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Start using network coding over the radio link

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This commit is contained in:
Jeremy Lakeman 2013-11-25 15:06:05 +10:30
parent d67dfa22b2
commit 76267904d9
7 changed files with 274 additions and 207 deletions
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1
commandline.c
View File

@ -980,7 +980,6 @@ int app_mdp_ping(const struct cli_parsed *parsed, struct cli_context *context)
int r = mdp_send(mdp_sockfd, &mdp_header, payload, sizeof(payload)); int r = mdp_send(mdp_sockfd, &mdp_header, payload, sizeof(payload));
if (r<0) if (r<0)
WHY_perror("mdp_send"); WHY_perror("mdp_send");
else
tx_count++; tx_count++;
} }

4
fakeradio.c
View File

@ -193,14 +193,14 @@ int write_bytes(struct radio_state *s)
wrote=8; wrote=8;
if (s->last_char_ms) if (s->last_char_ms)
wrote = write(s->fd, s->rxbuffer, wrote); wrote = write(s->fd, s->rxbuffer, wrote);
if (wrote>0){ if (wrote<=0)
abort();
log_time(); log_time();
fprintf(stderr, "Wrote to %s\n", s->name); fprintf(stderr, "Wrote to %s\n", s->name);
dump(NULL, s->rxbuffer, wrote); dump(NULL, s->rxbuffer, wrote);
if (wrote < s->rxb_len) if (wrote < s->rxb_len)
bcopy(&s->rxbuffer[wrote], s->rxbuffer, s->rxb_len - wrote); bcopy(&s->rxbuffer[wrote], s->rxbuffer, s->rxb_len - wrote);
s->rxb_len -= wrote; s->rxb_len -= wrote;
}
return wrote; return wrote;
} }

187
network_coding.c
View File

@ -26,21 +26,25 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#include <stdarg.h> #include <stdarg.h>
#include "network_coding.h" #include "network_coding.h"
#include "dataformats.h" #include "dataformats.h"
#include "log.h"
#include "mem.h"
#define FLAG_NEW 1 #define FLAG_NEW 1
struct nc_packet{ struct nc_packet{
uint8_t sequence; uint8_t sequence;
uint32_t combination; uint32_t combination;
size_t len;
uint8_t flags; uint8_t flags;
uint8_t *payload; uint8_t *payload;
}; };
struct nc_half { struct nc_half {
uint8_t last_ack;
// Define the size parameters of the network coding data structures // Define the size parameters of the network coding data structures
uint8_t window_size; // limited to the number of bits we can fit in a uint32_t uint8_t window_size; // limited to the number of bits we can fit in a uint32_t
uint8_t window_start; // sequence of first datagram in sending window uint8_t window_start; // sequence of first datagram in sending window
uint8_t unseen; // sequence of first unseen packet
size_t datagram_size; // number of bytes in each fixed sized unit size_t datagram_size; // number of bytes in each fixed sized unit
uint8_t deliver_next; // sequence of next packet that should be delivered uint8_t deliver_next; // sequence of next packet that should be delivered
// dynamically sized array of pointers to packet buffers // dynamically sized array of pointers to packet buffers
@ -51,6 +55,7 @@ struct nc_half {
// At the receiver, this should be 2*maximum window size to allow for older packets we can't decode yet // At the receiver, this should be 2*maximum window size to allow for older packets we can't decode yet
uint8_t max_queue_size; uint8_t max_queue_size;
uint8_t queue_size; // # of packets currently in the array uint8_t queue_size; // # of packets currently in the array
int count_new; // number of un-sent degrees of freedom
}; };
struct nc{ struct nc{
@ -115,24 +120,24 @@ int nc_tx_has_room(struct nc *n)
int nc_tx_enqueue_datagram(struct nc *n, unsigned char *d, size_t len) int nc_tx_enqueue_datagram(struct nc *n, unsigned char *d, size_t len)
{ {
