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 //config:config SLATTACH
16 //config: bool "slattach (6.2 kb)"
17 //config: default y
18 //config: help
19 //config: slattach configures serial line as SLIP network interface.
20
21 //applet:IF_SLATTACH(APPLET(slattach, BB_DIR_SBIN, BB_SUID_DROP))
22 /* shouldn't be NOEXEC: may sleep indefinitely */
23
24 //kbuild:lib-$(CONFIG_SLATTACH) += slattach.o
25
26 //usage:#define slattach_trivial_usage
27 //usage: "[-ehmLF] [-c SCRIPT] [-s BAUD] [-p PROTOCOL] SERIAL_DEVICE"
28 //usage:#define slattach_full_usage "\n\n"
29 //usage: "Configure serial line as SLIP network interface\n"
30 //usage: "\n -p PROT Protocol: slip, cslip (default), slip6, clisp6, adaptive"
31 //usage: "\n -s BAUD Line speed"
32 //usage: "\n -e Exit after initialization"
33 //usage: "\n -h Exit if carrier is lost (else never exits)"
34 //usage: "\n -c PROG Run PROG on carrier loss"
35 //usage: "\n -m Do NOT set raw 8bit mode"
36 //usage: "\n -L Enable 3-wire operation"
37 //usage: "\n -F Disable RTS/CTS flow control"
38
39 #include "libbb.h"
40 #include "common_bufsiz.h"
41 #include "libiproute/utils.h" /* invarg_1_to_2() */
42
43 struct globals {
44 int saved_disc;
45 struct termios saved_state;
46 } FIX_ALIASING;
47 #define G (*(struct globals*)bb_common_bufsiz1)
48 #define INIT_G() do { setup_common_bufsiz(); } while (0)
49
50 #define serial_fd 3
51
tcsetattr_serial_or_warn(struct termios * state)52 static int tcsetattr_serial_or_warn(struct termios *state)
53 {
54 int ret;
55
56 ret = tcsetattr(serial_fd, TCSANOW, state);
57 if (ret != 0) {
58 bb_simple_perror_msg("tcsetattr");
59 return 1; /* used as exitcode */
60 }
61 return ret; /* 0 */
62 }
63
64 static void restore_state_and_exit(int exitcode) NORETURN;
restore_state_and_exit(int exitcode)65 static void restore_state_and_exit(int exitcode)
66 {
67 struct termios state;
68
69 /* Restore line discipline */
70 if (ioctl_or_warn(serial_fd, TIOCSETD, &G.saved_disc)) {
71 exitcode = 1;
72 }
73
74 /* Hangup */
75 memcpy(&state, &G.saved_state, sizeof(state));
76 cfsetispeed(&state, B0);
77 cfsetospeed(&state, B0);
78 exitcode |= tcsetattr_serial_or_warn(&state);
79 sleep1();
80
81 /* Restore line status */
82 if (tcsetattr_serial_or_warn(&G.saved_state))
83 exit(EXIT_FAILURE);
84
85 if (ENABLE_FEATURE_CLEAN_UP)
86 close(serial_fd);
87
88 exit(exitcode);
89 }
90
sig_handler(int signo UNUSED_PARAM)91 static void sig_handler(int signo UNUSED_PARAM)
92 {
93 restore_state_and_exit(EXIT_SUCCESS);
94 }
95
96 int slattach_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
slattach_main(int argc UNUSED_PARAM,char ** argv)97 int slattach_main(int argc UNUSED_PARAM, char **argv)
98 {
99 /* Line discipline code table */
100 static const char proto_names[] ALIGN1 =
101 "slip\0" /* 0 */
102 "cslip\0" /* 1 */
103 "slip6\0" /* 2 */
104 "cslip6\0" /* 3 */
105 "adaptive\0" /* 8 */
106 ;
107 static const int int_N_SLIP = N_SLIP;
108
109 int encap, opt, fd;
110 struct termios state;
111 const char *proto = "cslip";
112 const char *extcmd; /* Command to execute after hangup */
113 const char *baud_str;
114 int baud_code = baud_code; /* for compiler */
115
