From 0dacea92d26c31d453c58de2e99c178fee554166 Mon Sep 17 00:00:00 2001 From: Ed Swierk Date: Thu, 16 Nov 2017 06:06:06 -0800 Subject: 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 Signed-off-by: Jason Wang --- hw/net/e1000.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'hw/net/e1000.c') diff --git a/hw/net/e1000.c b/hw/net/e1000.c index c0abee4f7e..05a00cba31 100644 --- a/hw/net/e1000.c +++ b/hw/net/e1000.c @@ -503,7 +503,7 @@ putsum(uint8_t *data, uint32_t n, uint32_t sloc, uint32_t css, uint32_t cse) n = cse + 1; if (sloc < n-1) { sum = net_checksum_add(n-css, data+css); - stw_be_p(data + sloc, net_checksum_finish(sum)); + stw_be_p(data + sloc, net_checksum_finish_nozero(sum)); } } -- cgit v1.2.3