contiki/apps/oma-lwm2m/lwm2m-json.c

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2016-05-04 18:39:08 +00:00
/*
* Copyright (c) 2016, Eistec AB.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \addtogroup oma-lwm2m
* @{
*/
/**
* \file
* Implementation of the Contiki OMA LWM2M JSON writer
* \author
* Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
#include "lwm2m-object.h"
#include "lwm2m-json.h"
#include "lwm2m-plain-text.h"
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <inttypes.h>
#define DEBUG 0
#if DEBUG
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
/*---------------------------------------------------------------------------*/
static size_t
write_boolean(const lwm2m_context_t *ctx, uint8_t *outbuf, size_t outlen,
int value)
{
int len = snprintf((char *)outbuf, outlen, "{\"e\":[{\"n\":\"%u\",\"bv\":%s}]}\n", ctx->resource_id, value ? "true" : "false");
if((len < 0) || (len >= outlen)) {
return 0;
}
return len;
}
/*---------------------------------------------------------------------------*/
static size_t
write_int(const lwm2m_context_t *ctx, uint8_t *outbuf, size_t outlen,
int32_t value)
{
int len = snprintf((char *)outbuf, outlen, "{\"e\":[{\"n\":\"%u\",\"v\":%" PRId32 "}]}\n", ctx->resource_id, value);
if((len < 0) || (len >= outlen)) {
return 0;
}
return len;
}
/*---------------------------------------------------------------------------*/
static size_t
write_float32fix(const lwm2m_context_t *ctx, uint8_t *outbuf, size_t outlen,
int32_t value, int bits)
{
size_t len = 0;
int res;
res = snprintf((char *)outbuf, outlen, "{\"e\":[{\"n\":\"%u\",\"v\":", ctx->resource_id);
if(res <= 0 || res >= outlen) {
return 0;
}
len += res;
outlen -= res;
res = lwm2m_plain_text_write_float32fix(&outbuf[len], outlen, value, bits);
if((res <= 0) || (res >= outlen)) {
return 0;
}
len += res;
outlen -= res;
res = snprintf((char *)&outbuf[len], outlen, "}]}\n");
if((res <= 0) || (res >= outlen)) {
return 0;
}
len += res;
return len;
}
/*---------------------------------------------------------------------------*/
static size_t
write_string(const lwm2m_context_t *ctx, uint8_t *outbuf, size_t outlen,
const char *value, size_t stringlen)
{
size_t i;
size_t len = 0;
int res;
PRINTF("{\"e\":[{\"n\":\"%u\",\"sv\":\"", ctx->resource_id);
res = snprintf((char *)outbuf, outlen, "{\"e\":[{\"n\":\"%u\",\"sv\":\"", ctx->resource_id);
if(res < 0 || res >= outlen) {
return 0;
}
len += res;
for (i = 0; i < stringlen && len < outlen; ++i) {
/* Escape special characters */
/* TODO: Handle UTF-8 strings */
if(value[i] < '\x20') {
PRINTF("\\x%x", value[i]);
res = snprintf((char *)&outbuf[len], outlen - len, "\\x%x", value[i]);
if((res < 0) || (res >= (outlen - len))) {
return 0;
}
len += res;
continue;
} else if(value[i] == '"' || value[i] == '\\') {
PRINTF("\\");
outbuf[len] = '\\';
++len;
if(len >= outlen) {
return 0;
}
}
PRINTF("%c", value[i]);
outbuf[len] = value[i];
++len;
if(len >= outlen) {
return 0;
}
}
PRINTF("\"}]}\n");
res = snprintf((char *)&outbuf[len], outlen - len, "\"}]}\n");
if((res < 0) || (res >= (outlen - len))) {
return 0;
}
len += res;
return len;
}
/*---------------------------------------------------------------------------*/
const lwm2m_writer_t lwm2m_json_writer = {
write_int,
write_string,
write_float32fix,
write_boolean
};
/*---------------------------------------------------------------------------*/
/** @} */