From 955dd3251c9e9b0a1469015748e4600f68e8de0a Mon Sep 17 00:00:00 2001 From: David Gibson Date: Tue, 22 Aug 2023 15:29:57 +1000 Subject: tcp, udp: Don't pre-fill IPv4 destination address in headers Because packets sent on the tap interface will always be going to the guest/namespace, we more-or-less know what address they'll be going to. So we pre-fill this destination address in our header buffers for IPv4. We can't do the same for IPv6 because we could need either the global or link-local address for the guest. In future we're going to want more flexibility for the destination address, so this pre-filling will get in the way. Change the flow so we always fill in the IPv4 destination address for each packet, rather than prefilling it from proto_update_l2_buf(). In fact for TCP we already redundantly filled the destination for each packet anyway. Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- udp.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) (limited to 'udp.c') diff --git a/udp.c b/udp.c index 6bb515a..f4ed660 100644 --- a/udp.c +++ b/udp.c @@ -276,10 +276,8 @@ static void udp_update_check4(struct udp4_l2_buf_t *buf) * udp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses * @eth_d: Ethernet destination address, NULL if unchanged * @eth_s: Ethernet source address, NULL if unchanged - * @ip_da: Pointer to IPv4 destination address, NULL if unchanged */ -void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s, - const struct in_addr *ip_da) +void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s) { int i; @@ -289,10 +287,6 @@ void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s, tap_update_mac(&b4->taph, eth_d, eth_s); tap_update_mac(&b6->taph, eth_d, eth_s); - - if (ip_da) { - b4->iph.daddr = ip_da->s_addr; - } } } @@ -578,6 +572,7 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport, ip_len = udp4_l2_mh_sock[n].msg_len + sizeof(b->iph) + sizeof(b->uh); b->iph.tot_len = htons(ip_len); + b->iph.daddr = c->ip4.addr_seen.s_addr; src_port = ntohs(b->s_in.sin_port); -- cgit v1.2.3