ip link: support for the CAN netlink

I developed this application to test the Linux kernel series [1]. As
described in it I could not use the iproute2 package since the
microcontroller is without MMU.

function                                             old     new   delta
do_set_can                                             -     920    +920
packed_usage                                       34645   34908    +263
get_float_1000                                         -     164    +164
.rodata                                           105427  105539    +112
do_iplink                                           1313    1381     +68
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 3/0 up/down: 1527/0)           Total: 1527 bytes

cc: Marc Kleine-Budde <mkl@pengutronix.de>
[1] https://marc.info/?l=linux-netdev&m=167999323611710&w=2
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

configs/TEST_nommu_defconfig

@@ -703,6 +703,7 @@ CONFIG_FEATURE_INETD_RPC=y
 CONFIG_IP=y
 CONFIG_FEATURE_IP_ADDRESS=y
 CONFIG_FEATURE_IP_LINK=y
+CONFIG_FEATURE_IP_LINK_CAN=y
 CONFIG_FEATURE_IP_ROUTE=y
 CONFIG_FEATURE_IP_TUNNEL=y
 CONFIG_FEATURE_IP_RULE=y

networking/ip.c

@@ -74,6 +74,12 @@
 //config:	help
 //config:	Configure network devices with "ip".
 //config:
+//config:config FEATURE_IP_LINK_CAN
+//config:	bool "ip link set type can"
+//config:	default y
+//config:	help
+//config:	Configure CAN devices with "ip".
+//config:
 //config:config FEATURE_IP_ROUTE
 //config:	bool "ip route"
 //config:	default y
@@ -152,16 +158,61 @@
 //usage:#define iplink_trivial_usage
 //usage:       /*Usage:iplink*/"set IFACE [up|down] [arp on|off] [multicast on|off]\n"
 //usage:       "	[promisc on|off] [mtu NUM] [name NAME] [qlen NUM] [address MAC]\n"
-//usage:       "	[master IFACE | nomaster] [netns PID]"
+//usage:       "	[master IFACE | nomaster] [netns PID]"IF_FEATURE_IP_LINK_CAN(" [type TYPE ARGS]")
 // * short help shows only "set" command, long help continues (with just one "\n")
 // * and shows all other commands:
 //usage:#define iplink_full_usage "\n"
 //usage:       "iplink add [link IFACE] IFACE [address MAC] type TYPE [ARGS]\n"
 //usage:       "iplink delete IFACE type TYPE [ARGS]\n"
-//usage:       "	TYPE ARGS := vlan VLANARGS | vrf table NUM\n"
+//usage:       "	TYPE ARGS := vlan VLANARGS | vrf table NUM"IF_FEATURE_IP_LINK_CAN(" | can CANARGS")"\n"
 //usage:       "	VLANARGS := id VLANID [protocol 802.1q|802.1ad] [reorder_hdr on|off]\n"
 //usage:       "		[gvrp on|off] [mvrp on|off] [loose_binding on|off]\n"
+//usage:       IF_FEATURE_IP_LINK_CAN(
+//usage:       "	CANARGS := [bitrate BITRATE [sample-point SAMPLE-POINT]] |\n"
+//usage:       "		[tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1\n"
+//usage:       "		phase-seg2 PHASE-SEG2 [sjw SJW]]\n"
+//usage:       "		[dbitrate BITRATE [dsample-point SAMPLE-POINT]] |\n"
+//usage:       "		[dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1\n"
+//usage:       "		dphase-seg2 PHASE-SEG2 [dsjw SJW]]\n"
+//usage:       "		[loopback on|off] [listen-only on|off] [triple-sampling on|off]\n"
+//usage:       "		[one-shot on|off] [berr-reporting on|off]\n"
+//usage:       "		[fd on|off] [fd-non-iso on|off] [presume-ack on|off]\n"
+//usage:       "		[restart-ms TIME-MS] [restart]\n"
+//usage:       "		[termination 0..65535]\n"
+//usage:       )
 //usage:       "iplink show [IFACE]"
+//upstream man ip-link-can:
+//Usage: ip link set DEVICE type can
+//	[ bitrate BITRATE [ sample-point SAMPLE-POINT] ] |
+//	[ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1
+//	  phase-seg2 PHASE-SEG2 [ sjw SJW ] ]
+//
+//	[ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] |
+//	[ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1
+//	  dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ]
+//
+//	[ loopback { on | off } ]
+//	[ listen-only { on | off } ]
+//	[ triple-sampling { on | off } ]
+//	[ one-shot { on | off } ]
+//	[ berr-reporting { on | off } ]
+//	[ fd { on | off } ]
+//	[ fd-non-iso { on | off } ]
+//	[ presume-ack { on | off } ]
+//
+//	[ restart-ms TIME-MS ]
+//	[ restart ]
+//
+//	[ termination { 0..65535 } ]
+//
+//	Where: BITRATE	:= { 1..1000000 }
+//		  SAMPLE-POINT	:= { 0.000..0.999 }
+//		  TQ		:= { NUMBER }
+//		  PROP-SEG	:= { 1..8 }
+//		  PHASE-SEG1	:= { 1..8 }
+//		  PHASE-SEG2	:= { 1..8 }
+//		  SJW		:= { 1..4 }
+//		  RESTART-MS	:= { 0 | NUMBER }
 //upstream man ip-link:
 //=====================
 //ip link add [link DEV] [ name ] NAME

