/*
 * Copyright (c) 2001, Adam Dunkels.
 * Copyright (c) 2009, 2010 Joakim Eriksson, Niclas Finne, Dogan Yazar.
 * 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. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 * This file is part of the uIP TCP/IP stack.
 *
 *
 */

/* Below define allows importing saved output into Wireshark as "Raw IP" packet type */
#define WIRESHARK_IMPORT_FORMAT 1
/* for cfmakeraw on Linux */
#define _BSD_SOURCE 1
#define _DEFAULT_SOURCE 1

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/time.h>

#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#include <sys/ioctl.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#include <err.h>

int verbose = 1;
const char *ipaddr;
const char *netmask;
int slipfd = 0;
uint16_t basedelay = 0, delaymsec = 0;
uint32_t startsec, startmsec, delaystartsec, delaystartmsec;
int timestamp = 0, flowcontrol = 0;

int ssystem(const char *fmt, ...) __attribute__((__format__(__printf__, 1, 2)));
void write_to_serial(int outfd, void *inbuf, int len);

void slip_send(int fd, unsigned char c);
void slip_send_char(int fd, unsigned char c);

//#define PROGRESS(s) fprintf(stderr, s)
#define PROGRESS(s) do { } while (0)

char tundev[1024] = { "" };

int
ssystem(const char *fmt, ...) __attribute__((__format__(__printf__, 1, 2)));

int
ssystem(const char *fmt, ...)
{
    char cmd[128];
    va_list ap;
    va_start(ap, fmt);
    vsnprintf(cmd, sizeof(cmd), fmt, ap);
    va_end(ap);
    printf("%s\n", cmd);
    fflush(stdout);
    return system(cmd);
}

#define SLIP_END     0300
#define SLIP_ESC     0333
#define SLIP_ESC_END 0334
#define SLIP_ESC_ESC 0335


/* get sockaddr, IPv4 or IPv6: */
void *
get_in_addr(struct sockaddr *sa)
{
    if (sa->sa_family == AF_INET) {
        return &(((struct sockaddr_in *)sa)->sin_addr);
    }

    return &(((struct sockaddr_in6 *)sa)->sin6_addr);
}
void
stamptime(void)
{
    static long startsecs = 0, startmsecs = 0;
    long secs, msecs;
    struct timeval tv;
    time_t t;

    gettimeofday(&tv, NULL) ;
    msecs = tv.tv_usec / 1000;
    secs = tv.tv_sec;

    if (startsecs) {
        secs -= startsecs;
        msecs -= startmsecs;

        if (msecs < 0) {
            secs--;
            msecs += 1000;
        }

        fprintf(stderr, "%04li.%03li ", secs, msecs);
    }
    else {
        char timec[20];
        startsecs = secs;
        startmsecs = msecs;
        t = time(NULL);
        struct tm *tmp = localtime(&t);
        strftime(timec, sizeof(timec), "%T", tmp);
        //    fprintf(stderr,"\n%s.%03lu ",timec,msecs);
        fprintf(stderr, "\n%s ", timec);
    }
}

int
is_sensible_string(const unsigned char *s, size_t len)
{
    if(len > 0) {
        if (s[0] == 0x60) {
            /* Possibly IPv6 packet with default traffic class, assume non-printable */
            return 0;
        }
    }

    int ret = 0;
    for (size_t i = 0; i < len; i++) {
        if (s[i] == '\r' || s[i] == '\n' || s[i] == '\t') {
            continue;
        }
        else if (s[i] < ' ' || '~' < s[i]) {
            return 0;
        }
        /* only return 1 if the string contains at least one letter or number */
        if('A' <= s[i] && s[i] <= 'Z') {
            ret = 1;
        }
        else if('a' <= s[i] && s[i] <= 'z') {
            ret = 1;
        }
        else if('0' <= s[i] && s[i] <= '9') {
            ret = 1;
        }
    }

    return ret;
}

/*
 * Read from serial, when we have a packet write it to tun. No output
 * buffering, input buffered by stdio.
 */
void
serial_to_tun(FILE *inslip, int outfd)
{
    static union {
        unsigned char inbuf[2000];
    } uip;
    static unsigned int inbufptr = 0;
    /* cppcheck-suppress variableScope
     * rationale: cannot be reduced if built on linux */
    int ret;
    unsigned char c;