if (len!=n->tx.datagram_size){ if (len==0 || len>n->tx.datagram_size)
fprintf(stderr, "Invalid length %zd (%zd)\n", len, n->tx.datagram_size); return WHYF("Invalid length %zd (%zd)", len, n->tx.datagram_size);
return -1;
}
if (!nc_tx_has_room(n)) if (!nc_tx_has_room(n))
return 1; return 1;
// Add datagram to queue // Add datagram to queue
uint8_t seq = n->tx.window_start + n->tx.queue_size; uint8_t seq = n->tx.window_start + n->tx.queue_size;
int index = seq & (n->tx.max_queue_size -1); int index = seq & (n->tx.max_queue_size -1);
if (n->tx.packets[index].payload){ if (n->tx.packets[index].payload)
fprintf(stderr, "Attempted to replace TX payload %d (%d) with %d without freeing it first\n",index,n->tx.packets[index].sequence, seq); FATALF("Attempted to replace TX payload %d (%d) with %d without freeing it first",index,n->tx.packets[index].sequence, seq);
exit(-1); n->tx.packets[index].payload = emalloc(len);
} if (!n->tx.packets[index].payload)
n->tx.packets[index].payload = malloc(len); return 1;
n->tx.packets[index].sequence = seq; n->tx.packets[index].sequence = seq;
n->tx.packets[index].combination = 0x80000000; n->tx.packets[index].combination = 0x80000000;
n->tx.packets[index].flags = FLAG_NEW; n->tx.packets[index].flags = FLAG_NEW;
n->tx.count_new++;
n->tx.packets[index].len = len;
bcopy(d, n->tx.packets[index].payload, len); bcopy(d, n->tx.packets[index].payload, len);
n->tx.queue_size++; n->tx.queue_size++;
return 0; return 0;
@ -147,23 +152,6 @@ static int _compare_uint8(uint8_t one, uint8_t two)
return -1; return -1;
} }
static int _nc_get_ack(struct nc_half *n, uint8_t *first_unseen, uint8_t *window_size)
{
uint8_t seq;
for (seq = n->window_start; ;seq++){
int index = seq & (n->max_queue_size -1);
if (n->packets[index].sequence != seq || !n->packets[index].payload)
break;
}
*window_size = 32 - (seq - n->deliver_next);
if (*window_size > n->max_queue_size)
*window_size = n->max_queue_size;
*first_unseen = seq;
return 0;
}
static int _nc_ack(struct nc_half *n, uint8_t first_unseen, uint8_t window_size) static int _nc_ack(struct nc_half *n, uint8_t first_unseen, uint8_t window_size)
{ {
if (window_size>n->max_queue_size) if (window_size>n->max_queue_size)
@ -200,12 +188,13 @@ static uint32_t _combine_masks(const struct nc_packet *src, const struct nc_pack
return dst->combination ^ mask; return dst->combination ^ mask;
} }
static void _combine_packets(const struct nc_packet *src, struct nc_packet *dst, size_t datagram_size) static void _combine_packets(const struct nc_packet *src, struct nc_packet *dst)
{ {
// TODO verify that this combination mask is set correctly. if (dst->len < src->len)
FATALF("Expected the destination buffer to be at least %zu", src->len);
dst->combination = _combine_masks(src, dst); dst->combination = _combine_masks(src, dst);
size_t i; size_t i;
for(i=0;i<datagram_size;i++) for(i=0; i < src->len; i++)
dst->payload[i]^=src->payload[i]; dst->payload[i]^=src->payload[i];
} }
@ -234,20 +223,36 @@ static int _nc_tx_combine_random_payloads(struct nc_half *n, struct nc_packet *p
if (n->packets[index].flags & FLAG_NEW){ if (n->packets[index].flags & FLAG_NEW){
if (added_new) if (added_new)
continue; continue;
_combine_packets(&n->packets[index], packet, n->datagram_size); _combine_packets(&n->packets[index], packet);
added_new = 1; added_new = 1;
n->count_new --;
n->packets[index].flags =0; n->packets[index].flags =0;
continue; continue;
} }
if (combination&1) if (combination&1)
_combine_packets(&n->packets[index], packet, n->datagram_size); _combine_packets(&n->packets[index], packet);
combination>>=1; combination>>=1;
} }
return 0; return 0;