networking/libiproute/iplink.c

@@ -11,6 +11,9 @@
 #include <netinet/if_ether.h>
 
 #include <linux/if_vlan.h>
+#if ENABLE_FEATURE_IP_LINK_CAN
+# include <linux/can/netlink.h>
+#endif
 #include "ip_common.h"  /* #include "libbb.h" is inside */
 #include "rt_names.h"
 #include "utils.h"
@@ -28,6 +31,11 @@
 #undef  IFLA_VLAN_PROTOCOL
 #define IFLA_VLAN_PROTOCOL      5
 
+#ifndef NLMSG_TAIL
+#define NLMSG_TAIL(nmsg) \
+	((struct rtattr *) (((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
+#endif
+
 #ifndef IFLA_LINKINFO
 # define IFLA_LINKINFO 18
 # define IFLA_INFO_KIND 1
@@ -55,6 +63,11 @@ struct ifla_vlan_flags {
 
 #define str_on_off "on\0""off\0"
 
+enum {
+	PARM_on = 0,
+	PARM_off
+};
+
 /* Exits on error */
 static int get_ctl_fd(void)
 {
@@ -241,10 +254,257 @@ static void die_must_be_on_off(const char *msg)
 	bb_error_msg_and_die("argument of \"%s\" must be \"on\" or \"off\"", msg);
 }
 
