1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
#include <mpack.h>
#include <stdio.h>
// MIN() macro
#include <sys/param.h>
#include "i2ctcpv1.h"
int i2ctcp_read(i2ctcp_msg_t * target, const char * buf, size_t buf_sz) {
// at start of message
if (target->_rdata == 0) {
// NOTE: The entire start of a message needs to be readable from the buffer
// at this point. When target->addr can be read and target->length is past
// the end of the current buffer block, this function will crash and burn.
// This is a highly unlikely scenario, as i2ctcp_read is called for each
// chunk of a TCP frame, and frames (should) include only one puzzle bus
// message. The check here is kind of optional.
if (buf_sz < 4) return -1;
// mpack reader is used for the first buffer block, as it contains the data
// size info
mpack_reader_t reader;
mpack_reader_init_data(&reader, buf, buf_sz);
target->addr = mpack_expect_u16(&reader);
target->length = target->_rdata = mpack_expect_bin(&reader);
target->data = (char *) malloc(target->length);
// read remaining data in (header) packet
size_t to_read = mpack_reader_remaining(&reader, NULL);
mpack_read_bytes(&reader, target->data, to_read);
target->_rdata -= to_read;
} else {
// continue reading chunks of target->data until the amount of bytes
// specified in target->length
size_t to_read = MIN(buf_sz, target->_rdata);
char * data = target->data + target->length - target->_rdata;
memcpy(data, buf, to_read);
target->_rdata -= to_read;
}
// if rdata = 0, the message was completely read
return target->_rdata;
}
void i2ctcp_read_reset(i2ctcp_msg_t * target) {
target->_rdata = 0;
}
bool i2ctcp_write(const i2ctcp_msg_t * target, char ** buf, size_t * buf_sz) {
mpack_writer_t writer;
mpack_writer_init_growable(&writer, buf, buf_sz);
mpack_write_u16(&writer, target->addr);
mpack_write_bin(&writer, target->data, target->length);
// finish writing
return mpack_writer_destroy(&writer) == mpack_ok;
}
|