343 lines
10 KiB
C
343 lines
10 KiB
C
/*
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* Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
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* Copyright (C) 2000, 2001 Internet Software Consortium.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/* $Id: lwres_noop.c,v 1.19 2007/06/19 23:47:22 tbox Exp $ */
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/*! \file */
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/**
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* These are low-level routines for creating and parsing lightweight
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* resolver no-op request and response messages.
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*
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* The no-op message is analogous to a ping packet: a packet is sent to
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* the resolver daemon and is simply echoed back. The opcode is intended
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* to allow a client to determine if the server is operational or not.
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*
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* There are four main functions for the no-op opcode. One render
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* function converts a no-op request structure -- lwres_nooprequest_t --
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* to the lighweight resolver's canonical format. It is complemented by a
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* parse function that converts a packet in this canonical format to a
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* no-op request structure. Another render function converts the no-op
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* response structure -- lwres_noopresponse_t to the canonical format.
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* This is complemented by a parse function which converts a packet in
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* canonical format to a no-op response structure.
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*
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* These structures are defined in \link lwres.h <lwres/lwres.h.> \endlink They are shown below.
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*
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* \code
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* #define LWRES_OPCODE_NOOP 0x00000000U
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*
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* typedef struct {
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* lwres_uint16_t datalength;
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* unsigned char *data;
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* } lwres_nooprequest_t;
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*
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* typedef struct {
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* lwres_uint16_t datalength;
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* unsigned char *data;
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* } lwres_noopresponse_t;
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* \endcode
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*
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* Although the structures have different types, they are identical. This
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* is because the no-op opcode simply echos whatever data was sent: the
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* response is therefore identical to the request.
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*
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* lwres_nooprequest_render() uses resolver context ctx to convert no-op
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* request structure req to canonical format. The packet header structure
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* pkt is initialised and transferred to buffer b. The contents of *req
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* are then appended to the buffer in canonical format.
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* lwres_noopresponse_render() performs the same task, except it converts
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* a no-op response structure lwres_noopresponse_t to the lightweight
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* resolver's canonical format.
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*
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* lwres_nooprequest_parse() uses context ctx to convert the contents of
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* packet pkt to a lwres_nooprequest_t structure. Buffer b provides space
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* to be used for storing this structure. When the function succeeds, the
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* resulting lwres_nooprequest_t is made available through *structp.
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* lwres_noopresponse_parse() offers the same semantics as
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* lwres_nooprequest_parse() except it yields a lwres_noopresponse_t
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* structure.
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*
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* lwres_noopresponse_free() and lwres_nooprequest_free() release the
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* memory in resolver context ctx that was allocated to the
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* lwres_noopresponse_t or lwres_nooprequest_t structures referenced via
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* structp.
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*
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* \section lwres_noop_return Return Values
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*
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* The no-op opcode functions lwres_nooprequest_render(),
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* lwres_noopresponse_render() lwres_nooprequest_parse() and
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* lwres_noopresponse_parse() all return #LWRES_R_SUCCESS on success. They
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* return #LWRES_R_NOMEMORY if memory allocation fails.
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* #LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer
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* b is too small to accommodate the packet header or the
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* lwres_nooprequest_t and lwres_noopresponse_t structures.
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* lwres_nooprequest_parse() and lwres_noopresponse_parse() will return
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* #LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the
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* received packet. These functions will return #LWRES_R_FAILURE if
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* pktflags in the packet header structure #lwres_lwpacket_t indicate that
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* the packet is not a response to an earlier query.
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*
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* \section lwres_noop_see See Also
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*
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* lwpacket.c
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*/
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#include <config.h>
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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#include <lwres/lwbuffer.h>
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#include <lwres/lwpacket.h>
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#include <lwres/lwres.h>
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#include <lwres/result.h>
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#include "context_p.h"
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#include "assert_p.h"
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/*% Uses resolver context ctx to convert no-op request structure req to canonical format. */
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lwres_result_t
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lwres_nooprequest_render(lwres_context_t *ctx, lwres_nooprequest_t *req,
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lwres_lwpacket_t *pkt, lwres_buffer_t *b)
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{
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unsigned char *buf;
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size_t buflen;
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int ret;
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size_t payload_length;
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REQUIRE(ctx != NULL);
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REQUIRE(req != NULL);
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REQUIRE(pkt != NULL);
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REQUIRE(b != NULL);
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payload_length = sizeof(lwres_uint16_t) + req->datalength;
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buflen = LWRES_LWPACKET_LENGTH + payload_length;
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buf = CTXMALLOC(buflen);
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if (buf == NULL)
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return (LWRES_R_NOMEMORY);
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lwres_buffer_init(b, buf, buflen);
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pkt->length = buflen;
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pkt->version = LWRES_LWPACKETVERSION_0;
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pkt->pktflags &= ~LWRES_LWPACKETFLAG_RESPONSE;
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pkt->opcode = LWRES_OPCODE_NOOP;
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pkt->result = 0;
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pkt->authtype = 0;
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pkt->authlength = 0;
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ret = lwres_lwpacket_renderheader(b, pkt);
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if (ret != LWRES_R_SUCCESS) {
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lwres_buffer_invalidate(b);
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CTXFREE(buf, buflen);
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return (ret);
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}
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INSIST(SPACE_OK(b, payload_length));
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/*
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* Put the length and the data. We know this will fit because we
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* just checked for it.
