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$Id: lwres_gnba.3,v 1.6 2001/01/09 21:49:58 bwelling Exp $
.Dd Jun 30, 2000 .Dt LWRES_GNBA 3 .Os BIND9 9 .Sh NAME .Nm lwres_gnbarequest_render , .Nm lwres_gnbaresponse_render , .Nm lwres_gnbarequest_parse , .Nm lwres_gnbaresponse_parse , .Nm lwres_gnbaresponse_free , .Nm lwres_gnbarequest_free .Nd lightweight resolver getnamebyaddress message handling .Sh SYNOPSIS .Fd #include <lwres/lwres.h> .Fd .Ft lwres_result_t .Fo lwres_gnbarequest_render .Fa "lwres_context_t *ctx" .Fa "lwres_gnbarequest_t *req" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_buffer_t *b" .Fc .Ft lwres_result_t .Fo lwres_gnbaresponse_render .Fa "lwres_context_t *ctx" .Fa "lwres_gnbaresponse_t *req" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_buffer_t *b" .Fc .Ft lwres_result_t .Fo lwres_gnbarequest_parse .Fa "lwres_context_t *ctx" .Fa "lwres_buffer_t *b" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_gnbarequest_t **structp" .Fc .Ft lwres_result_t .Fo lwres_gnbaresponse_parse .Fa "lwres_context_t *ctx" .Fa "lwres_buffer_t *b" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_gnbaresponse_t **structp" .Fc .Ft void .Fo lwres_gnbaresponse_free .Fa "lwres_context_t *ctx" .Fa "lwres_gnbaresponse_t **structp" .Fc .Ft void .Fo lwres_gnbarequest_free .Fa "lwres_context_t *ctx" .Fa "lwres_gnbarequest_t **structp" .Fc .Sh DESCRIPTION These are low-level routines for creating and parsing lightweight resolver address-to-name lookup request and response messages.
p There are four main functions for the getnamebyaddr opcode. One render function converts a getnamebyaddr request structure - .Dv lwres_gnbarequest_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 getnamebyaddr request structure. Another render function converts the getnamebyaddr response structure - .Dv lwres_gnbaresponse_t to the canonical format. This is complemented by a parse function which converts a packet in canonical format to a getnamebyaddr response structure.
p These structures are defined in
a lwres/lwres.h . They are shown below. d -literal -offset indent #define LWRES_OPCODE_GETNAMEBYADDR 0x00010002U typedef struct { lwres_uint32_t flags; lwres_addr_t addr; } lwres_gnbarequest_t; typedef struct { lwres_uint32_t flags; lwres_uint16_t naliases; char *realname; char **aliases; lwres_uint16_t realnamelen; lwres_uint16_t *aliaslen; void *base; size_t baselen; } lwres_gnbaresponse_t; .Ed
p .Fn lwres_gnbarequest_render uses resolver context .Fa ctx to convert getnamebyaddr request structure .Fa req to canonical format. The packet header structure .Fa pkt is initialised and transferred to buffer .Fa b . The contents of .Fa *req are then appended to the buffer in canonical format. .Fn lwres_gnbaresponse_render performs the same task, except it converts a getnamebyaddr response structure .Dv lwres_gnbaresponse_t to the lightweight resolver's canonical format.
p .Fn lwres_gnbarequest_parse uses context .Fa ctx to convert the contents of packet .Fa pkt to a .Dv lwres_gnbarequest_t structure. Buffer .Fa b provides space to be used for storing this structure. When the function succeeds, the resulting .Dv lwres_gnbarequest_t is made available through .Fa *structp . .Fn lwres_gnbaresponse_parse offers the same semantics as .Fn lwres_gnbarequest_parse except it yields a .Dv lwres_gnbaresponse_t structure.
p .Fn lwres_gnbaresponse_free and .Fn lwres_gnbarequest_free release the memory in resolver context .Fa ctx that was allocated to the .Dv lwres_gnbaresponse_t or .Dv lwres_gnbarequest_t structures referenced via .Fa structp . Any memory associated with ancillary buffers and strings for those structures is also discarded. .Sh RETURN VALUES The getnamebyaddr opcode functions .Fn lwres_gnbarequest_render , .Fn lwres_gnbaresponse_render .Fn lwres_gnbarequest_parse and .Fn lwres_gnbaresponse_parse all return .Er LWRES_R_SUCCESS on success. They return .Er LWRES_R_NOMEMORY if memory allocation fails. .Er LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer .Fa b is too small to accommodate the packet header or the .Dv lwres_gnbarequest_t and .Dv lwres_gnbaresponse_t structures. .Fn lwres_gnbarequest_parse and .Fn lwres_gnbaresponse_parse will return .Er LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the received packet. These functions will return .Er LWRES_R_FAILURE if .Li pktflags in the packet header structure .Dv lwres_lwpacket_t indicate that the packet is not a response to an earlier query. .Sh SEE ALSO .Xr lwres_packet 3