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6lowpan fragmentation bugfix: the 6lowpan code had an unfortunate

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interaction with the behavior of the rdc layer. If the first packet of a
fragment transmission was lost, the remaining packets would get dropped
on reception. Moreover, the reception code contained a bug that
sometimes would cause fragments to be misidentified as fragments. Taken
together, these problems would result in a pathelogical network
breakdown if too many fragmented packets would occur simultaneously.
This commit is contained in:
Adam Dunkels 2013-07-28 22:32:09 +02:00
parent 7987a6dac7
commit 0aa448f190
2 changed files with 73 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
core/net/mac/nullrdc.c
View File

@ -119,10 +119,12 @@ static struct seqno received_seqnos[MAX_SEQNOS];
#endif /* NULLRDC_802154_AUTOACK || NULLRDC_802154_AUTOACK_HW */
/*---------------------------------------------------------------------------*/
static void
send_packet(mac_callback_t sent, void *ptr)
static int
send_one_packet(mac_callback_t sent, void *ptr)
{
int ret;
int last_sent_ok = 0;
packetbuf_set_addr(PACKETBUF_ADDR_SENDER, &rimeaddr_node_addr);
#if NULLRDC_802154_AUTOACK || NULLRDC_802154_AUTOACK_HW
packetbuf_set_attr(PACKETBUF_ATTR_MAC_ACK, 1);
@ -228,22 +230,49 @@ send_packet(mac_callback_t sent, void *ptr)
#endif /* ! NULLRDC_802154_AUTOACK */
}
if(ret == MAC_TX_OK) {
last_sent_ok = 1;
}
mac_call_sent_callback(sent, ptr, ret, 1);
return last_sent_ok;
}
/*---------------------------------------------------------------------------*/
static void
send_packet(mac_callback_t sent, void *ptr)
{
send_one_packet(sent, ptr);
}
/*---------------------------------------------------------------------------*/
static void
send_list(mac_callback_t sent, void *ptr, struct rdc_buf_list *buf_list)
{
while(buf_list != NULL) {
/* We backup the next pointer, as it may be nullified by
* mac_call_sent_callback() */
struct rdc_buf_list *next = buf_list->next;
int last_sent_ok;
queuebuf_to_packetbuf(buf_list->buf);
send_packet(sent, ptr);
buf_list = buf_list->next;
last_sent_ok = send_one_packet(sent, ptr);
/* If packet transmission was not successful, we should back off and let
* upper layers retransmit, rather than potentially sending out-of-order
* packet fragments. */
if(!last_sent_ok) {
return;
}
buf_list = next;
}
}
/*---------------------------------------------------------------------------*/
static void
packet_input(void)
{
int original_datalen;
uint8_t *original_dataptr;
original_datalen = packetbuf_datalen();
original_dataptr = packetbuf_dataptr();
#ifdef NETSTACK_DECRYPT
NETSTACK_DECRYPT();
#endif /* NETSTACK_DECRYPT */
@ -264,6 +293,8 @@ packet_input(void)
PRINTF("nullrdc: not for us\n");
#endif /* NULLRDC_ADDRESS_FILTER */
} else {
int duplicate = 0;
#if NULLRDC_802154_AUTOACK || NULLRDC_802154_AUTOACK_HW
/* Check for duplicate packet by comparing the sequence number
of the incoming packet with the last few ones we saw. */
@ -275,16 +306,18 @@ packet_input(void)
/* Drop the packet. */
PRINTF("nullrdc: drop duplicate link layer packet %u\n",
packetbuf_attr(PACKETBUF_ATTR_PACKET_ID));
return;
duplicate = 1;
}
}
for(i = MAX_SEQNOS - 1; i > 0; --i) {
memcpy(&received_seqnos[i], &received_seqnos[i - 1],
sizeof(struct seqno));
if(!duplicate) {
for(i = MAX_SEQNOS - 1; i > 0; --i) {
memcpy(&received_seqnos[i], &received_seqnos[i - 1],
sizeof(struct seqno));
}
received_seqnos[0].seqno = packetbuf_attr(PACKETBUF_ATTR_PACKET_ID);
rimeaddr_copy(&received_seqnos[0].sender,
packetbuf_addr(PACKETBUF_ADDR_SENDER));
}
received_seqnos[0].seqno = packetbuf_attr(PACKETBUF_ATTR_PACKET_ID);
rimeaddr_copy(&received_seqnos[0].sender,
packetbuf_addr(PACKETBUF_ADDR_SENDER));
#endif /* NULLRDC_802154_AUTOACK */
#if NULLRDC_SEND_802154_ACK
@ -304,7 +337,9 @@ packet_input(void)
}
}
#endif /* NULLRDC_SEND_ACK */
NETSTACK_MAC.input();
if(!duplicate) {
NETSTACK_MAC.input();
}
}
}
/*---------------------------------------------------------------------------*/

26
core/net/sicslowpan.c
View File

@ -1590,6 +1590,7 @@ input(void)
uint16_t frag_size = 0;
/* offset of the fragment in the IP packet */
uint8_t frag_offset = 0;
uint8_t is_fragment = 0;
#if SICSLOWPAN_CONF_FRAG
/* tag of the fragment */
uint16_t frag_tag = 0;
@ -1626,6 +1627,7 @@ input(void)
rime_hdr_len += SICSLOWPAN_FRAG1_HDR_LEN;
/* printf("frag1 %d %d\n", reass_tag, frag_tag);*/
first_fragment = 1;
is_fragment = 1;
break;
case SICSLOWPAN_DISPATCH_FRAGN:
/*
@ -1648,11 +1650,29 @@ input(void)
if(processed_ip_in_len + packetbuf_datalen() - rime_hdr_len >= frag_size) {
last_fragment = 1;
}
is_fragment = 1;
break;
default:
break;
}
/* We are currently reassembling a packet, but have just received the first
* fragment of another packet. We can either ignore it and hope to receive
* the rest of the under-reassembly packet fragments, or we can discard the
* previous packet altogether, and start reassembling the new packet.
*
* We discard the previous packet, and start reassembling the new packet.
* This lessens the negative impacts of too high SICSLOWPAN_REASS_MAXAGE.
*/
#define PRIORITIZE_NEW_PACKETS 1
#if PRIORITIZE_NEW_PACKETS
if(processed_ip_in_len > 0 && first_fragment
&& !rimeaddr_cmp(&frag_sender, packetbuf_addr(PACKETBUF_ADDR_SENDER))) {
sicslowpan_len = 0;
processed_ip_in_len = 0;
}
#endif /* PRIORITIZE_NEW_PACKETS */
if(processed_ip_in_len > 0) {
/* reassembly is ongoing */
/* printf("frag %d %d\n", reass_tag, frag_tag);*/
@ -1674,6 +1694,12 @@ input(void)
* start it if we received a fragment
*/
if((frag_size > 0) && (frag_size <= UIP_BUFSIZE)) {
/* We are currently not reassembling a packet, but have received a packet fragment
* that is not the first one. */
if(is_fragment && !first_fragment) {
return;
}
sicslowpan_len = frag_size;
reass_tag = frag_tag;
timer_set(&reass_timer, SICSLOWPAN_REASS_MAXAGE * CLOCK_SECOND / 16);