} }
int nc_tx_packet_urgency(struct nc *n)
{
// new data? send asap
if (n->tx.count_new)
return URGENCY_ASAP;
// ack required? send soon
if (n->rx.unseen != n->rx.last_ack)
return URGENCY_ASAP;
// no new data at either end? don't care
if (!n->tx.queue_size && !n->rx.queue_size)
return URGENCY_IDLE;
// send soon-ish
return URGENCY_SOON;
}
// construct a packet and return the payload size // construct a packet and return the payload size
int nc_tx_produce_packet(struct nc *n, uint8_t *datagram, uint32_t buffer_size) int nc_tx_produce_packet(struct nc *n, uint8_t *datagram, uint32_t buffer_size)
{ {
@ -255,32 +260,57 @@ int nc_tx_produce_packet(struct nc *n, uint8_t *datagram, uint32_t buffer_size)
if (buffer_size < n->tx.datagram_size+NC_HEADER_LEN) if (buffer_size < n->tx.datagram_size+NC_HEADER_LEN)
return -1; return -1;
if (_nc_get_ack(&n->rx, &datagram[0], &datagram[1])) uint8_t window_size = 32 - (n->rx.unseen - n->rx.deliver_next);
return -1; if (window_size > n->rx.max_queue_size)
window_size = n->rx.max_queue_size;
if (!n->tx.queue_size){ datagram[0]=n->rx.unseen;
// No data to send, just send an ack datagram[1]=window_size;
// TODO don't ack too often n->rx.last_ack = n->rx.unseen;
return 2; size_t len=2;
}
if (n->tx.queue_size){
// Produce linear combination // Produce linear combination
struct nc_packet packet={ struct nc_packet packet={
.sequence = n->tx.window_start, .sequence = n->tx.window_start,
.combination = 0, .combination = 0,
.payload = &datagram[NC_HEADER_LEN], .payload = &datagram[NC_HEADER_LEN],
.len = buffer_size - NC_HEADER_LEN,
}; };
bzero(packet.payload, packet.len);
if (_nc_tx_combine_random_payloads(&n->tx, &packet)) if (_nc_tx_combine_random_payloads(&n->tx, &packet))
return -1; return -1;
// TODO assert actual_combination? (should never be zero) // TODO assert actual_combination? (should never be zero)
// Write out bitmap of actual combinations involved // Write out bitmap of actual combinations involved
datagram[2] = packet.sequence; datagram[2] = packet.sequence;
write_uint32(&datagram[3], packet.combination); write_uint32(&datagram[3], packet.combination);
return NC_HEADER_LEN+n->tx.datagram_size; len = packet.len + NC_HEADER_LEN;
// truncate zero bytes from the end
while(!datagram[len-1])
len--;
}
return len;
} }
static int _nc_dump_half(struct nc_half *n)
{
DEBUGF(" window start; %d", n->window_start);
DEBUGF(" queue size; %d", n->queue_size);
DEBUGF(" max queue size; %d", n->max_queue_size);
int i;
for (i=0;i<n->max_queue_size;i++){
if (!n->packets[i].payload)
continue;
DEBUGF(" %02d: 0x%02x, 0x%08x",
i, n->packets[i].sequence, n->packets[i].combination);
}
return 0;
}
// note, the incoming packet buffer must be allocated from the heap
// this function will take responsibility for releasing it
static int _nc_rx_combine_packet(struct nc_half *n, struct nc_packet *packet) static int _nc_rx_combine_packet(struct nc_half *n, struct nc_packet *packet)
{ {
int i; int i;
@ -296,12 +326,12 @@ static int _nc_rx_combine_packet(struct nc_half *n, struct nc_packet *packet)
// rx packet doesn't add any new information // rx packet doesn't add any new information
if (new_mask==0){ if (new_mask==0){
free(packet->payload);
return 1; return 1;
} }
if (new_mask < packet->combination){ if (new_mask < packet->combination)
_combine_packets(&n->packets[i], packet, n->datagram_size); _combine_packets(&n->packets[i], packet);
}
} }
// the new packet must contain new information that will cause a new packet to be seen. // the new packet must contain new information that will cause a new packet to be seen.
