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$Id: lwres_gabn.3,v 1.2 2000/07/27 09:44:42 tale Exp $
.Dd Jun 30, 2000 .Dt LWRES_GABN 3 .Os BIND9 9 .Sh NAME .Nm lwres_gabnrequest_render , .Nm lwres_gabnresponse_render , .Nm lwres_gabnrequest_parse , .Nm lwres_gabnresponse_parse , .Nm lwres_gabnresponse_free , .Nm lwres_gabnrequest_free .Nd lightweight resolver getaddrbyname functions .Sh SYNOPSIS .Fd #include <lwres/lwres.h> .Fd .Ft lwres_result_t .Fo lwres_gabnrequest_render .Fa "lwres_context_t *ctx" .Fa "lwres_gabnrequest_t *req" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_buffer_t *b" .Fc .Ft lwres_result_t .Fo lwres_gabnresponse_render .Fa "lwres_context_t *ctx" .Fa "lwres_gabnresponse_t *req" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_buffer_t *b" .Fc .Ft lwres_result_t .Fo lwres_gabnrequest_parse .Fa "lwres_context_t *ctx" .Fa "lwres_buffer_t *b" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_gabnrequest_t **structp" .Fc .Ft lwres_result_t .Fo lwres_gabnresponse_parse .Fa "lwres_context_t *ctx" .Fa "lwres_buffer_t *b" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_gabnresponse_t **structp" .Fc .Ft void .Fo lwres_gabnresponse_free .Fa "lwres_context_t *ctx" .Fa "lwres_gabnresponse_t **structp" .Fc .Ft void .Fo lwres_gabnrequest_free .Fa "lwres_context_t *ctx" .Fa "lwres_gabnrequest_t **structp" .Fc .Sh DESCRIPTION These functions implement the lightweight resolver's getaddrbyname opcode .Dv LWRES_OPCODE_GETADDRSBYNAME . They provide a forward lookup mechanism, mapping a hostname to its address or addresses.
p There are four main functions for the getaddrbyname opcode. One render function converts a getaddrbyname request structure - .Dv lwres_gabnrequest_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 getaddrbyname request structure. Another render function converts the getaddrbyname response structure - .Dv lwres_gabnresponse_t to the canonical format. This is complemented by a parse function which converts a packet in canonical format to a getaddrbyname response structure.
p These structures are defined in
a lwres/lwres.h . They are shown below. d -literal -offset indent #define LWRES_OPCODE_GETADDRSBYNAME 0x00010001U typedef struct lwres_addr lwres_addr_t; typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t; typedef struct { lwres_uint32_t flags; lwres_uint32_t addrtypes; lwres_uint16_t namelen; char *name; } lwres_gabnrequest_t; 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; .Ed
p .Fn lwres_gabnrequest_render uses resolver context .Fa ctx to convert getaddrbyname 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_gabnresponse_render performs the same task, except it converts a getaddrbyname response structure .Dv lwres_gabnresponse_t to the lightweight resolver's canonical format.
p .Fn lwres_gabnrequest_parse uses context .Fa ctx to convert the contents of packet .Fa pkt to a .Dv lwres_gabnrequest_t structure. Buffer .Fa b provides space to be used for storing this structure. When the function succeeds, the resulting .Dv lwres_gabnrequest_t is made available through .Fa *structp . .Fn lwres_gabnresponse_parse offers the same semantics as .Fn lwres_gabnrequest_parse except it yields a .Dv lwres_gabnresponse_t structure.
p .Fn lwres_gabnresponse_free and .Fn lwres_gabnrequest_free release the memory in resolver context .Fa ctx that was allocated to the .Dv lwres_gabnresponse_t or .Dv lwres_gabnrequest_t structures referenced via .Fa structp . Any memory associated with ancillary buffers and strings for those structures is also discarded. .Sh RETURN VALUES The getaddrbyname opcode functions .Fn lwres_gabnrequest_render , .Fn lwres_gabnresponse_render .Fn lwres_gabnrequest_parse and .Fn lwres_gabnresponse_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_gabnrequest_t and .Dv lwres_gabnresponse_t structures. .Fn lwres_gabnrequest_parse and .Fn lwres_gabnresponse_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