/* This example is placed in the public domain. */
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <time.h>

#include <libmnl/libmnl.h>
#include <linux/can/netlink.h>
#include <linux/if.h>
#include <linux/if_link.h>
#include <linux/rtnetlink.h>

static void incomplete_command(void) __attribute__((noreturn));

#define NEXT_ARG()				\
	do { \
		if (argc <= 0) incomplete_command();	\
		argv++; \
		argc--; \
	} while (0)

static void duparg2(const char *key, const char *arg)
{
	fprintf(stderr,
		"Error: either \"%s\" is duplicate, or \"%s\" is a garbage.\n",
		key, arg);
	exit(-1);
}

static void incomplete_command(void)
{
	fprintf(stderr, "Command line is not complete. Try option \"help\"\n");
	exit(EXIT_FAILURE);
}

/* Returns false if 'prefix' is a not empty prefix of 'string'.
 */
static bool matches(const char *prefix, const char *string)
{
	if (!*prefix)
		return true;

	while (*string && *prefix == *string) {
		prefix++;
		string++;
	}

	return !!*prefix;
}

static int get_u16(__u16 *val, const char *arg, int base)
{
	unsigned long res;
	char *ptr;

	if (!arg || !*arg)
		return -1;

	res = strtoul(arg, &ptr, base);

	/* empty string or trailing non-digits */
	if (!ptr || ptr == arg || *ptr)
		return -1;

	/* overflow */
	if (res == ULONG_MAX && errno == ERANGE)
		return -1;

	if (res > 0xFFFFUL)
		return -1;

	*val = res;
	return 0;
}

static int get_u32(__u32 *val, const char *arg, int base)
{
	unsigned long res;
	char *ptr;

	if (!arg || !*arg)
		return -1;

	res = strtoul(arg, &ptr, base);

	/* empty string or trailing non-digits */
	if (!ptr || ptr == arg || *ptr)
		return -1;

	/* overflow */
	if (res == ULONG_MAX && errno == ERANGE)
		return -1;

	/* in case UL > 32 bits */
	if (res > 0xFFFFFFFFUL)
		return -1;

	*val = res;
	return 0;
}

static int get_float(float *val, const char *arg)
{
	float res;
	char *ptr;

	if (!arg || !*arg)
		return -1;

	res = strtof(arg, &ptr);
	if (!ptr || ptr == arg || *ptr)
		return -1;

	*val = res;
	return 0;
}

static void set_ctrlmode(char *name, char *arg,
			 struct can_ctrlmode *cm, __u32 flags)
{
	if (strcmp(arg, "on") == 0) {
		cm->flags |= flags;
	} else if (strcmp(arg, "off") != 0) {
		fprintf(stderr,
			"Error: argument of \"%s\" must be \"on\" or \"off\", not \"%s\"\n",
			name, arg);
		exit(EXIT_FAILURE);
	}

	cm->mask |= flags;
}

static void invarg(const char *msg, const char *arg)
{
	fprintf(stderr, "Error: argument \"%s\" is wrong: %s\n", arg, msg);
	exit(-1);
}

static void print_usage(FILE *f)
{
	fprintf(f,
		"Usage: ip link set DEVICE type can\n"
		"\t[ bitrate BITRATE [ sample-point SAMPLE-POINT] ] |\n"
		"\t[ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1\n \t  phase-seg2 PHASE-SEG2 [ sjw SJW ] ]\n"
		"\n"
		"\t[ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] |\n"
		"\t[ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1\n \t  dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ]\n"
		"\n"
		"\t[ loopback { on | off } ]\n"
		"\t[ listen-only { on | off } ]\n"
		"\t[ triple-sampling { on | off } ]\n"
		"\t[ one-shot { on | off } ]\n"
		"\t[ berr-reporting { on | off } ]\n"
		"\t[ fd { on | off } ]\n"
		"\t[ fd-non-iso { on | off } ]\n"
		"\t[ presume-ack { on | off } ]\n"
		"\t[ cc-len8-dlc { on | off } ]\n"
		"\n"
		"\t[ restart-ms TIME-MS ]\n"
		"\t[ restart ]\n"
		"\n"
		"\t[ termination { 0..65535 } ]\n"
		"\n"
		"\tWhere: BITRATE	:= { 1..1000000 }\n"
		"\t	  SAMPLE-POINT	:= { 0.000..0.999 }\n"
		"\t	  TQ		:= { NUMBER }\n"
		"\t	  PROP-SEG	:= { 1..8 }\n"
		"\t	  PHASE-SEG1	:= { 1..8 }\n"
		"\t	  PHASE-SEG2	:= { 1..8 }\n"
		"\t	  SJW		:= { 1..4 }\n"
		"\t	  RESTART-MS	:= { 0 | NUMBER }\n"
		);
}

static void usage(void)
{
	print_usage(stderr);
}

static int iplink_set_can_parse(int argc, char **argv, struct nlmsghdr *nlh)
{
	struct can_bittiming bt = {}, dbt = {};
	struct can_ctrlmode cm = {};

	while (argc > 0) {
		if (matches(*argv, "bitrate") == 0) {
			NEXT_ARG();
			if (get_u32(&bt.bitrate, *argv, 0))
				invarg("invalid \"bitrate\" value\n", *argv);
		} else if (matches(*argv, "sample-point") == 0) {
			float sp;

