133 lines
5.5 KiB
C
133 lines
5.5 KiB
C
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/*
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* Copyright (c) 2014, Ralf Schlatterbeck Open Source Consulting
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/**
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* \defgroup Generic CoAP Resource Handler
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*
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* This factors the boilerplate code necessary for defining a resource
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* together with the necessary handler. Currently this supports
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* text/plain and application/json and outputs the resource with its
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* name in json format. This may change in the future as more CoRE
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* standards (e.g. see RFC 6690) get defined.
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*
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* @{
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*/
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/**
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* \file
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* Generic CoAP Resource Handler
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* \author
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* Ralf Schlatterbeck <rsc@runtux.com>
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*/
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#define STR__(s) #s
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#define STR_(s) STR__(s)
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/*
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* A macro that extends the resource definition and also sets up the
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* necessary handler function that calls format/parse routines that
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* convert from/to string (fs and ts). The ts function needs to return
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* the length written, similar to sprintf.
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* The content type definitions ct="0 5" are text/plain and
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* application/json, respectively, see rfc7252 Table 9 p. 91.
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* Yes, this *is* a hack. But I hate boilerplate code.
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*/
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#define GENERIC_RESOURCE(name, methods, path, title, unit, fs, ts) \
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void name##_handler \
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( void *request \
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, void *response \
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, uint8_t *buffer \
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, uint16_t ps \
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, int32_t *offset \
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) \
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{ \
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generic_handler \
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(request, response, buffer, ps, offset, STR_(name), fs, ts); \
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} \
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\
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RESOURCE ( name, methods, path \
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, "title=\"" STR_(title) "\"" \
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";rt=UCUM:\"" STR_(unit) "\"" \
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";ct=\"0 5\"" \
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)
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/**
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* \brief Parse a resource in json format
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* \param bytes: Input string received via coap
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* \param len: Length of input string
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* \param name: Name to search in json input
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* \param buf: Output buffer
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* \param buflen: Output buffer length
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* \return 0 for success, -1 for error
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*
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* If compiled with DEBUG also prints the error encountered
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*/
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extern int8_t json_parse_variable
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(const uint8_t *bytes, size_t len, char *name, char *buf, size_t buflen);
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/**
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* \brief Generic coap resource handler
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* \param name: The name of the variable in json
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* \param from_str: Application method to parse value from string
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* and act on it, may be NULL in which case the resource only
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* supports GET not PUT
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* \param to_str: Application method to format value for output;
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* the function may chose to format differently for coap or text
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* The other parameters are the same as a normal resource handler
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* This helps avoid boilerplate code for request handlers
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*
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* The callback functions get the name of the parameter as a first
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* argument, this allows to re-use the same function for different
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* parameters. The from_str in addition gets the string to parse.
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* For the to_str function the is_json flag allows to generate a
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* different string depending on the content-type. In addition it gets a
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* buffer and the size of the buffer. It needs to return the number of
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* bytes output, similar to sprintf.
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*/
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extern void generic_handler
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( void *request
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, void *response
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, uint8_t *buffer
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, uint16_t preferred_size
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, int32_t *offset
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, char *name
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, void (*from_str)(const char *name, const char *s)
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, size_t (*to_str)(const char *name, uint8_t is_json, char *buf, size_t bsize)
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);
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/*
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* VI settings, see coding style
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* ex:ts=8:et:sw=2
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*/
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/** @} */
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