On Wed, Feb 07, 2024 at 11:40:40AM +0100, Stefano Brivio wrote:On Fri, 2 Feb 2024 15:11:33 +0100 Laurent Vivier <lvivier(a)redhat.com> wrote:Right. This is pretty much explicitly the IP protocol number, which is an 8-bit field in the IPv4 header.We can find the same function to compute the IPv4 header checksum in tcp.c and udp.c Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- ip.h | 14 ++++++++++++++ tcp.c | 23 ++--------------------- udp.c | 19 +------------------ 3 files changed, 17 insertions(+), 39 deletions(-) diff --git a/ip.h b/ip.h index b2e08bc049f3..ff7902c45a95 100644 --- a/ip.h +++ b/ip.h @@ -9,6 +9,8 @@ #include <netinet/ip.h> #include <netinet/ip6.h> +#include "checksum.h" + #define IN4_IS_ADDR_UNSPECIFIED(a) \ ((a)->s_addr == htonl_constant(INADDR_ANY)) #define IN4_IS_ADDR_BROADCAST(a) \ @@ -83,4 +85,16 @@ struct ipv6_opt_hdr { char *ipv6_l4hdr(const struct pool *p, int idx, size_t offset, uint8_t *proto, size_t *dlen); +static inline uint16_t ipv4_hdr_checksum(struct iphdr *iph, int proto)A function comment would be nice. A couple of doubts: - why is this an inline in ip.h, instead of a function in checksum.c? That would be more natural, I think - this would be the first Layer-4 protocol number passed as int: we use uint8_t elsewhere. Now, socket(2) and similar all take an int, but using uint8_t internally keeps large arrays such as tap4_l4 a bit smaller. The only value defined in Linux UAPI exceeding eight bits is IPPROTO_MPTCP, 262, because that's never on the wire (the TCP protocol number is used instead). And we won't meet that either.In practice, it doesn't matter what we use here, but still uint8_t would be consistent.-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson+{ + uint32_t sum = L2_BUF_IP4_PSUM(proto); + + sum += iph->tot_len; + sum += (iph->saddr >> 16) & 0xffff; + sum += iph->saddr & 0xffff; + sum += (iph->daddr >> 16) & 0xffff; + sum += iph->daddr & 0xffff; + + return ~csum_fold(sum); +} #endif /* IP_H */ diff --git a/tcp.c b/tcp.c index 4c9c5fb51c60..293ab12d8c21 100644 --- a/tcp.c +++ b/tcp.c @@ -934,23 +934,6 @@ static void tcp_sock_set_bufsize(const struct ctx *c, int s) trace("TCP: failed to set SO_SNDBUF to %i", v); } -/** - * tcp_update_check_ip4() - Update IPv4 with variable parts from stored one - * @buf: L2 packet buffer with final IPv4 header - */ -static void tcp_update_check_ip4(struct tcp4_l2_buf_t *buf) -{ - uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_TCP); - - sum += buf->iph.tot_len; - sum += (buf->iph.saddr >> 16) & 0xffff; - sum += buf->iph.saddr & 0xffff; - sum += (buf->iph.daddr >> 16) & 0xffff; - sum += buf->iph.daddr & 0xffff; - - buf->iph.check = (uint16_t)~csum_fold(sum); -} - /** * tcp_update_check_tcp4() - Update TCP checksum from stored one * @buf: L2 packet buffer with final IPv4 header @@ -1393,10 +1376,8 @@ do { \ b->iph.saddr = a4->s_addr; b->iph.daddr = c->ip4.addr_seen.s_addr; - if (check) - b->iph.check = *check; - else - tcp_update_check_ip4(b); + b->iph.check = check ? *check : + ipv4_hdr_checksum(&b->iph, IPPROTO_TCP); SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq); diff --git a/udp.c b/udp.c index d514c864ab5b..6f867df81c05 100644 --- a/udp.c +++ b/udp.c @@ -270,23 +270,6 @@ static void udp_invert_portmap(struct udp_port_fwd *fwd) } } -/** - * udp_update_check4() - Update checksum with variable parts from stored one - * @buf: L2 packet buffer with final IPv4 header - */ -static void udp_update_check4(struct udp4_l2_buf_t *buf) -{ - uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_UDP); - - sum += buf->iph.tot_len; - sum += (buf->iph.saddr >> 16) & 0xffff; - sum += buf->iph.saddr & 0xffff; - sum += (buf->iph.daddr >> 16) & 0xffff; - sum += buf->iph.daddr & 0xffff; - - buf->iph.check = (uint16_t)~csum_fold(sum); -} - /** * udp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses * @eth_d: Ethernet destination address, NULL if unchanged @@ -614,7 +597,7 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport, b->iph.saddr = b->s_in.sin_addr.s_addr; } - udp_update_check4(b); + b->iph.check = ipv4_hdr_checksum(&b->iph, IPPROTO_UDP); b->uh.source = b->s_in.sin_port; b->uh.dest = htons(dstport); b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));