#ifdef __linux__
    ret = fread(&c, 1, 1, inslip);

    if (ret == -1 || ret == 0) {
        err(1, "serial_to_tun: read");
    }

    goto after_fread;
#endif

    while (1) {
        if (inbufptr >= sizeof(uip.inbuf)) {
            if (timestamp) {
                stamptime();
            }

            fprintf(stderr, "*** dropping large %u byte packet\n", inbufptr);
            inbufptr = 0;
        }

        ret = fread(&c, 1, 1, inslip);
#ifdef __linux__
    after_fread:
#endif

        if (ret == -1) {
            err(1, "serial_to_tun: read");
        }

        if (ret == 0) {
            clearerr(inslip);
            return;
        }

        /*  fprintf(stderr, ".");*/
        switch (c) {
            case SLIP_END:
                if (inbufptr > 0) {
                    if (uip.inbuf[0] == '!') {
                        if (uip.inbuf[1] == 'M') {
                            /* Read gateway MAC address and autoconfigure tap0 interface */
                            char macs[24];
                            unsigned int pos = 0;

                            for (unsigned int i = 0; i < 16; i++) {
                                macs[pos++] = uip.inbuf[2 + i];

                                if ((i & 1) == 1 && i < 14) {
                                    macs[pos++] = ':';
                                }
                            }

                            if (timestamp) {
                                stamptime();
                            }

                            macs[pos] = '\0';
                            fprintf(stderr, "*** Gateway's MAC address: %s\n", macs);

                            if (timestamp) {
                                stamptime();
                            }

                            ssystem("ifconfig %s down", tundev);

                            if (timestamp) {
                                stamptime();
                            }

                            ssystem("ifconfig %s hw ether %s", tundev, &macs[6]);

                            if (timestamp) {
                                stamptime();
                            }

                            ssystem("ifconfig %s up", tundev);
                        }
                    }
                    else if (uip.inbuf[0] == '?') {
                        if (uip.inbuf[1] == 'P') {
                            /* Prefix info requested */
                            struct in6_addr addr;
                            char *s = strchr(ipaddr, '/');

                            if (s != NULL) {
                                *s = '\0';
                            }

                            inet_pton(AF_INET6, ipaddr, &addr);

                            if (timestamp) {
                                stamptime();
                            }

                            fprintf(stderr, "*** Address:%s => %02x%02x:%02x%02x:%02x%02x:%02x%02x\n",
                                    ipaddr,
                                    addr.s6_addr[0], addr.s6_addr[1],
                                    addr.s6_addr[2], addr.s6_addr[3],
                                    addr.s6_addr[4], addr.s6_addr[5],
                                    addr.s6_addr[6], addr.s6_addr[7]);
                            slip_send(slipfd, '!');
                            slip_send(slipfd, 'P');

                            for (unsigned int i = 0; i < 8; i++) {
                                /* need to call the slip_send_char for stuffing */
                                slip_send_char(slipfd, addr.s6_addr[i]);
                            }

                            slip_send(slipfd, SLIP_END);
                        }

#define DEBUG_LINE_MARKER '\r'
                    }
                    else if (uip.inbuf[0] == DEBUG_LINE_MARKER) {
                        fwrite(uip.inbuf + 1, inbufptr - 1, 1, stdout);
                    }
                    else if (is_sensible_string(uip.inbuf, inbufptr)) {
                        if (verbose == 1) { /* strings already echoed below for verbose>1 */
                            if (timestamp) {
                                stamptime();
                            }