			NEXT_ARG();
			if (get_float(&sp, *argv))
				invarg("invalid \"sample-point\" value\n",
				       *argv);

			bt.sample_point = (__u32)(sp * 1000);
		} else if (matches(*argv, "tq") == 0) {
			NEXT_ARG();
			if (get_u32(&bt.tq, *argv, 0))
				invarg("invalid \"tq\" value\n", *argv);
		} else if (matches(*argv, "prop-seg") == 0) {
			NEXT_ARG();
			if (get_u32(&bt.prop_seg, *argv, 0))
				invarg("invalid \"prop-seg\" value\n", *argv);
		} else if (matches(*argv, "phase-seg1") == 0) {
			NEXT_ARG();
			if (get_u32(&bt.phase_seg1, *argv, 0))
				invarg("invalid \"phase-seg1\" value\n", *argv);
		} else if (matches(*argv, "phase-seg2") == 0) {
			NEXT_ARG();
			if (get_u32(&bt.phase_seg2, *argv, 0))
				invarg("invalid \"phase-seg2\" value\n", *argv);
		} else if (matches(*argv, "sjw") == 0) {
			NEXT_ARG();
			if (get_u32(&bt.sjw, *argv, 0))
				invarg("invalid \"sjw\" value\n", *argv);
		} else if (matches(*argv, "dbitrate") == 0) {
			NEXT_ARG();
			if (get_u32(&dbt.bitrate, *argv, 0))
				invarg("invalid \"dbitrate\" value\n", *argv);
		} else if (matches(*argv, "dsample-point") == 0) {
			float sp;

			NEXT_ARG();
			if (get_float(&sp, *argv))
				invarg("invalid \"dsample-point\" value\n", *argv);
			dbt.sample_point = (__u32)(sp * 1000);
		} else if (matches(*argv, "dtq") == 0) {
			NEXT_ARG();
			if (get_u32(&dbt.tq, *argv, 0))
				invarg("invalid \"dtq\" value\n", *argv);
		} else if (matches(*argv, "dprop-seg") == 0) {
			NEXT_ARG();
			if (get_u32(&dbt.prop_seg, *argv, 0))
				invarg("invalid \"dprop-seg\" value\n", *argv);
		} else if (matches(*argv, "dphase-seg1") == 0) {
			NEXT_ARG();
			if (get_u32(&dbt.phase_seg1, *argv, 0))
				invarg("invalid \"dphase-seg1\" value\n", *argv);
		} else if (matches(*argv, "dphase-seg2") == 0) {
			NEXT_ARG();
			if (get_u32(&dbt.phase_seg2, *argv, 0))
				invarg("invalid \"dphase-seg2\" value\n", *argv);
		} else if (matches(*argv, "dsjw") == 0) {
			NEXT_ARG();
			if (get_u32(&dbt.sjw, *argv, 0))
				invarg("invalid \"dsjw\" value\n", *argv);
		} else if (matches(*argv, "loopback") == 0) {
			NEXT_ARG();
			set_ctrlmode("loopback", *argv, &cm,
				     CAN_CTRLMODE_LOOPBACK);
		} else if (matches(*argv, "listen-only") == 0) {
			NEXT_ARG();
			set_ctrlmode("listen-only", *argv, &cm,
				     CAN_CTRLMODE_LISTENONLY);
		} else if (matches(*argv, "triple-sampling") == 0) {
			NEXT_ARG();
			set_ctrlmode("triple-sampling", *argv, &cm,
				     CAN_CTRLMODE_3_SAMPLES);
		} else if (matches(*argv, "one-shot") == 0) {
			NEXT_ARG();
			set_ctrlmode("one-shot", *argv, &cm,
				     CAN_CTRLMODE_ONE_SHOT);
		} else if (matches(*argv, "berr-reporting") == 0) {
			NEXT_ARG();
			set_ctrlmode("berr-reporting", *argv, &cm,
				     CAN_CTRLMODE_BERR_REPORTING);
		} else if (matches(*argv, "fd") == 0) {
			NEXT_ARG();
			set_ctrlmode("fd", *argv, &cm,
				     CAN_CTRLMODE_FD);
		} else if (matches(*argv, "fd-non-iso") == 0) {
			NEXT_ARG();
			set_ctrlmode("fd-non-iso", *argv, &cm,
				     CAN_CTRLMODE_FD_NON_ISO);
		} else if (matches(*argv, "presume-ack") == 0) {
			NEXT_ARG();
			set_ctrlmode("presume-ack", *argv, &cm,
				     CAN_CTRLMODE_PRESUME_ACK);
#if defined(CAN_CTRLMODE_CC_LEN8_DLC)
		} else if (matches(*argv, "cc-len8-dlc") == 0) {
			NEXT_ARG();
			set_ctrlmode("cc-len8-dlc", *argv, &cm,
				     CAN_CTRLMODE_CC_LEN8_DLC);
#endif
		} else if (matches(*argv, "restart") == 0) {
			__u32 val = 1;

			mnl_attr_put(nlh, IFLA_CAN_RESTART, sizeof(val), &val);
		} else if (matches(*argv, "restart-ms") == 0) {
			__u32 val;