@ -311,15 +341,12 @@ static int _nc_rx_combine_packet(struct nc_half *n, struct nc_packet *packet)
int index = packet->sequence & (n->max_queue_size -1); int index = packet->sequence & (n->max_queue_size -1);
if (n->packets[index].payload){ if (n->packets[index].payload){
fprintf(stderr, "Attempted to replace RX payload %d (%d) with %d without freeing it first\n",index,n->packets[index].sequence, packet->sequence); _nc_dump_half(n);
exit(-1); free(packet->payload);
FATALF("Attempted to replace RX payload %d (%d) with %d without freeing it first",index,n->packets[index].sequence, packet->sequence);
return 1;
} }
// try to duplicate the payload first, we don't want to reduce existing packets if this fails.
unsigned char *dup_payload = malloc(n->datagram_size);
if (!dup_payload)
return -1;
bcopy(packet->payload, dup_payload, n->datagram_size);
// reduce other stored packets // reduce other stored packets
for (i=0;i<n->max_queue_size;i++){ for (i=0;i<n->max_queue_size;i++){
if (!n->packets[i].payload || _compare_uint8(n->packets[i].sequence, packet->sequence) > 0) if (!n->packets[i].payload || _compare_uint8(n->packets[i].sequence, packet->sequence) > 0)
@ -328,15 +355,23 @@ static int _nc_rx_combine_packet(struct nc_half *n, struct nc_packet *packet)
// n->packets[i].sequence, n->packets[i].combination, // n->packets[i].sequence, n->packets[i].combination,
// packet->sequence, packet->combination); // packet->sequence, packet->combination);
uint32_t new_mask = _combine_masks(packet, &n->packets[i]); uint32_t new_mask = _combine_masks(packet, &n->packets[i]);
if (new_mask < n->packets[i].combination){ if (new_mask < n->packets[i].combination)
_combine_packets(packet, &n->packets[i], n->datagram_size); _combine_packets(packet, &n->packets[i]);
}
} }
// add the packet to our incoming list // add the packet to our incoming list
n->packets[index]=*packet; n->packets[index]=*packet;
n->packets[index].payload = dup_payload;
n->queue_size++; n->queue_size++;
// find the first missing seq
uint8_t seq;
for (seq = n->window_start; ;seq++){
int index = seq & (n->max_queue_size -1);
if (n->packets[index].sequence != seq || !n->packets[index].payload)
break;
}
n->unseen = seq;
return 0; return 0;
} }
@ -357,28 +392,27 @@ static void _nc_rx_advance_window(struct nc_half *n, uint8_t new_window_start)
} }
} }
int nc_rx_packet(struct nc *n, uint8_t *payload, size_t len) int nc_rx_packet(struct nc *n, const uint8_t *payload, size_t len)
{ {
if (len!=2 && len != NC_HEADER_LEN+n->rx.datagram_size){ if (len>=2){
fprintf(stderr, "len=%zd\n",len); _nc_ack(&n->tx, payload[0], payload[1]);
return -1;
} }
_nc_ack(&n->tx, payload[0], payload[1]); if (len<NC_HEADER_LEN)
return 1;
if (len < NC_HEADER_LEN+n->rx.datagram_size)
return 0;
uint8_t new_window_start = payload[2]; uint8_t new_window_start = payload[2];
// assume incoming packets can be padded with zero's up to n->rx.datagram_size
struct nc_packet packet={ struct nc_packet packet={
.sequence = new_window_start, .sequence = new_window_start,
.combination = read_uint32(&payload[3]), .combination = read_uint32(&payload[3]),
.payload = &payload[NC_HEADER_LEN], .payload = emalloc_zero(n->rx.datagram_size),
.len = n->rx.datagram_size,
}; };
bcopy(&payload[NC_HEADER_LEN], packet.payload, len - NC_HEADER_LEN);
int r = _nc_rx_combine_packet(&n->rx, &packet); int r = _nc_rx_combine_packet(&n->rx, &packet);
_nc_rx_advance_window(&n->rx, new_window_start); _nc_rx_advance_window(&n->rx, new_window_start);
return r; return r;
@ -414,31 +448,12 @@ int nc_rx_next_delivered(struct nc *n, uint8_t *payload, int buffer_size)
queue is full. queue is full.
4. nc_tx_ack_dof() works, rejects bad input, and correctly releases buffers. 4. nc_tx_ack_dof() works, rejects bad input, and correctly releases buffers.
5. nc_tx_random_linear_combination() works, rejects bad input, and produces valid 5. nc_tx_random_linear_combination() works, rejects bad input, and produces valid
linear combinations of the enqueued datagrams, and never produces all zeroes. linear combinations of the enqueuedumd datagrams, and never produces all zeroes.
6. nc_rx_linear_combination() works, rejects bad input 6. nc_rx_linear_combination() works, rejects bad input
7. nc_rx_linear_combination() rejects when RX queue full, when combination starts 7. nc_rx_linear_combination() rejects when RX queue full, when combination starts
before current window. before current window.
