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