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LWRES_NOOP(3) | BIND9 | LWRES_NOOP(3) |
NAME¶
lwres_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free - lightweight resolver no-op message handlingSYNOPSIS¶
#include <lwres/lwres.h>
lwres_result_t
lwres_nooprequest_render(lwres_context_t *ctx,
lwres_nooprequest_t *req,
lwres_lwpacket_t *pkt,
lwres_buffer_t *b);
lwres_result_t
lwres_noopresponse_render(lwres_context_t *ctx,
lwres_noopresponse_t *req,
lwres_lwpacket_t *pkt,
lwres_buffer_t *b);
lwres_result_t
lwres_nooprequest_parse(lwres_context_t *ctx,
lwres_buffer_t *b,
lwres_lwpacket_t *pkt,
lwres_nooprequest_t **structp);
lwres_result_t
lwres_noopresponse_parse(lwres_context_t *ctx,
lwres_buffer_t *b,
lwres_lwpacket_t *pkt,
lwres_noopresponse_t **structp);
void
lwres_noopresponse_free(lwres_context_t *ctx,
lwres_noopresponse_t **structp);
void
lwres_nooprequest_free(lwres_context_t *ctx,
lwres_nooprequest_t **structp);
DESCRIPTION¶
These are low-level routines for creating and parsing lightweight resolver no-op request and response messages. The no-op message is analogous to a ping packet: a packet is sent to the resolver daemon and is simply echoed back. The opcode is intended to allow a client to determine if the server is operational or not. There are four main functions for the no-op opcode. One render function converts a no-op request structure — 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 — 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. These structures are defined in lwres/lwres.h. They are shown below.#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;
RETURN VALUES¶
The no-op opcode functions lwres_nooprequest_render(), lwres_noopresponse_render() lwres_nooprequest_parse() and lwres_noopresponse_parse() all return LWRES_R_SUCCESS on success. They return LWRES_R_NOMEMORY if memory allocation fails. LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer b is too small to accommodate the packet header or the lwres_nooprequest_t and lwres_noopresponse_t structures. lwres_nooprequest_parse() and lwres_noopresponse_parse() will return LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the received packet. These functions will return LWRES_R_FAILURE if pktflags in the packet header structure lwres_lwpacket_t indicate that the packet is not a response to an earlier query.SEE ALSO¶
lwres_packet(3)COPYRIGHT¶
Copyright © 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")June 30, 2000 | BIND9 |