                            fwrite(uip.inbuf, inbufptr, 1, stdout);
                        }
                    }
                    else {
                        if (verbose > 2) {
                            if (timestamp) {
                                stamptime();
                            }

                            printf("Packet from SLIP of length %u - write TUN\n", inbufptr);

                            if (verbose > 4) {
#if WIRESHARK_IMPORT_FORMAT
                                printf("0000");

                                for (unsigned int i = 0; i < inbufptr; i++) {
                                    printf(" %02x", uip.inbuf[i]);
                                }

#else
                                printf("         ");

                                for (unsigned int i = 0; i < inbufptr; i++) {
                                    printf("%02x", uip.inbuf[i]);

                                    if ((i & 3) == 3) {
                                        printf(" ");
                                    }

                                    if ((i & 15) == 15) {
                                        printf("\n         ");
                                    }
                                }

#endif
                                printf("\n");
                            }
                        }

                        if (write(outfd, uip.inbuf, inbufptr) != inbufptr) {
                            err(1, "serial_to_tun: write");
                        }
                    }

                    inbufptr = 0;
                }

                break;

            case SLIP_ESC:
                if (fread(&c, 1, 1, inslip) != 1) {
                    clearerr(inslip);
                    /* Put ESC back and give up! */
                    ungetc(SLIP_ESC, inslip);
                    return;
                }

                switch (c) {
                    case SLIP_ESC_END:
                        c = SLIP_END;
                        break;

                    case SLIP_ESC_ESC:
                        c = SLIP_ESC;
                        break;
                }

                /* FALLTHROUGH */
            default:
                uip.inbuf[inbufptr++] = c;

                /* Echo lines as they are received for verbose=2,3,5+ */
                /* Echo all printable characters for verbose==4 */
                if ((verbose == 2) || (verbose == 3) || (verbose > 4)) {
                    if (c == '\n') {
                        if (is_sensible_string(uip.inbuf, inbufptr)) {
                            if (timestamp) {
                                stamptime();
                            }

                            fwrite(uip.inbuf, inbufptr, 1, stdout);
                            inbufptr = 0;
                        }
                    }
                }
                else if (verbose == 4) {
                    if (c == 0 || c == '\r' || c == '\n' || c == '\t' || (c >= ' ' && c <= '~')) {
                        fwrite(&c, 1, 1, stdout);

                        if (c == '\n') if (timestamp) {
                                stamptime();
                            }
                    }
                }

                break;
        }
    }
}

unsigned char slip_buf[2000];
unsigned int slip_end, slip_begin;

void
slip_send_char(int fd, unsigned char c)
{
    switch (c) {
        case SLIP_END:
            slip_send(fd, SLIP_ESC);
            slip_send(fd, SLIP_ESC_END);
            break;

        case SLIP_ESC:
            slip_send(fd, SLIP_ESC);
            slip_send(fd, SLIP_ESC_ESC);
            break;

        default:
            slip_send(fd, c);
            break;
    }
}

int
slip_empty()
{
    return slip_end == 0;
}

void
slip_flushbuf(int fd)
{
    int n;

    if (slip_empty()) {
        return;
    }

    n = write(fd, slip_buf + slip_begin, (slip_end - slip_begin));

    if (n == -1 && errno != EAGAIN) {
        err(1, "slip_flushbuf write failed");
    }
    else if (n == -1) {
        PROGRESS("Q");      /* Outqueue is full! */
    }
    else {
        slip_begin += n;

        if (slip_begin == slip_end) {
            slip_begin = slip_end = 0;
        }
    }
}

void
slip_send(int fd, unsigned char c)
{
    if (slip_end >= sizeof(slip_buf)) {
        err(1, "slip_send overflow");
    }

    slip_buf[slip_end] = c;
    slip_end++;
    if (slip_end >= sizeof(slip_buf)) {
        /* attempt to flush what is in the buffer */
        slip_flushbuf(fd);
    }
}

void
write_to_serial(int outfd, void *inbuf, int len)
{
    u_int8_t *p = inbuf;
    int i;

    if (verbose > 2) {
        if (timestamp) {
            stamptime();
        }

        printf("Packet from TUN of length %d - write SLIP\n", len);

        if (verbose > 4) {
#if WIRESHARK_IMPORT_FORMAT
            printf("0000");

            for (i = 0; i < len; i++) {
                printf(" %02x", p[i]);
            }

#else
            printf("         ");

            for (i = 0; i < len; i++) {
                printf("%02x", p[i]);

                if ((i & 3) == 3) {
                    printf(" ");
                }

                if ((i & 15) == 15) {
                    printf("\n         ");
                }
            }

