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path: root/networking/slattach.c (plain)
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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"
17//config: default y
18//config: select PLATFORM_LINUX
19//config: help
20//config: slattach is a small utility to attach network interfaces to serial
21//config: lines.
22
23//applet:IF_SLATTACH(APPLET(slattach, BB_DIR_SBIN, BB_SUID_DROP))
24
25//kbuild:lib-$(CONFIG_SLATTACH) += slattach.o
26
27//usage:#define slattach_trivial_usage
28//usage: "[-cehmLF] [-s SPEED] [-p PROTOCOL] DEVICE"
29//usage:#define slattach_full_usage "\n\n"
30//usage: "Attach network interface(s) to serial line(s)\n"
31//usage: "\n -p PROT Set protocol (slip, cslip, slip6, clisp6 or adaptive)"
32//usage: "\n -s SPD Set line speed"
33//usage: "\n -e Exit after initializing device"
34//usage: "\n -h Exit when the carrier is lost"
35//usage: "\n -c PROG Run PROG when the line is hung up"
36//usage: "\n -m Do NOT initialize the line in raw 8 bits mode"
37//usage: "\n -L Enable 3-wire operation"
38//usage: "\n -F Disable RTS/CTS flow control"
39
40#include "libbb.h"
41#include "common_bufsiz.h"
42#include "libiproute/utils.h" /* invarg_1_to_2() */
43
44struct globals {
45 int handle;
46 int saved_disc;
47 struct termios saved_state;
48} FIX_ALIASING;
49#define G (*(struct globals*)bb_common_bufsiz1)
50#define handle (G.handle )
51#define saved_disc (G.saved_disc )
52#define saved_state (G.saved_state )
53#define INIT_G() do { setup_common_bufsiz(); } while (0)
54
55
56/*
57 * Save tty state and line discipline
58 *
59 * It is fine here to bail out on errors, since we haven modified anything yet
60 */
61static void save_state(void)
62{
63 /* Save line status */
64 if (tcgetattr(handle, &saved_state) < 0)
65 bb_perror_msg_and_die("get state");
66
67 /* Save line discipline */
68 xioctl(handle, TIOCGETD, &saved_disc);
69}
70
71static int set_termios_state_or_warn(struct termios *state)
72{
73 int ret;
74
75 ret = tcsetattr(handle, TCSANOW, state);
76 if (ret < 0) {
77 bb_perror_msg("set state");
78 return 1; /* used as exitcode */
79 }
80 return 0;
81}
82
83/*
84 * Restore state and line discipline for ALL managed ttys
85 *
86 * Restoring ALL managed ttys is the only way to have a single
87 * hangup delay.
88 *
89 * Go on after errors: we want to restore as many controlled ttys
90 * as possible.
91 */
92static void restore_state_and_exit(int exitcode) NORETURN;
93static void restore_state_and_exit(int exitcode)
94{
95 struct termios state;
96
97 /* Restore line discipline */
98 if (ioctl_or_warn(handle, TIOCSETD, &saved_disc) < 0) {
99 exitcode = 1;
100 }
101
102 /* Hangup */
103 memcpy(&state, &saved_state, sizeof(state));
104 cfsetispeed(&state, B0);
105 cfsetospeed(&state, B0);
106 if (set_termios_state_or_warn(&state))
107 exitcode = 1;
108 sleep(1);
109
110 /* Restore line status */
111 if (set_termios_state_or_warn(&saved_state))
112 exit(EXIT_FAILURE);
113 if (ENABLE_FEATURE_CLEAN_UP)
114 close(handle);
115
116 exit(exitcode);
117}
118
119/*
120 * Set tty state, line discipline and encapsulation
121 */
122static void set_state(struct termios *state, int encap)
123{
124 int disc;
125
126 /* Set line status */
127 if (set_termios_state_or_warn(state))
128 goto bad;
129 /* Set line discliple (N_SLIP always) */
130 disc = N_SLIP;
131 if (ioctl_or_warn(handle, TIOCSETD, &disc) < 0) {
132 goto bad;
133 }
134
135 /* Set encapsulation (SLIP, CSLIP, etc) */
