lwres/man/lwres_resutil.html

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cd32f419a8a5432fbb139f56ee73cbf68b9350ccTinderbox User><TITLE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>lwres_resutil</TITLE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><META
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14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><H1
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><A
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntNAME="AEN1"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt></A
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>lwres_resutil</H1
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><DIV
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntCLASS="REFNAMEDIV"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><A
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntNAME="AEN8"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt></A
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><H2
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>Name</H2
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr&nbsp;--&nbsp;lightweight resolver utility functions</DIV
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><DIV
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="REFSYNOPSISDIV"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><A
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntNAME="AEN14"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt></A
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><H2
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>Synopsis</H2
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><DIV
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntCLASS="FUNCSYNOPSIS"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt></P
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><A
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntNAME="AEN15"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt></A
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><PRE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntCLASS="FUNCSYNOPSISINFO"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>#include &lt;lwres/lwres.h&gt;</PRE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><CODE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><CODE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntCLASS="FUNCDEF"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>lwres_result_t
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Huntlwres_string_parse</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>(lwres_buffer_t *b, char **c, lwres_uint16_t *len);</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt></P
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><P
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="FUNCDEF"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>lwres_result_t
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Huntlwres_addr_parse</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>(lwres_buffer_t *b, lwres_addr_t *addr);</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt></P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><P
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><CODE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntCLASS="FUNCDEF"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>lwres_result_t
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Huntlwres_getaddrsbyname</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>(lwres_context_t *ctx, const char *name, lwres_uint32_t addrtypes, lwres_gabnresponse_t **structp);</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt></P
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><P
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="FUNCDEF"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>lwres_result_t
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Huntlwres_getnamebyaddr</CODE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>(lwres_context_t *ctx, lwres_uint32_t addrtype, lwres_uint16_t addrlen, const unsigned char *addr, lwres_gnbaresponse_t **structp);</CODE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt></P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt></P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt></DIV
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt></DIV
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><DIV
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="REFSECT1"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><A
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntNAME="AEN43"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt></A
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><H2
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>DESCRIPTION</H2
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><CODE
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntCLASS="FUNCTION"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>lwres_string_parse()</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt> retrieves a DNS-encoded
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Huntstring starting the current pointer of lightweight resolver buffer
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt<VAR
14a656f94b1fd0ababd84a772228dfa52276ba15Evan HuntCLASS="PARAMETER"
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt>b</VAR
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>: i.e.  <CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="CONSTANT"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>b-&gt;current</CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>.
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntWhen the function returns, the address of the first byte of the
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Huntencoded string is returned via <VAR
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="PARAMETER"
cd32f419a8a5432fbb139f56ee73cbf68b9350ccTinderbox User>*c</VAR
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt> and the
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Huntlength of that string is given by <VAR
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="PARAMETER"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>*len</VAR
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>.  The
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Huntbuffer's current pointer is advanced to point at the character
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Huntfollowing the string length, the encoded string, and the trailing
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt<SPAN
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="TYPE"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>NULL</SPAN
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt> character.</P
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt><P
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt><CODE
0f66aced2640d964aeb6db41210711ba0640d7f2Evan HuntCLASS="FUNCTION"
0f66aced2640d964aeb6db41210711ba0640d7f2Evan Hunt>lwres_addr_parse()</CODE
> extracts an address from the
buffer <VAR
CLASS="PARAMETER"
>b</VAR
>.  The buffer's current pointer
<CODE
CLASS="CONSTANT"
>b-&gt;current</CODE
> 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
<CODE
CLASS="CONSTANT"
>addr-&gt;address</CODE
> and
<CODE
CLASS="CONSTANT"
>addr-&gt;length</CODE
> indicates the size in bytes of
the address that was copied.  <CODE
CLASS="CONSTANT"
>b-&gt;current</CODE
> is
advanced to point at the next byte of available data in the buffer
following the encoded address.</P
><P
><CODE
CLASS="FUNCTION"
>lwres_getaddrsbyname()</CODE
>
and
<CODE
CLASS="FUNCTION"
>lwres_getnamebyaddr()</CODE
>
use the
<SPAN
CLASS="TYPE"
>lwres_gnbaresponse_t</SPAN
>
structure defined below:
<PRE
CLASS="PROGRAMLISTING"
>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;</PRE
>
The contents of this structure are not manipulated directly but
they are controlled through the
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres_gabn</SPAN
>(3)</SPAN
>
functions.</P
><P
>The lightweight resolver uses
<CODE
CLASS="FUNCTION"
>lwres_getaddrsbyname()</CODE
> to perform foward lookups.
