[PATCH 6/6] udp: Clean up UDP checksum generation for inbound IPv6 packets

Currently we open code the calculation of the UDP checksum, which involves temporarily mangling the IPv6 header to match the UDP checksum pseudo-header. It also assumes that the payload is contiguous with the headers, which is true for now, but we want to change in future. We already have a helper which correcly calculates UDP over IPv6 checksums, which doesn't require temporarily modifying the headers and which handles a non-contiguous payload, so use it. It turns out we were already initializing the IPv6 version, nexthdr and hop_limit fields, even though we overwrote them for each packet here, so we can just leave those in place now. Signed-off-by: David Gibson --- udp.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/udp.c b/udp.c index a0080b1a..ee1481f9 100644 --- a/udp.c +++ b/udp.c @@ -676,13 +676,7 @@ static size_t udp_update_hdr6(const struct ctx *c, struct udp6_l2_buf_t *b, b->uh.source = htons(srcport); b->uh.dest = htons(dstport); b->uh.len = b->ip6h.payload_len; - - b->ip6h.hop_limit = IPPROTO_UDP; - b->ip6h.version = b->ip6h.nexthdr = b->uh.check = 0; - b->uh.check = csum(&b->ip6h, ip_len, 0); - b->ip6h.version = 6; - b->ip6h.nexthdr = IPPROTO_UDP; - b->ip6h.hop_limit = 255; + csum_udp6(&b->uh, src, dst, b->data, datalen); return tap_iov_len(c, &b->taph, ip_len); } -- 2.44.0