On Sat, 17 Feb 2024 16:07:25 +0100 Laurent Vivier <lvivier(a)redhat.com> wrote:Replace the macro SET_TCP_HEADER_COMMON_V4_V6() by a new function tcp_fill_header(). Move IPv4 and IPv6 code from tcp_l2_buf_fill_headers() to tcp_fill_ipv4_header() and tcp_fill_ipv6_header() Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- Notes: v3: - add to sub-series part 1 v2: - extract header filling functions from "tcp: extract buffer management from tcp_send_flag()" - rename them tcp_fill_flag_header()/tcp_fill_ipv4_header(), tcp_fill_ipv6_header() - use upside-down Christmas tree arguments order - replace (void *) by (struct tcphdr *) tcp.c | 154 +++++++++++++++++++++++++++++++++++++++------------------- 1 file changed, 104 insertions(+), 50 deletions(-) diff --git a/tcp.c b/tcp.c index aa03c20712f6..bc57a4f6e611 100644 --- a/tcp.c +++ b/tcp.c @@ -1324,6 +1324,108 @@ void tcp_defer_handler(struct ctx *c) tcp_l2_data_buf_flush(c); } +/** + * tcp_fill_header() - Fill the TCP header fields for a given TCP segment. + * + * @th: Pointer to the TCP header structure + * @conn: Pointer to the TCP connection structure + * @seq: Sequence number + */ +static void tcp_fill_header(struct tcphdr *th, + const struct tcp_tap_conn *conn, uint32_t seq) +{ + th->source = htons(conn->fport); + th->dest = htons(conn->eport); + th->seq = htonl(seq); + th->ack_seq = htonl(conn->seq_ack_to_tap); + if (conn->events & ESTABLISHED) { + th->window = htons(conn->wnd_to_tap); + } else { + unsigned wnd = conn->wnd_to_tap << conn->ws_to_tap; + + th->window = htons(MIN(wnd, USHRT_MAX)); + } +} + +/** + * tcp_fill_ipv4_header() - Fill 802.3, IPv4, TCP headers in pre-cooked buffers + * @c: Execution context + * @conn: Connection pointer + * @iph: Pointer to IPv4 header, immediately followed by a TCP header + * @plen: Payload length (including TCP header options) + * @check: Checksum, if already known + * @seq: Sequence number for this segment + * + * Return: IP frame length including L2 headers, host order + */ +static size_t tcp_fill_ipv4_header(const struct ctx *c, + const struct tcp_tap_conn *conn, + struct iphdr *iph, size_t plen, + const uint16_t *check, uint32_t seq) +{ + size_t ip_len = plen + sizeof(struct iphdr) + sizeof(struct tcphdr); + const struct in_addr *a4 = inany_v4(&conn->faddr); + struct tcphdr *th = (struct tcphdr *)(iph + 1); + + iph->tot_len = htons(ip_len); + iph->saddr = a4->s_addr;The reasoning behind the fact that a4 isn't NULL here is relatively simple to follow: you already check for inany_v4(&conn->faddr) in the caller, if it evaluates to true, you call this. Still, it's a bit too convoluted for Coverity's taste. Could you perhaps add an ASSERT(a4) before this block to make it obvious? It's a bit annoying that we extract the address twice, but I don't see a much better alternative compared to what you did. -- Stefano