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block.h
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126 lines (109 loc) · 4.35 KB
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/* block.h -- block transfer
*
* Copyright (C) 2010--2012 Olaf Bergmann <bergmann@tzi.org>
*
* This file is part of the CoAP library libcoap. Please see
* README for terms of use.
*/
#ifndef _COAP_BLOCK_H_
#define _COAP_BLOCK_H_
#include "option.h"
#include "encode.h"
#include "pdu.h"
/**
* @defgroup block Block Transfer
* @{
*/
/**
* Structure of Block options.
*/
typedef struct {
unsigned int num:20; /**< block number */
unsigned int m:1; /**< 1 if more blocks follow, 0 otherwise */
unsigned int szx:3; /**< block size */
} coap_block_t;
/** Returns the value of the least significant byte of a Block option @p opt. */
#define COAP_OPT_BLOCK_LAST(opt) ( COAP_OPT_VALUE(opt) + (COAP_OPT_LENGTH(opt) - 1) )
/** Returns the value of the More-bit of a Block option @p opt. */
#define COAP_OPT_BLOCK_MORE(opt) ( *COAP_OPT_BLOCK_LAST(opt) & 0x08 )
/** Returns the value of the SZX-field of a Block option @p opt. */
#define COAP_OPT_BLOCK_SZX(opt) ( *COAP_OPT_BLOCK_LAST(opt) & 0x07 )
/** Implementation of COAP_OPT_BLOCK_NUM */
static inline unsigned int
_coap_block_num_impl(const coap_opt_t *block_opt) {
unsigned int num = 0;
if (COAP_OPT_LENGTH(block_opt) > 1)
num = coap_decode_var_bytes(COAP_OPT_VALUE(block_opt),
COAP_OPT_LENGTH(block_opt) - 1);
return (num << 4) | ((*COAP_OPT_BLOCK_LAST(block_opt) & 0xF0) >> 4);
}
/** Returns the value of field @c num in the given block option @p Block. */
#define COAP_OPT_BLOCK_NUM(Block) _coap_block_num_impl(Block)
/**
* Checks if more than @p num blocks are required to deliver @p data_len
* bytes of data for a block size of 1 << (@p szx + 4).
*/
static inline int
coap_more_blocks(size_t data_len, unsigned int num, unsigned short szx) {
return ((num+1) << (szx + 4)) < data_len;
}
/** Sets the More-bit in @p block_opt */
static inline void
coap_opt_block_set_m(coap_opt_t *block_opt, int m) {
if (m)
*(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) |= 0x08;
else
*(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) &= ~0x08;
}
/**
* Initializes @p block from @p pdu. @p type must be either COAP_OPTION_BLOCK1
* or COAP_OPTION_BLOCK2. When option @p type was found in @p pdu, @p block
* is initialized with values from this option and the function returns the
* value @c 1. Otherwise, @c 0 is returned.
*
* @param pdu The pdu to search for option @p type.
* @param type The option to search for (must be COAP_OPTION_BLOCK1 or
* COAP_OPTION_BLOCK2)
* @param block The block structure to initilize.
* @return @c 1 on success, @c 0 otherwise.
*/
int coap_get_block(coap_pdu_t *pdu, unsigned short type, coap_block_t *block);
/**
* Writes a block option of type @p type to message @p pdu. If the
* requested block size is too large to fit in @p pdu, it is reduced
* accordingly. An exception is made for the final block when less
* space is required. The actual length of the resource is specified
* in @p data_length.
*
* This function may change *block to reflect the values written to
* @p pdu. As the function takes into consideration the remaining space
* @p pdu, no more options should be added after coap_write_block_opt()
* has returned.
*
* @param block The block structure to use. On return, this object
* is updated according to the values that have been
* written to @p pdu.
* @param type COAP_OPTION_BLOCK1 or COAP_OPTION_BLOCK2
* @param pdu The message where the block option should be
* written.
* @param data_length The length of the actual data that will be added
* the @p pdu by calling coap_add_block().
* @return @c 1 on success, or a negative value on error.
*/
int coap_write_block_opt(coap_block_t *block, unsigned short type,
coap_pdu_t *pdu, size_t data_length);
/**
* Adds the @p block_num block of size 1 << (@p block_szx + 4) from
* source @p data to @p pdu.
*
* @param pdu The message to add the block
* @param len The length of @p data.
* @param data The source data to fill the block with
* @param block_num The actual block number
* @param block_szx Encoded size of block @p block_number
* @return @c 1 on success, @c 0 otherwise.
*/
int coap_add_block(coap_pdu_t *pdu, unsigned int len, const unsigned char *data,
unsigned int block_num, unsigned char block_szx);
/**@}*/
#endif /* _COAP_BLOCK_H_ */