#endif
            printf("\n");
        }
    }

    /* It would be ``nice'' to send a SLIP_END here but it's not
     * really necessary.
     */
    /* slip_send(outfd, SLIP_END); */

    for (i = 0; i < len; i++) {
        switch (p[i]) {
            case SLIP_END:
                slip_send(outfd, SLIP_ESC);
                slip_send(outfd, SLIP_ESC_END);
                break;

            case SLIP_ESC:
                slip_send(outfd, SLIP_ESC);
                slip_send(outfd, SLIP_ESC_ESC);
                break;

            default:
                slip_send(outfd, p[i]);
                break;
        }
    }

    slip_send(outfd, SLIP_END);
    PROGRESS("t");
}


/*
 * Read from tun, write to slip.
 */
int
tun_to_serial(int infd, int outfd)
{
    struct {
        unsigned char inbuf[2000];
    } uip;

    int size = read(infd, uip.inbuf, 2000);

    if (size == -1) {
        err(1, "tun_to_serial: read");
    }

    write_to_serial(outfd, uip.inbuf, size);
    return size;
}

#ifndef BAUDRATE
#define BAUDRATE B115200
#endif
speed_t b_rate = BAUDRATE;

void
stty_telos(int fd)
{
    struct termios tty;
    speed_t speed = b_rate;
    int i;

    if (tcflush(fd, TCIOFLUSH) == -1) {
        err(1, "tcflush");
    }

    if (tcgetattr(fd, &tty) == -1) {
        err(1, "tcgetattr");
    }

    cfmakeraw(&tty);

    /* Nonblocking read. */
    tty.c_cc[VTIME] = 0;
    tty.c_cc[VMIN] = 0;

    if (flowcontrol) {
        tty.c_cflag |= CRTSCTS;
    }
    else {
        tty.c_cflag &= ~CRTSCTS;
    }

    tty.c_cflag &= ~HUPCL;
    tty.c_cflag &= ~CLOCAL;

    cfsetispeed(&tty, speed);
    cfsetospeed(&tty, speed);

    if (tcsetattr(fd, TCSAFLUSH, &tty) == -1) {
        err(1, "tcsetattr");
    }

#if 1
    /* Nonblocking read and write. */
    /* if (fcntl(fd, F_SETFL, O_NONBLOCK) == -1) err(1, "fcntl"); */

    tty.c_cflag |= CLOCAL;

    if (tcsetattr(fd, TCSAFLUSH, &tty) == -1) {
        err(1, "tcsetattr");
    }

    i = TIOCM_DTR;

    if (ioctl(fd, TIOCMBIS, &i) == -1) {
        err(1, "ioctl");
    }

#endif

    usleep(10 * 1000);      /* Wait for hardware 10ms. */

    /* Flush input and output buffers. */
    if (tcflush(fd, TCIOFLUSH) == -1) {
        err(1, "tcflush");
    }
}

int
devopen(const char *dev, int flags)
{
    char t[1024];
    strcpy(t, "/dev/");
    /* cppcheck-suppress bufferAccessOutOfBounds
     * reason: seems to be a cppcheck bug */
    strncat(t, dev, sizeof(t) - 5);
    return open(t, flags);
}

#ifdef __linux__
#include <linux/if.h>
#include <linux/if_tun.h>

int
tun_alloc(char *dev, int tap)
{
    struct ifreq ifr;
    int fd, err;

    if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
        return -1;
    }

    memset(&ifr, 0, sizeof(ifr));