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*/
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lwres_buffer_putuint16(b, req->datalength);
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lwres_buffer_putmem(b, req->data, req->datalength);
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INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
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return (LWRES_R_SUCCESS);
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}
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/*% Converts a no-op response structure lwres_noopresponse_t to the lightweight resolver's canonical format. */
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lwres_result_t
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lwres_noopresponse_render(lwres_context_t *ctx, lwres_noopresponse_t *req,
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lwres_lwpacket_t *pkt, lwres_buffer_t *b)
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{
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unsigned char *buf;
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size_t buflen;
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int ret;
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size_t payload_length;
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REQUIRE(ctx != NULL);
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REQUIRE(req != NULL);
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REQUIRE(pkt != NULL);
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REQUIRE(b != NULL);
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payload_length = sizeof(lwres_uint16_t) + req->datalength;
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buflen = LWRES_LWPACKET_LENGTH + payload_length;
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buf = CTXMALLOC(buflen);
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if (buf == NULL)
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return (LWRES_R_NOMEMORY);
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lwres_buffer_init(b, buf, buflen);
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pkt->length = buflen;
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pkt->version = LWRES_LWPACKETVERSION_0;
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pkt->pktflags |= LWRES_LWPACKETFLAG_RESPONSE;
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pkt->opcode = LWRES_OPCODE_NOOP;
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pkt->authtype = 0;
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pkt->authlength = 0;
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ret = lwres_lwpacket_renderheader(b, pkt);
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if (ret != LWRES_R_SUCCESS) {
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lwres_buffer_invalidate(b);
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CTXFREE(buf, buflen);
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return (ret);
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}
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INSIST(SPACE_OK(b, payload_length));
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/*
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* Put the length and the data. We know this will fit because we
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* just checked for it.
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*/
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lwres_buffer_putuint16(b, req->datalength);
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lwres_buffer_putmem(b, req->data, req->datalength);
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INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
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return (LWRES_R_SUCCESS);
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}
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/*% Uses context ctx to convert the contents of packet pkt to a lwres_nooprequest_t structure. */
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lwres_result_t
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lwres_nooprequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
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lwres_lwpacket_t *pkt, lwres_nooprequest_t **structp)
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{
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int ret;
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lwres_nooprequest_t *req;
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REQUIRE(ctx != NULL);
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REQUIRE(b != NULL);
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REQUIRE(pkt != NULL);
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REQUIRE(structp != NULL && *structp == NULL);
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if ((pkt->pktflags & LWRES_LWPACKETFLAG_RESPONSE) != 0)
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return (LWRES_R_FAILURE);
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req = CTXMALLOC(sizeof(lwres_nooprequest_t));
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if (req == NULL)
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return (LWRES_R_NOMEMORY);
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if (!SPACE_REMAINING(b, sizeof(lwres_uint16_t))) {
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ret = LWRES_R_UNEXPECTEDEND;
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goto out;
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}
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req->datalength = lwres_buffer_getuint16(b);
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if (!SPACE_REMAINING(b, req->datalength)) {
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ret = LWRES_R_UNEXPECTEDEND;
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goto out;
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}
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req->data = b->base + b->current;
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lwres_buffer_forward(b, req->datalength);
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if (LWRES_BUFFER_REMAINING(b) != 0) {
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ret = LWRES_R_TRAILINGDATA;
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goto out;
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}
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/* success! */
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*structp = req;
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return (LWRES_R_SUCCESS);
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/* Error return */
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out:
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CTXFREE(req, sizeof(lwres_nooprequest_t));
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return (ret);
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}
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/*% Offers the same semantics as lwres_nooprequest_parse() except it yields a lwres_noopresponse_t structure. */
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lwres_result_t
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lwres_noopresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
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lwres_lwpacket_t *pkt, lwres_noopresponse_t **structp)
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{
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int ret;
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lwres_noopresponse_t *req;
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REQUIRE(ctx != NULL);
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REQUIRE(b != NULL);
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REQUIRE(pkt != NULL);
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REQUIRE(structp != NULL && *structp == NULL);
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if ((pkt->pktflags & LWRES_LWPACKETFLAG_RESPONSE) == 0)
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return (LWRES_R_FAILURE);
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req = CTXMALLOC(sizeof(lwres_noopresponse_t));
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if (req == NULL)
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return (LWRES_R_NOMEMORY);
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if (!SPACE_REMAINING(b, sizeof(lwres_uint16_t))) {
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ret = LWRES_R_UNEXPECTEDEND;
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goto out;
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}
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req->datalength = lwres_buffer_getuint16(b);
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if (!SPACE_REMAINING(b, req->datalength)) {
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ret = LWRES_R_UNEXPECTEDEND;
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goto out;
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}
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req->data = b->base + b->current;
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lwres_buffer_forward(b, req->datalength);
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if (LWRES_BUFFER_REMAINING(b) != 0) {
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ret = LWRES_R_TRAILINGDATA;
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goto out;
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}
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/* success! */
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*structp = req;
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return (LWRES_R_SUCCESS);
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/* Error return */
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out:
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CTXFREE(req, sizeof(lwres_noopresponse_t));
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return (ret);
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}
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/*% Release the memory in resolver context ctx. */
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void
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lwres_noopresponse_free(lwres_context_t *ctx, lwres_noopresponse_t **structp)
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{
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lwres_noopresponse_t *noop;
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REQUIRE(ctx != NULL);
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REQUIRE(structp != NULL && *structp != NULL);
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noop = *structp;
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*structp = NULL;
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CTXFREE(noop, sizeof(lwres_noopresponse_t));
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}
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/*% Release the memory in resolver context ctx. */
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void
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lwres_nooprequest_free(lwres_context_t *ctx, lwres_nooprequest_t **structp)
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{
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lwres_nooprequest_t *noop;
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REQUIRE(ctx != NULL);
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REQUIRE(structp != NULL && *structp != NULL);
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noop = *structp;
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*structp = NULL;
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CTXFREE(noop, sizeof(lwres_nooprequest_t));
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}
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