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ospf3: include pseudo-header in checksum calculation

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This commit is contained in:
Hannes Gredler
2023-10-13 08:23:15 +00:00
parent 868db84356
commit 626abb52da
1 changed files with 28 additions and 1 deletions
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29
code/lspgen/src/lspgen_packet.c
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@@ -177,6 +177,33 @@ calculate_cksum(uint8_t *buf, uint16_t len)
return ~_fold(_checksum(buf, len));
}
/*
* Calculate an ospf3 checksum including the pseudoheader as per
* https://www.rfc-editor.org/rfc/rfc2460#page-27
*
* Expects the IPv6 header at the beginning of buf and a correctly set packet length field.
*/
uint16_t
calculate_ospf3_cksum(uint8_t *buf, uint16_t len)
{
uint32_t cksum;
uint8_t protocol[4] = {0, 0, 0, 89} ; /* Protocol pseudoheader */
if (len < 40) {
return 0;
}
cksum = 0;
cksum += _checksum(buf+8, 16); /* source-ip */
cksum += _checksum(buf+24, 16); /* destination-ip */
cksum += _checksum(buf+4, 2); /* packet-length */
cksum += _checksum(protocol, 4); /* protocol */
cksum += _checksum(buf+40, len-40);
return ~_fold(cksum);
}
/*
* Calculate the size of the authentication data to be inserted.
* Helper for calculating when to start a new packet.
@@ -1117,8 +1144,8 @@ lspgen_serialize_ospf3_state(lsdb_attr_t *attr, lsdb_packet_t *packet, uint16_t
switch (packet->prev_attr_cp[0]) {
case OSPF_MSG_LSUPDATE:
write_be_uint(buf0->data+40+2, 2, buf0->idx - 40); /* Packet length */
write_be_uint(buf0->data+40+12, 2, calculate_cksum(buf0->data+40, buf0->idx-40)); /* Checksum */
write_be_uint(buf0->data+4, 2, buf0->idx - 40); /* Payload length */
write_le_uint(buf0->data+40+12, 2, calculate_ospf3_cksum(buf0->data, buf0->idx)); /* Checksum */
break;
default:
break;