    /* Flags: IFF_TUN   - TUN device (no Ethernet headers)
     *        IFF_TAP   - TAP device
     *
     *        IFF_NO_PI - Do not provide packet information
     */
    ifr.ifr_flags = (tap ? IFF_TAP : IFF_TUN) | IFF_NO_PI;

    if (*dev != 0) {
        strncpy(ifr.ifr_name, dev, IFNAMSIZ);
    }

    if ((err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0) {
        close(fd);
        return err;
    }

    strcpy(dev, ifr.ifr_name);
    return fd;
}
#else
int
tun_alloc(char *dev, int tap)
{
    (void) tap;
    return devopen(dev, O_RDWR);
}
#endif

void
cleanup(void)
{
#ifndef __APPLE__

    if (timestamp) {
        stamptime();
    }

    ssystem("ifconfig %s down", tundev);
#ifndef __linux__
    ssystem("sysctl -w net.ipv6.conf.all.forwarding=1");
#endif

    /* ssystem("arp -d %s", ipaddr); */
    if (timestamp) {
        stamptime();
    }

    ssystem("netstat -nr"
            " | awk '{ if ($2 == \"%s\") print \"route delete -net \"$1; }'"
            " | sh",
            tundev);
#else
    {
        char   *itfaddr = strdup(ipaddr);
        char   *prefix = index(itfaddr, '/');

        if (timestamp) {
            stamptime();
        }

        ssystem("ifconfig %s inet6 %s remove", tundev, ipaddr);

        if (timestamp) {
            stamptime();
        }

        ssystem("ifconfig %s down", tundev);

        if (prefix != NULL) {
            *prefix = '\0';
        }

        ssystem("route delete -inet6 %s", itfaddr);
        free(itfaddr);
    }
#endif
}

void
sigcleanup(int signo)
{
    fprintf(stderr, "signal %d\n", signo);
    exit(0);            /* exit(0) will call cleanup() */
}

static int got_sigalarm;

void
sigalarm(int signo)
{
    (void) signo; /* not used */
    got_sigalarm = 1;
    return;
}

void
sigalarm_reset()
{
#ifdef __linux__
#define TIMEOUT (997*1000)
#else
#define TIMEOUT (2451*1000)
#endif
    ualarm(TIMEOUT, TIMEOUT);
    got_sigalarm = 0;
}

void
ifconf(const char *tundev, const char *ipaddr)
{
#ifdef __linux__

    if (timestamp) {
        stamptime();
    }

    ssystem("ifconfig %s inet `hostname` up", tundev);

    if (timestamp) {
        stamptime();
    }

    ssystem("ifconfig %s add %s", tundev, ipaddr);

    /* radvd needs a link local address for routing */
#if 0
    /* fe80::1/64 is good enough */
    ssystem("ifconfig %s add fe80::1/64", tundev);
#elif 1
    /* Generate a link local address a la sixxs/aiccu */
    /* First a full parse, stripping off the prefix length */
    {
        char lladdr[40];
        char c, *ptr = (char *)ipaddr;
        uint16_t digit, ai, a[8], cc, scc, i;

        for (ai = 0; ai < 8; ai++) {
            a[ai] = 0;
        }

        ai = 0;
        cc = scc = 0;

        while ((c = *(ptr++))) {
            if (c == '/') {
                break;
            }

            if (c == ':') {
                if (cc) {
                    scc = ai;
                }

                cc = 1;

                if (++ai > 7) {
                    break;
                }
            }
            else {
                cc = 0;
                digit = c - '0';

                if (digit > 9) {
                    digit = 10 + (c & 0xdf) - 'A';
                }

                a[ai] = (a[ai] << 4) + digit;
            }
        }

        /* Get # elided and shift what's after to the end */
        cc = 8 - ai;

