On Wed, Apr 02, 2025 at 07:23:36PM +0200, Laurent Vivier wrote:Use packet_base() and extract headers using IOV_PEEK_HEADER() rather than packet_get(). Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- tcp.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/tcp.c b/tcp.c index 790714a08793..a9c04551d9d6 100644 --- a/tcp.c +++ b/tcp.c @@ -1643,14 +1643,19 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn, for (i = idx, iov_i = 0; i < (int)p->count; i++) { uint32_t seq, seq_offset, ack_seq; const struct tcphdr *th; - char *data; + struct iov_tail data; + unsigned int count; + struct tcphdr thc; size_t off; - th = packet_get(p, i, 0, sizeof(*th), &len); + if (!packet_base(p, i, &data)) + return -1; + + th = IOV_PEEK_HEADER(&data, thc); if (!th) return -1; - len += sizeof(*th); + len = iov_tail_size(&data); off = th->doff * 4UL; if (off < sizeof(*th) || off > len) return -1; @@ -1661,9 +1666,7 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn, } len -= off; - data = packet_get(p, i, off, len, NULL); - if (!data) - continue; + data.off = off;You can use iov_drop() rather than reaching into the internals of iov_tail here, no?seq = ntohl(th->seq); if (SEQ_LT(seq, conn->seq_from_tap) && len <= 1) { @@ -1737,10 +1740,11 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn, continue; } - tcp_iov[iov_i].iov_base = data + seq_offset; - tcp_iov[iov_i].iov_len = len - seq_offset; - seq_from_tap += tcp_iov[iov_i].iov_len; - iov_i++; + count = iov_copy(&tcp_iov[iov_i], UIO_MAXIOV - iov_i, + &data.iov[0], data.cnt, data.off + seq_offset, + len - seq_offset);Here again it matters if you run out of space in the destination iov, and I don't think you have a check above which prevents it.+ seq_from_tap += iov_size(&tcp_iov[iov_i], count);We already called iov_size() on &data above. We should be able to derive the total length here from that minus headers, without having to recount the IOV, no?+ iov_i += count; if (keep == i) keep = -1;-- David Gibson (he or they) | 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