deac/osd-contiki
1
0
Fork 0
Code Issues Pull requests Releases Wiki Activity

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

Browse source 
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
Download patch file Download diff file Expand all files Collapse all files

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);