/contrib/bind9/lib/lwres/man/lwres_noop.3
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- .\" Copyright (C) 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
- .\" Copyright (C) 2000, 2001 Internet Software Consortium.
- .\"
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- .\" $Id$
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- .hy 0
- .ad l
- .\" Title: lwres_noop
- .\" Author:
- .\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
- .\" Date: Jun 30, 2000
- .\" Manual: BIND9
- .\" Source: BIND9
- .\"
- .TH "LWRES_NOOP" "3" "Jun 30, 2000" "BIND9" "BIND9"
- .\" disable hyphenation
- .nh
- .\" disable justification (adjust text to left margin only)
- .ad l
- .SH "NAME"
- lwres_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free \- lightweight resolver no\-op message handling
- .SH "SYNOPSIS"
- .nf
- #include <lwres/lwres.h>
- .fi
- .HP 40
- .BI "lwres_result_t lwres_nooprequest_render(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
- .HP 41
- .BI "lwres_result_t lwres_noopresponse_render(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
- .HP 39
- .BI "lwres_result_t lwres_nooprequest_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_nooprequest_t\ **" "structp" ");"
- .HP 40
- .BI "lwres_result_t lwres_noopresponse_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_noopresponse_t\ **" "structp" ");"
- .HP 29
- .BI "void lwres_noopresponse_free(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ **" "structp" ");"
- .HP 28
- .BI "void lwres_nooprequest_free(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ **" "structp" ");"
- .SH "DESCRIPTION"
- .PP
- These are low\-level routines for creating and parsing lightweight resolver no\-op request and response messages.
- .PP
- The no\-op message is analogous to a
- \fBping\fR
- 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.
- .PP
- There are four main functions for the no\-op opcode. One render function converts a no\-op request structure \(em
- \fBlwres_nooprequest_t\fR
- \(em 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 \(em
- \fBlwres_noopresponse_t\fR
- to the canonical format. This is complemented by a parse function which converts a packet in canonical format to a no\-op response structure.
- .PP
- These structures are defined in
- \fIlwres/lwres.h\fR. They are shown below.
- .PP
- .RS 4
- .nf
- #define LWRES_OPCODE_NOOP 0x00000000U
- .fi
- .RE
- .sp
- .PP
- .RS 4
- .nf
- typedef struct {
- lwres_uint16_t datalength;
- unsigned char *data;
- } lwres_nooprequest_t;
- .fi
- .RE
- .sp
- .PP
- .RS 4
- .nf
- typedef struct {
- lwres_uint16_t datalength;
- unsigned char *data;
- } lwres_noopresponse_t;
- .fi
- .RE
- .sp
- .PP
- 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.
- .PP
- \fBlwres_nooprequest_render()\fR
- uses resolver context
- \fIctx\fR
- to convert no\-op request structure
- \fIreq\fR
- to canonical format. The packet header structure
- \fIpkt\fR
- is initialised and transferred to buffer
- \fIb\fR. The contents of
- \fI*req\fR
- are then appended to the buffer in canonical format.
- \fBlwres_noopresponse_render()\fR
- performs the same task, except it converts a no\-op response structure
- \fBlwres_noopresponse_t\fR
- to the lightweight resolver's canonical format.
- .PP
- \fBlwres_nooprequest_parse()\fR
- uses context
- \fIctx\fR
- to convert the contents of packet
- \fIpkt\fR
- to a
- \fBlwres_nooprequest_t\fR
- structure. Buffer
- \fIb\fR
- provides space to be used for storing this structure. When the function succeeds, the resulting
- \fBlwres_nooprequest_t\fR
- is made available through
- \fI*structp\fR.
- \fBlwres_noopresponse_parse()\fR
- offers the same semantics as
- \fBlwres_nooprequest_parse()\fR
- except it yields a
- \fBlwres_noopresponse_t\fR
- structure.
- .PP
- \fBlwres_noopresponse_free()\fR
- and
- \fBlwres_nooprequest_free()\fR
- release the memory in resolver context
- \fIctx\fR
- that was allocated to the
- \fBlwres_noopresponse_t\fR
- or
- \fBlwres_nooprequest_t\fR
- structures referenced via
- \fIstructp\fR.
- .SH "RETURN VALUES"
- .PP
- The no\-op opcode functions
- \fBlwres_nooprequest_render()\fR,
- \fBlwres_noopresponse_render()\fR
- \fBlwres_nooprequest_parse()\fR
- and
- \fBlwres_noopresponse_parse()\fR
- all return
- \fBLWRES_R_SUCCESS\fR
- on success. They return
- \fBLWRES_R_NOMEMORY\fR
- if memory allocation fails.
- \fBLWRES_R_UNEXPECTEDEND\fR
- is returned if the available space in the buffer
- \fIb\fR
- is too small to accommodate the packet header or the
- \fBlwres_nooprequest_t\fR
- and
- \fBlwres_noopresponse_t\fR
- structures.
- \fBlwres_nooprequest_parse()\fR
- and
- \fBlwres_noopresponse_parse()\fR
- will return
- \fBLWRES_R_UNEXPECTEDEND\fR
- if the buffer is not empty after decoding the received packet. These functions will return
- \fBLWRES_R_FAILURE\fR
- if
- \fBpktflags\fR
- in the packet header structure
- \fBlwres_lwpacket_t\fR
- indicate that the packet is not a response to an earlier query.
- .SH "SEE ALSO"
- .PP
- \fBlwres_packet\fR(3)
- .SH "COPYRIGHT"
- Copyright \(co 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
- .br
- Copyright \(co 2000, 2001 Internet Software Consortium.
- .br