[PATCH v3 0/5] tcp: use csum_iov() in tcp_update_check_tcp[4|6]()
For vhost-user, we will need to spread TCP payload over several buffers. To re-use tcp_update_check_tcp[4|6](), provide an iovec rather than a pointer to a buffer. This series updates also csum_iov() and pcap_iov() to add an offset of bytes to skip in the iovec array. It's based on top of "tcp: Use tcp_payload_t rather than tcphdr" that is added in the series for convenience. v3 adds "udp: Update UDP checksum using an iovec array" that modifies csum_udp4() and csum_udp6() in the same way. Laurent Vivier (5): tcp: Use tcp_payload_t rather than tcphdr pcap: Add an offset argument in pcap_iov() checksum: Add an offset argument in csum_iov() tcp: Update TCP checksum using an iovec array udp: Update UDP checksum using an iovec array checksum.c | 46 +++++++++++----- checksum.h | 7 ++- pcap.c | 5 +- pcap.h | 2 +- tap.c | 14 ++++- tap.h | 2 +- tcp.c | 145 +++++++++++++++++++++++++++++++++++++------------ tcp_buf.c | 29 ---------- tcp_internal.h | 29 ++++++++++ udp.c | 17 ++++-- 10 files changed, 203 insertions(+), 93 deletions(-) -- 2.46.0
As tcp_update_check_tcp4() and tcp_update_check_tcp6() compute the
checksum using the TCP header and the TCP payload, it is clearer
to use a pointer to tcp_payload_t that includes tcphdr and payload
rather than a pointer to tcphdr (and guessing TCP header is
followed by the payload).
Move tcp_payload_t and tcp_flags_t to tcp_internal.h.
(They will be used also by vhost-user).
Signed-off-by: Laurent Vivier
The offset is passed directly to pcap_frame() and allows
any headers that are not part of the frame to
capture to be skipped.
Signed-off-by: Laurent Vivier
The offset allows any headers that are not part of the data
to checksum to be skipped.
Signed-off-by: Laurent Vivier
TCP header and payload are supposed to be in the same buffer,
and tcp_update_check_tcp4()/tcp_update_check_tcp6() compute
the checksum from the base address of the header using the
length of the IP payload.
In the future (for vhost-user) we need to dispatch the TCP header and
the TCP payload through several buffers. To be able to manage that, we
provide an iovec array that points to the data of the TCP frame.
We provide also an offset to be able to provide an array that contains
the TCP frame embedded in an lower level frame, and this offset points
to the TCP header inside the iovec array.
Signed-off-by: Laurent Vivier
On 26/09/2024 15:29, Laurent Vivier wrote:
TCP header and payload are supposed to be in the same buffer, and tcp_update_check_tcp4()/tcp_update_check_tcp6() compute the checksum from the base address of the header using the length of the IP payload.
In the future (for vhost-user) we need to dispatch the TCP header and the TCP payload through several buffers. To be able to manage that, we provide an iovec array that points to the data of the TCP frame. We provide also an offset to be able to provide an array that contains the TCP frame embedded in an lower level frame, and this offset points to the TCP header inside the iovec array.
Signed-off-by: Laurent Vivier
--- checksum.c | 1 - tcp.c | 127 +++++++++++++++++++++++++++++++++++++++++------------ 2 files changed, 99 insertions(+), 29 deletions(-) ... /** * tcp_update_check_tcp6() - Calculate TCP checksum for IPv6 - * @ip6h: IPv6 header - * @bp: TCP header followed by TCP payload - */ -static void tcp_update_check_tcp6(const struct ipv6hdr *ip6h, - struct tcp_payload_t *bp) + * @src: IPv6 source address + * @dst: IPv6 destination address + * @iov: Pointer to the array of IO vectors + * @iov_cnt: Length of the array + * @l4offset: IPv6 payload offset in the iovec array + */ +void tcp_update_check_tcp6(const struct in6_addr *src, + const struct in6_addr *dst, + const struct iovec *iov, int iov_cnt, + size_t l4offset) { - uint16_t l4len = ntohs(ip6h->payload_len); - uint32_t sum = proto_ipv6_header_psum(l4len, IPPROTO_TCP, - &ip6h->saddr, &ip6h->daddr); + size_t check_ofs; + __sum16 *check; + int check_idx; + uint32_t sum; + + sum = proto_ipv6_header_psum(iov_size(iov, iov_cnt) - l4offset, + IPPROTO_TCP, src, dst); - bp->th.check = 0; - bp->th.check = csum(bp, l4len, sum); + check_idx = iov_skip_bytes(iov, iov_cnt, + l4offset + offsetof(struct tcphdr, check), + &check_ofs); + + if (check_idx >= iov_cnt) + die("TCP6 buffer is too small"); + if (check_ofs + sizeof(*check) > iov[check_idx].iov_len) + die("TCP6 checksum field memory is not contiguous"); +
I'm going to resend, I forgot to update tcp_update_check_tcp6(). Laurent
As for tcp_update_check_tcp4()/tcp_update_check_tcp6(),
change csum_udp4() and csum_udp6() to use an iovec array.
Signed-off-by: Laurent Vivier
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Laurent Vivier