Eelco Chaudron via dev <[email protected]> writes:
> Add the '--len' option to 'ovs-ofctl compose-packet', which
> allows truncation or extension (with zeros) of the generated
> packet.
>
> Fixes: 90b6e83beb60 ("tests: Fix NSH decap header test for real Ethernet
> devices.")
> Signed-off-by: Eelco Chaudron <[email protected]>
> ---
> tests/system-traffic.at | 4 ++--
> utilities/ovs-ofctl.c | 31 ++++++++++++++++++++++++++++---
> 2 files changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
> index 8f4fdf8b1..71a8afff2 100644
> --- a/tests/system-traffic.at
> +++ b/tests/system-traffic.at
> @@ -9996,12 +9996,12 @@ dnl Send the NSH packet with TCP SYN payload from
> p0(at_ns0) interface directed
> dnl to p1(at_ns1) interface.
> NS_CHECK_EXEC([at_ns0], [$PYTHON3 $srcdir/sendpkt.py p0 \
> "$(ovs-ofctl compose-packet --bare 'NSH_HEADER')" \
> - "$(ovs-ofctl compose-packet --bare 'TCP_SYN_PKT')"],
> + "$(ovs-ofctl compose-packet --len 64 --bare 'TCP_SYN_PKT')"],
> [0], [ignore])
>
> dnl Check the expected de-capsulated TCP packet on the egress interface
> OVS_WAIT_UNTIL([ovs-pcap p1.pcap | grep -q \
> - "^$(ovs-ofctl compose-packet --bare 'TCP_SYN_PKT')0*\$"])
> + "^$(ovs-ofctl compose-packet --len 64 --bare 'TCP_SYN_PKT')\$"])
>
> OVS_TRAFFIC_VSWITCHD_STOP
> AT_CLEANUP
> diff --git a/utilities/ovs-ofctl.c b/utilities/ovs-ofctl.c
> index ba3458e55..d949583c6 100644
> --- a/utilities/ovs-ofctl.c
> +++ b/utilities/ovs-ofctl.c
> @@ -160,6 +160,9 @@ static int print_bare = 0;
> /* -bad-csum: Makes "compose-packet" generate an invalid checksum. */
> static int bad_csum = 0;
>
> +/* --len: Makes "compose-packet" truncate or extend the payload. */
> +static unsigned int opt_len = 0;
> +
> /* --raw: Makes "ofp-print" read binary data from stdin. */
> static int raw = 0;
>
> @@ -223,6 +226,7 @@ parse_options(int argc, char *argv[])
> OPT_COLOR,
> OPT_MAY_CREATE,
> OPT_READ_ONLY,
> + OPT_LEN,
> DAEMON_OPTION_ENUMS,
> OFP_VERSION_OPTION_ENUMS,
> VLOG_OPTION_ENUMS,
> @@ -253,6 +257,7 @@ parse_options(int argc, char *argv[])
> {"bad-csum", no_argument, &bad_csum, 1},
> {"raw", no_argument, &raw, 1},
> {"read-only", no_argument, NULL, OPT_READ_ONLY},
> + {"len", required_argument, NULL, OPT_LEN},
> DAEMON_LONG_OPTIONS,
> OFP_VERSION_LONG_OPTIONS,
> VLOG_LONG_OPTIONS,
> @@ -382,6 +387,12 @@ parse_options(int argc, char *argv[])
> may_create = true;
> break;
>
> + case OPT_LEN:
> + if (!str_to_uint(optarg, 10, &opt_len)) {
> + ovs_fatal(0, "value %s on --len is invalid", optarg);
> + }
> + break;
> +
> DAEMON_OPTION_HANDLERS
> OFP_VERSION_OPTION_HANDLERS
> VLOG_OPTION_HANDLERS
> @@ -4934,9 +4945,10 @@ ofctl_parse_key_value(struct ovs_cmdl_context *ctx)
> }
> }
>
> -/* "compose-packet [--pcap|--bare] [--bad-csum] FLOW [L7]": Converts the
> - * OpenFlow flow specification FLOW to a packet with flow_compose() and
> prints
> - * the hex bytes of the packet, with offsets, to stdout.
> +/* "compose-packet [--pcap|--bare] [--bad-csum] [--len <length>] FLOW [L7]":
> + * Converts the OpenFlow flow specification FLOW to a packet with
> + * flow_compose() and prints the hex bytes of the packet, with offsets, to
> + * stdout.
> *
> * With --pcap, prints the packet in pcap format, so that you can do
> something
> * like "ovs-ofctl --pcap compose-packet udp | tcpdump -vvvv -r-" to use
> @@ -4949,6 +4961,9 @@ ofctl_parse_key_value(struct ovs_cmdl_context *ctx)
> *
> * With --bad-csum, produces a packet with an invalid IP checksum. (For
> IPv4.)
> *
> + * With --len, produces a packet that is either truncated or extended (with
> + * zeros) to the given length.
> + *
> * Regardless of the mode, the command also verifies that the flow extracted
> * from that packet matches the original FLOW.
> *
> @@ -4991,6 +5006,16 @@ ofctl_compose_packet(struct ovs_cmdl_context *ctx)
> flow_compose(&p, &flow1, l7, l7_len, bad_csum);
> free(l7);
>
> + if (opt_len) {
> + size_t p_len = dp_packet_size(&p);
> +
> + if (opt_len > p_len) {
> + dp_packet_put_zeros(&p, opt_len - p_len);
> + } else {
> + dp_packet_set_size(&p, opt_len);
> + }
> + }
> +
I think we should be using packet_expand() instead of the direct
dp_packet_put_zeros call - the reason is to ensure that checksums are
properly regenerated. WDYT?
> if (print_pcap) {
> struct pcap_file *p_file = ovs_pcap_stdout();
> ovs_pcap_write_header(p_file);
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