lwres_noop.c revision 0c27b3fe77ac1d5094ba3521e8142d9e7973133f
/*
* Copyright (C) 2000, 2001, 2004, 2005, 2007, 2013, 2016 Internet Systems Consortium, Inc. ("ISC")
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
/* $Id: lwres_noop.c,v 1.19 2007/06/19 23:47:22 tbox Exp $ */
/*! \file */
/**
* 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 \link lwres.h <lwres/lwres.h.> \endlink They are shown below.
*
* \code
* #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;
* \endcode
*
* 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.
*
* lwres_nooprequest_render() uses resolver context ctx to convert no-op
* request structure req to canonical format. The packet header structure
* pkt is initialised and transferred to buffer b. The contents of *req
* are then appended to the buffer in canonical format.
* lwres_noopresponse_render() performs the same task, except it converts
* a no-op response structure lwres_noopresponse_t to the lightweight
* resolver's canonical format.
*
* lwres_nooprequest_parse() uses context ctx to convert the contents of
* packet pkt to a lwres_nooprequest_t structure. Buffer b provides space
* to be used for storing this structure. When the function succeeds, the
* resulting lwres_nooprequest_t is made available through *structp.
* lwres_noopresponse_parse() offers the same semantics as
* lwres_nooprequest_parse() except it yields a lwres_noopresponse_t
* structure.
*
* lwres_noopresponse_free() and lwres_nooprequest_free() release the
* memory in resolver context ctx that was allocated to the
* lwres_noopresponse_t or lwres_nooprequest_t structures referenced via
* structp.
*
* \section lwres_noop_return 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.
*
* \section lwres_noop_see See Also
*
* lwpacket.c
*/
#include <config.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <lwres/lwbuffer.h>
#include <lwres/lwpacket.h>
#include <lwres/lwres.h>
#include <lwres/result.h>
#include "context_p.h"
#include "assert_p.h"
/*% Uses resolver context ctx to convert no-op request structure req to canonical format. */
lwres_result_t
lwres_nooprequest_render(lwres_context_t *ctx, lwres_nooprequest_t *req,
lwres_lwpacket_t *pkt, lwres_buffer_t *b)
{
unsigned char *buf;
size_t buflen;
int ret;
size_t payload_length;
REQUIRE(ctx != NULL);
REQUIRE(req != NULL);
REQUIRE(pkt != NULL);
REQUIRE(b != NULL);
payload_length = sizeof(lwres_uint16_t) + req->datalength;
buflen = LWRES_LWPACKET_LENGTH + payload_length;
buf = CTXMALLOC(buflen);
if (buf == NULL)
return (LWRES_R_NOMEMORY);
lwres_buffer_init(b, buf, (unsigned int)buflen);
pkt->length = (lwres_uint32_t)buflen;
pkt->version = LWRES_LWPACKETVERSION_0;
pkt->pktflags &= ~LWRES_LWPACKETFLAG_RESPONSE;
pkt->opcode = LWRES_OPCODE_NOOP;
pkt->result = 0;
pkt->authtype = 0;
pkt->authlength = 0;
ret = lwres_lwpacket_renderheader(b, pkt);
if (ret != LWRES_R_SUCCESS) {
lwres_buffer_invalidate(b);
CTXFREE(buf, buflen);
return (ret);
}
INSIST(SPACE_OK(b, payload_length));
/*
* Put the length and the data. We know this will fit because we
* just checked for it.
*/
lwres_buffer_putuint16(b, req->datalength);
lwres_buffer_putmem(b, req->data, req->datalength);
INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
return (LWRES_R_SUCCESS);
}
/*% Converts a no-op response structure lwres_noopresponse_t to the lightweight resolver's canonical format. */
lwres_result_t
lwres_noopresponse_render(lwres_context_t *ctx, lwres_noopresponse_t *req,
lwres_lwpacket_t *pkt, lwres_buffer_t *b)
{
unsigned char *buf;
size_t buflen;
int ret;
size_t payload_length;
REQUIRE(ctx != NULL);
REQUIRE(req != NULL);
REQUIRE(pkt != NULL);
REQUIRE(b != NULL);
payload_length = sizeof(lwres_uint16_t) + req->datalength;
buflen = LWRES_LWPACKET_LENGTH + payload_length;
buf = CTXMALLOC(buflen);
if (buf == NULL)
return (LWRES_R_NOMEMORY);
lwres_buffer_init(b, buf, (unsigned int)buflen);
pkt->length = (lwres_uint32_t)buflen;
pkt->version = LWRES_LWPACKETVERSION_0;
pkt->pktflags |= LWRES_LWPACKETFLAG_RESPONSE;
pkt->opcode = LWRES_OPCODE_NOOP;
pkt->authtype = 0;
pkt->authlength = 0;
ret = lwres_lwpacket_renderheader(b, pkt);
if (ret != LWRES_R_SUCCESS) {
lwres_buffer_invalidate(b);
CTXFREE(buf, buflen);
return (ret);
}
INSIST(SPACE_OK(b, payload_length));
/*
* Put the length and the data. We know this will fit because we
* just checked for it.