*/ */
static int _nc_dump_half(struct nc_half *n)
{
fprintf(stderr, " window start; %d\n", n->window_start);
fprintf(stderr, " queue size; %d\n", n->queue_size);
fprintf(stderr, " max queue size; %d\n", n->max_queue_size);
int i;
for (i=0;i<n->max_queue_size;i++){
if (!n->packets[i].payload)
continue;
fprintf(stderr, " %02d: 0x%02x, 0x%08x ",
i, n->packets[i].sequence, n->packets[i].combination);
int j;
for(j=0;j<32;j++)
fprintf(stderr, "%0d",(n->packets[i].combination>>(31-j))&1);
fprintf(stderr, "\n");
}
return 0;
}
static void _nc_dump(struct nc *n) static void _nc_dump(struct nc *n)
{ {
fprintf(stderr, "TX\n"); fprintf(stderr, "TX\n");

15
network_coding.h
View File

@ -3,4 +3,19 @@
#define NC_HEADER_LEN 7 #define NC_HEADER_LEN 7
#define URGENCY_ASAP 0
#define URGENCY_SOON 1
#define URGENCY_IDLE 2
struct nc;
struct nc *nc_new(uint8_t max_window_size, uint8_t datagram_size);
int nc_free(struct nc *n);
int nc_tx_has_room(struct nc *n);
int nc_tx_enqueue_datagram(struct nc *n, unsigned char *d, size_t len);
int nc_tx_produce_packet(struct nc *n, uint8_t *datagram, uint32_t buffer_size);
int nc_rx_packet(struct nc *n, const uint8_t *payload, size_t len);
int nc_rx_next_delivered(struct nc *n, uint8_t *payload, int buffer_size);
int nc_tx_packet_urgency(struct nc *n);
#endif #endif

197
radio_link.c
View File

@ -49,6 +49,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#include "overlay_buffer.h" #include "overlay_buffer.h"
#include "golay.h" #include "golay.h"
#include "radio_link.h" #include "radio_link.h"
#include "network_coding.h"
#define MAVLINK_MSG_ID_RADIO 166 #define MAVLINK_MSG_ID_RADIO 166
#define MAVLINK_MSG_ID_DATASTREAM 67 #define MAVLINK_MSG_ID_DATASTREAM 67
@ -73,17 +74,18 @@ struct mavlink_RADIO_v10 {
*/ */
#define PAYLOAD_FRAGMENT 0xFF
#define FEC_LENGTH 32 #define FEC_LENGTH 32
#define FEC_MAX_BYTES 223 #define FEC_MAX_BYTES 223
#define RADIO_HEADER_LENGTH 6 #define RADIO_HEADER_LENGTH 6
#define RADIO_USED_HEADER_LENGTH 4 #define RADIO_ACTUAL_HEADER_LENGTH 4
#define RADIO_CRC_LENGTH 2 #define RADIO_CRC_LENGTH 2
#define LINK_PAYLOAD_MTU (LINK_MTU - FEC_LENGTH - RADIO_HEADER_LENGTH - RADIO_CRC_LENGTH) #define LINK_NC_MTU (LINK_MTU - FEC_LENGTH - RADIO_ACTUAL_HEADER_LENGTH)
#define LINK_PAYLOAD_MTU (LINK_NC_MTU - NC_HEADER_LEN)
struct radio_link_state{ struct radio_link_state{
// next seq for transmission struct nc *network_coding;
int tx_seq;
// small buffer for parsing incoming bytes from the serial interface, // small buffer for parsing incoming bytes from the serial interface,
// looking for recoverable link layer packets // looking for recoverable link layer packets
@ -94,8 +96,6 @@ struct radio_link_state{
// decoded length of next link layer packet // decoded length of next link layer packet
// including all header and footer bytes // including all header and footer bytes
int payload_length; int payload_length;
// last rx seq for reassembly
int seq;
// offset within payload that we have found a valid looking header // offset within payload that we have found a valid looking header
int payload_start; int payload_start;
// offset after payload_start for incoming bytes // offset after payload_start for incoming bytes
@ -152,6 +152,7 @@ int decode_rs_8(data_t *data, int *eras_pos, int no_eras, int pad);
int radio_link_free(struct overlay_interface *interface) int radio_link_free(struct overlay_interface *interface)
{ {
if (interface->radio_link_state){ if (interface->radio_link_state){
nc_free(interface->radio_link_state->network_coding);
free(interface->radio_link_state); free(interface->radio_link_state);
interface->radio_link_state=NULL; interface->radio_link_state=NULL;
} }
@ -161,6 +162,7 @@ int radio_link_free(struct overlay_interface *interface)
