Re: [PATCH v2 iproute2 net-next] tc: m_vlan: Add vlan modify action

[Stephen Hemminger]

On Thu, 22 Sep 2016 21:01:05 +0300
Shmulik Ladkani  wrote:

> The 'vlan modify' action allows to replace an existing 802.1q tag
> according to user provided settings.
> It accepts same arguments as the 'vlan push' action.
> 
> For example, this replaces vid 6 with vid 5:
> 
>  # tc filter add dev veth0 parent : pref 1 protocol 802.1q \
>   basic match 'meta(vlan mask 0xfff eq 6)' \
>   action vlan modify id 5 continue
> 
> Signed-off-by: Shmulik Ladkani 

Applied to net-next (for 4.9)

[PATCH v2 iproute2 net-next] tc: m_vlan: Add vlan modify action

[Shmulik Ladkani]

The 'vlan modify' action allows to replace an existing 802.1q tag
according to user provided settings.
It accepts same arguments as the 'vlan push' action.

For example, this replaces vid 6 with vid 5:

 # tc filter add dev veth0 parent : pref 1 protocol 802.1q \
  basic match 'meta(vlan mask 0xfff eq 6)' \
  action vlan modify id 5 continue

Signed-off-by: Shmulik Ladkani 
---
 v2: Coding. No need to encapsule action_names[] access into a function

 include/linux/tc_act/tc_vlan.h |  1 +
 man/man8/tc-vlan.8 | 25 +++--
 tc/m_vlan.c| 40 +++-
 3 files changed, 51 insertions(+), 15 deletions(-)

diff --git a/include/linux/tc_act/tc_vlan.h b/include/linux/tc_act/tc_vlan.h
index be72b6e384..bddb272b84 100644
--- a/include/linux/tc_act/tc_vlan.h
+++ b/include/linux/tc_act/tc_vlan.h
@@ -16,6 +16,7 @@
 
 #define TCA_VLAN_ACT_POP   1
 #define TCA_VLAN_ACT_PUSH  2
+#define TCA_VLAN_ACT_MODIFY3
 
 struct tc_vlan {
tc_gen;
diff --git a/man/man8/tc-vlan.8 b/man/man8/tc-vlan.8
index 4d0c5c8a15..af3de1c54e 100644
--- a/man/man8/tc-vlan.8
+++ b/man/man8/tc-vlan.8
@@ -6,7 +6,7 @@ vlan - vlan manipulation module
 .in +8
 .ti -8
 .BR tc " ... " "action vlan" " { " pop " |"
-.IR PUSH " } [ " CONTROL " ]"
+.IR PUSH " | " MODIFY " } [ " CONTROL " ]"
 
 .ti -8
 .IR PUSH " := "
@@ -17,22 +17,30 @@ vlan - vlan manipulation module
 .BI id " VLANID"
 
 .ti -8
+.IR MODIFY " := "
+.BR modify " [ " protocol
+.IR VLANPROTO " ]"
+.BR " [ " priority
+.IR VLANPRIO " ] "
+.BI id " VLANID"
+
+.ti -8
 .IR CONTROL " := { "
 .BR reclassify " | " pipe " | " drop " | " continue " | " pass " }"
 .SH DESCRIPTION
 The
 .B vlan
 action allows to perform 802.1Q en- or decapsulation on a packet, reflected by
-the two operation modes
-.IR POP " and " PUSH .
+the operation modes
+.IR POP ", " PUSH " and " MODIFY .
 The
 .I POP
 mode is simple, as no further information is required to just drop the
 outer-most VLAN encapsulation. The
-.I PUSH
-mode on the other hand requires at least a
+.IR PUSH " and " MODIFY
+modes require at least a
 .I VLANID
-and allows to optionally choose the
+and allow to optionally choose the
 .I VLANPROTO
 to use.
 .SH OPTIONS
@@ -45,6 +53,11 @@ Encapsulation mode. Requires at least
 .B id
 option.
 .TP
+.B modify
+Replace mode. Existing 802.1Q tag is replaced. Requires at least
+.B id
+option.
+.TP
 .BI id " VLANID"
 Specify the VLAN ID to encapsulate into.
 .I VLANID
diff --git a/tc/m_vlan.c b/tc/m_vlan.c
index 05a63b48f1..b32f746015 100644
--- a/tc/m_vlan.c
+++ b/tc/m_vlan.c
@@ -19,10 +19,17 @@
 #include "tc_util.h"
 #include 
 
+static const char * const action_names[] = {
+   [TCA_VLAN_ACT_POP] = "pop",
+   [TCA_VLAN_ACT_PUSH] = "push",
+   [TCA_VLAN_ACT_MODIFY] = "modify",
+};
+
 static void explain(void)
 {
fprintf(stderr, "Usage: vlan pop\n");
fprintf(stderr, "   vlan push [ protocol VLANPROTO ] id VLANID [ 
priority VLANPRIO ] [CONTROL]\n");
+   fprintf(stderr, "   vlan modify [ protocol VLANPROTO ] id VLANID [ 
priority VLANPRIO ] [CONTROL]\n");
fprintf(stderr, "   VLANPROTO is one of 802.1Q or 802.1AD\n");
fprintf(stderr, "with default: 802.1Q\n");
fprintf(stderr, "   CONTROL := reclassify | pipe | drop | continue 
| pass\n");
@@ -34,6 +41,11 @@ static void usage(void)
exit(-1);
 }
 
+static bool has_push_attribs(int action)
+{
+   return action == TCA_VLAN_ACT_PUSH || action == TCA_VLAN_ACT_MODIFY;
+}
+
 static int parse_vlan(struct action_util *a, int *argc_p, char ***argv_p,
  int tca_id, struct nlmsghdr *n)
 {
@@ -71,9 +83,17 @@ static int parse_vlan(struct action_util *a, int *argc_p, 
char ***argv_p,
return -1;
}
action = TCA_VLAN_ACT_PUSH;
+   } else if (matches(*argv, "modify") == 0) {
+   if (action) {
+   fprintf(stderr, "unexpected \"%s\" - action 
already specified\n",
+   *argv);
+   explain();
+   return -1;
+   }
+   action = TCA_VLAN_ACT_MODIFY;
} else if (matches(*argv, "id") == 0) {
-   if (action != TCA_VLAN_ACT_PUSH) {
-   fprintf(stderr, "\"%s\" is only valid for 
push\n",
+   if (!has_push_attribs(action)) {
+   fprintf(stderr, "\"%s\" is only valid for 
push/modify\n",
*argv);
explain();
return -1;
@@ -83,8 +103,8 @@ static int parse_vlan(struct action_util *a, int *argc_p, 
char ***argv_p,
invarg("id is invalid", *argv);