lib/util/getpass.c

   1 /*
   2  *  Unix SMB/CIFS implementation.
   3  *
   4  *  getpass.c - platform independent getpass function.
   5  *
   6  *  Copyright (c) 2010-2012 Andreas Schneider <asn@samba.org>
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 3 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include "includes.h"
  23
  24 #include "system/filesys.h"
  25 #include "system/terminal.h"
  26
  27 #if !defined(SMB_MALLOC)
  28 #undef malloc
  29 #define SMB_MALLOC(s) malloc((s))
  30 #endif
  31
  32 /**
  33  * @internal
  34  *
  35  * @brief Get the password from the console.
  36  *
  37  * @param[in]  prompt   The prompt to display.
  38  *
  39  * @param[in]  buf      The buffer to fill.
  40  *
  41  * @param[in]  len      The length of the buffer.
  42  *
  43  * @param[in]  verify   Should the password be verified?
  44  *
  45  * @return              1 on success, 0 on error.
  46  */
  47 static int samba_gets(const char *prompt, char *buf, size_t len, bool verify)
  48 {
  49         char *tmp;
  50         char *ptr = NULL;
  51         int ok = 0;
  52
  53         tmp = SMB_MALLOC(len);
  54         if (tmp == NULL) {
  55                 return 0;
  56         }
  57         memset(tmp,'\0',len);
  58
  59         /* read the password */
  60         while (!ok) {
  61                 if (buf[0] != '\0') {
  62                         fprintf(stdout, "%s[%s] ", prompt, buf);
  63                 } else {
  64                         fprintf(stdout, "%s", prompt);
  65                 }
  66                 fflush(stdout);
  67                 if (fgets(tmp, len, stdin) == NULL) {
  68                         free(tmp);
  69                         return 0;
  70                 }
  71
  72                 if ((ptr = strchr(tmp, '\n'))) {
  73                         *ptr = '\0';
  74                 }
  75                 fprintf(stdout, "\n");
  76
  77                 if (*tmp) {
  78                         strncpy(buf, tmp, len);
  79                 }
  80
  81                 if (verify) {
  82                         char *key_string;
  83
  84                         key_string = SMB_MALLOC(len);
  85                         if (key_string == NULL) {
  86                                 break;
  87                         }
  88                         memset(key_string, '\0', len);
  89
  90                         fprintf(stdout, "\nVerifying, please re-enter. %s", prompt);
  91                         fflush(stdout);
  92                         if (! fgets(key_string, len, stdin)) {
  93                                 memset(key_string, '\0', len);
  94                                 SAFE_FREE(key_string);
  95                                 clearerr(stdin);
  96                                 continue;
  97                         }
  98                         if ((ptr = strchr(key_string, '\n'))) {
  99                                 *ptr = '\0';
 100                         }
 101                         fprintf(stdout, "\n");
 102                         if (strcmp(buf, key_string)) {
 103                                 printf("\n\07\07Mismatch - try again\n");
 104                                 memset(key_string, '\0', len);
 105                                 SAFE_FREE(key_string);
 106                                 fflush(stdout);
 107                                 continue;
 108                         }
 109                         memset(key_string, '\0', len);
 110                         SAFE_FREE(key_string);
 111                 }
 112                 ok = 1;
 113         }
 114         memset(tmp, '\0', len);
 115         free(tmp);
 116
 117         return ok;
 118 }
 119
 120 /**
 121  * @brief Get a password from the console.
 122  *
 123  * You should make sure that the buffer is an empty string!
 124  *
 125  * You can also use this function to ask for a username. Then you can fill the
 126  * buffer with the username and it is shows to the users. If the users just
 127  * presses enter the buffer will be untouched.
 128  *
 129  * @code
 130  *   char username[128];
 131  *
 132  *   snprintf(username, sizeof(username), "john");
 133  *
 134  *   samba_getpass("Username:", username, sizeof(username), 1, 0);
 135  * @endcode
 136  *
 137  * The prompt will look like this:
 138  *
 139  *   Username: [john]
 140  *
 141  * If you press enter then john is used as the username, or you can type it in
 142  * to change it.
 143  *
 144  * @param[in]  prompt   The prompt to show to ask for the password.
 145  *
 146  * @param[out] buf    The buffer the password should be stored. It NEEDS to be
 147  *                      empty or filled out.
 148  *
 149  * @param[in]  len      The length of the buffer.
 150  *
 151  * @param[in]  echo     Should we echo what you type.
 152  *
 153  * @param[in]  verify   Should we ask for the password twice.
 154  *
 155  * @return              0 on success, -1 on error.
 156  */
 157 int samba_getpass(const char *prompt,
 158                   char *buf,
 159                   size_t len,
 160                   bool echo,
 161                   bool verify)
 162 {
 163         struct termios attr;
 164         struct termios old_attr;
 165         int ok = 0;
 166         int fd = -1;
 167
 168         /* fgets needs at least len - 1 */
 169         if (prompt == NULL || buf == NULL || len < 2) {
 170                 return -1;
 171         }
 172
 173         if (isatty (STDIN_FILENO)) {
 174
 175                 ZERO_STRUCT(attr);
 176                 ZERO_STRUCT(old_attr);
 177
 178                 /* get local terminal attributes */
 179                 if (tcgetattr(STDIN_FILENO, &attr) < 0) {
 180                         perror("tcgetattr");
 181                         return -1;
 182                 }
 183
 184                 /* save terminal attributes */
 185                 memcpy(&old_attr, &attr, sizeof(attr));
 186                 if((fd = fcntl(0, F_GETFL, 0)) < 0) {
 187                         perror("fcntl");
 188                         return -1;
 189                 }
 190
 191                 /* disable echo */
 192                 if (!echo) {
 193                         attr.c_lflag &= ~(ECHO);
 194                 }
 195
 196                 /* write attributes to terminal */
 197                 if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &attr) < 0) {
 198                         perror("tcsetattr");
 199                         return -1;
 200                 }
 201         }
 202
 203         /* disable nonblocking I/O */
 204         if (fd & O_NDELAY) {
 205                 fcntl(0, F_SETFL, fd & ~O_NDELAY);
 206         }
 207
 208         ok = samba_gets(prompt, buf, len, verify);
 209
 210         if (isatty (STDIN_FILENO)) {
 211
 212                 /* reset terminal */
 213                 tcsetattr(STDIN_FILENO, TCSANOW, &old_attr);
 214         }
 215
 216         /* close fd */
 217         if (fd & O_NDELAY) {
 218                 fcntl(0, F_SETFL, fd);
 219         }
 220
 221         if (!ok) {
 222                 memset (buf, '\0', len);
 223                 return -1;
 224         }
 225
 226         /* force termination */
 227         buf[len - 1] = '\0';
 228
 229         return 0;
 230 }