git.distorted.org.uk Git - u/mdw/putty/blob - unix/uxcons.c

   1 /*
   2  * uxcons.c: various interactive-prompt routines shared between the
   3  * Unix console PuTTY tools
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <stdarg.h>
   9 #include <assert.h>
  10 #include <termios.h>
  11 #include <unistd.h>
  12
  13 #include "putty.h"
  14 #include "storage.h"
  15 #include "ssh.h"
  16
  17 int console_batch_mode = FALSE;
  18
  19 static void *console_logctx = NULL;
  20
  21 /*
  22  * Clean up and exit.
  23  */
  24 void cleanup_exit(int code)
  25 {
  26     /*
  27      * Clean up.
  28      */
  29     sk_cleanup();
  30     random_save_seed();
  31     exit(code);
  32 }
  33
  34 void update_specials_menu(void *frontend)
  35 {
  36 }
  37
  38 void notify_remote_exit(void *frontend)
  39 {
  40 }
  41
  42 void timer_change_notify(long next)
  43 {
  44 }
  45
  46 void verify_ssh_host_key(void *frontend, char *host, int port, char *keytype,
  47                          char *keystr, char *fingerprint)
  48 {
  49     int ret;
  50
  51     static const char absentmsg_batch[] =
  52         "The server's host key is not cached. You have no guarantee\n"
  53         "that the server is the computer you think it is.\n"
  54         "The server's %s key fingerprint is:\n"
  55         "%s\n"
  56         "Connection abandoned.\n";
  57     static const char absentmsg[] =
  58         "The server's host key is not cached. You have no guarantee\n"
  59         "that the server is the computer you think it is.\n"
  60         "The server's %s key fingerprint is:\n"
  61         "%s\n"
  62         "If you trust this host, enter \"y\" to add the key to\n"
  63         "PuTTY's cache and carry on connecting.\n"
  64         "If you want to carry on connecting just once, without\n"
  65         "adding the key to the cache, enter \"n\".\n"
  66         "If you do not trust this host, press Return to abandon the\n"
  67         "connection.\n"
  68         "Store key in cache? (y/n) ";
  69
  70     static const char wrongmsg_batch[] =
  71         "WARNING - POTENTIAL SECURITY BREACH!\n"
  72         "The server's host key does not match the one PuTTY has\n"
  73         "cached. This means that either the server administrator\n"
  74         "has changed the host key, or you have actually connected\n"
  75         "to another computer pretending to be the server.\n"
  76         "The new %s key fingerprint is:\n"
  77         "%s\n"
  78         "Connection abandoned.\n";
  79     static const char wrongmsg[] =
  80         "WARNING - POTENTIAL SECURITY BREACH!\n"
  81         "The server's host key does not match the one PuTTY has\n"
  82         "cached. This means that either the server administrator\n"
  83         "has changed the host key, or you have actually connected\n"
  84         "to another computer pretending to be the server.\n"
  85         "The new %s key fingerprint is:\n"
  86         "%s\n"
  87         "If you were expecting this change and trust the new key,\n"
  88         "enter \"y\" to update PuTTY's cache and continue connecting.\n"
  89         "If you want to carry on connecting but without updating\n"
  90         "the cache, enter \"n\".\n"
  91         "If you want to abandon the connection completely, press\n"
  92         "Return to cancel. Pressing Return is the ONLY guaranteed\n"
  93         "safe choice.\n"
  94         "Update cached key? (y/n, Return cancels connection) ";
  95
  96     static const char abandoned[] = "Connection abandoned.\n";
  97
  98     char line[32];
  99
 100     /*
 101      * Verify the key.