136 if (ioctl_or_warn(handle, SIOCSIFENCAP, &encap) < 0) {
137 bad:
138 restore_state_and_exit(EXIT_FAILURE);
139 }
140}
141
142static void sig_handler(int signo UNUSED_PARAM)
143{
144 restore_state_and_exit(EXIT_SUCCESS);
145}
146
147int slattach_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
148int slattach_main(int argc UNUSED_PARAM, char **argv)
149{
150 /* Line discipline code table */
151 static const char proto_names[] ALIGN1 =
152 "slip\0" /* 0 */
153 "cslip\0" /* 1 */
154 "slip6\0" /* 2 */
155 "cslip6\0" /* 3 */
156 "adaptive\0" /* 8 */
157 ;
158
159 int i, encap, opt;
160 struct termios state;
161 const char *proto = "cslip";
162 const char *extcmd; /* Command to execute after hangup */
163 const char *baud_str;
164 int baud_code = -1; /* Line baud rate (system code) */
165
166 enum {
167 OPT_p_proto = 1 << 0,
168 OPT_s_baud = 1 << 1,
169 OPT_c_extcmd = 1 << 2,
170 OPT_e_quit = 1 << 3,
171 OPT_h_watch = 1 << 4,
172 OPT_m_nonraw = 1 << 5,
173 OPT_L_local = 1 << 6,
174 OPT_F_noflow = 1 << 7
175 };
176
177 INIT_G();
178
179 /* Parse command line options */
180 opt = getopt32(argv, "p:s:c:ehmLF", &proto, &baud_str, &extcmd);
181 /*argc -= optind;*/
182 argv += optind;
183
184 if (!*argv)
185 bb_show_usage();
186
187 encap = index_in_strings(proto_names, proto);
188
189 if (encap < 0)
190 invarg_1_to_2(proto, "protocol");
191 if (encap > 3)
192 encap = 8;
193
194 /* We want to know if the baud rate is valid before we start touching the ttys */
195 if (opt & OPT_s_baud) {
196 baud_code = tty_value_to_baud(xatoi(baud_str));
197 if (baud_code < 0)
198 invarg_1_to_2(baud_str, "baud rate");
199 }
200
201 /* Trap signals in order to restore tty states upon exit */
202 if (!(opt & OPT_e_quit)) {
203 bb_signals(0
204 + (1 << SIGHUP)
205 + (1 << SIGINT)
206 + (1 << SIGQUIT)
207 + (1 << SIGTERM)
208 , sig_handler);
209 }
210
211 /* Open tty */
212 handle = open(*argv, O_RDWR | O_NDELAY);
213 if (handle < 0) {
214 char *buf = concat_path_file("/dev", *argv);
215 handle = xopen(buf, O_RDWR | O_NDELAY);
216 /* maybe if (ENABLE_FEATURE_CLEAN_UP) ?? */
217 free(buf);
218 }
219
220 /* Save current tty state */
221 save_state();
222
223 /* Configure tty */
224 memcpy(&state, &saved_state, sizeof(state));
225 if (!(opt & OPT_m_nonraw)) { /* raw not suppressed */
226 memset(&state.c_cc, 0, sizeof(state.c_cc));
227 state.c_cc[VMIN] = 1;
228 state.c_iflag = IGNBRK | IGNPAR;
229 state.c_oflag = 0;
230 state.c_lflag = 0;
231 state.c_cflag = CS8 | HUPCL | CREAD
232 | ((opt & OPT_L_local) ? CLOCAL : 0)
233 | ((opt & OPT_F_noflow) ? 0 : CRTSCTS);
234 cfsetispeed(&state, cfgetispeed(&saved_state));
235 cfsetospeed(&state, cfgetospeed(&saved_state));
236 }
237
238 if (opt & OPT_s_baud) {
239 cfsetispeed(&state, baud_code);
240 cfsetospeed(&state, baud_code);
241 }
242
243 set_state(&state, encap);
244
245 /* Exit now if option -e was passed */
246 if (opt & OPT_e_quit)
247 return 0;
248
249 /* If we're not requested to watch, just keep descriptor open
250 * until we are killed */
251 if (!(opt & OPT_h_watch))
252 while (1)
253 sleep(24*60*60);
254
255 /* Watch line for hangup */
256 while (1) {
257 if (ioctl(handle, TIOCMGET, &i) < 0 || !(i & TIOCM_CAR))
258 goto no_carrier;
259 sleep(15);
260 }
261
262 no_carrier:
263
264 /* Execute command on hangup */
265 if (opt & OPT_c_extcmd)
266 system(extcmd);
267
268 /* Restore states and exit */
269 restore_state_and_exit(EXIT_SUCCESS);
270}
271
generated by cgit at 2024-05-15 12:01:57 (GMT)