N/ACLASS="ERRORCODE"
3000N/A>LWRES_R_NOMEMORY</SPAN
3000N/A>
3000N/Awhen memory allocation requests fail and
3000N/A<SPAN
3291N/ACLASS="ERRORCODE"
3000N/A>LWRES_R_UNEXPECTEDEND</SPAN
3000N/A>
3291N/Aif the buffers used for sending queries and receiving replies are too
3000N/Asmall.</P
3000N/A></DIV
3000N/A><DIV
3000N/ACLASS="REFSECT1"
3000N/A><A
3000N/ANAME="AEN105"
3000N/A></A
3000N/A><H2
3291N/A>SEE ALSO</H2
3000N/A><P
3000N/A><SPAN
3000N/ACLASS="CITEREFENTRY"
3291N/A><SPAN
3000N/ACLASS="REFENTRYTITLE"
3000N/A>lwres_buffer</SPAN
3000N/A>(3)</SPAN
3291N/A>,
3000N/A
3000N/A<SPAN
3000N/ACLASS="CITEREFENTRY"
3000N/A><SPAN
3000N/ACLASS="REFENTRYTITLE"
3000N/A>lwres_gabn</SPAN
3000N/A>(3)</SPAN
3000N/A>.</P
3000N/A></DIV
3291N/A></BODY
3000N/A></HTML
3000N/A>
3000N/A