138 lines
4.6 KiB
C
138 lines
4.6 KiB
C
/*
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* block.h -- block transfer
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*
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* Copyright (C) 2010-2012,2014-2015 Olaf Bergmann <bergmann@tzi.org>
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*
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* This file is part of the CoAP library libcoap. Please see README for terms
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* of use.
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*/
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#ifndef _COAP_BLOCK_H_
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#define _COAP_BLOCK_H_
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#include "encode.h"
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#include "option.h"
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#include "pdu.h"
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/**
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* @defgroup block Block Transfer
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* @{
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*/
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#ifndef COAP_MAX_BLOCK_SZX
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/**
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* The largest value for the SZX component in a Block option. Note that
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* 1 << (COAP_MAX_BLOCK_SZX + 4) should not exceed COAP_MAX_PDU_SIZE.
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*/
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#define COAP_MAX_BLOCK_SZX 4
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#endif /* COAP_MAX_BLOCK_SZX */
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/**
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* Structure of Block options.
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*/
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typedef struct {
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unsigned int num; /**< block number */
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unsigned int m:1; /**< 1 if more blocks follow, 0 otherwise */
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unsigned int szx:3; /**< block size */
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} coap_block_t;
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/**
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* Returns the value of the least significant byte of a Block option @p opt.
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* For zero-length options (i.e. num == m == szx == 0), COAP_OPT_BLOCK_LAST
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* returns @c NULL.
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*/
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#define COAP_OPT_BLOCK_LAST(opt) \
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(COAP_OPT_LENGTH(opt) ? (COAP_OPT_VALUE(opt) + (COAP_OPT_LENGTH(opt)-1)) : 0)
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/** Returns the value of the More-bit of a Block option @p opt. */
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#define COAP_OPT_BLOCK_MORE(opt) \
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(COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x08) : 0)
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/** Returns the value of the SZX-field of a Block option @p opt. */
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#define COAP_OPT_BLOCK_SZX(opt) \
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(COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x07) : 0)
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/**
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* Returns the value of field @c num in the given block option @p block_opt.
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*/
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unsigned int coap_opt_block_num(const coap_opt_t *block_opt);
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/**
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* Checks if more than @p num blocks are required to deliver @p data_len
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* bytes of data for a block size of 1 << (@p szx + 4).
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*/
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static inline int
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coap_more_blocks(size_t data_len, unsigned int num, unsigned short szx) {
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return ((num+1) << (szx + 4)) < data_len;
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}
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/** Sets the More-bit in @p block_opt */
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static inline void
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coap_opt_block_set_m(coap_opt_t *block_opt, int m) {
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if (m)
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*(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) |= 0x08;
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else
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*(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) &= ~0x08;
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}
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/**
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* Initializes @p block from @p pdu. @p type must be either COAP_OPTION_BLOCK1
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* or COAP_OPTION_BLOCK2. When option @p type was found in @p pdu, @p block is
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* initialized with values from this option and the function returns the value
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* @c 1. Otherwise, @c 0 is returned.
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*
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* @param pdu The pdu to search for option @p type.
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* @param type The option to search for (must be COAP_OPTION_BLOCK1 or
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* COAP_OPTION_BLOCK2).
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* @param block The block structure to initilize.
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*
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* @return @c 1 on success, @c 0 otherwise.
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*/
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int coap_get_block(coap_pdu_t *pdu, unsigned short type, coap_block_t *block);
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/**
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* Writes a block option of type @p type to message @p pdu. If the requested
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* block size is too large to fit in @p pdu, it is reduced accordingly. An
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* exception is made for the final block when less space is required. The actual
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* length of the resource is specified in @p data_length.
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*
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* This function may change *block to reflect the values written to @p pdu. As
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* the function takes into consideration the remaining space @p pdu, no more
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* options should be added after coap_write_block_opt() has returned.
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*
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* @param block The block structure to use. On return, this object is
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* updated according to the values that have been written to
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* @p pdu.
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* @param type COAP_OPTION_BLOCK1 or COAP_OPTION_BLOCK2.
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* @param pdu The message where the block option should be written.
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* @param data_length The length of the actual data that will be added the @p
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* pdu by calling coap_add_block().
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*
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* @return @c 1 on success, or a negative value on error.
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*/
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int coap_write_block_opt(coap_block_t *block,
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unsigned short type,
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coap_pdu_t *pdu,
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size_t data_length);
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/**
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* Adds the @p block_num block of size 1 << (@p block_szx + 4) from source @p
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* data to @p pdu.
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*
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* @param pdu The message to add the block.
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* @param len The length of @p data.
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* @param data The source data to fill the block with.
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* @param block_num The actual block number.
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* @param block_szx Encoded size of block @p block_number.
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*
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* @return @c 1 on success, @c 0 otherwise.
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*/
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int coap_add_block(coap_pdu_t *pdu,
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unsigned int len,
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const unsigned char *data,
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unsigned int block_num,
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unsigned char block_szx);
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/**@}*/
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#endif /* _COAP_BLOCK_H_ */
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