/* test program for 
 *   https://community.openvpn.net/openvpn/ticket/1226
 *   https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=248172
 *
 * run as: "./tester tun0" or "tap3" etc.
 * it will open the named tun/tap device, "ifconfig" an inet6 address,
 * and then monitor the output of "ifconfig $dev" for the next 10 seconds
 * on whether IFDISABLED is set (which should not happen)
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/time.h>

void run_it(char *cmd)
{
    printf("run cmd: '%s'\n", cmd);
    if(system(cmd)<0)
	{ fprintf(stderr, "running system() failed: %s, exit\n", strerror(errno)); exit(10); }
}

int main(int argc, char ** argv)
{

    if (argc != 2)
	{ fprintf(stderr, "%s: need one argument, tun/tap device name ('tun0')\n", argv[0]); exit(1); }

    char *ifname = argv[1];
    char devname[200];
    snprintf(devname,sizeof(devname)-1,"/dev/%s",ifname);

    int tunfd = open(devname, O_RDWR);
    if (tunfd<0)
	{ fprintf(stderr, "cannot open %s: %s\n", devname, strerror(errno)); exit(2); }
    printf( "%s open ok, fd=%d\n", devname, tunfd );
    
    /* nonblocking mode, close on exec */
    if (fcntl(tunfd, F_SETFL, O_NONBLOCK) < 0 ||
        fcntl(tunfd, F_SETFD, FD_CLOEXEC) < 0 )
	{ fprintf(stderr, "cannot set tunfd to O_NONBLOCK & FD_CLOEXEC: %s\n", strerror(errno)); exit(3); }

    /* ifconfig an inet6 address */
    char cmdbuf[1000];
    snprintf(cmdbuf, sizeof(cmdbuf), "ifconfig %s inet6 fd00:abcd:204:4::1001/64 mtu 1500 up", ifname);
    run_it(cmdbuf);

    /* monitor "ifconfig $dev" output for IFDISABLED
     */

    time_t start = time(NULL);

    while( time(NULL) < start+10 )
    {
	snprintf(cmdbuf, sizeof(cmdbuf), "ifconfig %s", ifname);
	FILE * pfp = popen(cmdbuf, "r");
	if (!pfp)
	    { fprintf(stderr, "cannot popen('%s'): %s\n", cmdbuf, strerror(errno)); exit(3); }
	
	char pipebuf[2000];
	int r = fread(pipebuf, 1, sizeof(pipebuf)-1, pfp);
	fclose(pfp);

        if (r<0)
	    { fprintf(stderr, "error reading from pipe: %s\n", strerror(errno)); exit(3); }
        pipebuf[r] = 0;

	printf( "read %d bytes, time since start=%ds\n%s", r, (int)(time(NULL)-start), pipebuf);

        if (strstr(pipebuf, "IFDISABLED"))
	    { printf( "    *** FOUND ***\n" ); }
	sleep(1);
    }

    /* clean up: close fd, destroy device */
    close(tunfd);

    snprintf(cmdbuf, sizeof(cmdbuf), "ifconfig %s destroy", ifname);
    run_it(cmdbuf);
    
    exit(0);
}