slattach: new applet.

include/applets.h

@@ -296,6 +296,7 @@ USE_FEATURE_SH_IS_HUSH(APPLET_NOUSAGE(sh, hush, _BB_DIR_BIN, _BB_SUID_NEVER))
 USE_FEATURE_SH_IS_LASH(APPLET_NOUSAGE(sh, lash, _BB_DIR_BIN, _BB_SUID_NEVER))
 USE_FEATURE_SH_IS_MSH(APPLET_NOUSAGE(sh, msh, _BB_DIR_BIN, _BB_SUID_NEVER))
 USE_SHA1SUM(APPLET_ODDNAME(sha1sum, md5_sha1_sum, _BB_DIR_USR_BIN, _BB_SUID_NEVER, sha1sum))
+USE_SLATTACH(APPLET(slattach, _BB_DIR_SBIN, _BB_SUID_NEVER))
 USE_SLEEP(APPLET_NOFORK(sleep, sleep, _BB_DIR_BIN, _BB_SUID_NEVER, sleep))
 USE_SOFTLIMIT(APPLET_ODDNAME(softlimit, chpst, _BB_DIR_USR_BIN, _BB_SUID_NEVER, softlimit))
 USE_SORT(APPLET_NOEXEC(sort, sort, _BB_DIR_USR_BIN, _BB_SUID_NEVER, sort))

include/usage.h

@@ -2991,6 +2991,20 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
        "	-s	Don't output anything, status code shows success\n" \
        "	-w	Warn about improperly formatted SHA1 checksum lines")
 
+#define slattach_trivial_usage \
+       "[-cehmLF] [-s speed] [-p protocol] DEVICEs"
+#define slattach_full_usage \
+       "Attach network interface(s) to serial line(s)\n" \
+     "\nOptions:" \
+     "\n	-p	Set protocol (slip, cslip, slip6, clisp6 or adaptive)" \
+     "\n	-s	Set line speed" \
+     "\n	-e	Exit after initializing device" \
+     "\n	-h	Exit when the carrier is lost" \
+     "\n	-c	Execute a command when the line is hung up" \
+     "\n	-m	Do NOT initialize the line in raw 8 bits mode" \
+     "\n	-L	Enable 3-wire operation" \
+     "\n	-F	Disable RTS/CTS flow control" \
+ 
 #define sleep_trivial_usage \
 	USE_FEATURE_FANCY_SLEEP("[") "N" USE_FEATURE_FANCY_SLEEP("]...")
 #define sleep_full_usage \

networking/Config.in

@@ -548,6 +548,12 @@ config ROUTE
 	help
 	  Route displays or manipulates the kernel's IP routing tables.
 
+config SLATTACH
+	bool "slattach"
+	default n
+	help
+	  slattach is a small utility to attach network interfaces to serial lines.
+
 config TELNET
 	bool "telnet"
 	default n

networking/Kbuild

@@ -27,6 +27,7 @@ lib-$(CONFIG_PING)         += ping.o
 lib-$(CONFIG_PING6)        += ping.o
 lib-$(CONFIG_PSCAN)        += pscan.o
 lib-$(CONFIG_ROUTE)        += route.o
+lib-$(CONFIG_SLATTACH)     += slattach.o
 lib-$(CONFIG_TELNET)       += telnet.o
 lib-$(CONFIG_TELNETD)      += telnetd.o
 lib-$(CONFIG_TFTP)         += tftp.o

