[openssh.git] / readpass.c

/*
 * 
 * readpass.c
 * 
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * 
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * 
 * Created: Mon Jul 10 22:08:59 1995 ylo
 * 
 * Functions for reading passphrases and passwords.
 * 
 */

#include "includes.h"
RCSID("$Id$");

#include "xmalloc.h"
#include "ssh.h"

/* Saved old terminal mode for read_passphrase. */
static struct termios saved_tio;

/* Old interrupt signal handler for read_passphrase. */
static void (*old_handler) (int sig) = NULL;

/* Interrupt signal handler for read_passphrase. */

void 
intr_handler(int sig)
{
	/* Restore terminal modes. */
	tcsetattr(fileno(stdin), TCSANOW, &saved_tio);
	/* Restore the old signal handler. */
	signal(sig, old_handler);
	/* Resend the signal, with the old handler. */
	kill(getpid(), sig);
}

/*
 * Reads a passphrase from /dev/tty with echo turned off.  Returns the
 * passphrase (allocated with xmalloc).  Exits if EOF is encountered. The
 * passphrase if read from stdin if from_stdin is true (as is the case with
 * ssh-keygen).
 */

char *
read_passphrase(const char *prompt, int from_stdin)
{
	char buf[1024], *cp;
	struct termios tio;
	FILE *f;

	if (from_stdin)
		f = stdin;
	else {
		/*
		 * Read the passphrase from /dev/tty to make it possible to
		 * ask it even when stdin has been redirected.
		 */
		f = fopen("/dev/tty", "r");
		if (!f) {
			/* No controlling terminal and no DISPLAY.  Nowhere to read. */
			fprintf(stderr, "You have no controlling tty and no DISPLAY.  Cannot read passphrase.\n");
			exit(1);
		}
	}

	/* Display the prompt (on stderr because stdout might be redirected). */
	fflush(stdout);
	fprintf(stderr, "%s", prompt);
	fflush(stderr);

	/* Get terminal modes. */
	tcgetattr(fileno(f), &tio);
	saved_tio = tio;
	/* Save signal handler and set the new handler. */
	old_handler = signal(SIGINT, intr_handler);

	/* Set new terminal modes disabling all echo. */
	tio.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);
	tcsetattr(fileno(f), TCSANOW, &tio);