+#if ENABLE_FEATURE_IP_LINK_CAN
+static uint32_t get_float_1000(char *arg, const char *errmsg)
+{
+	uint32_t ret;
+	double d;
+	char *ptr;
+
+	errno = 0;
+//TODO: needs setlocale(LC_NUMERIC, "C")?
+	d = strtod(arg, &ptr);
+	if (errno || ptr == arg || *ptr
+	 || d > (0xFFFFFFFFU / 1000) || d < 0
+	) {
+		invarg_1_to_2(arg, errmsg); /* does not return */
+	}
+	ret = d * 1000;
+
+	return ret;
+}
+
+static void do_set_can(char *dev, char **argv)
+{
+	struct can_bittiming bt = {}, dbt = {};
+	struct can_ctrlmode cm = {};
+	char *keyword;
+	static const char keywords[] ALIGN1 =
+		"bitrate\0""sample-point\0""tq\0"
+		"prop-seg\0""phase-seg1\0""phase-seg2\0""sjw\0"
+		"dbitrate\0""dsample-point\0""dtq\0"
+		"dprop-seg\0""dphase-seg1\0""dphase-seg2\0""dsjw\0"
+		"loopback\0""listen-only\0""triple-sampling\0"
+		"one-shot\0""berr-reporting\0"
+		"fd\0""fd-non-iso\0""presume-ack\0"
+		"cc-len8-dlc\0""restart\0""restart-ms\0"
+		"termination\0";
+	enum { ARG_bitrate = 0, ARG_sample_point, ARG_tq,
+		ARG_prop_seg, ARG_phase_seg1, ARG_phase_seg2, ARG_sjw,
+		ARG_dbitrate, ARG_dsample_point, ARG_dtq,
+		ARG_dprop_seg, ARG_dphase_seg1, ARG_dphase_seg2, ARG_dsjw,
+		ARG_loopback, ARG_listen_only, ARG_triple_sampling,
+		ARG_one_shot, ARG_berr_reporting,
+		ARG_fd, ARG_fd_non_iso, ARG_presume_ack,
+		ARG_cc_len8_dlc, ARG_restart, ARG_restart_ms,
+		ARG_termination };
+	struct rtnl_handle rth;
+	struct {
+		struct nlmsghdr  n;
+		struct ifinfomsg i;
+		char buf[1024];
+	} req;
+	size_t dev_len;
+	struct rtattr *linkinfo, *data;
+	smalluint key, param;
+
+	memset(&req, 0, sizeof(req));
+
+	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+	req.n.nlmsg_flags = NLM_F_REQUEST;
+	req.n.nlmsg_type = RTM_NEWLINK;
+	req.i.ifi_family = preferred_family;
+	xrtnl_open(&rth);
+	req.i.ifi_index = xll_name_to_index(dev);
+	dev_len = strlen(dev);
+	if (dev_len < 2 || dev_len > IFNAMSIZ)
+		invarg_1_to_2(dev, "dev");
+
+	addattr_l(&req.n, sizeof(req), IFLA_IFNAME, dev, dev_len);
+	linkinfo = NLMSG_TAIL(&req.n);
+	addattr_l(&req.n, sizeof(req), IFLA_LINKINFO, NULL, 0);
+	addattr_l(&req.n, sizeof(req), IFLA_INFO_KIND, (void *)"can",
+		  strlen("can"));
+	data = NLMSG_TAIL(&req.n);
+	addattr_l(&req.n, sizeof(req), IFLA_INFO_DATA, NULL, 0);
+	while (*argv) {
+		key = index_in_substrings(keywords, *argv);
+		keyword = *argv;
+		//printf("%s: key: %d, *argv: %s\n", __func__, key, *argv);
+		switch (key) {
+		case ARG_bitrate:
+		case ARG_tq:
+		case ARG_prop_seg:
+		case ARG_phase_seg1:
+		case ARG_phase_seg2:
+		case ARG_sjw: {
+			uint32_t *val;
+			NEXT_ARG();
+			if (key == ARG_bitrate)
+				val = &bt.bitrate;
+			else if (key == ARG_tq)
+				val = &bt.tq;
+			else if (key == ARG_prop_seg)
+				val = &bt.prop_seg;
+			else if (key == ARG_phase_seg1)
+				val = &bt.phase_seg1;
+			else if (key == ARG_phase_seg2)
+				val = &bt.phase_seg2;
+			else
+				val = &bt.sjw;
+
+			*val = get_u32(*argv, keyword);
+			break;
+		}
+		case ARG_sample_point: {
+			NEXT_ARG();
+			bt.sample_point = get_float_1000(*argv, keyword);
+			break;
+		}
+		case ARG_dbitrate:
+		case ARG_dtq:
+		case ARG_dprop_seg:
+		case ARG_dphase_seg1:
+		case ARG_dphase_seg2:
+		case ARG_dsjw: {
+			uint32_t *val;
+			NEXT_ARG();
+			if (key == ARG_dbitrate)
+				val = &dbt.bitrate;
+			else if (key == ARG_dtq)
+				val = &dbt.tq;
+			else if (key == ARG_dprop_seg)
+				val = &dbt.prop_seg;
+			else if (key == ARG_dphase_seg1)
+				val = &dbt.phase_seg1;
+			else if (key == ARG_dphase_seg2)
+				val = &dbt.phase_seg2;
+			else
+				val = &dbt.sjw;
+
+			*val = get_u32(*argv, keyword);
+			break;
+		}
+		case ARG_dsample_point: {
+			NEXT_ARG();
