LWRES_RESUTIL(3)              BIND9              LWRES_RESUTIL(3)



NAME
       lwres_string_parse, lwres_addr_parse,
       lwres_getaddrsbyname, lwres_getnamebyaddr - lightweight
       resolver utility functions

SYNOPSIS
       #include 

       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).



BIND9                      Jun 30, 2000          LWRES_RESUTIL(3)