        for (i = 0; i < cc; i++) {
            if ((8 - i - cc) <= scc) {
                a[7 - i] = 0;
            }
            else {
                a[7 - i] = a[8 - i - cc];
                a[8 - i - cc] = 0;
            }
        }

        sprintf(lladdr, "fe80::%x:%x:%x:%x", a[1] & 0xfefd, a[2], a[3], a[7]);

        if (timestamp) {
            stamptime();
        }

        ssystem("ifconfig %s add %s/64", tundev, lladdr);
    }
#endif /* link local */
#elif defined(__APPLE__)
    {
        char *itfaddr = strdup(ipaddr);
        char *prefix = index(itfaddr, '/');

        if (prefix != NULL) {
            *prefix = '\0';
        }

        if (timestamp) {
            stamptime();
        }

        ssystem("ifconfig %s inet6 up", tundev);

        if (timestamp) {
            stamptime();
        }

        ssystem("ifconfig %s inet6 %s add", tundev, ipaddr);

        if (timestamp) {
            stamptime();
        }

        ssystem("sysctl -w net.inet6.ip6.forwarding=1");
        free(itfaddr);
    }
#else

    if (timestamp) {
        stamptime();
    }

    ssystem("ifconfig %s inet `hostname` %s up", tundev, ipaddr);

    if (timestamp) {
        stamptime();
    }

    ssystem("sysctl -w net.inet.ip.forwarding=1");
#endif /* !__linux__ */

    if (timestamp) {
        stamptime();
    }

    ssystem("ifconfig %s\n", tundev);
}

int
main(int argc, char **argv)
{
    int c;
    int tunfd;
    fd_set rset, wset;
    FILE *inslip;
    const char *siodev = NULL;
    const char *host = NULL;
    const char *port = NULL;
    const char *prog;
    int baudrate = -2;
    int tap = 0;
    slipfd = 0;

    prog = argv[0];
    setvbuf(stdout, NULL, _IOLBF, 0); /* Line buffered output. */

    while ((c = getopt(argc, argv, "B:HLhs:t:v::d::a:p:T")) != -1) {
        switch (c) {
            case 'B':
                baudrate = atoi(optarg);
                break;

            case 'H':
                flowcontrol = 1;
                break;

            case 'L':
                timestamp = 1;
                break;

            case 's':
                if (strncmp("/dev/", optarg, 5) == 0) {
                    siodev = optarg + 5;
                }
                else {
                    siodev = optarg;
                }

                break;

            case 't':
                if (strncmp("/dev/", optarg, 5) == 0) {
                    strncpy(tundev, optarg + 5, sizeof(tundev));
                }
                else {
                    strncpy(tundev, optarg, sizeof(tundev));
                }

                break;

            case 'a':
                host = optarg;
                break;

            case 'p':
                port = optarg;
                break;

            case 'd':
                basedelay = 10;

                if (optarg) {
                    basedelay = atoi(optarg);
                }

                break;

            case 'v':
                verbose = 2;

                if (optarg) {
                    verbose = atoi(optarg);
                }

                break;

            case 'T':
                tap = 1;
                break;

