[PATCH iproute2-next 2/2] iprule: Add DSCP support

[Ido Schimmel <idosch@nvidia.com>]

Add support for 'dscp' selector in ip-rule.

Rules can be added with a numeric DSCP value:

 # ip rule add dscp 1 table 100
 # ip rule add dscp 0x02 table 200

Or using symbolic names from /usr/share/iproute2/rt_dsfield or
/etc/iproute2/rt_dsfield:

 # ip rule add dscp AF42 table 300

Dump output:

 $ ip rule show
 0:      from all lookup local
 32763:  from all lookup 300 dscp AF42
 32764:  from all lookup 200 dscp 2
 32765:  from all lookup 100 dscp 1
 32766:  from all lookup main
 32767:  from all lookup default

Dump can be filtered by DSCP value:

 $ ip rule show dscp 1
 32765:  from all lookup 100 dscp 1

Or by a symbolic name:

 $ ip rule show dscp AF42
 32763:  from all lookup 300 dscp AF42

When the numeric option is specified, symbolic names will be translated
to numeric values:

 $ ip -N rule show
 0:      from all lookup 255
 32763:  from all lookup 300 dscp 36
 32764:  from all lookup 200 dscp 2
 32765:  from all lookup 100 dscp 1
 32766:  from all lookup 254
 32767:  from all lookup 253

The same applies to the JSON output in order to be consistent with
existing fields such as "tos" and "table":

 $ ip -j -p rule show dscp AF42
 [ {
         "priority": 32763,
         "src": "all",
         "table": "300",
         "dscp": "AF42"
     } ]

 $ ip -j -p -N rule show dscp AF42
 [ {
         "priority": 32763,
         "src": "all",
         "table": "300",
         "dscp": "36"
     } ]

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 include/rt_names.h    |  2 ++
 ip/iprule.c           | 36 ++++++++++++++++++++++++++++++++++++
 lib/rt_names.c        | 23 +++++++++++++++++++++++
 man/man8/ip-rule.8.in | 17 +++++++++++++++++
 4 files changed, 78 insertions(+)

diff --git a/include/rt_names.h b/include/rt_names.h
index 0275030704c1..a5c73f3872a3 100644
--- a/include/rt_names.h
+++ b/include/rt_names.h
@@ -11,6 +11,7 @@ const char *rtnl_rttable_n2a(__u32 id, char *buf, int len);
 const char *rtnl_rtrealm_n2a(int id, char *buf, int len);
 const char *rtnl_dsfield_n2a(int id, char *buf, int len);
 const char *rtnl_dsfield_get_name(int id);
+const char *rtnl_dscp_n2a(int id, char *buf, int len);
 const char *rtnl_group_n2a(int id, char *buf, int len);
 
 int rtnl_rtprot_a2n(__u32 *id, const char *arg);
@@ -19,6 +20,7 @@ int rtnl_rtscope_a2n(__u32 *id, const char *arg);
 int rtnl_rttable_a2n(__u32 *id, const char *arg);
 int rtnl_rtrealm_a2n(__u32 *id, const char *arg);
 int rtnl_dsfield_a2n(__u32 *id, const char *arg);
+int rtnl_dscp_a2n(__u32 *id, const char *arg);
 int rtnl_group_a2n(int *id, const char *arg);
 
 const char *inet_proto_n2a(int proto, char *buf, int len);
diff --git a/ip/iprule.c b/ip/iprule.c
index 81938f2ed80c..ae067c72a66d 100644
--- a/ip/iprule.c
+++ b/ip/iprule.c
@@ -46,6 +46,7 @@ static void usage(void)
 		"            [ ipproto PROTOCOL ]\n"
 		"            [ sport [ NUMBER | NUMBER-NUMBER ]\n"
 		"            [ dport [ NUMBER | NUMBER-NUMBER ] ]\n"
+		"            [ dscp DSCP ]\n"
 		"ACTION := [ table TABLE_ID ]\n"
 		"          [ protocol PROTO ]\n"
 		"          [ nat ADDRESS ]\n"
@@ -67,6 +68,7 @@ static struct
 	unsigned int tos, tosmask;
 	unsigned int pref, prefmask;
 	unsigned int fwmark, fwmask;
+	unsigned int dscp, dscpmask;
 	uint64_t tun_id;
 	char iif[IFNAMSIZ];
 	char oif[IFNAMSIZ];
@@ -219,6 +221,17 @@ static bool filter_nlmsg(struct nlmsghdr *n, struct rtattr **tb, int host_len)
 		}
 	}
 
