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 /*
 141  * Ask whether the selected cipher is acceptable (since it was
 142  * below the configured 'warn' threshold).
 143  * cs: 0 = both ways, 1 = client->server, 2 = server->client
 144  */
 145 void askcipher(void *frontend, char *ciphername, int cs)
 146 {
 147     HANDLE hin;
 148     DWORD savemode, i;
 149
 150     static const char msg[] =
 151         "The first %scipher supported by the server is\n"
 152         "%s, which is below the configured warning threshold.\n"
 153         "Continue with connection? (y/n) ";
 154     static const char msg_batch[] =
 155         "The first %scipher supported by the server is\n"
 156         "%s, which is below the configured warning threshold.\n"
 157         "Connection abandoned.\n";
 158     static const char abandoned[] = "Connection abandoned.\n";
 159
 160     char line[32];
 161
 162     if (console_batch_mode) {
 163         fprintf(stderr, msg_batch,
 164                 (cs == 0) ? "" :
 165                 (cs == 1) ? "client-to-server " : "server-to-client ",
 166                 ciphername);
 167         cleanup_exit(1);
 168     }
 169
 170     fprintf(stderr, msg,
 171             (cs == 0) ? "" :
 172             (cs == 1) ? "client-to-server " : "server-to-client ",
 173             ciphername);
 174     fflush(stderr);
 175
 176     hin = GetStdHandle(STD_INPUT_HANDLE);
 177     GetConsoleMode(hin, &savemode);
 178     SetConsoleMode(hin, (savemode | ENABLE_ECHO_INPUT |
 179                          ENABLE_PROCESSED_INPUT | ENABLE_LINE_INPUT));
 180     ReadFile(hin, line, sizeof(line) - 1, &i, NULL);
 181     SetConsoleMode(hin, savemode);
 182
 183     if (line[0] == 'y' || line[0] == 'Y') {
 184         return;
 185     } else {
 186         fprintf(stderr, abandoned);
 187         cleanup_exit(0);
 188     }
 189 }
 190
 191 /*
 192  * Ask whether to wipe a session log file before writing to it.
 193  * Returns 2 for wipe, 1 for append, 0 for cancel (don't log).
 194  */
 195 int askappend(void *frontend, Filename filename)
 196 {
 197     HANDLE hin;
 198     DWORD savemode, i;
 199
 200     static const char msgtemplate[] =
 201         "The session log file \"%.*s\" already exists.\n"
 202         "You can overwrite it with a new session log,\n"
 203         "append your session log to the end of it,\n"
 204         "or disable session logging for this session.\n"
 205         "Enter \"y\" to wipe the file, \"n\" to append to it,\n"
 206         "or just press Return to disable logging.\n"
 207         "Wipe the log file? (y/n, Return cancels logging) ";
 208
 209     static const char msgtemplate_batch[] =
 210         "The session log file \"%.*s\" already exists.\n"
 211         "Logging will not be enabled.\n";
 212
 213     char line[32];
 214
 215     if (console_batch_mode) {
 216         fprintf(stderr, msgtemplate_batch, FILENAME_MAX, filename.path);
 217         fflush(stderr);
 218         return 0;
 219     }
 220     fprintf(stderr, msgtemplate, FILENAME_MAX, filename.path);
 221     fflush(stderr);
 222
 223     hin = GetStdHandle(STD_INPUT_HANDLE);
 224     GetConsoleMode(hin, &savemode);
 225     SetConsoleMode(hin, (savemode | ENABLE_ECHO_INPUT |
 226                          ENABLE_PROCESSED_INPUT | ENABLE_LINE_INPUT));
 227     ReadFile(hin, line, sizeof(line) - 1, &i, NULL);
 228     SetConsoleMode(hin, savemode);
 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, 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     HANDLE hin, hout;
 279     DWORD savemode, newmode, i;
 280
 281     if (console_batch_mode) {
 282         if (maxlen > 0)
 283             str[0] = '\0';
 284     } else {
 285         hin = GetStdHandle(STD_INPUT_HANDLE);
 286         hout = GetStdHandle(STD_OUTPUT_HANDLE);
 287         if (hin == INVALID_HANDLE_VALUE || hout == INVALID_HANDLE_VALUE) {
 288             fprintf(stderr, "Cannot get standard input/output handles\n");
 289             cleanup_exit(1);
 290         }
 291
 292         GetConsoleMode(hin, &savemode);
 293         newmode = savemode | ENABLE_PROCESSED_INPUT | ENABLE_LINE_INPUT;
 294         if (is_pw)
 295             newmode &= ~ENABLE_ECHO_INPUT;
 296         else
 297             newmode |= ENABLE_ECHO_INPUT;
 298         SetConsoleMode(hin, newmode);
 299
 300         WriteFile(hout, prompt, strlen(prompt), &i, NULL);
 301         ReadFile(hin, str, maxlen - 1, &i, NULL);
 302
 303         SetConsoleMode(hin, savemode);
 304
 305         if ((int) i > maxlen)
 306             i = maxlen - 1;
 307         else
 308             i = i - 2;
 309         str[i] = '\0';
 310
 311         if (is_pw)
 312             WriteFile(hout, "\r\n", 2, &i, NULL);
 313
 314     }
 315     return 1;
 316 }
 317
 318 void frontend_keypress(void *handle)
 319 {
 320     /*
 321      * This is nothing but a stub, in console code.
 322      */
 323     return;
 324 }