			NEXT_ARG();
			if (get_u32(&val, *argv, 0))
				invarg("invalid \"restart-ms\" value\n", *argv);

			mnl_attr_put(nlh, IFLA_CAN_RESTART_MS, sizeof(val), &val);
		} else if (matches(*argv, "termination") == 0) {
			__u16 val;

			NEXT_ARG();
			if (get_u16(&val, *argv, 0))
				invarg("invalid \"termination\" value\n",
				       *argv);

			mnl_attr_put(nlh, IFLA_CAN_TERMINATION, sizeof(val), &val);
		} else {
			fprintf(stderr, "unknown option \"%s\"\n", *argv);
			usage();
			return -1;
		}

		NEXT_ARG();
	}

	if (bt.bitrate || bt.tq)
		mnl_attr_put(nlh, IFLA_CAN_BITTIMING, sizeof(bt), &bt);

	if (cm.mask)
		mnl_attr_put(nlh, IFLA_CAN_CTRLMODE, sizeof(cm), &cm);

	return 0;
}

int main(int argc, char *argv[])
{
	char buf[MNL_SOCKET_BUFFER_SIZE];
	struct mnl_socket *nl;
	struct nlmsghdr *nlh;
	struct ifinfomsg *ifm;
	int ret;
	unsigned int seq, portid;
	struct nlattr *linkinfo, *data;
	const char *signatures[] = {
		"ip", "link", "set", ""
	};
	char *type = NULL;
	char *dev = NULL;
	int i;

	NEXT_ARG();
	for (i = 0; argc > 0 && signatures[i][0];) {
		if (matches(*argv, signatures[i]))
			incomplete_command();

		NEXT_ARG();
		i++;
	}

	if (argc == 0)
		incomplete_command();

	nlh = mnl_nlmsg_put_header(buf);
	nlh->nlmsg_type	= RTM_NEWLINK;
	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	nlh->nlmsg_seq = seq = time(NULL);
	ifm = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifm));
	ifm->ifi_family = AF_UNSPEC;
	ifm->ifi_change = 0;
	ifm->ifi_flags = 0;

	while (argc > 0) {
		if (matches(*argv, "up") == 0) {
			ifm->ifi_change |= IFF_UP;
			ifm->ifi_flags |= IFF_UP;
		} else if (matches(*argv, "down") == 0) {
			ifm->ifi_change |= IFF_UP;
			ifm->ifi_flags &= ~IFF_UP;
		} else if (matches(*argv, "type") == 0) {
			NEXT_ARG();
			type = *argv;
			NEXT_ARG();
			break;
		} else if (matches(*argv, "help") == 0) {
			usage();
			exit(EXIT_FAILURE);
		} else {
			if (matches(*argv, "dev") == 0)
				NEXT_ARG();

			if (dev)
				duparg2("dev", *argv);

			dev = *argv;
		}

		NEXT_ARG();
	}

	if (dev)
		mnl_attr_put_str(nlh, IFLA_IFNAME, dev);

	if (type) {
		if (matches(type, "can")) {
			fprintf(stderr, "unknown type \"%s\"\n", type);
			usage();
			exit(EXIT_FAILURE);
		}

		linkinfo = mnl_attr_nest_start(nlh, IFLA_LINKINFO);
		mnl_attr_put_str(nlh, IFLA_INFO_KIND, "can");
		data = mnl_attr_nest_start(nlh, IFLA_INFO_DATA);

		if (iplink_set_can_parse(argc, argv, nlh))
			return -1;

		mnl_attr_nest_end(nlh, data);
		mnl_attr_nest_end(nlh, linkinfo);
	}

	nl = mnl_socket_open(NETLINK_ROUTE);
	if (nl == NULL) {
		perror("mnl_socket_open");
		exit(EXIT_FAILURE);
	}

	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
		perror("mnl_socket_bind");
		exit(EXIT_FAILURE);
	}

	portid = mnl_socket_get_portid(nl);

	mnl_nlmsg_fprintf(stdout, nlh, nlh->nlmsg_len,
			  sizeof(struct ifinfomsg));

	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
		perror("mnl_socket_sendto");
		exit(EXIT_FAILURE);
	}

	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	if (ret == -1) {
		perror("mnl_socket_recvfrom");
		exit(EXIT_FAILURE);
	}

	ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
	if (ret == -1) {
		perror("mnl_cb_run");
		exit(EXIT_FAILURE);
	}

	mnl_socket_close(nl);

	return 0;
}