Patched isotpsend with non-blocking socket and epoll_wait

isotpsendnb.c

/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
/*
 * isotpsend.c
 *
 * Copyright (c) 2008 Volkswagen Group Electronic Research
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Volkswagen nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * Alternatively, provided that this notice is retained in full, this
 * software may be distributed under the terms of the GNU General
 * Public License ("GPL") version 2, in which case the provisions of the
 * GPL apply INSTEAD OF those given above.
 *
 * The provided data structures and external interfaces from this code
 * are not restricted to be used by modules with a GPL compatible license.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * Send feedback to <linux-can@vger.kernel.org>
 *
 */

#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <poll.h>
#include <errno.h>

#include <sys/epoll.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>

#include <linux/can.h>
#include <linux/can/isotp.h>

#define NO_CAN_ID 0xFFFFFFFFU
#define BUFSIZE 67000 /* size > 66000 kernel buf to test socket API internal checks */
#define ZERO_STRING "ZERO"

void print_usage(char *prg)
{
	fprintf(stderr, "\nUsage: %s [options] <CAN interface>\n", prg);
	fprintf(stderr, "Options:\n");
	fprintf(stderr, "         -s <can_id>  (source can_id. Use 8 digits for extended IDs)\n");
	fprintf(stderr, "         -d <can_id>  (destination can_id. Use 8 digits for extended IDs)\n");
	fprintf(stderr, "         -x <addr>[:<rxaddr>]  (extended addressing / opt. separate rxaddr)\n");
	fprintf(stderr, "         -p [tx]:[rx]  (set and enable tx/rx padding bytes)\n");
	fprintf(stderr, "         -P <mode>     (check rx padding for (l)ength (c)ontent (a)ll)\n");
	fprintf(stderr, "         -t <time ns>  (frame transmit time (N_As) in nanosecs) (*)\n");
	fprintf(stderr, "         -f <time ns>  (ignore FC and force local tx stmin value in nanosecs)\n");
	fprintf(stderr, "         -D <len>      (send a fixed PDU with len bytes - no STDIN data)\n");
	fprintf(stderr, "         -l <num>      (send num PDUs - use 'i' for infinite loop)\n");
	fprintf(stderr, "         -g <usecs>    (wait given usecs before sending a PDU)\n");
	fprintf(stderr, "         -b            (block until the PDU transmission is completed)\n");
	fprintf(stderr, "         -S            (SF broadcast mode - for functional addressing)\n");
	fprintf(stderr, "         -C            (CF broadcast mode - no wait for flow controls)\n");
	fprintf(stderr, "         -L <mtu>:<tx_dl>:<tx_flags>  (link layer options for CAN FD)\n");
	fprintf(stderr, "\nCAN IDs and addresses are given and expected in hexadecimal values.\n");
	fprintf(stderr, "The pdu data is expected on STDIN in space separated ASCII hex values.\n");
	fprintf(stderr, "(*) = Use '-t %s' to set N_As to zero for Linux version 5.18+\n", ZERO_STRING);
	fprintf(stderr, "\n");
}

int main(int argc, char **argv)
{
    int s;
    struct sockaddr_can addr;
    static struct can_isotp_options opts;
    static struct can_isotp_ll_options llopts;
    int opt;
    extern int optind, opterr, optopt;
    unsigned int loops = 1; /* one (== no) loop by default */
    useconds_t usecs = 0; /* wait before sending the PDU */
    __u32 force_tx_stmin = 0;
    unsigned char buf[BUFSIZE];
    int buflen = 0;
    int datalen = 0;
    int retval = 0;

    addr.can_addr.tp.tx_id = addr.can_addr.tp.rx_id = NO_CAN_ID;

    while ((opt = getopt(argc, argv, "s:d:x:p:P:t:f:D:l:g:bSCL:?")) != -1) {
	    switch (opt) {
	    case 's':
		    addr.can_addr.tp.tx_id = strtoul(optarg, NULL, 16);
		    if (strlen(optarg) > 7)
			    addr.can_addr.tp.tx_id |= CAN_EFF_FLAG;
		    break;

	    case 'd':
		    addr.can_addr.tp.rx_id = strtoul(optarg, NULL, 16);
		    if (strlen(optarg) > 7)
			    addr.can_addr.tp.rx_id |= CAN_EFF_FLAG;
		    break;

	    case 'x':
	    {
		    int elements = sscanf(optarg, "%hhx:%hhx",
					  &opts.ext_address,
					  &opts.rx_ext_address);

		    if (elements == 1)
			    opts.flags |= CAN_ISOTP_EXTEND_ADDR;
		    else if (elements == 2)
			    opts.flags |= (CAN_ISOTP_EXTEND_ADDR | CAN_ISOTP_RX_EXT_ADDR);
		    else {
			    printf("incorrect extended addr values '%s'.\n", optarg);
			    print_usage(basename(argv[0]));
			    exit(0);
		    }
		    break;
	    }

	    case 'p':
	    {
		    int elements = sscanf(optarg, "%hhx:%hhx",
					  &opts.txpad_content,
					  &opts.rxpad_content);

		    if (elements == 1)
			    opts.flags |= CAN_ISOTP_TX_PADDING;
		    else if (elements == 2)
			    opts.flags |= (CAN_ISOTP_TX_PADDING | CAN_ISOTP_RX_PADDING);
		    else if (sscanf(optarg, ":%hhx", &opts.rxpad_content) == 1)
			    opts.flags |= CAN_ISOTP_RX_PADDING;
		    else {
			    printf("incorrect padding values '%s'.\n", optarg);
			    print_usage(basename(argv[0]));
			    exit(0);
		    }
		    break;
	    }

