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