1 /* block.c -- block transfer
3 * Copyright (C) 2010--2012 Olaf Bergmann <bergmann@tzi.org>
5 * This file is part of the CoAP library libcoap. Please see
6 * README for terms of use.
9 #include "include/coap/config.h"
11 #if defined(HAVE_ASSERT_H) && !defined(assert)
16 /* On Arduino the abort function, needed for assert, is defined in std lib */
20 #include "include/coap/debug.h"
21 #include "include/coap/block.h"
23 #define min(a,b) ((a) < (b) ? (a) : (b))
27 coap_opt_block_num(const coap_opt_t *block_opt) {
31 len = coap_opt_length(block_opt);
38 num = coap_decode_var_bytes(COAP_OPT_VALUE(block_opt),
39 COAP_OPT_LENGTH(block_opt) - 1);
42 return (num << 4) | ((*COAP_OPT_BLOCK_LAST(block_opt) & 0xF0) >> 4);
46 coap_get_block(coap_pdu_t *pdu, unsigned short type, coap_block_t *block) {
47 coap_opt_iterator_t opt_iter;
51 memset(block, 0, sizeof(coap_block_t));
53 if (pdu && (option = coap_check_option(pdu, type, &opt_iter)) != NULL) {
54 block->szx = COAP_OPT_BLOCK_SZX(option);
55 if (COAP_OPT_BLOCK_MORE(option))
57 block->num = coap_opt_block_num(option);
65 coap_write_block_opt(coap_block_t *block, unsigned short type,
66 coap_pdu_t *pdu, size_t data_length) {
67 size_t start, want, avail;
73 if (type != COAP_OPTION_BLOCK2) {
74 warn("coap_write_block_opt: skipped unknown option\n");
78 start = block->num << (block->szx + 4);
79 if (data_length <= start) {
80 debug("illegal block requested\n");
84 avail = pdu->max_size - pdu->length - 4;
85 want = 1 << (block->szx + 4);
87 /* check if entire block fits in message */
89 block->m = want < data_length - start;
91 /* Sender has requested a block that is larger than the remaining
92 * space in pdu. This is ok if the remaining data fits into the pdu
93 * anyway. The block size needs to be adjusted only if there is more
94 * data left that cannot be delivered in this message. */
96 if (data_length - start <= avail) {
98 /* it's the final block and everything fits in the message */
104 /* we need to decrease the block size */
105 if (avail < 16) { /* bad luck, this is the smallest block size */
106 debug("not enough space, even the smallest block does not fit");
109 debug("decrease block size for %d to %d\n", avail, coap_fls(avail) - 5);
111 block->szx = coap_fls(avail) - 5;
113 block->num <<= szx - block->szx;
117 /* to re-encode the block option */
118 coap_add_option(pdu, type,
119 coap_encode_var_bytes(buf, ((block->num << 4) | (block->m << 3) | block->szx)), buf);
125 coap_add_block(coap_pdu_t *pdu, unsigned int len, const unsigned char *data,
126 unsigned int block_num, unsigned char block_szx) {
128 start = block_num << (block_szx + 4);
133 return coap_add_data(pdu,
134 min(len - start, (unsigned int)(1 << (block_szx + 4))),
137 #endif /* WITHOUT_BLOCK */