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Added a safeguard to fragmentation reassembly: if there are additional bytes in the final fragment, we shave them off in the spirit of being 'liberal in what we accept'

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This commit is contained in:
Adam Dunkels 2011-09-05 14:26:48 +02:00
parent bfc314a037
commit f7a3a8476f
1 changed files with 21 additions and 2 deletions
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21
core/net/sicslowpan.c
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@ -1486,7 +1486,7 @@ input(void)
#if SICSLOWPAN_CONF_FRAG
/* tag of the fragment */
uint16_t frag_tag = 0;
uint8_t first_fragment = 0;
uint8_t first_fragment = 0, last_fragment = 0;
#endif /*SICSLOWPAN_CONF_FRAG*/
/* init */
@ -1532,6 +1532,15 @@ input(void)
PRINTFI("size %d, tag %d, offset %d)\n",
frag_size, frag_tag, frag_offset);
rime_hdr_len += SICSLOWPAN_FRAGN_HDR_LEN;
/* If this is the last fragment, we may shave off any extrenous
bytes at the end. We must be liberal in what we accept. */
PRINTFI("last_fragment?: processed_ip_len %d rime_payload_len %d frag_size %d\n",
processed_ip_len, packetbuf_datalen() - rime_hdr_len, frag_size);
if(processed_ip_len + packetbuf_datalen() - rime_hdr_len >= frag_size) {
last_fragment = 1;
}
break;
default:
break;
@ -1631,7 +1640,15 @@ input(void)
if(first_fragment != 0) {
processed_ip_len += uncomp_hdr_len;
}
/* For the last fragment, we are OK if there is extrenous bytes at
the end of the packet. */
if(last_fragment != 0) {
processed_ip_len = frag_size;
} else {
processed_ip_len += rime_payload_len;
}
PRINTF("processed_ip_len %d, rime_payload_len %d\n", processed_ip_len, rime_payload_len);
} else {
#endif /* SICSLOWPAN_CONF_FRAG */
sicslowpan_len = rime_payload_len + uncomp_hdr_len;
@ -1642,6 +1659,8 @@ input(void)
* If we have a full IP packet in sicslowpan_buf, deliver it to
* the IP stack
*/
PRINTF("sicslowpan_init processed_ip_len %d, sicslowpan_len %d\n",
processed_ip_len, sicslowpan_len);
if(processed_ip_len == 0 || (processed_ip_len == sicslowpan_len)) {
PRINTFI("sicslowpan input: IP packet ready (length %d)\n",
sicslowpan_len);