	/* Read the passphrase from the terminal. */
	if (fgets(buf, sizeof(buf), f) == NULL) {
		/* Got EOF.  Just exit. */
		/* Restore terminal modes. */
		tcsetattr(fileno(f), TCSANOW, &saved_tio);
		/* Restore the signal handler. */
		signal(SIGINT, old_handler);
		/* Print a newline (the prompt probably didn\'t have one). */
		fprintf(stderr, "\n");
		/* Close the file. */
		if (f != stdin)
			fclose(f);
		exit(1);
	}
	/* Restore terminal modes. */
	tcsetattr(fileno(f), TCSANOW, &saved_tio);
	/* Restore the signal handler. */
	(void) signal(SIGINT, old_handler);
	/* Remove newline from the passphrase. */
	if (strchr(buf, '\n'))
		*strchr(buf, '\n') = 0;
	/* Allocate a copy of the passphrase. */
	cp = xstrdup(buf);
	/*
	 * Clear the buffer so we don\'t leave copies of the passphrase
	 * laying around.
	 */
	memset(buf, 0, sizeof(buf));
	/* Print a newline since the prompt probably didn\'t have one. */
	fprintf(stderr, "\n");
	/* Close the file. */
	if (f != stdin)
		fclose(f);
	return cp;
}
Commit	Line	Data
8efc0c15	1	/*
5260325f	2	*
	3	* readpass.c
	4	*
	5	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	6	*
	7	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	8	* All rights reserved
	9	*
	10	* Created: Mon Jul 10 22:08:59 1995 ylo
	11	*
	12	* Functions for reading passphrases and passwords.
	13	*
	14	*/
8efc0c15	15
	16	#include "includes.h"
	17	RCSID("$Id$");
	18
	19	#include "xmalloc.h"
	20	#include "ssh.h"
	21
	22	/* Saved old terminal mode for read_passphrase. */
	23	static struct termios saved_tio;
	24
	25	/* Old interrupt signal handler for read_passphrase. */
5260325f	26	static void (*old_handler) (int sig) = NULL;
8efc0c15	27
	28	/* Interrupt signal handler for read_passphrase. */
	29
5260325f	30	void
5260325f	31	intr_handler(int sig)
8efc0c15	32	{
5260325f	33	/* Restore terminal modes. */
	34	tcsetattr(fileno(stdin), TCSANOW, &saved_tio);
	35	/* Restore the old signal handler. */
	36	signal(sig, old_handler);
	37	/* Resend the signal, with the old handler. */
	38	kill(getpid(), sig);
8efc0c15	39	}
8efc0c15	40
aa3378df	41	/*
	42	* Reads a passphrase from /dev/tty with echo turned off. Returns the
	43	* passphrase (allocated with xmalloc). Exits if EOF is encountered. The
	44	* passphrase if read from stdin if from_stdin is true (as is the case with
	45	* ssh-keygen).
	46	*/
8efc0c15	47
5260325f	48	char *
5260325f	49	read_passphrase(const char *prompt, int from_stdin)
8efc0c15	50	{
5260325f	51	char buf[1024], *cp;
	52	struct termios tio;
	53	FILE *f;
	54
	55	if (from_stdin)
	56	f = stdin;
	57	else {
aa3378df	58	/*
	59	* Read the passphrase from /dev/tty to make it possible to
	60	* ask it even when stdin has been redirected.
	61	*/
5260325f	62	f = fopen("/dev/tty", "r");
	63	if (!f) {
	64	/* No controlling terminal and no DISPLAY. Nowhere to read. */
	65	fprintf(stderr, "You have no controlling tty and no DISPLAY. Cannot read passphrase.\n");
	66	exit(1);
	67	}
8efc0c15	68	}
8efc0c15	69
5260325f	70	/* Display the prompt (on stderr because stdout might be redirected). */
	71	fflush(stdout);
	72	fprintf(stderr, "%s", prompt);
	73	fflush(stderr);
	74
	75	/* Get terminal modes. */
	76	tcgetattr(fileno(f), &tio);
	77	saved_tio = tio;
	78	/* Save signal handler and set the new handler. */
	79	old_handler = signal(SIGINT, intr_handler);
	80
	81	/* Set new terminal modes disabling all echo. */
	82	tio.c_lflag &= ~(ECHO \| ECHOE \| ECHOK \| ECHONL);
	83	tcsetattr(fileno(f), TCSANOW, &tio);
	84
	85	/* Read the passphrase from the terminal. */
	86	if (fgets(buf, sizeof(buf), f) == NULL) {
	87	/* Got EOF. Just exit. */
	88	/* Restore terminal modes. */
	89	tcsetattr(fileno(f), TCSANOW, &saved_tio);
	90	/* Restore the signal handler. */
	91	signal(SIGINT, old_handler);
	92	/* Print a newline (the prompt probably didn\'t have one). */
	93	fprintf(stderr, "\n");
	94	/* Close the file. */
	95	if (f != stdin)
	96	fclose(f);
	97	exit(1);
	98	}
	99	/* Restore terminal modes. */
	100	tcsetattr(fileno(f), TCSANOW, &saved_tio);
	101	/* Restore the signal handler. */
	102	(void) signal(SIGINT, old_handler);
	103	/* Remove newline from the passphrase. */
	104	if (strchr(buf, '\n'))
	105	*strchr(buf, '\n') = 0;
	106	/* Allocate a copy of the passphrase. */
	107	cp = xstrdup(buf);
aa3378df	108	/*
	109	* Clear the buffer so we don\'t leave copies of the passphrase
	110	* laying around.
	111	*/
5260325f	112	memset(buf, 0, sizeof(buf));
	113	/* Print a newline since the prompt probably didn\'t have one. */
	114	fprintf(stderr, "\n");
	115	/* Close the file. */
	116	if (f != stdin)
	117	fclose(f);
	118	return cp;
8efc0c15	119	}