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Annotation of src/usr.bin/ssh/readpass.c, Revision 1.7

1.1       deraadt     1: /*
1.6       deraadt     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:  */
1.1       deraadt    15:
                     16: #include "includes.h"
1.7     ! markus     17: RCSID("$Id: readpass.c,v 1.6 1999/11/24 00:26:03 deraadt Exp $");
1.1       deraadt    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. */
1.5       markus     26: static void (*old_handler) (int sig) = NULL;
1.1       deraadt    27:
                     28: /* Interrupt signal handler for read_passphrase. */
                     29:
1.5       markus     30: void
                     31: intr_handler(int sig)
1.1       deraadt    32: {
1.5       markus     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);
1.1       deraadt    39: }
                     40:
1.7     ! markus     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:  */
1.1       deraadt    47:
1.5       markus     48: char *
                     49: read_passphrase(const char *prompt, int from_stdin)
1.1       deraadt    50: {
1.5       markus     51:        char buf[1024], *cp;
                     52:        struct termios tio;
                     53:        FILE *f;
                     54:
                     55:        if (from_stdin)
                     56:                f = stdin;
                     57:        else {
1.7     ! markus     58:                /*
        !            59:                 * Read the passphrase from /dev/tty to make it possible to
        !            60:                 * ask it even when stdin has been redirected.
        !            61:                 */
1.5       markus     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:                }
1.1       deraadt    68:        }
                     69:
1.5       markus     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);
1.7     ! markus    108:        /*
        !           109:         * Clear the buffer so we don\'t leave copies of the passphrase
        !           110:         * laying around.
        !           111:         */
1.5       markus    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;
1.1       deraadt   119: }