Hostname <VAR
CLASS="PARAMETER"
>name</VAR
> is looked up using the resolver
context <VAR
CLASS="PARAMETER"
>ctx</VAR
> for memory allocation.
<VAR
CLASS="PARAMETER"
>addrtypes</VAR
> is a bitmask indicating which type of
addresses are to be looked up.  Current values for this bitmask are
<SPAN
CLASS="TYPE"
>LWRES_ADDRTYPE_V4</SPAN
> for IPv4 addresses and
<SPAN
CLASS="TYPE"
>LWRES_ADDRTYPE_V6</SPAN
> for IPv6 addresses.  Results of the
lookup are returned in <VAR
CLASS="PARAMETER"
>*structp</VAR
>.</P
><P
><CODE
CLASS="FUNCTION"
>lwres_getnamebyaddr()</CODE
> performs reverse lookups.
Resolver context <VAR
CLASS="PARAMETER"
>ctx</VAR
> is used for memory
allocation.  The address type is indicated by
<VAR
CLASS="PARAMETER"
>addrtype</VAR
>: <SPAN
CLASS="TYPE"
>LWRES_ADDRTYPE_V4</SPAN
> or
<SPAN
CLASS="TYPE"
>LWRES_ADDRTYPE_V6</SPAN
>.  The address to be looked up is given
by <VAR
CLASS="PARAMETER"
>addr</VAR
> and its length is
<VAR
CLASS="PARAMETER"
>addrlen</VAR
> bytes.  The result of the function call
is made available through <VAR
CLASS="PARAMETER"
>*structp</VAR
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN84"
></A
><H2
>RETURN VALUES</H2
><P
>Successful calls to
<CODE
CLASS="FUNCTION"
>lwres_string_parse()</CODE
>
and
<CODE
CLASS="FUNCTION"
>lwres_addr_parse()</CODE
>
return
<SPAN
CLASS="ERRORCODE"
>LWRES_R_SUCCESS.</SPAN
>
Both functions return
<SPAN
CLASS="ERRORCODE"
>LWRES_R_FAILURE</SPAN
>
if the buffer is corrupt or
<SPAN
CLASS="ERRORCODE"
>LWRES_R_UNEXPECTEDEND</SPAN
>
if the buffer has less space than expected for the components of the
encoded string or address.</P
><P
><CODE
CLASS="FUNCTION"
>lwres_getaddrsbyname()</CODE
>
returns
<SPAN
CLASS="ERRORCODE"
>LWRES_R_SUCCESS</SPAN
>
on success and it returns
<SPAN
CLASS="ERRORCODE"
>LWRES_R_NOTFOUND</SPAN
>
if the hostname
<VAR
CLASS="PARAMETER"
>name</VAR
>
could not be found.</P
><P
><SPAN
CLASS="ERRORCODE"
>LWRES_R_SUCCESS</SPAN
>
is returned by a successful call to
<CODE
CLASS="FUNCTION"
>lwres_getnamebyaddr()</CODE
>.</P
><P
>Both
<CODE
CLASS="FUNCTION"
>lwres_getaddrsbyname()</CODE
>
and
<CODE
CLASS="FUNCTION"
>lwres_getnamebyaddr()</CODE
>
return
<SPAN
CLASS="ERRORCODE"
>LWRES_R_NOMEMORY</SPAN
>
when memory allocation requests fail and
<SPAN
CLASS="ERRORCODE"
>LWRES_R_UNEXPECTEDEND</SPAN
>
if the buffers used for sending queries and receiving replies are too
small.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN105"
></A
><H2
>SEE ALSO</H2
><P
><SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres_buffer</SPAN
>(3)</SPAN
>,

<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres_gabn</SPAN
>(3)</SPAN
>.</P
></DIV
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>