int radio_link_init(struct overlay_interface *interface) int radio_link_init(struct overlay_interface *interface)
{ {
interface->radio_link_state = emalloc_zero(sizeof(struct radio_link_state)); interface->radio_link_state = emalloc_zero(sizeof(struct radio_link_state));
interface->radio_link_state->network_coding = nc_new(16, LINK_PAYLOAD_MTU);
return 0; return 0;
} }
@ -171,48 +173,35 @@ void radio_link_state_html(struct strbuf *b, struct overlay_interface *interface
strbuf_sprintf(b, "Remote RSSI: %ddB<br>", state->remote_rssi); strbuf_sprintf(b, "Remote RSSI: %ddB<br>", state->remote_rssi);
} }
// write a new link layer packet to interface->txbuffer static int encode_next_packet(struct radio_link_state *link_state)
// consuming more bytes from the next interface->tx_packet if required
static int radio_link_encode_packet(struct radio_link_state *link_state)
{ {
// if we have nothing interesting left to send, don't create a packet at all while (link_state->tx_packet && nc_tx_has_room(link_state->network_coding)){
if (!link_state->tx_packet) // queue one packet
return 0; uint8_t next_packet[LINK_PAYLOAD_MTU];
bzero(next_packet, sizeof(next_packet));
ob_checkpoint(link_state->tx_packet);
int count = ob_remaining(link_state->tx_packet); int count = ob_remaining(link_state->tx_packet);
int startP = (ob_position(link_state->tx_packet) == 0); if (count > LINK_PAYLOAD_MTU -1){
int endP = 1; count = LINK_PAYLOAD_MTU -1;
if (count > LINK_PAYLOAD_MTU){ next_packet[0]=PAYLOAD_FRAGMENT;
count = LINK_PAYLOAD_MTU; }else
endP = 0; next_packet[0]=count;
ob_get_bytes(link_state->tx_packet, &next_packet[1], count);
if (nc_tx_enqueue_datagram(link_state->network_coding, next_packet, LINK_PAYLOAD_MTU)==0){
if (config.debug.radio_link)
DEBUGF("Enqueued fragment len %d", count+1);
}else{
ob_rewind(link_state->tx_packet);
break;
} }
if (!ob_remaining(link_state->tx_packet)){
link_state->txbuffer[0]=0xfe; // mavlink v1.0 magic header
// we need to add FEC_LENGTH for FEC, but the length field doesn't include the expected headers or CRC
int len = count + FEC_LENGTH - RADIO_CRC_LENGTH;
link_state->txbuffer[1]=len; // mavlink payload length
link_state->txbuffer[2]=(len & 0xF);
link_state->txbuffer[3]=0;
// add golay encoding so that decoding the actual length is more reliable
golay_encode(&link_state->txbuffer[1]);
link_state->txbuffer[4]=(link_state->tx_seq++) & 0x3f;
if (startP) link_state->txbuffer[4]|=0x40;
if (endP) link_state->txbuffer[4]|=0x80;
link_state->txbuffer[5]=MAVLINK_MSG_ID_DATASTREAM;
ob_get_bytes(link_state->tx_packet, &link_state->txbuffer[6], count);
encode_rs_8(&link_state->txbuffer[4], &link_state->txbuffer[6+count], FEC_MAX_BYTES - (count+2));
link_state->tx_bytes=len + RADIO_CRC_LENGTH + RADIO_HEADER_LENGTH;
if (endP){
ob_free(link_state->tx_packet); ob_free(link_state->tx_packet);
link_state->tx_packet=NULL; link_state->tx_packet=NULL;
overlay_queue_schedule_next(gettime_ms()); overlay_queue_schedule_next(gettime_ms());
} }
}
return 0; return 0;
} }
@ -240,6 +229,41 @@ int radio_link_queue_packet(struct overlay_interface *interface, struct overlay_
return 0; return 0;
} }
static int send_link_packet(struct overlay_interface *interface)
{
struct radio_link_state *link_state = interface->radio_link_state;
int data_length = nc_tx_produce_packet(link_state->network_coding,
&link_state->txbuffer[RADIO_ACTUAL_HEADER_LENGTH], LINK_NC_MTU);
// if we have nothing interesting to send, don't create a packet at all
if (data_length <=0)
return 0;
link_state->txbuffer[0]=0xfe; // mavlink v1.0 magic header
// the current firmware assumes that the whole packet contains 6 bytes of header and 2 bytes of crc
// that are not counted in the length.