            case '?':
            case 'h':
            default:
                fprintf(stderr, "usage:  %s [options] ipaddress\n", prog);
                fprintf(stderr, "example: tunslip6 -L -v2 -s ttyUSB1 aaaa::1/64\n");
                fprintf(stderr, "Options are:\n");
#ifndef __APPLE__
                fprintf(stderr, " -B baudrate    9600,19200,38400,57600,115200 (default),230400,460800,921600\n");
#else
                fprintf(stderr, " -B baudrate    9600,19200,38400,57600,115200 (default),230400\n");
#endif
                fprintf(stderr, " -H             Hardware CTS/RTS flow control (default disabled)\n");
                fprintf(stderr, " -L             Log output format (adds time stamps)\n");
                fprintf(stderr, " -s siodev      Serial device (default /dev/ttyUSB0)\n");
                fprintf(stderr, " -T             Make tap interface (default is tun interface)\n");
                fprintf(stderr, " -t tundev      Name of interface (default tap0 or tun0)\n");
                fprintf(stderr, " -v[level]      Verbosity level\n");
                fprintf(stderr, "    -v0         No messages\n");
                fprintf(stderr, "    -v1         Encapsulated SLIP debug messages (default)\n");
                fprintf(stderr, "    -v2         Printable strings after they are received\n");
                fprintf(stderr, "    -v3         Printable strings and SLIP packet notifications\n");
                fprintf(stderr, "    -v4         All printable characters as they are received\n");
                fprintf(stderr, "    -v5         All SLIP packets in hex\n");
                fprintf(stderr, "    -v          Equivalent to -v3\n");
                fprintf(stderr, " -d[basedelay]  Minimum delay between outgoing SLIP packets.\n");
                fprintf(stderr, "                Actual delay is basedelay*(#6LowPAN fragments) milliseconds.\n");
                fprintf(stderr, "                -d is equivalent to -d10.\n");
                fprintf(stderr, " -a serveraddr  \n");
                fprintf(stderr, " -p serverport  \n");
                exit(1);
                break;
        }
    }

    argc -= (optind - 1);
    argv += (optind - 1);

    if (argc != 2 && argc != 3) {
        err(1, "usage: %s [-B baudrate] [-H] [-L] [-s siodev] [-t tundev] [-T] [-v verbosity] [-d delay] [-a serveraddress] [-p serverport] ipaddress",
            prog);
    }

    ipaddr = argv[1];

    switch (baudrate) {
        case -2:
            break;          /* Use default. */

        case 9600:
            b_rate = B9600;
            break;

        case 19200:
            b_rate = B19200;
            break;

        case 38400:
            b_rate = B38400;
            break;

        case 57600:
            b_rate = B57600;
            break;

        case 115200:
            b_rate = B115200;
            break;

        case 230400:
            b_rate = B230400;
            break;
#ifndef __APPLE__

        case 460800:
            b_rate = B460800;
            break;

        case 921600:
            b_rate = B921600;
            break;
#endif

        default:
            err(1, "unknown baudrate %d", baudrate);
            break;
    }

    if (*tundev == '\0') {
        /* Use default. */
        if (tap) {
            strcpy(tundev, "tap0");
        }
        else {
            strcpy(tundev, "tun0");
        }
    }

    if (host != NULL) {
        struct addrinfo hints, *servinfo, *p;
        int rv;
        char s[INET6_ADDRSTRLEN];

        if (port == NULL) {
            port = "60001";
        }

        memset(&hints, 0, sizeof hints);
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;

        if ((rv = getaddrinfo(host, port, &hints, &servinfo)) != 0) {
            err(1, "getaddrinfo: %s", gai_strerror(rv));
        }

        /* loop through all the results and connect to the first we can */
        for (p = servinfo; p != NULL; p = p->ai_next) {
            if ((slipfd = socket(p->ai_family, p->ai_socktype,
                                 p->ai_protocol)) == -1) {
                perror("client: socket");
                continue;
            }

            if (connect(slipfd, p->ai_addr, p->ai_addrlen) == -1) {
                close(slipfd);
                perror("client: connect");
                continue;
            }

            break;
        }

        if (p == NULL) {
            err(1, "can't connect to ``%s:%s''", host, port);
        }

        fcntl(slipfd, F_SETFL, O_NONBLOCK);

        inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),
                  s, sizeof(s));
        fprintf(stderr, "slip connected to ``%s:%s''\n", s, port);

        /* all done with this structure */
        freeaddrinfo(servinfo);