+	if (filter.dscpmask) {
+		if (tb[FRA_DSCP]) {
+			__u8 dscp = rta_getattr_u8(tb[FRA_DSCP]);
+
+			if (filter.dscp != dscp)
+				return false;
+		} else {
+			return false;
+		}
+	}
+
 	table = frh_get_table(frh, tb);
 	if (filter.tb > 0 && filter.tb ^ table)
 		return false;
@@ -468,6 +481,14 @@ int print_rule(struct nlmsghdr *n, void *arg)
 				     rtnl_rtprot_n2a(protocol, b1, sizeof(b1)));
 		}
 	}
+
+	if (tb[FRA_DSCP]) {
+		__u8 dscp = rta_getattr_u8(tb[FRA_DSCP]);
+
+		print_string(PRINT_ANY, "dscp", " dscp %s",
+			     rtnl_dscp_n2a(dscp, b1, sizeof(b1)));
+	}
+
 	print_string(PRINT_FP, NULL, "\n", "");
 	close_json_object();
 	fflush(fp);
@@ -697,6 +718,14 @@ static int iprule_list_flush_or_save(int argc, char **argv, int action)
 			else if (ret != 2)
 				invarg("invalid dport range\n", *argv);
 			filter.dport = r;
+		} else if (strcmp(*argv, "dscp") == 0) {
+			__u32 dscp;
+
+			NEXT_ARG();
+			if (rtnl_dscp_a2n(&dscp, *argv))
+				invarg("invalid dscp\n", *argv);
+			filter.dscp = dscp;
+			filter.dscpmask = 1;
 		} else {
 			if (matches(*argv, "dst") == 0 ||
 			    matches(*argv, "to") == 0) {
@@ -975,6 +1004,13 @@ static int iprule_modify(int cmd, int argc, char **argv)
 				invarg("invalid dport range\n", *argv);
 			addattr_l(&req.n, sizeof(req), FRA_DPORT_RANGE, &r,
 				  sizeof(r));
+		} else if (strcmp(*argv, "dscp") == 0) {
+			__u32 dscp;
+
+			NEXT_ARG();
+			if (rtnl_dscp_a2n(&dscp, *argv))
+				invarg("invalid dscp\n", *argv);
+			addattr8(&req.n, sizeof(req), FRA_DSCP, dscp);
 		} else {
 			int type;
 
diff --git a/lib/rt_names.c b/lib/rt_names.c
index e967e0cac5b4..723f0917b0ae 100644
--- a/lib/rt_names.c
+++ b/lib/rt_names.c
@@ -625,6 +625,17 @@ const char *rtnl_dsfield_get_name(int id)
 	return rtnl_rtdsfield_tab[id];
 }
 
+const char *rtnl_dscp_n2a(int id, char *buf, int len)
+{
+	if (!numeric) {
+		const char *name = rtnl_dsfield_get_name(id << 2);
+
+		if (name != NULL)
+			return name;
+	}
+	snprintf(buf, len, "%u", id);
+	return buf;
+}
 
 int rtnl_dsfield_a2n(__u32 *id, const char *arg)
 {
@@ -658,6 +669,18 @@ int rtnl_dsfield_a2n(__u32 *id, const char *arg)
 	return 0;
 }
 
+int rtnl_dscp_a2n(__u32 *id, const char *arg)
+{
+	if (get_u32(id, arg, 0) == 0)
+		return 0;
+
+	if (rtnl_dsfield_a2n(id, arg) != 0)
+		return -1;
+	/* Convert from DS field to DSCP */
+	*id >>= 2;
+
+	return 0;
+}
 
 static struct rtnl_hash_entry dflt_group_entry = {
 	.id = 0, .name = "default"
diff --git a/man/man8/ip-rule.8.in b/man/man8/ip-rule.8.in
index 48f8222fe193..51f3050ae8f8 100644
--- a/man/man8/ip-rule.8.in
+++ b/man/man8/ip-rule.8.in
@@ -36,6 +36,8 @@ ip-rule \- routing policy database management
 .IR PREFIX " ] [ "
 .B  tos
 .IR TOS " ] [ "
+.B  dscp
+.IR DSCP " ] [ "
 .B  fwmark
 .IR FWMARK\fR[\fB/\fIMASK "] ] [ "
 .B  iif
@@ -234,6 +236,21 @@ a device.
 .BI dsfield " TOS"
 select the TOS value to match.
 
+.TP
+.BI dscp " DSCP"
+select the DSCP value to match. DSCP values can be written either directly as
+numeric values (valid values are 0-63), or using symbolic names specified in
+.BR @SYSCONF_USR_DIR@/rt_dsfield " or " @SYSCONF_ETC_DIR@/rt_dsfield
+(has precedence if exists).
+However, note that the file specifies full 8-bit dsfield values, whereas
+.B ip rule
+will only use the higher six bits.
+.B ip rule show
+will similarly format DSCP values as symbolic names if possible. The
+command line option
+.B -N
+turns the show translation off.
+
 .TP
 .BI fwmark " MARK"
 select the
-- 
2.46.2