release/src/router/busybox/networking/slattach.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Stripped down version of net-tools for busybox.
   4  *
   5  * Author: Ignacio Garcia Perez (iggarpe at gmail dot com)
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  *
   9  * There are some differences from the standard net-tools slattach:
  10  *
  11  * - The -l option is not supported.
  12  *
  13  * - The -F options allows disabling of RTS/CTS flow control.
  14  */
  15
  16 //usage:#define slattach_trivial_usage
  17 //usage:       "[-cehmLF] [-s SPEED] [-p PROTOCOL] DEVICE"
  18 //usage:#define slattach_full_usage "\n\n"
  19 //usage:       "Attach network interface(s) to serial line(s)\n"
  20 //usage:     "\n        -p PROT Set protocol (slip, cslip, slip6, clisp6 or adaptive)"
  21 //usage:     "\n        -s SPD  Set line speed"
  22 //usage:     "\n        -e      Exit after initializing device"
  23 //usage:     "\n        -h      Exit when the carrier is lost"
  24 //usage:     "\n        -c PROG Run PROG when the line is hung up"
  25 //usage:     "\n        -m      Do NOT initialize the line in raw 8 bits mode"
  26 //usage:     "\n        -L      Enable 3-wire operation"
  27 //usage:     "\n        -F      Disable RTS/CTS flow control"
  28
  29 #include "libbb.h"
  30 #include "libiproute/utils.h" /* invarg() */
  31
  32 struct globals {
  33         int handle;
  34         int saved_disc;
  35         struct termios saved_state;
  36 } FIX_ALIASING;
  37 #define G (*(struct globals*)&bb_common_bufsiz1)
  38 #define handle       (G.handle      )
  39 #define saved_disc   (G.saved_disc  )
  40 #define saved_state  (G.saved_state )
  41 #define INIT_G() do { } while (0)
  42
  43
  44 /*
  45  * Save tty state and line discipline
  46  *
  47  * It is fine here to bail out on errors, since we haven modified anything yet
  48  */
  49 static void save_state(void)
  50 {
  51         /* Save line status */
  52         if (tcgetattr(handle, &saved_state) < 0)
  53                 bb_perror_msg_and_die("get state");
  54
  55         /* Save line discipline */
  56         xioctl(handle, TIOCGETD, &saved_disc);
  57 }
  58
  59 static int set_termios_state_or_warn(struct termios *state)
  60 {
  61         int ret;
  62
  63         ret = tcsetattr(handle, TCSANOW, state);
  64         if (ret < 0) {
  65                 bb_perror_msg("set state");
  66                 return 1; /* used as exitcode */
  67         }
  68         return 0;
  69 }
  70
  71 /*
  72  * Restore state and line discipline for ALL managed ttys
  73  *
  74  * Restoring ALL managed ttys is the only way to have a single
  75  * hangup delay.
  76  *
  77  * Go on after errors: we want to restore as many controlled ttys
  78  * as possible.
  79  */
  80 static void restore_state_and_exit(int exitcode) NORETURN;
  81 static void restore_state_and_exit(int exitcode)
  82 {
  83         struct termios state;
  84
  85         /* Restore line discipline */
  86         if (ioctl_or_warn(handle, TIOCSETD, &saved_disc) < 0) {
  87                 exitcode = 1;
  88         }
  89
  90         /* Hangup */
  91         memcpy(&state, &saved_state, sizeof(state));
  92         cfsetispeed(&state, B0);
  93         cfsetospeed(&state, B0);
  94         if (set_termios_state_or_warn(&state))
  95                 exitcode = 1;
  96         sleep(1);
  97
  98         /* Restore line status */
  99         if (set_termios_state_or_warn(&saved_state))
 100                 exit(EXIT_FAILURE);
 101         if (ENABLE_FEATURE_CLEAN_UP)
 102                 close(handle);
 103
 104         exit(exitcode);
 105 }
 106
 107 /*
 108  * Set tty state, line discipline and encapsulation
 109  */
 110 static void set_state(struct termios *state, int encap)
 111 {
 112         int disc;
 113
 114         /* Set line status */
 115         if (set_termios_state_or_warn(state))
 116                 goto bad;
 117         /* Set line discliple (N_SLIP always) */
 118         disc = N_SLIP;
 119         if (ioctl_or_warn(handle, TIOCSETD, &disc) < 0) {
 120                 goto bad;
 121         }
 122
 123         /* Set encapsulation (SLIP, CSLIP, etc) */
 124         if (ioctl_or_warn(handle, SIOCSIFENCAP, &encap) < 0) {
 125  bad:
 126                 restore_state_and_exit(EXIT_FAILURE);
 127         }
 128 }
 129
 130 static void sig_handler(int signo UNUSED_PARAM)
 131 {
 132         restore_state_and_exit(EXIT_SUCCESS);
 133 }
 134
 135 int slattach_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 136 int slattach_main(int argc UNUSED_PARAM, char **argv)
