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net: ipv4: fix icmp checksum calculation

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If ICMP packets do not fit in 1 net_pkt fragment the checksum
will be calculated incorrectly.

The problem shows up when using ping with the -s option to
create large ping requests. Eventhough the ping command does
accept the reply without complaining, Wireshark warns that
the icmp checksum is incorrect.

Signed-off-by: Erwin Rol <erwin@erwinrol.com>
This commit is contained in:
Erwin Rol 2017-06-28 23:14:45 +02:00 • committed by Jukka Rissanen
commit 6e80eb46c8
1 changed files with 2 additions and 6 deletions
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8
subsys/net/ip/utils.c
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@ -446,7 +446,7 @@ static inline u16_t calc_chksum_pkt(u16_t sum, struct net_pkt *pkt,
u16_t net_calc_chksum(struct net_pkt *pkt, u8_t proto)
{
u16_t upper_layer_len;
u16_t sum;
u16_t sum = 0;
switch (net_pkt_family(pkt)) {
#if defined(CONFIG_NET_IPV4)
@ -456,11 +456,7 @@ u16_t net_calc_chksum(struct net_pkt *pkt, u8_t proto)
net_pkt_ipv6_ext_len(pkt) -
net_pkt_ip_hdr_len(pkt);
if (proto == IPPROTO_ICMP) {
return htons(calc_chksum(0, net_pkt_ip_data(pkt) +
net_pkt_ip_hdr_len(pkt),
upper_layer_len));
} else {
if (proto != IPPROTO_ICMP) {
sum = calc_chksum(upper_layer_len + proto,
(u8_t *)&NET_IPV4_HDR(pkt)->src,
2 * sizeof(struct in_addr));