@@ -77,6 +77,7 @@ pedit - generic packet editor action
.IR VAL " | "
.BR add
.IR VAL " | "
+.BR decrement " | "
.BR preserve " } [ " retain
.IR RVAL " ]"
@@ -96,7 +97,7 @@ chosen automatically based on the header field size.
.B ex
Use extended pedit.
.I EXTENDED_LAYERED_OP
-and the add
+and the add/decrement
.I CMD_SPEC
are allowed only in this mode.
.TP
@@ -288,6 +289,11 @@ is defined by the size of the addressed header field in
.IR EXTENDED_LAYERED_OP .
This operation is supported only for extended layered op.
.TP
+.BI decrement
+Decrement the addressed data by one.
+This operation is supported only for
+.BR ip " " ttl " and " ip6 " " hoplimit "."
+.TP
.B preserve
Keep the addressed data as is.
.TP
@@ -41,7 +41,7 @@ static void explain(void)
"\t\tATC:= at <atval> offmask <maskval> shift <shiftval>\n"
"\t\tNOTE: offval is byte offset, must be multiple of 4\n"
"\t\tNOTE: maskval is a 32 bit hex number\n \t\tNOTE: shiftval is a shift value\n"
- "\t\tCMD:= clear | invert | set <setval>| add <addval> | retain\n"
+ "\t\tCMD:= clear | invert | set <setval> | add <addval> | decrement | retain\n"
"\t<LAYERED>:= ip <ipdata> | ip6 <ip6data>\n"
" \t\t| udp <udpdata> | tcp <tcpdata> | icmp <icmpdata>\n"
"\tCONTROL:= reclassify | pipe | drop | continue | pass |\n"
@@ -340,6 +340,9 @@ int parse_cmd(int *argc_p, char ***argv_p, __u32 len, int type, __u32 retain,
int res = -1;
int argc = *argc_p;
char **argv = *argv_p;
+ int flags = type;
+
+ type &= 0xff; /* strip flags */
if (argc <= 0)
return -1;
@@ -360,15 +363,24 @@ int parse_cmd(int *argc_p, char ***argv_p, __u32 len, int type, __u32 retain,
if (matches(*argv, "add") == 0)
tkey->cmd = TCA_PEDIT_KEY_EX_CMD_ADD;
- if (!sel->extended && tkey->cmd) {
- fprintf(stderr,
- "Non extended mode. only 'set' command is supported\n");
- return -1;
- }
+ if (!sel->extended && tkey->cmd)
+ goto non_ext_only_set_cmd;
NEXT_ARG();
if (parse_val(&argc, &argv, val, type))
return -1;
+ } else if (matches(*argv, "decrement") == 0) {
+ if ((flags & TFLAG_ALLOW_DEC) == 0) {
+ fprintf(stderr,
+ "decrement command is not supported for this field\n");
+ return -1;
+ }
+
+ if (!sel->extended)
+ goto non_ext_only_set_cmd;
+
+ tkey->cmd = TCA_PEDIT_KEY_EX_CMD_ADD;
+ *v = retain; /* decrement by overflow */
} else if (matches(*argv, "preserve") == 0) {
retain = 0;
} else {
@@ -431,6 +443,10 @@ done:
*argv_p = argv;
return res;
+non_ext_only_set_cmd:
+ fprintf(stderr,
+ "Non extended mode. only 'set' command is supported\n");
+ return -1;
}
static int parse_offset(int *argc_p, char ***argv_p, struct m_pedit_sel *sel,
@@ -33,6 +33,8 @@
#define TU32 4
#define TMAC 5
+#define TFLAG_ALLOW_DEC (1<<8)
+
#define RU32 0xFFFFFFFF
#define RU16 0xFFFF
#define RU8 0xFF
@@ -68,7 +68,7 @@ parse_ip(int *argc_p, char ***argv_p,
if (strcmp(*argv, "ttl") == 0) {
NEXT_ARG();
tkey->off = 8;
- res = parse_cmd(&argc, &argv, 1, TU32, RU8, sel, tkey);
+ res = parse_cmd(&argc, &argv, 1, TU32 | TFLAG_ALLOW_DEC, RU8, sel, tkey);
goto done;
}
if (strcmp(*argv, "protocol") == 0) {
@@ -71,7 +71,7 @@ parse_ip6(int *argc_p, char ***argv_p,
if (strcmp(*argv, "hoplimit") == 0) {
NEXT_ARG();
tkey->off = 7;
- res = parse_cmd(&argc, &argv, 1, TU32, RU8, sel, tkey);
+ res = parse_cmd(&argc, &argv, 1, TU32 | TFLAG_ALLOW_DEC, RU8, sel, tkey);
goto done;
}
if (strcmp(*argv, "traffic_class") == 0) {
Implement a decrement operation for ttl and hoplimit. Since this is just syntactic sugar, it goes that: tc filter add ... action pedit ex munge ip ttl dec ... tc filter add ... action pedit ex munge ip6 hoplimit dec ... is just a more readable version of this: tc filter add ... action pedit ex munge ip ttl add 0xff ... tc filter add ... action pedit ex munge ip6 hoplimit add 0xff ... This feature was suggested by some pseudo tc examples in Mellanox's documentation[1], but wasn't present in neither their mlnx-iproute2 nor iproute2. In order to avoid adding an extra parameter to parse_cmd(), I have re-used the `int type` parameter to also carry flags. Tested with skip_sw on Mellanox ConnectX-6 Dx. [1] https://docs.mellanox.com/pages/viewpage.action?pageId=47033989 Signed-off-by: Asbjørn Sloth Tønnesen <asbjorn@asbjorn.st> --- man/man8/tc-pedit.8 | 8 +++++++- tc/m_pedit.c | 28 ++++++++++++++++++++++------ tc/m_pedit.h | 2 ++ tc/p_ip.c | 2 +- tc/p_ip6.c | 2 +- 5 files changed, 33 insertions(+), 9 deletions(-)