 137 {
 138         /* Line discipline code table */
 139         static const char proto_names[] ALIGN1 =
 140                 "slip\0"        /* 0 */
 141                 "cslip\0"       /* 1 */
 142                 "slip6\0"       /* 2 */
 143                 "cslip6\0"      /* 3 */
 144                 "adaptive\0"    /* 8 */
 145                 ;
 146
 147         int i, encap, opt;
 148         struct termios state;
 149         const char *proto = "cslip";
 150         const char *extcmd;   /* Command to execute after hangup */
 151         const char *baud_str;
 152         int baud_code = -1;   /* Line baud rate (system code) */
 153
 154         enum {
 155                 OPT_p_proto  = 1 << 0,
 156                 OPT_s_baud   = 1 << 1,
 157                 OPT_c_extcmd = 1 << 2,
 158                 OPT_e_quit   = 1 << 3,
 159                 OPT_h_watch  = 1 << 4,
 160                 OPT_m_nonraw = 1 << 5,
 161                 OPT_L_local  = 1 << 6,
 162                 OPT_F_noflow = 1 << 7
 163         };
 164
 165         INIT_G();
 166
 167         /* Parse command line options */
 168         opt = getopt32(argv, "p:s:c:ehmLF", &proto, &baud_str, &extcmd);
 169         /*argc -= optind;*/
 170         argv += optind;
 171
 172         if (!*argv)
 173                 bb_show_usage();
 174
 175         encap = index_in_strings(proto_names, proto);
 176
 177         if (encap < 0)
 178                 invarg(proto, "protocol");
 179         if (encap > 3)
 180                 encap = 8;
 181
 182         /* We want to know if the baud rate is valid before we start touching the ttys */
 183         if (opt & OPT_s_baud) {
 184                 baud_code = tty_value_to_baud(xatoi(baud_str));
 185                 if (baud_code < 0)
 186                         invarg(baud_str, "baud rate");
 187         }
 188
 189         /* Trap signals in order to restore tty states upon exit */
 190         if (!(opt & OPT_e_quit)) {
 191                 bb_signals(0
 192                         + (1 << SIGHUP)
 193                         + (1 << SIGINT)
 194                         + (1 << SIGQUIT)
 195                         + (1 << SIGTERM)
 196                         , sig_handler);
 197         }
 198
 199         /* Open tty */
 200         handle = open(*argv, O_RDWR | O_NDELAY);
 201         if (handle < 0) {
 202                 char *buf = concat_path_file("/dev", *argv);
 203                 handle = xopen(buf, O_RDWR | O_NDELAY);
 204                 /* maybe if (ENABLE_FEATURE_CLEAN_UP) ?? */
 205                 free(buf);
 206         }
 207
 208         /* Save current tty state */
 209         save_state();
 210
 211         /* Configure tty */
 212         memcpy(&state, &saved_state, sizeof(state));
 213         if (!(opt & OPT_m_nonraw)) { /* raw not suppressed */
 214                 memset(&state.c_cc, 0, sizeof(state.c_cc));
 215                 state.c_cc[VMIN] = 1;
 216                 state.c_iflag = IGNBRK | IGNPAR;
 217                 state.c_oflag = 0;
 218                 state.c_lflag = 0;
 219                 state.c_cflag = CS8 | HUPCL | CREAD
 220                               | ((opt & OPT_L_local) ? CLOCAL : 0)
 221                               | ((opt & OPT_F_noflow) ? 0 : CRTSCTS);
 222                 cfsetispeed(&state, cfgetispeed(&saved_state));
 223                 cfsetospeed(&state, cfgetospeed(&saved_state));
 224         }
 225
 226         if (opt & OPT_s_baud) {
 227                 cfsetispeed(&state, baud_code);
 228                 cfsetospeed(&state, baud_code);
 229         }
 230
 231         set_state(&state, encap);
 232
 233         /* Exit now if option -e was passed */
 234         if (opt & OPT_e_quit)
 235                 return 0;
 236
 237         /* If we're not requested to watch, just keep descriptor open
 238          * until we are killed */
 239         if (!(opt & OPT_h_watch))
 240                 while (1)
 241                         sleep(24*60*60);
 242
 243         /* Watch line for hangup */
 244         while (1) {
 245                 if (ioctl(handle, TIOCMGET, &i) < 0 || !(i & TIOCM_CAR))
 246                         goto no_carrier;
 247                 sleep(15);
 248         }
 249
 250  no_carrier:
 251
 252         /* Execute command on hangup */
 253         if (opt & OPT_c_extcmd)
 254                 system(extcmd);
 255
 256         /* Restore states and exit */
 257         restore_state_and_exit(EXIT_SUCCESS);
 258 }