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$Id: lwres_noop.3,v 1.2 2000/07/27 09:45:28 tale Exp $
.Dd Jun 30, 2000 .Dt LWRES_NOOP 3 .Os BIND9 9 .Sh NAME .Nm lwres_nooprequest_render , .Nm lwres_noopresponse_render , .Nm lwres_nooprequest_parse , .Nm lwres_noopresponse_parse , .Nm lwres_noopresponse_free , .Nm lwres_nooprequest_free .Nd lightweight resolver no-op functions .Sh SYNOPSIS .Fd #include <lwres/lwres.h> .Fd .Ft lwres_result_t .Fo lwres_nooprequest_render .Fa "lwres_context_t *ctx" .Fa "lwres_nooprequest_t *req" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_buffer_t *b" .Fc .Ft lwres_result_t .Fo lwres_noopresponse_render .Fa "lwres_context_t *ctx" .Fa "lwres_noopresponse_t *req" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_buffer_t *b" .Fc .Ft lwres_result_t .Fo lwres_nooprequest_parse .Fa "lwres_context_t *ctx" .Fa "lwres_buffer_t *b" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_nooprequest_t **structp" .Fc .Ft lwres_result_t .Fo lwres_noopresponse_parse .Fa "lwres_context_t *ctx" .Fa "lwres_buffer_t *b" .Fa "lwres_lwpacket_t *pkt" .Fa "lwres_noopresponse_t **structp" .Fc .Ft void .Fo lwres_noopresponse_free .Fa "lwres_context_t *ctx" .Fa "lwres_noopresponse_t **structp" .Fc .Ft void .Fo lwres_nooprequest_free .Fa "lwres_context_t *ctx" .Fa "lwres_nooprequest_t **structp" .Fc .Sh DESCRIPTION These functions implement the lightweight resolver's no-op opcode .Dv LWRES_OPCODE_NOOP . This is analogous to a \*qping\*q test: a packet is sent to the lightweight resolver daemon and is simply echoed back. The opcode is intended to allow a client to determine if the server is operational or not.
p There are four main functions for the no-op opcode. One render function converts a no-op request structure - .Dv 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 - .Dv 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.
p These structures are defined in
a lwres/lwres.h . They are shown below. d -literal -offset indent #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; .Ed 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.
p .Fn lwres_nooprequest_render uses resolver context .Fa ctx to convert no-op 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_noopresponse_render performs the same task, except it converts a no-op response structure .Dv lwres_noopresponse_t to the lightweight resolver's canonical format.
p .Fn lwres_nooprequest_parse uses context .Fa ctx to convert the contents of packet .Fa pkt to a .Dv lwres_nooprequest_t structure. Buffer .Fa b provides space to be used for storing this structure. When the function succeeds, the resulting .Dv lwres_nooprequest_t is made available through .Fa *structp . .Fn lwres_noopresponse_parse offers the same semantics as .Fn lwres_nooprequest_parse except it yields a .Dv lwres_noopresponse_t structure.
p .Fn lwres_noopresponse_free and .Fn lwres_nooprequest_free release the memory in resolver context .Fa ctx that was allocated to the .Dv lwres_noopresponse_t or .Dv lwres_nooprequest_t structures referenced via .Fa structp . .Sh RETURN VALUES The no-op opcode functions .Fn lwres_nooprequest_render , .Fn lwres_noopresponse_render .Fn lwres_nooprequest_parse and .Fn lwres_noopresponse_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_nooprequest_t and .Dv lwres_noopresponse_t structures. .Fn lwres_nooprequest_parse and .Fn lwres_noopresponse_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