    }
    else {
        if (siodev != NULL) {
            slipfd = devopen(siodev, O_RDWR | O_NONBLOCK);

            if (slipfd == -1) {
                err(1, "can't open siodev ``/dev/%s''", siodev);
            }
        }
        else {
            static const char *siodevs[] = {
                "ttyUSB0", "cuaU0", "ucom0" /* linux, fbsd6, fbsd5 */
            };
            int i;

            for (i = 0; i < 3; i++) {
                siodev = siodevs[i];
                slipfd = devopen(siodev, O_RDWR | O_NONBLOCK);

                if (slipfd != -1) {
                    break;
                }
            }

            if (slipfd == -1) {
                err(1, "can't open siodev");
            }
        }

        if (timestamp) {
            stamptime();
        }

        fprintf(stderr, "********SLIP started on ``/dev/%s''\n", siodev);
        stty_telos(slipfd);
    }

    slip_send(slipfd, SLIP_END);
    inslip = fdopen(slipfd, "r");

    if (inslip == NULL) {
        err(1, "main: fdopen");
    }

    tunfd = tun_alloc(tundev, tap);

    if (tunfd == -1) {
        err(1, "main: open");
    }

    if (timestamp) {
        stamptime();
    }

    fprintf(stderr, "opened %s device ``/dev/%s''\n",
            tap ? "tap" : "tun", tundev);

    atexit(cleanup);
    signal(SIGHUP, sigcleanup);
    signal(SIGTERM, sigcleanup);
    signal(SIGINT, sigcleanup);
    signal(SIGALRM, sigalarm);
    ifconf(tundev, ipaddr);

    while (1) {
        int maxfd = 0;
        FD_ZERO(&rset);
        FD_ZERO(&wset);

        /* do not send IPA all the time... - add get MAC later... */
        /*     if (got_sigalarm) { */
        /*       /\* Send "?IPA". *\/ */
        /*       slip_send(slipfd, '?'); */
        /*       slip_send(slipfd, 'I'); */
        /*       slip_send(slipfd, 'P'); */
        /*       slip_send(slipfd, 'A'); */
        /*       slip_send(slipfd, SLIP_END); */
        /*       got_sigalarm = 0; */
        /*     } */

        if (!slip_empty()) {        /* Anything to flush? */
            FD_SET(slipfd, &wset);
        }

        FD_SET(slipfd, &rset);  /* Read from slip ASAP! */

        if (slipfd > maxfd) {
            maxfd = slipfd;
        }

        /* We only have one packet at a time queued for slip output. */
        if (slip_empty()) {
            FD_SET(tunfd, &rset);

            if (tunfd > maxfd) {
                maxfd = tunfd;
            }
        }

        int ret = select(maxfd + 1, &rset, &wset, NULL, NULL);

        if (ret == -1 && errno != EINTR) {
            err(1, "select");
        }
        else if (ret > 0) {
            if (FD_ISSET(slipfd, &rset)) {
                serial_to_tun(inslip, tunfd);
            }

            if (FD_ISSET(slipfd, &wset)) {
                slip_flushbuf(slipfd);
                sigalarm_reset();
            }

            /* Optional delay between outgoing packets */
            /* Base delay times number of 6lowpan fragments to be sent */
            if (delaymsec) {
                struct timeval tv;
                int dmsec;
                gettimeofday(&tv, NULL) ;
                dmsec = (tv.tv_sec - delaystartsec) * 1000 + tv.tv_usec / 1000 - delaystartmsec;

                if (dmsec < 0) {
                    delaymsec = 0;
                }

                if (dmsec > delaymsec) {
                    delaymsec = 0;
                }
            }

            if (delaymsec == 0) {
                if (slip_empty() && FD_ISSET(tunfd, &rset)) {
                    int size = tun_to_serial(tunfd, slipfd);
                    (void) size; /* fix warning unused but set variable */
                    slip_flushbuf(slipfd);
                    sigalarm_reset();

                    if (basedelay) {
                        struct timeval tv;
                        gettimeofday(&tv, NULL) ;
                        // delaymsec=basedelay*(1+(size/120));//multiply by # of 6lowpan packets?
                        delaymsec = basedelay;
                        delaystartsec = tv.tv_sec;
                        delaystartmsec = tv.tv_usec / 1000;
                    }
                }
            }
        }
    }
}