diff options
| author | Ed Swierk <eswierk@skyportsystems.com> | 2017-11-16 06:06:06 -0800 |
|---|---|---|
| committer | Jason Wang <jasowang@redhat.com> | 2017-11-20 11:08:00 +0800 |
| commit | 0dacea92d26c31d453c58de2e99c178fee554166 (patch) | |
| tree | 5b8fd0c05385e02a586fbc136808821e603ea14f /include/net | |
| parent | ebc2327f0793deed845e2f7aeddf43b367c5c71c (diff) | |
net: Transmit zero UDP checksum as 0xFFFF
The checksum algorithm used by IPv4, TCP and UDP allows a zero value
to be represented by either 0x0000 and 0xFFFF. But per RFC 768, a zero
UDP checksum must be transmitted as 0xFFFF because 0x0000 is a special
value meaning no checksum.
Substitute 0xFFFF whenever a checksum is computed as zero when
modifying a UDP datagram header. Doing this on IPv4 and TCP checksums
is unnecessary but legal. Add a wrapper for net_checksum_finish() that
makes the substitution.
(We can't just change net_checksum_finish(), as that function is also
used by receivers to verify checksums, and in that case the expected
value is always 0x0000.)
Signed-off-by: Ed Swierk <eswierk@skyportsystems.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/checksum.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/net/checksum.h b/include/net/checksum.h index 7df472c2fe..05a0d273fe 100644 --- a/include/net/checksum.h +++ b/include/net/checksum.h @@ -34,6 +34,12 @@ net_checksum_add(int len, uint8_t *buf) } static inline uint16_t +net_checksum_finish_nozero(uint32_t sum) +{ + return net_checksum_finish(sum) ?: 0xFFFF; +} + +static inline uint16_t net_raw_checksum(uint8_t *data, int length) { return net_checksum_finish(net_checksum_add(length, data)); |