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Alphabetical listing for L

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LWRES_NOOP(3)
NAME
  lwres_nooprequest_render, lwres_noopresponse_render,
  lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free,
  lwres_nooprequest_free - lightweight resolver no-op message handling

SYNOPSIS
  #include <lwres/lwres.h>

  lwres_result_t lwres_nooprequest_render(lwres_context_t *ctx,
  lwres_nooprequest_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);

  lwres_result_t lwres_noopresponse_render(lwres_context_t *ctx,
  lwres_noopresponse_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);

  lwres_result_t lwres_nooprequest_parse(lwres_context_t *ctx, lwres_buffer_t
  *b, lwres_lwpacket_t *pkt, lwres_nooprequest_t **structp);

  lwres_result_t lwres_noopresponse_parse(lwres_context_t *ctx,
  lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_noopresponse_t **structp);

  void lwres_noopresponse_free(lwres_context_t *ctx, lwres_noopresponse_t
  **structp);

  void lwres_nooprequest_free(lwres_context_t *ctx, lwres_nooprequest_t
  **structp);

DESCRIPTION
  These are low-level routines for creating and parsing lightweight  resolver
  no-op request and response messages.

  The no-op message is analogous to a ping packet: a packet is	sent  to  the
  resolver daemon and is simply echoed back.  The opcode is intended to allow
  a client to determine if the server is operational or not.

  There are four main functions for the no-op opcode.	One  render  function
  converts   a	no-op  request	structure  -  lwres_nooprequest_t  -  to  the
  lighweight resolver's canonical format.  It  is  complemented	 by  a	parse
  function that converts a packet in this canonical format to a no-op request
  structure.  Another render function converts the no-op response structure -
  lwres_noopresponse_t	to  the	 canonical format.  This is complemented by a
  parse function which converts a packet  in  canonical	 format	 to  a	no-op
  response structure.

  These structures are defined in lwres/lwres.h.  They are shown below.

  #define LWRES_OPCODE_NOOP	  0x00000000U

  typedef struct {
	  lwres_uint16_t  datalength;
	  unsigned char	  *data;
  } lwres_nooprequest_t;

  typedef struct {
	  lwres_uint16_t  datalength;
	  unsigned char	  *data;
  } lwres_noopresponse_t;

  Although the structures have different types, they are identical.  This  is
  because  the no-op opcode simply echos whatever data was sent: the response
  is therefore identical to the request.

  lwres_nooprequest_render() uses  resolver  context  ctx  to  convert	no-op
  request  structure req to canonical format. The packet header structure pkt
  is initialised and transferred to buffer b. The contents of *req  are	 then
  appended  to	the  buffer  in canonical format. lwres_noopresponse_render()
  performs the same task, except  it  converts	a  no-op  response  structure
  lwres_noopresponse_t to the lightweight resolver's canonical format.

  lwres_nooprequest_parse() uses context  ctx  to  convert  the	 contents  of
  packet  pkt  to a lwres_nooprequest_t structure. Buffer b provides space to
  be used for  storing	this  structure.  When	the  function  succeeds,  the
  resulting   lwres_nooprequest_t   is	 made	available  through  *structp.
  lwres_noopresponse_parse()	 offers	    the	    same     semantics	   as
  lwres_nooprequest_parse()   except   it   yields   a	 lwres_noopresponse_t
  structure.

  lwres_noopresponse_free() and lwres_nooprequest_free() release  the  memory
  in  resolver	context ctx that was allocated to the lwres_noopresponse_t or
  lwres_nooprequest_t structures referenced via structp.

RETURN VALUES
  The	   no-op      opcode	  functions	  lwres_nooprequest_render(),
  lwres_noopresponse_render()	       lwres_nooprequest_parse()	  and
  lwres_noopresponse_parse() all return	 LWRES_R_SUCCESS  on  success.	 They
  return  LWRES_R_NOMEMORY if memory allocation fails.	LWRES_R_UNEXPECTEDEND
  is returned if the available	space  in  the	buffer	b  is  too  small  to
  accommodate	 the   packet	header	 or   the   lwres_nooprequest_t	  and
  lwres_noopresponse_t	   structures.	    lwres_nooprequest_parse()	  and
  lwres_noopresponse_parse()  will return LWRES_R_UNEXPECTEDEND if the buffer
  is not empty after decoding the  received  packet.   These  functions	 will
  return   LWRES_R_FAILURE   if	 pktflags  in  the  packet  header  structure
  lwres_lwpacket_t indicate that the packet is not a response to  an  earlier
  query.

SEE ALSO
  lwres_packet(3)

Index for Section 3

Alphabetical listing for L

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