*/
lwres_buffer_putuint16(b, req->datalength);
lwres_buffer_putmem(b, req->data, req->datalength);
INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
return (LWRES_R_SUCCESS);
}
/*% Uses context ctx to convert the contents of packet pkt to a lwres_nooprequest_t structure. */
lwres_result_t
lwres_nooprequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
lwres_lwpacket_t *pkt, lwres_nooprequest_t **structp)
{
int ret;
lwres_nooprequest_t *req;
REQUIRE(ctx != NULL);
REQUIRE(b != NULL);
REQUIRE(pkt != NULL);
REQUIRE(structp != NULL && *structp == NULL);
if ((pkt->pktflags & LWRES_LWPACKETFLAG_RESPONSE) != 0)
return (LWRES_R_FAILURE);
req = CTXMALLOC(sizeof(lwres_nooprequest_t));
if (req == NULL)
return (LWRES_R_NOMEMORY);
if (!SPACE_REMAINING(b, sizeof(lwres_uint16_t))) {
ret = LWRES_R_UNEXPECTEDEND;
goto out;
}
req->datalength = lwres_buffer_getuint16(b);
if (!SPACE_REMAINING(b, req->datalength)) {
ret = LWRES_R_UNEXPECTEDEND;
goto out;
}
req->data = b->base + b->current;
lwres_buffer_forward(b, req->datalength);
if (LWRES_BUFFER_REMAINING(b) != 0) {
ret = LWRES_R_TRAILINGDATA;
goto out;
}
/* success! */
*structp = req;
return (LWRES_R_SUCCESS);
/* Error return */
out:
CTXFREE(req, sizeof(lwres_nooprequest_t));
return (ret);
}
/*% Offers the same semantics as lwres_nooprequest_parse() except it yields a lwres_noopresponse_t structure. */
lwres_result_t
lwres_noopresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
lwres_lwpacket_t *pkt, lwres_noopresponse_t **structp)
{
int ret;
lwres_noopresponse_t *req;
REQUIRE(ctx != NULL);
REQUIRE(b != NULL);
REQUIRE(pkt != NULL);
REQUIRE(structp != NULL && *structp == NULL);
if ((pkt->pktflags & LWRES_LWPACKETFLAG_RESPONSE) == 0)
return (LWRES_R_FAILURE);
req = CTXMALLOC(sizeof(lwres_noopresponse_t));
if (req == NULL)
return (LWRES_R_NOMEMORY);
if (!SPACE_REMAINING(b, sizeof(lwres_uint16_t))) {
ret = LWRES_R_UNEXPECTEDEND;
goto out;
}
req->datalength = lwres_buffer_getuint16(b);
if (!SPACE_REMAINING(b, req->datalength)) {
ret = LWRES_R_UNEXPECTEDEND;
goto out;
}
req->data = b->base + b->current;
lwres_buffer_forward(b, req->datalength);
if (LWRES_BUFFER_REMAINING(b) != 0) {
ret = LWRES_R_TRAILINGDATA;
goto out;
}
/* success! */
*structp = req;
return (LWRES_R_SUCCESS);
/* Error return */
out:
CTXFREE(req, sizeof(lwres_noopresponse_t));
return (ret);
}
/*% Release the memory in resolver context ctx. */
void
lwres_noopresponse_free(lwres_context_t *ctx, lwres_noopresponse_t **structp)
{
lwres_noopresponse_t *noop;
REQUIRE(ctx != NULL);
REQUIRE(structp != NULL && *structp != NULL);
noop = *structp;
*structp = NULL;
CTXFREE(noop, sizeof(lwres_noopresponse_t));
}
/*% Release the memory in resolver context ctx. */
void
lwres_nooprequest_free(lwres_context_t *ctx, lwres_nooprequest_t **structp)
{
lwres_nooprequest_t *noop;
REQUIRE(ctx != NULL);
REQUIRE(structp != NULL && *structp != NULL);
noop = *structp;
*structp = NULL;
CTXFREE(noop, sizeof(lwres_nooprequest_t));
}