networking/slattach.c

@@ -0,0 +1,240 @@
+/*
+ * Stripped down version of net-tools for busybox.
+ *
+ * Author: Ignacio Garcia Perez (iggarpe at gmail dot com)
+ *
+ * License: GPLv2 or later, see LICENSE file in this tarball.
+ *
+ * There are some differences from the standard net-tools slattach:
+ *
+ * - The -l option is not supported.
+ *
+ * - The -F options allows disabling of RTS/CTS flow control.
+ */
+
+#include "libbb.h"
+
+/* Line discipline code table */
+static const char *const proto_names[] = {
+	"slip",		/* 0 */
+	"cslip",	/* 1 */
+	"slip6",	/* 2 */
+	"cslip6",	/* 3 */
+	"adaptive",	/* 8 */
+	NULL
+};
+
+struct globals {
+	int handle;
+	int saved_disc;
+	struct termios saved_state;
+};
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define handle       (G.handle      )
+#define saved_disc   (G.saved_disc  )
+#define saved_state  (G.saved_state )
+#define INIT_G() do {} while (0)
+
+
+/*
+ * Save tty state and line discipline
+ *
+ * It is fine here to bail out on errors, since we haven modified anything yet
+ */
+static void save_state(void)
+{
+	/* Save line status */
+	if (tcgetattr(handle, &saved_state) < 0)
+		bb_perror_msg_and_die("get state");
+
+	/* Save line discipline */
+	if (ioctl(handle, TIOCGETD, &saved_disc) < 0)
+		bb_perror_msg_and_die("get discipline");
+}
+
+/*
+ * Restore state and line discipline for ALL managed ttys
+ *
+ * Restoring ALL managed ttys is the only way to have a single
+ * hangup delay.
+ *
+ * Go on after errors: we want to restore as many controlled ttys
+ * as possible.
+ */
+static void restore_state_and_exit(int exitcode) ATTRIBUTE_NORETURN;
+static void restore_state_and_exit(int exitcode)
+{
+	struct termios state;
+
+	/* Restore line discipline */
+	if (ioctl(handle, TIOCSETD, &saved_disc) < 0) {
+		bb_perror_msg("set discipline");
+		exitcode = 1;
+	}
+
+	/* Hangup */
+	memcpy(&state, &saved_state, sizeof(state));
+	cfsetispeed(&state, B0);
+	cfsetospeed(&state, B0);
+	if (tcsetattr(handle, TCSANOW, &state) < 0) {
+		bb_perror_msg("set state");
+		exitcode = 1;
+	}
+
+	sleep(1);
+
+	/* Restore line status */
+	if (tcsetattr(handle, TCSANOW, &saved_state) < 0) {
+		bb_perror_msg_and_die("set state");
+	}
+
+	if (ENABLE_FEATURE_CLEAN_UP)
+		close(handle);
+
+	exit(exitcode);
+}
+
+/*
+ * Set tty state, line discipline and encapsulation
+ */
+static void set_state(struct termios *state, int encap)
+{
+	int disc;
+
+	/* Set line status */
+	if (tcsetattr(handle, TCSANOW, state) < 0) {
+		bb_perror_msg("set state");
+		goto bad;
+	}
+
+	/* Set line discliple (N_SLIP always) */
+	disc = N_SLIP;
+	if (ioctl(handle, TIOCSETD, &disc) < 0) {
+		bb_perror_msg("set discipline");
+		goto bad;
+	}
+
+	/* Set encapsulation (SLIP, CSLIP, etc) */
+	if (ioctl(handle, SIOCSIFENCAP, &encap) < 0) {
+		bb_perror_msg("set encapsulation");
+ bad:
+		restore_state_and_exit(1);
+	}
+}
+
+static void sig_handler(int signo)
+{
+	restore_state_and_exit(0);
+}
+
+int slattach_main(int argc, char **argv);
+int slattach_main(int argc, char **argv)
+{
+	int i, encap, opt;
+	struct termios state;
+	const char *proto = "cslip";
+	const char *extcmd;				/* Command to execute after hangup */
+	const char *baud_str;
+	int baud_code = -1;				/* Line baud rate (system code) */
+
+	enum {
+		OPT_p_proto  = 1 << 0,
+		OPT_s_baud   = 1 << 1,
+		OPT_c_extcmd = 1 << 2,
+		OPT_e_quit   = 1 << 3,
+		OPT_h_watch  = 1 << 4,
+		OPT_m_nonraw = 1 << 5,
+		OPT_L_local  = 1 << 6,
+		OPT_F_noflow = 1 << 7,
+	};
+
+	INIT_G();
+
+	/* Parse command line options */
+	opt = getopt32(argc, argv, "p:s:c:ehmLF", &proto, &baud_str, &extcmd);
+	/*argc -= optind;*/
+	argv += optind;
+
+	if (!*argv)
+		bb_show_usage();
+
+	encap = index_in_str_array(proto_names, proto);
+
+	if (encap < 0)
+		bb_error_msg_and_die("invalid protocol %s", proto);
+	if (encap > 3)
+		encap = 8;
+
+	/* We want to know if the baud rate is valid before we start touching the ttys */
+	if (opt & OPT_s_baud) {
+		baud_code = tty_value_to_baud(xatoi(baud_str));
+		if (baud_code < 0)
+			bb_error_msg_and_die("invalid baud rate");
+	}
+
+	/* Trap signals in order to restore tty states upon exit */
+	if (!(opt & OPT_e_quit)) {
+		signal(SIGHUP, sig_handler);
+		signal(SIGINT, sig_handler);
+		signal(SIGQUIT, sig_handler);
+		signal(SIGTERM, sig_handler);
+	}
+
+	/* Open tty */ 
+	handle = open(*argv, O_RDWR | O_NDELAY);
+	if (handle < 0) {
+		char *buf = xasprintf("/dev/%s", *argv);
+		handle = xopen(buf, O_RDWR | O_NDELAY);
+		/* maybe if (ENABLE_FEATURE_CLEAN_UP) ?? */
+		free(buf);
+	}
+
+	/* Save current tty state */
+	save_state();
+
+	/* Confgure tty */
+	memcpy(&state, &saved_state, sizeof(state));
+	if (!(opt & OPT_m_nonraw)) { /* raw not suppressed */
+		memset(&state.c_cc, 0, sizeof(state.c_cc));
+		state.c_cc[VMIN] = 1;
+		state.c_iflag = IGNBRK | IGNPAR;
+		state.c_oflag = 0;
+		state.c_lflag = 0;
+		state.c_cflag = CS8 | HUPCL | CREAD
+		              | ((opt & OPT_L_local) ? CLOCAL : 0)
+		              | ((opt & OPT_F_noflow) ? 0 : CRTSCTS);
+	}
+
+	if (opt & OPT_s_baud) {
+		cfsetispeed(&state, baud_code);
+		cfsetospeed(&state, baud_code);
+	}
+
+	set_state(&state, encap);
+
+	/* Exit now if option -e was passed */
+	if (opt & OPT_e_quit)
+		return 0;
+
+	/* If we're not requested to watch, just keep descriptor open
+	 * till we are killed */
+	if (!(opt & OPT_h_watch))
+		while (1)
+			sleep(24*60*60);
+
+	/* Watch line for hangup */
+	while (1) {
+		if (ioctl(handle, TIOCMGET, &i) < 0 || !(i & TIOCM_CAR))
+			goto no_carrier;
+		sleep(15);
+	}
+
+ no_carrier:
+
+	/* Execute command on hangup */
+	if (opt & OPT_c_extcmd)
+		system(extcmd);
+
+	/* Restore states and exit */
+	restore_state_and_exit(0);
+}