int whole_packet = data_length + FEC_LENGTH + RADIO_ACTUAL_HEADER_LENGTH;
int radio_length = whole_packet - RADIO_HEADER_LENGTH - RADIO_CRC_LENGTH;
link_state->txbuffer[1]=radio_length; // mavlink payload length
link_state->txbuffer[2]=(radio_length & 0xF);
link_state->txbuffer[3]=0;
// add golay encoding so that decoding the actual length is more reliable
golay_encode(&link_state->txbuffer[1]);
encode_rs_8(&link_state->txbuffer[RADIO_ACTUAL_HEADER_LENGTH],
&link_state->txbuffer[RADIO_ACTUAL_HEADER_LENGTH + data_length],
FEC_MAX_BYTES - data_length);
link_state->tx_bytes=whole_packet;
if (config.debug.radio_link)
DEBUGF("Produced packet len %d", whole_packet);
return 0;
}
static int build_heartbeat(struct radio_link_state *link_state) static int build_heartbeat(struct radio_link_state *link_state)
{ {
int count=9; int count=9;
@ -280,6 +304,9 @@ int radio_link_tx(struct overlay_interface *interface)
while(1){ while(1){
// encode more data if we have a packet waiting, and have space
encode_next_packet(link_state);
if (link_state->tx_bytes){ if (link_state->tx_bytes){
if (link_state->next_tx_allowed > now){ if (link_state->next_tx_allowed > now){
interface->alarm.alarm = link_state->next_tx_allowed; interface->alarm.alarm = link_state->next_tx_allowed;
@ -318,14 +345,25 @@ int radio_link_tx(struct overlay_interface *interface)
if (link_state->remaining_space < LINK_MTU + HEARTBEAT_SIZE) if (link_state->remaining_space < LINK_MTU + HEARTBEAT_SIZE)
link_state->next_heartbeat = now; link_state->next_heartbeat = now;
if (!link_state->tx_packet){ int urgency = nc_tx_packet_urgency(link_state->network_coding);
// finished current packet, wait for more. time_ms_t delay = 500;
switch (urgency){
case URGENCY_ASAP:
delay=20;
break;
case URGENCY_SOON:
delay=200;
break;
}
if (link_state->last_packet + delay > now){
interface->alarm.alarm = link_state->last_packet + delay;
if (interface->alarm.alarm > next_tick)
interface->alarm.alarm = next_tick; interface->alarm.alarm = next_tick;
break; break;
} }
// encode another packet fragment send_link_packet(interface);
radio_link_encode_packet(link_state);
link_state->last_packet = now; link_state->last_packet = now;
} }
@ -369,7 +407,7 @@ static int parse_heartbeat(struct radio_link_state *state, const unsigned char *
} }
static int radio_link_parse(struct overlay_interface *interface, struct radio_link_state *state, static int radio_link_parse(struct overlay_interface *interface, struct radio_link_state *state,
size_t packet_length, uint8_t *payload, int *backtrack) int packet_length, unsigned char *payload, int *backtrack)
{ {
*backtrack=0; *backtrack=0;
if (packet_length==17){ if (packet_length==17){
@ -385,57 +423,58 @@ static int radio_link_parse(struct overlay_interface *interface, struct radio_li
return 0; return 0;
} }
size_t data_bytes = packet_length - (RADIO_USED_HEADER_LENGTH + FEC_LENGTH); payload += RADIO_ACTUAL_HEADER_LENGTH;
packet_length -= RADIO_ACTUAL_HEADER_LENGTH + FEC_LENGTH;
int errors=decode_rs_8(&payload[4], NULL, 0, FEC_MAX_BYTES - data_bytes); int errors=decode_rs_8(payload, NULL, 0, FEC_MAX_BYTES - packet_length);
if (errors==-1){ if (errors==-1){
if (config.debug.radio_link) if (config.debug.radio_link)
DEBUGF("Reed-Solomon error correction failed"); DEBUGF("Reed-Solomon error correction failed");
return 0; return 0;
} }
*backtrack=errors; *backtrack=errors;
data_bytes -= 2;
int seq=payload[4]&0x3f;
if (config.debug.radio_link){ int rx = nc_rx_packet(state->network_coding, payload, packet_length);
DEBUGF("Received RS protected message, len: %zd, errors: %d, seq: %d, flags:%s%s",
data_bytes,
errors,
seq,
payload[4]&0x40?" start":"",
payload[4]&0x80?" end":"");
}
if (seq != ((state->seq+1)&0x3f)){
// reject partial packet if we missed a sequence number
if (config.debug.radio_link) if (config.debug.radio_link)
DEBUGF("Rejecting packet, sequence jumped from %d to %d", state->seq, seq); DEBUGF("RX returned %d", rx);
state->packet_length=sizeof(state->dst)+1;
}
if (payload[4]&0x40){ if (rx==0){
// start a new packet // we received an interesting packet, can we deliver anything?