+			dbt.sample_point = get_float_1000(*argv, keyword);
+			break;
+		}
+		case ARG_loopback:
+		case ARG_listen_only:
+		case ARG_triple_sampling:
+		case ARG_one_shot:
+		case ARG_berr_reporting:
+		case ARG_fd:
+		case ARG_fd_non_iso:
+		case ARG_presume_ack:
+		case ARG_cc_len8_dlc: {
+			uint32_t flag = 0;
+
+			NEXT_ARG();
+			param = index_in_strings(str_on_off, *argv);
+			if (param < 0)
+				die_must_be_on_off(keyword);
+
+			if (key == ARG_loopback)
+				flag = CAN_CTRLMODE_LOOPBACK;
+			else if (key == ARG_listen_only)
+				flag = CAN_CTRLMODE_LISTENONLY;
+			else if (key == ARG_triple_sampling)
+				flag = CAN_CTRLMODE_3_SAMPLES;
+			else if (key == ARG_one_shot)
+				flag = CAN_CTRLMODE_ONE_SHOT;
+			else if (key == ARG_berr_reporting)
+				flag = CAN_CTRLMODE_BERR_REPORTING;
+			else if (key == ARG_fd)
+				flag = CAN_CTRLMODE_FD;
+			else if (key == ARG_fd_non_iso)
+				flag = CAN_CTRLMODE_FD_NON_ISO;
+			else if (key == ARG_presume_ack)
+				flag = CAN_CTRLMODE_PRESUME_ACK;
+			else
+#if defined(CAN_CTRLMODE_CC_LEN8_DLC)
+				flag = CAN_CTRLMODE_CC_LEN8_DLC;
+#else
+				die_must_be_on_off(keyword);
+#endif
+			cm.mask |= flag;
+			if (param == PARM_on)
+				cm.flags |= flag;
+
+			break;
+		}
+		case ARG_restart: {
+			uint32_t val = 1;
+			/*NEXT_ARG(); - WRONG? */
+			addattr_l(&req.n, sizeof(req), IFLA_CAN_RESTART, &val, sizeof(val));
+			break;
+		}
+		case ARG_restart_ms: {
+			uint32_t val;
+			NEXT_ARG();
+			val = get_u32(*argv, keyword);
+			addattr_l(&req.n, sizeof(req), IFLA_CAN_RESTART_MS, &val, sizeof(val));
+			break;
+		}
+		case ARG_termination: {
+			uint16_t val;
+			NEXT_ARG();
+			val = get_u16(*argv, keyword);
+			addattr_l(&req.n, sizeof(req), IFLA_CAN_TERMINATION, &val, sizeof(val));
+			break;
+		}
+		default:
+			break;
+		}
+		argv++;
+	}
+
+	if (bt.bitrate || bt.tq)
+		addattr_l(&req.n, sizeof(req), IFLA_CAN_BITTIMING, &bt, sizeof(bt));
+
+	if (cm.mask)
+		addattr_l(&req.n, sizeof(req), IFLA_CAN_CTRLMODE, &cm, sizeof(cm));
+
+	data->rta_len = (void *)NLMSG_TAIL(&req.n) - (void *)data;
+	linkinfo->rta_len = (void *)NLMSG_TAIL(&req.n) - (void *)linkinfo;
+
+	if (rtnl_talk(&rth, &req.n, 0, 0, NULL, NULL, NULL) < 0)
+		xfunc_die();
+}
+
+static void set_type(char *type, char *dev, char **argv)
+{
+/* When we have more than just "type can ARGS" supported, maybe:
+	static const char keywords[] ALIGN1 = ""
+		IF_FEATURE_IP_LINK_CAN("can\0")
+		;
+	typedef void FAST_FUNC(*ip_type_set_func_ptr_t)(char*, char**);
+	static const ip_type_set_func_ptr_t funcs[] ALIGN_PTR = {
+		IF_FEATURE_IP_LINK_CAN(do_set_can,)
+	};
+	ip_type_set_func_ptr_t func;
+	int key;
+
+	key = index_in_substrings(keywords, type);
+	if (key < 0)
+		invarg_1_to_2(type, "type");
+	func = funcs[key];
+	func(dev, argv);
+*/
+	if (strcmp(type, "can") != 0)
+		invarg_1_to_2(type, "type");
+	do_set_can(dev, argv);
+}
+#endif
+
 /* Return value becomes exitcode. It's okay to not return at all */
 static int do_set(char **argv)
 {
 	char *dev = NULL;
+#if ENABLE_FEATURE_IP_LINK_CAN
+	char *type = NULL;
+#endif
 	uint32_t mask = 0;
 	uint32_t flags = 0;
 	int qlen = -1;
@@ -261,18 +521,24 @@ static int do_set(char **argv)
 		"up\0""down\0""name\0""mtu\0""qlen\0""multicast\0"
 		"arp\0""promisc\0""address\0""netns\0"
 		"master\0""nomaster\0"
+#if ENABLE_FEATURE_IP_LINK_CAN
+		"type\0"
+#endif
 		"dev\0" /* must be last */;
 	enum { ARG_up = 0, ARG_down, ARG_name, ARG_mtu, ARG_qlen, ARG_multicast,
 		ARG_arp, ARG_promisc, ARG_addr, ARG_netns,
 		ARG_master, ARG_nomaster,
+#if ENABLE_FEATURE_IP_LINK_CAN
+		ARG_type,
+#endif
 		ARG_dev };
-	enum { PARM_on = 0, PARM_off };
 	smalluint key;
 