116 enum {
117 OPT_p_proto = 1 << 0,
118 OPT_s_baud = 1 << 1,
119 OPT_c_extcmd = 1 << 2,
120 OPT_e_quit = 1 << 3,
121 OPT_h_watch = 1 << 4,
122 OPT_m_nonraw = 1 << 5,
123 OPT_L_local = 1 << 6,
124 OPT_F_noflow = 1 << 7
125 };
126
127 INIT_G();
128
129 /* Parse command line options */
130 opt = getopt32(argv, "^" "p:s:c:ehmLF" "\0" "=1",
131 &proto, &baud_str, &extcmd
132 );
133 /*argc -= optind;*/
134 argv += optind;
135
136 encap = index_in_strings(proto_names, proto);
137 if (encap < 0)
138 invarg_1_to_2(proto, "protocol");
139 if (encap > 3)
140 encap = 8;
141
142 /* We want to know if the baud rate is valid before we start touching the ttys */
143 if (opt & OPT_s_baud) {
144 baud_code = tty_value_to_baud(xatoi(baud_str));
145 if (baud_code < 0)
146 invarg_1_to_2(baud_str, "baud rate");
147 }
148
149 /* Open tty */
150 fd = open(*argv, O_RDWR | O_NDELAY);
151 if (fd < 0) {
152 char *buf = concat_path_file("/dev", *argv);
153 fd = xopen(buf, O_RDWR | O_NDELAY);
154 /* maybe if (ENABLE_FEATURE_CLEAN_UP) ?? */
155 free(buf);
156 }
157 xmove_fd(fd, serial_fd);
158
159 /* Save current tty state */
160 if (tcgetattr(serial_fd, &G.saved_state) != 0)
161 bb_simple_perror_msg_and_die("tcgetattr");
162 /* Save line discipline */
163 xioctl(serial_fd, TIOCGETD, &G.saved_disc);
164
165 /* Trap signals in order to restore tty states upon exit */
166 if (!(opt & OPT_e_quit)) {
167 bb_signals(0
168 + (1 << SIGHUP)
169 + (1 << SIGINT)
170 + (1 << SIGQUIT)
171 + (1 << SIGTERM)
172 , sig_handler);
173 }
174
175 /* Configure tty */
176 memcpy(&state, &G.saved_state, sizeof(state));
177 if (!(opt & OPT_m_nonraw)) { /* raw not suppressed */
178 memset(&state.c_cc, 0, sizeof(state.c_cc));
179 state.c_cc[VMIN] = 1;
180 state.c_iflag = IGNBRK | IGNPAR;
181 /*state.c_oflag = 0;*/
182 /*state.c_lflag = 0;*/
183 state.c_cflag = CS8 | HUPCL | CREAD
184 | ((opt & OPT_L_local) ? CLOCAL : 0)
185 | ((opt & OPT_F_noflow) ? 0 : CRTSCTS);
186 cfsetispeed(&state, cfgetispeed(&G.saved_state));
187 cfsetospeed(&state, cfgetospeed(&G.saved_state));
188 }
189 if (opt & OPT_s_baud) {
190 cfsetispeed(&state, baud_code);
191 cfsetospeed(&state, baud_code);
192 }
193 /* Set line status */
194 if (tcsetattr_serial_or_warn(&state))
195 goto bad;
196 /* Set line disclipline (N_SLIP always) */
197 if (ioctl_or_warn(serial_fd, TIOCSETD, (void*)&int_N_SLIP))
198 goto bad;
199 /* Set encapsulation (SLIP, CSLIP, etc) */
200 if (ioctl_or_warn(serial_fd, SIOCSIFENCAP, &encap))
201 goto bad;
202
203 /* Exit now if option -e was passed */
204 if (opt & OPT_e_quit)
205 return EXIT_SUCCESS;
206
207 /* If we're not requested to watch, just keep descriptor open
208 * until we are killed */
209 if (!(opt & OPT_h_watch))
210 while (1)
211 sleep(24*60*60);
212
213 /* Watch line for hangup */
214 while (1) {
215 int modem_stat;
216 if (ioctl(serial_fd, TIOCMGET, &modem_stat))
217 break;
218 if (!(modem_stat & TIOCM_CAR))
219 break;
220 sleep(15);
221 }
222
223 /* Execute command on hangup */
224 if (opt & OPT_c_extcmd)
225 system(extcmd);
226
227 /* Restore states and exit */
228 restore_state_and_exit(EXIT_SUCCESS);
229 bad:
230 restore_state_and_exit(EXIT_FAILURE);
231 }
232