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internet checksum: use signed long for accumulator

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We used to use 'unsigned long' for the accumulating variable when calculating
internet checksums. However, 'signed long' is more in accordance with RFC 1071
and will allow us to share the same back end for folding, once we implement
incremental updating of internet checksums.

Ref #4555
This commit is contained in:
Martin Stein 2022-07-16 11:04:56 +02:00 committed by Christian Helmuth
parent 6b3ed6c75b
commit d69e89f5cb
1 changed files with 2 additions and 2 deletions
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4
repos/os/src/lib/net/internet_checksum.cc
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@ -31,7 +31,7 @@ struct Packed_uint8
static uint16_t checksum_of_raw_data(Packed_uint16 const *data_ptr,
size_t data_sz,
addr_t sum)
signed long sum)
{
/* add up bytes in pairs */
for (; data_sz > 1; data_sz -= sizeof(Packed_uint16)) {
@ -77,7 +77,7 @@ uint16_t Net::internet_checksum_pseudo_ip(Packed_uint16 const *data_ptr,
* | 4 bytes | 4 bytes | 1 byte | 1 byte | 2 bytes |
* --------------------------------------------------------------
*/
addr_t sum = host_to_big_endian((uint16_t)ip_prot) + ip_data_sz_be;
signed long sum { host_to_big_endian((uint16_t)ip_prot) + ip_data_sz_be };
for (size_t i = 0; i < Ipv4_packet::ADDR_LEN; i += 2)
sum += *(uint16_t*)&ip_src.addr[i] + *(uint16_t*)&ip_dst.addr[i];