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 cipher is acceptable (since it was
 147  * below the configured 'warn' threshold).
 148  * cs: 0 = both ways, 1 = client->server, 2 = server->client
 149  */
 150 void askcipher(void *frontend, char *ciphername, int cs)
 151 {
 152     static const char msg[] =
 153         "The first %scipher supported by the server is\n"
 154         "%s, which is below the configured warning threshold.\n"
 155         "Continue with connection? (y/n) ";
 156     static const char msg_batch[] =
 157         "The first %scipher supported by the server is\n"
 158         "%s, which is below the configured warning threshold.\n"
 159         "Connection abandoned.\n";
 160     static const char abandoned[] = "Connection abandoned.\n";
 161
 162     char line[32];
 163
 164     if (console_batch_mode) {
 165         fprintf(stderr, msg_batch,
 166                 (cs == 0) ? "" :
 167                 (cs == 1) ? "client-to-server " : "server-to-client ",
 168                 ciphername);
 169         cleanup_exit(1);
 170     }
 171
 172     fprintf(stderr, msg,
 173             (cs == 0) ? "" :
 174             (cs == 1) ? "client-to-server " : "server-to-client ",
 175             ciphername);
 176     fflush(stderr);
 177
 178     {
 179         struct termios oldmode, newmode;
 180         tcgetattr(0, &oldmode);
 181         newmode = oldmode;
 182         newmode.c_lflag |= ECHO | ISIG | ICANON;
 183         tcsetattr(0, TCSANOW, &newmode);
 184         line[0] = '\0';
 185         read(0, line, sizeof(line) - 1);
 186         tcsetattr(0, TCSANOW, &oldmode);
 187     }
 188
 189     if (line[0] == 'y' || line[0] == 'Y') {
 190         return;
 191     } else {
 192         fprintf(stderr, abandoned);
 193         cleanup_exit(0);
 194     }
 195 }
 196
 197 /*
 198  * Ask whether to wipe a session log file before writing to it.
 199  * Returns 2 for wipe, 1 for append, 0 for cancel (don't log).
 200  */
 201 int askappend(void *frontend, Filename filename)
 202 {
 203     static const char msgtemplate[] =
 204         "The session log file \"%.*s\" already exists.\n"
 205         "You can overwrite it with a new session log,\n"
 206         "append your session log to the end of it,\n"
 207         "or disable session logging for this session.\n"
 208         "Enter \"y\" to wipe the file, \"n\" to append to it,\n"
 209         "or just press Return to disable logging.\n"
 210         "Wipe the log file? (y/n, Return cancels logging) ";
 211
 212     static const char msgtemplate_batch[] =
 213         "The session log file \"%.*s\" already exists.\n"
 214         "Logging will not be enabled.\n";
 215
 216     char line[32];
 217
 218     if (console_batch_mode) {
 219         fprintf(stderr, msgtemplate_batch, FILENAME_MAX, filename.path);
 220         fflush(stderr);
 221         return 0;
 222     }
 223     fprintf(stderr, msgtemplate, FILENAME_MAX, filename.path);
 224     fflush(stderr);
 225
 226     {
 227         struct termios oldmode, newmode;
 228         tcgetattr(0, &oldmode);
 229         newmode = oldmode;
 230         newmode.c_lflag |= ECHO | ISIG | ICANON;
 231         tcsetattr(0, TCSANOW, &newmode);
 232         line[0] = '\0';
 233         read(0, line, sizeof(line) - 1);
 234         tcsetattr(0, TCSANOW, &oldmode);
 235     }
 236
 237     if (line[0] == 'y' || line[0] == 'Y')
 238         return 2;
 239     else if (line[0] == 'n' || line[0] == 'N')
 240         return 1;
 241     else
 242         return 0;
 243 }
 244
 245 /*
 246  * Warn about the obsolescent key file format.
 247  *
 248  * Uniquely among these functions, this one does _not_ expect a
 249  * frontend handle. This means that if PuTTY is ported to a
 250  * platform which requires frontend handles, this function will be
 251  * an anomaly. Fortunately, the problem it addresses will not have
 252  * been present on that platform, so it can plausibly be
 253  * implemented as an empty function.
 254  */
 255 void old_keyfile_warning(void)
 256 {
 257     static const char message[] =
 258         "You are loading an SSH 2 private key which has an\n"
 259         "old version of the file format. This means your key\n"
 260         "file is not fully tamperproof. Future versions of\n"
 261         "PuTTY may stop supporting this private key format,\n"
 262         "so we recommend you convert your key to the new\n"
 263         "format.\n"
 264         "\n"
 265         "Once the key is loaded into PuTTYgen, you can perform\n"
 266         "this conversion simply by saving it again.\n";
 267
 268     fputs(message, stderr);
 269 }
 270
 271 void console_provide_logctx(void *logctx)
 272 {
 273     console_logctx = logctx;
 274 }
 275
 276 void logevent(void *frontend, const char *string)
 277 {
 278     if (console_logctx)
 279         log_eventlog(console_logctx, string);
 280 }
 281
 282 int console_get_line(const char *prompt, char *str,
 283                      int maxlen, int is_pw)
 284 {
 285     struct termios oldmode, newmode;
 286     int i;
 287
 288     if (console_batch_mode) {
 289         if (maxlen > 0)
 290             str[0] = '\0';
 291         return 0;
 292     } else {
 293         tcgetattr(0, &oldmode);
 294         newmode = oldmode;
 295         newmode.c_lflag |= ISIG | ICANON;
 296         if (is_pw)
 297             newmode.c_lflag &= ~ECHO;
 298         else
 299             newmode.c_lflag |= ECHO;
 300         tcsetattr(0, TCSANOW, &newmode);
 301
 302         fputs(prompt, stdout);
 303         fflush(stdout);
 304         i = read(0, str, maxlen - 1);
 305
 306         tcsetattr(0, TCSANOW, &oldmode);
 307
 308         if (i > 0 && str[i-1] == '\n')
 309             i--;
 310         str[i] = '\0';
 311
 312         if (is_pw)
 313             fputs("\n", stdout);
 314
 315         return 1;
 316     }
 317 }
 318
 319 void frontend_keypress(void *handle)
 320 {
 321     /*
 322      * This is nothing but a stub, in console code.
 323      */
 324     return;
 325 }
 326
 327 int is_interactive(void)
 328 {
 329     return isatty(0);
 330 }
 331
 332 /*
 333  * X11-forwarding-related things suitable for console.
 334  */
 335
 336 const char platform_x11_best_transport[] = "unix";
 337
 338 char *platform_get_x_display(void) {
 339     return dupstr(getenv("DISPLAY"));
 340 }