state->packet_length=0; uint8_t fragment[LINK_PAYLOAD_MTU];
} while(1){
int len=nc_rx_next_delivered(state->network_coding, fragment, sizeof(fragment));
if (len<=0)
break;
int fragment_len=fragment[0];
if (fragment_len == PAYLOAD_FRAGMENT)
fragment_len = len -1;
state->seq=payload[4]&0x3f; // is this fragment length invalid?
if (state->packet_length + data_bytes > sizeof(state->dst)){ if (fragment_len > len -1)
if (config.debug.radio_link) state->packet_length=sizeof(state->dst);
DEBUG("Fragmented packet is too long or a previous piece was missed - discarding");
state->packet_length=sizeof(state->dst)+1;
return 1;
}
bcopy(&payload[RADIO_HEADER_LENGTH], &state->dst[state->packet_length], data_bytes); // can we fit this fragment into our payload buffer?
state->packet_length+=data_bytes; if (fragment_len+state->packet_length < sizeof(state->dst)){
bcopy(&fragment[1], &state->dst[state->packet_length], fragment_len);
state->packet_length+=fragment_len;
if (payload[4]&0x80) { // is this the last fragment?
if (fragment[0] != PAYLOAD_FRAGMENT){
if (config.debug.radio_link) if (config.debug.radio_link)
DEBUGF("PDU Complete (length=%d)",state->packet_length); DEBUGF("PDU Complete (length=%d)",state->packet_length);
packetOkOverlay(interface, state->dst, state->packet_length, -1, NULL, 0); if (packetOkOverlay(interface, state->dst, state->packet_length, -1, NULL, 0)){
state->packet_length=sizeof(state->dst)+1; dump("Invalid packet?", state->dst, state->packet_length);
} }
}
}
// reset the buffer for the next packet
if (fragment[0] != PAYLOAD_FRAGMENT)
state->packet_length=0;
}
}
return 1; return 1;
} }

1
tests/rhizomeprotocol
View File

@ -702,7 +702,6 @@ start_radio_instance() {
set debug.rhizome_tx on \ set debug.rhizome_tx on \
set debug.rhizome_rx on \ set debug.rhizome_rx on \
set debug.throttling on \ set debug.throttling on \
set debug.radio_link on \
set rhizome.advertise.interval 5000 \ set rhizome.advertise.interval 5000 \
set rhizome.rhizome_mdp_block_size 375 \ set rhizome.rhizome_mdp_block_size 375 \
set log.console.level debug \ set log.console.level debug \

6
tests/routing
View File

@ -296,10 +296,10 @@ setup_simulate_extender() {
foreach_instance +A +B start_routing_instance foreach_instance +A +B start_routing_instance
} }
test_simulate_extender() { test_simulate_extender() {
wait_until path_exists +A +B wait_until --timeout=20 path_exists +A +B
wait_until path_exists +B +A wait_until --timeout=20 path_exists +B +A
set_instance +A set_instance +A
executeOk_servald mdp ping --timeout=3 $SIDB 1 executeOk_servald mdp ping --interval=0.500 --timeout=10 $SIDB 20
tfw_cat --stdout --stderr tfw_cat --stdout --stderr
} }
teardown_simulate_extender() { teardown_simulate_extender() {