 102      */
 103     ret = verify_host_key(host, port, keytype, keystr);
 104
 105     if (ret == 0)                      /* success - key matched OK */
 106         return;
 107
 108     if (ret == 2) {                    /* key was different */
 109         if (console_batch_mode) {
 110             fprintf(stderr, wrongmsg_batch, keytype, fingerprint);
 111             cleanup_exit(1);
 112         }
 113         fprintf(stderr, wrongmsg, keytype, fingerprint);
 114         fflush(stderr);
 115     }
 116     if (ret == 1) {                    /* key was absent */
 117         if (console_batch_mode) {
 118             fprintf(stderr, absentmsg_batch, keytype, fingerprint);
 119             cleanup_exit(1);
 120         }
 121         fprintf(stderr, absentmsg, keytype, fingerprint);
 122         fflush(stderr);
 123     }
 124
 125     {
 126         struct termios oldmode, newmode;
 127         tcgetattr(0, &oldmode);
 128         newmode = oldmode;
 129         newmode.c_lflag |= ECHO | ISIG | ICANON;
 130         tcsetattr(0, TCSANOW, &newmode);
 131         line[0] = '\0';
 132         read(0, line, sizeof(line) - 1);
 133         tcsetattr(0, TCSANOW, &oldmode);
 134     }
 135
 136     if (line[0] != '\0' && line[0] != '\r' && line[0] != '\n') {
 137         if (line[0] == 'y' || line[0] == 'Y')
 138             store_host_key(host, port, keytype, keystr);
 139     } else {
 140         fprintf(stderr, abandoned);
 141         cleanup_exit(0);
 142     }
 143 }
 144
 145 /*
 146  * Ask whether the selected algorithm is acceptable (since it was
 147  * below the configured 'warn' threshold).
 148  */
 149 void askalg(void *frontend, const char *algtype, const char *algname)
 150 {
 151     static const char msg[] =
 152         "The first %s supported by the server is\n"
 153         "%s, which is below the configured warning threshold.\n"
 154         "Continue with connection? (y/n) ";
 155     static const char msg_batch[] =
 156         "The first %s supported by the server is\n"
 157         "%s, which is below the configured warning threshold.\n"
 158         "Connection abandoned.\n";
 159     static const char abandoned[] = "Connection abandoned.\n";
 160
 161     char line[32];
 162
 163     if (console_batch_mode) {
 164         fprintf(stderr, msg_batch, algtype, algname);
 165         cleanup_exit(1);
 166     }
 167
 168     fprintf(stderr, msg, algtype, algname);
 169     fflush(stderr);
 170
 171     {
 172         struct termios oldmode, newmode;
 173         tcgetattr(0, &oldmode);
 174         newmode = oldmode;
 175         newmode.c_lflag |= ECHO | ISIG | ICANON;
 176         tcsetattr(0, TCSANOW, &newmode);
 177         line[0] = '\0';
 178         read(0, line, sizeof(line) - 1);
 179         tcsetattr(0, TCSANOW, &oldmode);
 180     }
 181
 182     if (line[0] == 'y' || line[0] == 'Y') {
 183         return;
 184     } else {
 185         fprintf(stderr, abandoned);
 186         cleanup_exit(0);
 187     }
 188 }
 189
 190 /*
 191  * Ask whether to wipe a session log file before writing to it.
 192  * Returns 2 for wipe, 1 for append, 0 for cancel (don't log).