	    case 'P':
		    if (optarg[0] == 'l')
			    opts.flags |= CAN_ISOTP_CHK_PAD_LEN;
		    else if (optarg[0] == 'c')
			    opts.flags |= CAN_ISOTP_CHK_PAD_DATA;
		    else if (optarg[0] == 'a')
			    opts.flags |= (CAN_ISOTP_CHK_PAD_LEN | CAN_ISOTP_CHK_PAD_DATA);
		    else {
			    printf("unknown padding check option '%c'.\n", optarg[0]);
			    print_usage(basename(argv[0]));
			    exit(0);
		    }
		    break;

	    case 't':
		    if (!strncmp(optarg, ZERO_STRING, strlen(ZERO_STRING)))
			    opts.frame_txtime = CAN_ISOTP_FRAME_TXTIME_ZERO;
		    else
			    opts.frame_txtime = strtoul(optarg, NULL, 10);
		    break;

	    case 'f':
		    opts.flags |= CAN_ISOTP_FORCE_TXSTMIN;
		    force_tx_stmin = strtoul(optarg, NULL, 10);
		    break;

	    case 'D':
		    datalen = strtoul(optarg, NULL, 10);
		    if (!datalen || datalen >= BUFSIZE) {
			    print_usage(basename(argv[0]));
			    exit(0);
		    }
		    break;

	    case 'l':
		    if (optarg[0] == 'i') {
			    loops = 0; /* infinite loop */
		    } else {
			    loops = strtoul(optarg, NULL, 10);
			    if (!loops) {
				    fprintf(stderr, "Invalid argument for option -l!\n");
				    return 1;
			    }
		    }
		    break;

	    case 'g':
		    usecs = strtoul(optarg, NULL, 10);
		    break;

	    case 'b':
		    opts.flags |= CAN_ISOTP_WAIT_TX_DONE;
		    break;

	    case 'S':
		    opts.flags |= CAN_ISOTP_SF_BROADCAST;
		    break;

	    case 'C':
		    opts.flags |= CAN_ISOTP_CF_BROADCAST;
		    break;

	    case 'L':
		    if (sscanf(optarg, "%hhu:%hhu:%hhu",
			       &llopts.mtu,
			       &llopts.tx_dl,
			       &llopts.tx_flags) != 3) {
			    printf("unknown link layer options '%s'.\n", optarg);
			    print_usage(basename(argv[0]));
			    exit(0);
		    }
		    break;

	    case '?':
		    print_usage(basename(argv[0]));
		    exit(0);
		    break;

	    default:
		    fprintf(stderr, "Unknown option %c\n", opt);
		    print_usage(basename(argv[0]));
		    exit(1);
		    break;
	    }
    }

#define BC_FLAGS (CAN_ISOTP_SF_BROADCAST | CAN_ISOTP_CF_BROADCAST)

    if ((argc - optind != 1) ||
	(addr.can_addr.tp.tx_id == NO_CAN_ID) ||
	((opts.flags & BC_FLAGS) == BC_FLAGS) ||
	((addr.can_addr.tp.rx_id == NO_CAN_ID) &&
	 (!(opts.flags & BC_FLAGS)))) {
	    print_usage(basename(argv[0]));
	    exit(1);
    }

    if ((s = socket(PF_CAN, SOCK_DGRAM, CAN_ISOTP)) < 0) {
	perror("socket");
	exit(1);
    }

    if (setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_OPTS, &opts, sizeof(opts)) < 0) {
	perror("sockopt");
	exit(1);
    }


    if (llopts.tx_dl) {
	if (setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_LL_OPTS, &llopts, sizeof(llopts)) < 0) {
	    perror("link layer sockopt");
	    exit(1);
	}
    }

    if (opts.flags & CAN_ISOTP_FORCE_TXSTMIN)
	    setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_TX_STMIN, &force_tx_stmin, sizeof(force_tx_stmin));


    addr.can_family = AF_CAN;
    addr.can_ifindex = if_nametoindex(argv[optind]);
    if (!addr.can_ifindex) {
	perror("if_nametoindex");
	exit(1);
    }

    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
	perror("bind");
	close(s);
	exit(1);
    }
    fcntl(s, F_SETFL, O_RDWR | O_NONBLOCK);

    if (!datalen) {
	    while (buflen < BUFSIZE && scanf("%hhx", &buf[buflen]) == 1)
		    buflen++;
    } else {
	    for (buflen = 0; buflen < datalen; buflen++)
		    buf[buflen] = ((buflen % 0xFF) + 1) & 0xFF;
    }

	int epollfd = epoll_create(1);
	if (retval < 0) {
		perror("epoll_create");
		return 1;
	}
	struct epoll_event s_ev = {
		.events = EPOLLIN|EPOLLOUT|EPOLLRDHUP,
	};

	retval  = epoll_ctl(epollfd, EPOLL_CTL_ADD, s, &s_ev);
	if (retval < 0) {
		perror("epoll_ctl");
		return 1;
	}


loop:
    if (usecs)
	    usleep(usecs);

	retval = epoll_wait(epollfd, &s_ev, 1, 2000);
	if (retval < 0) {
		perror("epoll_wait");
		return 1;
	}

    retval = write(s, buf, buflen);
    if (retval < 0) {
		if (errno == EAGAIN)
			goto loop;
	    perror("write");
	    return retval;
    }

    if (retval != buflen)
	    fprintf(stderr, "wrote only %d from %d byte\n", retval, buflen);

    if (loops) {
	    if (--loops)
		    goto loop;
    } else {
	    goto loop;
    }

    /* 
     * due to a Kernel internal wait queue the PDU is sent completely
     * before close() returns.
     */
    close(s);

    return 0;
}