 	while (*argv) {
 		/* substring search ensures that e.g. "addr" and "address"
 		 * are both accepted */
 		key = index_in_substrings(keywords, *argv);
+		//printf("%s: key: %d, *argv: %s\n", __func__, key, *argv);
 		if (key == ARG_up) {
 			mask |= IFF_UP;
 			flags |= IFF_UP;
@@ -304,6 +570,13 @@ static int do_set(char **argv)
 		} else if (key == ARG_netns) {
 			NEXT_ARG();
 			netns = get_unsigned(*argv, "netns");
+#if ENABLE_FEATURE_IP_LINK_CAN
+		} else if (key == ARG_type) {
+			NEXT_ARG();
+			type = *argv;
+			argv++;
+			break;
+#endif
 		} else if (key >= ARG_dev) {
 			/* ^^^^^^ ">=" here results in "dev IFACE" treated as default */
 			if (key == ARG_dev) {
@@ -311,6 +584,7 @@ static int do_set(char **argv)
 			}
 			if (dev)
 				duparg2("dev", *argv);
+
 			dev = *argv;
 		} else {
 			/* "on|off" options */
@@ -496,6 +770,10 @@ static int do_set(char **argv)
 	}
 	if (mask)
 		do_chflags(dev, flags, mask);
+#if ENABLE_FEATURE_IP_LINK_CAN
+	if (type)
+		set_type(type, dev, argv);
+#endif
 	return 0;
 }
 
@@ -531,10 +809,6 @@ static void vlan_parse_opt(char **argv, struct nlmsghdr *n, unsigned int size)
 		PROTO_8021Q = 0,
 		PROTO_8021AD,
 	};
-	enum {
-		PARM_on = 0,
-		PARM_off
-	};
 	int arg;
 	uint16_t id, proto;
 	struct ifla_vlan_flags flags = {};
@@ -610,10 +884,6 @@ static void vrf_parse_opt(char **argv, struct nlmsghdr *n, unsigned int size)
 	addattr_l(n, size, IFLA_VRF_TABLE, &table, sizeof(table));
 }
 
-#ifndef NLMSG_TAIL
-#define NLMSG_TAIL(nmsg) \
-	((struct rtattr *) (((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
-#endif
 /* Return value becomes exitcode. It's okay to not return at all */
 static int do_add_or_delete(char **argv, const unsigned rtm)
 {