From 8f8c4d27eb2e023fd80986d8fdf8a68b37e3877e Mon Sep 17 00:00:00 2001 From: Laurent Vivier Date: Wed, 18 Sep 2024 15:13:28 +0200 Subject: tcp: Allow checksum to be disabled We can need not to set TCP checksum. Add a parameter to tcp_fill_headers4() and tcp_fill_headers6() to disable it. Signed-off-by: Laurent Vivier Reviewed-by: David Gibson Signed-off-by: Stefano Brivio --- tcp.c | 52 +++++++++++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 21 deletions(-) (limited to 'tcp.c') diff --git a/tcp.c b/tcp.c index 787df63..1962fcc 100644 --- a/tcp.c +++ b/tcp.c @@ -899,13 +899,14 @@ static void tcp_fill_header(struct tcphdr *th, /** * tcp_fill_headers4() - Fill 802.3, IPv4, TCP headers in pre-cooked buffers - * @conn: Connection pointer - * @taph: tap backend specific header - * @iph: Pointer to IPv4 header - * @th: Pointer to TCP header - * @dlen: TCP payload length - * @check: Checksum, if already known - * @seq: Sequence number for this segment + * @conn: Connection pointer + * @taph: tap backend specific header + * @iph: Pointer to IPv4 header + * @th: Pointer to TCP header + * @dlen: TCP payload length + * @check: Checksum, if already known + * @seq: Sequence number for this segment + * @no_tcp_csum: Do not set TCP checksum * * Return: The IPv4 payload length, host order */ @@ -913,7 +914,7 @@ static size_t tcp_fill_headers4(const struct tcp_tap_conn *conn, struct tap_hdr *taph, struct iphdr *iph, struct tcphdr *th, size_t dlen, const uint16_t *check, - uint32_t seq) + uint32_t seq, bool no_tcp_csum) { const struct flowside *tapside = TAPFLOW(conn); const struct in_addr *src4 = inany_v4(&tapside->oaddr); @@ -932,7 +933,10 @@ static size_t tcp_fill_headers4(const struct tcp_tap_conn *conn, tcp_fill_header(th, conn, seq); - tcp_update_check_tcp4(iph, th); + if (no_tcp_csum) + th->check = 0; + else + tcp_update_check_tcp4(iph, th); tap_hdr_update(taph, l3len + sizeof(struct ethhdr)); @@ -941,20 +945,21 @@ static size_t tcp_fill_headers4(const struct tcp_tap_conn *conn, /** * tcp_fill_headers6() - Fill 802.3, IPv6, TCP headers in pre-cooked buffers - * @conn: Connection pointer - * @taph: tap backend specific header - * @ip6h: Pointer to IPv6 header - * @th: Pointer to TCP header - * @dlen: TCP payload length - * @check: Checksum, if already known - * @seq: Sequence number for this segment + * @conn: Connection pointer + * @taph: tap backend specific header + * @ip6h: Pointer to IPv6 header + * @th: Pointer to TCP header + * @dlen: TCP payload length + * @check: Checksum, if already known + * @seq: Sequence number for this segment + * @no_tcp_csum: Do not set TCP checksum * * Return: The IPv6 payload length, host order */ static size_t tcp_fill_headers6(const struct tcp_tap_conn *conn, struct tap_hdr *taph, struct ipv6hdr *ip6h, struct tcphdr *th, - size_t dlen, uint32_t seq) + size_t dlen, uint32_t seq, bool no_tcp_csum) { const struct flowside *tapside = TAPFLOW(conn); size_t l4len = dlen + sizeof(*th); @@ -973,7 +978,10 @@ static size_t tcp_fill_headers6(const struct tcp_tap_conn *conn, tcp_fill_header(th, conn, seq); - tcp_update_check_tcp6(ip6h, th); + if (no_tcp_csum) + th->check = 0; + else + tcp_update_check_tcp6(ip6h, th); tap_hdr_update(taph, l4len + sizeof(*ip6h) + sizeof(struct ethhdr)); @@ -987,12 +995,14 @@ static size_t tcp_fill_headers6(const struct tcp_tap_conn *conn, * @dlen: TCP payload length * @check: Checksum, if already known * @seq: Sequence number for this segment + * @no_tcp_csum: Do not set TCP checksum * * Return: IP payload length, host order */ size_t tcp_l2_buf_fill_headers(const struct tcp_tap_conn *conn, struct iovec *iov, size_t dlen, - const uint16_t *check, uint32_t seq) + const uint16_t *check, uint32_t seq, + bool no_tcp_csum) { const struct flowside *tapside = TAPFLOW(conn); const struct in_addr *a4 = inany_v4(&tapside->oaddr); @@ -1001,13 +1011,13 @@ size_t tcp_l2_buf_fill_headers(const struct tcp_tap_conn *conn, return tcp_fill_headers4(conn, iov[TCP_IOV_TAP].iov_base, iov[TCP_IOV_IP].iov_base, iov[TCP_IOV_PAYLOAD].iov_base, dlen, - check, seq); + check, seq, no_tcp_csum); } return tcp_fill_headers6(conn, iov[TCP_IOV_TAP].iov_base, iov[TCP_IOV_IP].iov_base, iov[TCP_IOV_PAYLOAD].iov_base, dlen, - seq); + seq, no_tcp_csum); } /** -- cgit v1.2.3