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

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