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Implement patty_ax25_frame_encode_xid()

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Implement patty_ax25_frame_encode_xid() to encode a patty_ax25_params
object into a buffer to be used as an Information field
This commit is contained in:
XANTRONIX Development 2020-07-18 15:05:31 -04:00 • committed by XANTRONIX Industrial
parent 6911a59455
commit afbaeea95e
2 changed files with 108 additions and 0 deletions
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4
include/patty/ax25/frame.h
View file

@ -125,6 +125,10 @@ ssize_t patty_ax25_frame_encode(patty_ax25_frame *frame,
void *buf,
size_t len);
ssize_t patty_ax25_frame_encode_xid(patty_ax25_params *params,
void *buf,
size_t len);
ssize_t patty_ax25_frame_encode_reply_to(patty_ax25_frame *frame,
patty_ax25_frame *reply,
enum patty_ax25_frame_format format,

104
src/frame.c
View file

@ -518,6 +518,110 @@ error_toobig:
return -1;
}
static ssize_t encode_xid_param(void *data,
size_t offset,
enum patty_ax25_param_type type,
size_t bytes,
uint32_t value,
size_t len) {
uint8_t *buf = data;
size_t start = offset,
i;
if (offset + 2 + bytes > len || bytes > 4) {
goto error;
}
buf[offset++] = (uint8_t)type;
buf[offset++] = (uint8_t)bytes;
for (i=0; i<bytes; i++) {
uint8_t shift = (bytes-1-i) << 3;
buf[offset++] = (value & (0xff << shift)) >> shift;
}
return offset - start;
error:
errno = EIO;
return -1;
}
static inline size_t needbytes(uint32_t value) {
if (!(value & 0xffffff00)) return 1;
if (!(value & 0xffff0000)) return 2;
if (!(value & 0xff000000)) return 3;
return 4;
}
ssize_t patty_ax25_frame_encode_xid(patty_ax25_params *params,
void *data,
size_t len) {
size_t offset = 0;
ssize_t encoded;
struct {
uint8_t id;
size_t bytes;
uint32_t value;
} values[] = {
{ PATTY_AX25_PARAM_CLASSES, 2, params->classes },
{ PATTY_AX25_PARAM_HDLC, 3, params->hdlc },
{ PATTY_AX25_PARAM_INFO_TX, 0, params->info_tx },
{ PATTY_AX25_PARAM_INFO_RX, 0, params->info_rx },
{ PATTY_AX25_PARAM_WINDOW_TX, 1, params->window_tx },
{ PATTY_AX25_PARAM_WINDOW_RX, 1, params->window_rx },
{ PATTY_AX25_PARAM_ACK, 0, params->ack },
{ PATTY_AX25_PARAM_RETRY, 0, params->retry },
{ 0, 0 }
};
int i;
patty_ax25_frame_xid_group *group = (patty_ax25_frame_xid_group *)
((char *)data + offset);
memset(data, '\0', len);
group->format = PATTY_AX25_FRAME_XID_GROUP_ISO8885;
group->type = PATTY_AX25_FRAME_XID_GROUP_PARAMS;
offset += sizeof(*group);
for (i=0; values[i].id; i++) {
size_t bytes = values[i].bytes? values[i].bytes:
needbytes(values[i].value);
if (!(params->flags & (1 << values[i].id))) {
continue;
}
if ((encoded = encode_xid_param(data,
offset,
values[i].id,
bytes,
values[i].value,
len)) < 0) {
goto error_encode_xid_param;
} else {
offset += encoded;
}
}
group->len = htobe16(offset - sizeof(*group));
return offset;
error_encode_xid_param:
errno = EOVERFLOW;
return -1;
}
ssize_t patty_ax25_frame_encode_reply_to(patty_ax25_frame *frame,
patty_ax25_frame *reply,
enum patty_ax25_frame_format format,