1 /* block.h -- block transfer
3 * Copyright (C) 2010--2012,2014 Olaf Bergmann <bergmann@tzi.org>
5 * This file is part of the CoAP library libcoap. Please see
6 * README for terms of use.
10 #define _COAP_BLOCK_H_
21 * @defgroup block Block Transfer
25 #ifndef COAP_MAX_BLOCK_SZX
27 * The largest value for the SZX component in a Block option. Note
28 * that 1 << (COAP_MAX_BLOCK_SZX + 4) should not exceed
31 #define COAP_MAX_BLOCK_SZX 4
32 #endif /* COAP_MAX_BLOCK_SZX */
34 #if (COAP_MAX_PDU_SIZE - 6) < (1 << (COAP_MAX_BLOCK_SZX + 4))
35 #error "COAP_MAX_BLOCK_SZX too large"
39 * Structure of Block options.
42 unsigned int num:20; /**< block number */
43 unsigned int m:1; /**< 1 if more blocks follow, 0 otherwise */
44 unsigned int szx:3; /**< block size */
48 * Returns the value of the least significant byte of a Block option @p opt.
49 * For zero-length options (i.e. num == m == szx == 0), COAP_OPT_BLOCK_LAST
52 #define COAP_OPT_BLOCK_LAST(opt) \
53 (COAP_OPT_LENGTH(opt) ? (COAP_OPT_VALUE(opt) + (COAP_OPT_LENGTH(opt)-1)) : 0)
55 /** Returns the value of the More-bit of a Block option @p opt. */
56 #define COAP_OPT_BLOCK_MORE(opt) \
57 (COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x08) : 0)
59 /** Returns the value of the SZX-field of a Block option @p opt. */
60 #define COAP_OPT_BLOCK_SZX(opt) \
61 (COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x07) : 0)
64 * Returns the value of field @c num in the given block option @p
67 unsigned int coap_opt_block_num(const coap_opt_t *block_opt);
70 * Checks if more than @p num blocks are required to deliver @p data_len
71 * bytes of data for a block size of 1 << (@p szx + 4).
74 coap_more_blocks(size_t data_len, unsigned int num, unsigned short szx) {
75 return ((num+1) << (szx + 4)) < data_len;
78 /** Sets the More-bit in @p block_opt */
80 coap_opt_block_set_m(coap_opt_t *block_opt, int m) {
82 *(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) |= 0x08;
84 *(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) &= ~0x08;
88 * Initializes @p block from @p pdu. @p type must be either COAP_OPTION_BLOCK1
89 * or COAP_OPTION_BLOCK2. When option @p type was found in @p pdu, @p block
90 * is initialized with values from this option and the function returns the
91 * value @c 1. Otherwise, @c 0 is returned.
93 * @param pdu The pdu to search for option @p type.
94 * @param type The option to search for (must be COAP_OPTION_BLOCK1 or
96 * @param block The block structure to initilize.
97 * @return @c 1 on success, @c 0 otherwise.
99 int coap_get_block(coap_pdu_t *pdu, unsigned short type, coap_block_t *block);
102 * Writes a block option of type @p type to message @p pdu. If the
103 * requested block size is too large to fit in @p pdu, it is reduced
104 * accordingly. An exception is made for the final block when less
105 * space is required. The actual length of the resource is specified
108 * This function may change *block to reflect the values written to
109 * @p pdu. As the function takes into consideration the remaining space
110 * @p pdu, no more options should be added after coap_write_block_opt()
113 * @param block The block structure to use. On return, this object
114 * is updated according to the values that have been
116 * @param type COAP_OPTION_BLOCK1 or COAP_OPTION_BLOCK2
117 * @param pdu The message where the block option should be
119 * @param data_length The length of the actual data that will be added
120 * the @p pdu by calling coap_add_block().
121 * @return @c 1 on success, or a negative value on error.
123 int coap_write_block_opt(coap_block_t *block, unsigned short type,
124 coap_pdu_t *pdu, size_t data_length);
127 * Adds the @p block_num block of size 1 << (@p block_szx + 4) from
128 * source @p data to @p pdu.
130 * @param pdu The message to add the block
131 * @param len The length of @p data.
132 * @param data The source data to fill the block with
133 * @param block_num The actual block number
134 * @param block_szx Encoded size of block @p block_number
135 * @return @c 1 on success, @c 0 otherwise.
137 int coap_add_block(coap_pdu_t *pdu, unsigned int len, const unsigned char *data,
138 unsigned int block_num, unsigned char block_szx);
145 #endif /* _COAP_BLOCK_H_ */