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tc/pedit: p_ip: introduce editing ttl header 

Enable user to edit IP header ttl field.

For example, to forward any TCP packet and decrease its TTL by one:
$ tc filter add dev enp0s9 protocol ip parent ffff: \
    flower \
      ip_proto tcp \
    action pedit ex munge \
      ip ttl add 0xff pipe \
    action mirred egress \
      redirect dev veth0

Signed-off-by: Amir Vadai <amir@vadai.me>
This commit is contained in:
Amir Vadai 2017-04-23 15:53:52 +03:00 committed by Stephen Hemminger
parent c05ddaf9e0
commit 8d193d9607
2 changed files with 23 additions and 0 deletions
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17
man/man8/tc-pedit.8
View File

@ -28,6 +28,8 @@ pedit - generic packet editor action
.ti -8
.IR EXTENDED_LAYERED_OP " := { "
.BI ip " IPHDR_FIELD"
|
.BI ip " EX_IPHDR_FIELD"
.RI } " CMD_SPEC"
.ti -8
@ -39,6 +41,10 @@ pedit - generic packet editor action
.IR BEYOND_IPHDR_FIELD " := { "
.BR dport " | " sport " | " icmp_type " | " icmp_code " }"
.ti -8
.IR EX_IPHDR_FIELD " := { "
.BR ttl " }"
.ti -8
.IR CMD_SPEC " := {"
.BR clear " | " invert " | " set
@ -161,6 +167,17 @@ If it is not or the latter is bigger than the minimum of 20 bytes, this will do
unexpected things. These fields are eight-bit values.
.RE
.TP
.BI ip " EX_IPHDR_FIELD"
Supported only when
.I ex
is used. The supported keywords for
.I EX_IPHDR_FIELD
are:
.RS
.TP
.B ttl
.RE
.TP
.B clear
Clear the addressed data (i.e., set it to zero).
.TP

6
tc/p_ip.c
View File

@ -66,6 +66,12 @@ parse_ip(int *argc_p, char ***argv_p,
res = parse_cmd(&argc, &argv, 1, TU32, 0x0f, sel, tkey);
goto done;
}
if (strcmp(*argv, "ttl") == 0) {
NEXT_ARG();
tkey->off = 8;
res = parse_cmd(&argc, &argv, 1, TU32, RU8, sel, tkey);
goto done;
}
if (strcmp(*argv, "protocol") == 0) {
NEXT_ARG();
tkey->off = 9;