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/*
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: readpass.c,v 1.2 1999/09/30 05:03:05 deraadt Exp $");
#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 RETSIGTYPE (*old_handler)(int sig) = NULL;
/* Interrupt signal handler for read_passphrase. */
RETSIGTYPE 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)
{
if (getenv("DISPLAY"))
{
char command[512];
fprintf(stderr,
"Executing ssh-askpass to query the password...\n");
fflush(stdout);
fflush(stderr);
sprintf(command, "ssh-askpass '%.400s'", prompt);
f = popen(command, "r");
if (!fgets(buf, sizeof(buf), f))
{
pclose(f);
fprintf(stderr, "No passphrase supplied. Exiting.\n");
exit(1);
}
pclose(f);
if (strchr(buf, '\n'))
*strchr(buf, '\n') = 0;
return xstrdup(buf);
}
/* 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;
}
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