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

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