 193  */
 194 int askappend(void *frontend, Filename filename)
 195 {
 196     static const char msgtemplate[] =
 197         "The session log file \"%.*s\" already exists.\n"
 198         "You can overwrite it with a new session log,\n"
 199         "append your session log to the end of it,\n"
 200         "or disable session logging for this session.\n"
 201         "Enter \"y\" to wipe the file, \"n\" to append to it,\n"
 202         "or just press Return to disable logging.\n"
 203         "Wipe the log file? (y/n, Return cancels logging) ";
 204
 205     static const char msgtemplate_batch[] =
 206         "The session log file \"%.*s\" already exists.\n"
 207         "Logging will not be enabled.\n";
 208
 209     char line[32];
 210
 211     if (console_batch_mode) {
 212         fprintf(stderr, msgtemplate_batch, FILENAME_MAX, filename.path);
 213         fflush(stderr);
 214         return 0;
 215     }
 216     fprintf(stderr, msgtemplate, FILENAME_MAX, filename.path);
 217     fflush(stderr);
 218
 219     {
 220         struct termios oldmode, newmode;
 221         tcgetattr(0, &oldmode);
 222         newmode = oldmode;
 223         newmode.c_lflag |= ECHO | ISIG | ICANON;
 224         tcsetattr(0, TCSANOW, &newmode);
 225         line[0] = '\0';
 226         read(0, line, sizeof(line) - 1);
 227         tcsetattr(0, TCSANOW, &oldmode);
 228     }
 229
 230     if (line[0] == 'y' || line[0] == 'Y')
 231         return 2;
 232     else if (line[0] == 'n' || line[0] == 'N')
 233         return 1;
 234     else
 235         return 0;
 236 }
 237
 238 /*
 239  * Warn about the obsolescent key file format.
 240  *
 241  * Uniquely among these functions, this one does _not_ expect a
 242  * frontend handle. This means that if PuTTY is ported to a
 243  * platform which requires frontend handles, this function will be
 244  * an anomaly. Fortunately, the problem it addresses will not have
 245  * been present on that platform, so it can plausibly be
 246  * implemented as an empty function.
 247  */
 248 void old_keyfile_warning(void)
 249 {
 250     static const char message[] =
 251         "You are loading an SSH 2 private key which has an\n"
 252         "old version of the file format. This means your key\n"
 253         "file is not fully tamperproof. Future versions of\n"
 254         "PuTTY may stop supporting this private key format,\n"
 255         "so we recommend you convert your key to the new\n"
 256         "format.\n"
 257         "\n"
 258         "Once the key is loaded into PuTTYgen, you can perform\n"
 259         "this conversion simply by saving it again.\n";
 260
 261     fputs(message, stderr);
 262 }
 263
 264 void console_provide_logctx(void *logctx)
 265 {
 266     console_logctx = logctx;
 267 }
 268
 269 void logevent(void *frontend, const char *string)
 270 {
 271     if (console_logctx)
 272         log_eventlog(console_logctx, string);
 273 }
 274
 275 int console_get_line(const char *prompt, char *str,
 276                      int maxlen, int is_pw)
 277 {
 278     struct termios oldmode, newmode;
 279     int i;
 280
 281     if (console_batch_mode) {
 282         if (maxlen > 0)
 283             str[0] = '\0';
 284         return 0;
 285     } else {
 286         tcgetattr(0, &oldmode);
 287         newmode = oldmode;
 288         newmode.c_lflag |= ISIG | ICANON;
 289         if (is_pw)
 290             newmode.c_lflag &= ~ECHO;
 291         else
 292             newmode.c_lflag |= ECHO;
 293         tcsetattr(0, TCSANOW, &newmode);
 294
 295         fputs(prompt, stdout);
 296         fflush(stdout);
 297         i = read(0, str, maxlen - 1);
 298
 299         tcsetattr(0, TCSANOW, &oldmode);
 300
 301         if (i > 0 && str[i-1] == '\n')
 302             i--;
 303         str[i] = '\0';
 304
 305         if (is_pw)
 306             fputs("\n", stdout);
 307
 308         return 1;
 309     }
 310 }
 311
 312 void frontend_keypress(void *handle)
 313 {
 314     /*
 315      * This is nothing but a stub, in console code.
 316      */
 317     return;
 318 }
 319
 320 int is_interactive(void)
 321 {
 322     return isatty(0);
 323 }
 324
 325 /*
 326  * X11-forwarding-related things suitable for console.
 327  */
 328
 329 const char platform_x11_best_transport[] = "unix";
 330
 331 char *platform_get_x_display(void) {
 332     return dupstr(getenv("DISPLAY"));
 333 }