blob: 3031825e5fe65b5579ae1aeba73c72510e1476b1 [file] [log] [blame]
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
2
3readpass.c
4
5Author: Tatu Ylonen <ylo@cs.hut.fi>
6
7Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 All rights reserved
9
10Created: Mon Jul 10 22:08:59 1995 ylo
11
12Functions for reading passphrases and passwords.
13
14*/
15
16#include "includes.h"
17RCSID("$Id: readpass.c,v 1.1 1999/10/27 03:42:44 damien Exp $");
18
19#include "xmalloc.h"
20#include "ssh.h"
21
22/* Saved old terminal mode for read_passphrase. */
23static struct termios saved_tio;
24
25/* Old interrupt signal handler for read_passphrase. */
26static void (*old_handler)(int sig) = NULL;
27
28/* Interrupt signal handler for read_passphrase. */
29
30void intr_handler(int sig)
31{
32 /* Restore terminal modes. */
33 tcsetattr(fileno(stdin), TCSANOW, &saved_tio);
34 /* Restore the old signal handler. */
35 signal(sig, old_handler);
36 /* Resend the signal, with the old handler. */
37 kill(getpid(), sig);
38}
39
40/* Reads a passphrase from /dev/tty with echo turned off. Returns the
41 passphrase (allocated with xmalloc). Exits if EOF is encountered.
42 The passphrase if read from stdin if from_stdin is true (as is the
43 case with ssh-keygen). */
44
45char *read_passphrase(const char *prompt, int from_stdin)
46{
47 char buf[1024], *cp;
48 struct termios tio;
49 FILE *f;
50
51 if (from_stdin)
52 f = stdin;
53 else
54 {
55 /* Read the passphrase from /dev/tty to make it possible to ask it even
56 when stdin has been redirected. */
57 f = fopen("/dev/tty", "r");
58 if (!f)
59 {
60 /* No controlling terminal and no DISPLAY. Nowhere to read. */
61 fprintf(stderr, "You have no controlling tty and no DISPLAY. Cannot read passphrase.\n");
62 exit(1);
63 }
64 }
65
66 /* Display the prompt (on stderr because stdout might be redirected). */
67 fflush(stdout);
68 fprintf(stderr, "%s", prompt);
69 fflush(stderr);
70
71 /* Get terminal modes. */
72 tcgetattr(fileno(f), &tio);
73 saved_tio = tio;
74 /* Save signal handler and set the new handler. */
75 old_handler = signal(SIGINT, intr_handler);
76
77 /* Set new terminal modes disabling all echo. */
78 tio.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);
79 tcsetattr(fileno(f), TCSANOW, &tio);
80
81 /* Read the passphrase from the terminal. */
82 if (fgets(buf, sizeof(buf), f) == NULL)
83 {
84 /* Got EOF. Just exit. */
85 /* Restore terminal modes. */
86 tcsetattr(fileno(f), TCSANOW, &saved_tio);
87 /* Restore the signal handler. */
88 signal(SIGINT, old_handler);
89 /* Print a newline (the prompt probably didn\'t have one). */
90 fprintf(stderr, "\n");
91 /* Close the file. */
92 if (f != stdin)
93 fclose(f);
94 exit(1);
95 }
96 /* Restore terminal modes. */
97 tcsetattr(fileno(f), TCSANOW, &saved_tio);
98 /* Restore the signal handler. */
99 (void)signal(SIGINT, old_handler);
100 /* Remove newline from the passphrase. */
101 if (strchr(buf, '\n'))
102 *strchr(buf, '\n') = 0;
103 /* Allocate a copy of the passphrase. */
104 cp = xstrdup(buf);
105 /* Clear the buffer so we don\'t leave copies of the passphrase laying
106 around. */
107 memset(buf, 0, sizeof(buf));
108 /* Print a newline since the prompt probably didn\'t have one. */
109 fprintf(stderr, "\n");
110 /* Close the file. */
111 if (f != stdin)
112 fclose(f);
113 return cp;
114}