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LWRES_RESUTIL(3)
NAME
  lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname,
  lwres_getnamebyaddr - lightweight resolver utility functions

SYNOPSIS
  #include <lwres/lwres.h>

  lwres_result_t lwres_string_parse(lwres_buffer_t *b, char **c,
  lwres_uint16_t *len);

  lwres_result_t lwres_addr_parse(lwres_buffer_t *b, lwres_addr_t *addr);

  lwres_result_t lwres_getaddrsbyname(lwres_context_t *ctx, const char *name,
  lwres_uint32_t addrtypes, lwres_gabnresponse_t **structp);

  lwres_result_t lwres_getnamebyaddr(lwres_context_t *ctx, lwres_uint32_t
  addrtype, lwres_uint16_t addrlen, const unsigned char *addr,
  lwres_gnbaresponse_t **structp);

DESCRIPTION
  lwres_string_parse() retrieves a DNS-encoded string  starting	 the  current
  pointer  of  lightweight  resolver  buffer  b:  i.e.	b->current.  When the
  function returns, the address of the first byte of the  encoded  string  is
  returned  via	 *c  and  the  length  of  that	 string is given by *len. The
  buffer's current pointer is advanced to point at  the	 character  following
  the string length, the encoded string, and the trailing NULL character.

  lwres_addr_parse() extracts an address from  the  buffer  b.	The  buffer's
  current  pointer b->current 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 addr->address and addr->length
  indicates the size in bytes of the address that was copied.  b->current  is
  advanced  to	point  at  the	next  byte  of	available  data in the buffer
  following the encoded address.

  lwres_getaddrsbyname()     and      lwres_getnamebyaddr()	 use	  the
  lwres_gnbaresponse_t structure defined below:

  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;

  The contents of this structure are not manipulated directly  but  they  are
  controlled through the lwres_gabn(3) functions.

  The lightweight resolver  uses  lwres_getaddrsbyname()  to  perform  foward
  lookups.   Hostname  name  is	 looked up using the resolver context ctx for
  memory allocation.   addrtypes  is  a	 bitmask  indicating  which  type  of
  addresses  are  to  be  looked  up.  Current	values	for  this bitmask are
  LWRES_ADDRTYPE_V4  for  IPv4	addresses  and	LWRES_ADDRTYPE_V6  for	 IPv6
  addresses. Results of the lookup are returned in *structp.

  lwres_getnamebyaddr() performs reverse lookups.  Resolver  context  ctx  is
  used	for  memory  allocation.  The  address type is indicated by addrtype:
  LWRES_ADDRTYPE_V4 or LWRES_ADDRTYPE_V6. The address  to  be  looked  up  is
  given	 by  addr and its length is addrlen bytes. The result of the function
  call is made available through *structp.

RETURN VALUES
  Successful calls  to	lwres_string_parse()  and  lwres_addr_parse()  return
  LWRES_R_SUCCESS.   Both  functions  return LWRES_R_FAILURE if the buffer is
  corrupt or LWRES_R_UNEXPECTEDEND if the buffer has less space than expected
  for the components of the encoded string or address.

  lwres_getaddrsbyname() returns LWRES_R_SUCCESS on success  and  it  returns
  LWRES_R_NOTFOUND if the hostname name could not be found.

  LWRES_R_SUCCESS is returned by a successful call to lwres_getnamebyaddr().

  Both	  lwres_getaddrsbyname()     and     lwres_getnamebyaddr()     return
  LWRES_R_NOMEMORY    when    memory	allocation    requests	  fail	  and
  LWRES_R_UNEXPECTEDEND if the buffers used for sending queries and receiving
  replies are too small.

SEE ALSO
  lwres_buffer(3), lwres_gabn(3).

Index for Section 3

Alphabetical listing for L

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