mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-01-10 01:48:00 +00:00
f39c51f9a7
This gets rid of all those annoying 'win', 'ux' and 'gtk' prefixes which made filenames annoying to type and to tab-complete. Also, as with my other recent renaming sprees, I've taken the opportunity to expand and clarify some of the names so that they're not such cryptic abbreviations.
423 lines
12 KiB
C
423 lines
12 KiB
C
/*
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* 'psusan': Pseudo Ssh for Untappable, Separately Authenticated Networks
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*
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* This is a standalone application that speaks on its standard I/O
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* (or a listening Unix-domain socket) the server end of the bare
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* ssh-connection protocol used by PuTTY's connection sharing.
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*
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* The idea of this tool is that you can use it to communicate across
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* any 8-bit-clean data channel between two inconveniently separated
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* domains, provided the channel is already (as the name suggests)
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* adequately secured against eavesdropping and modification and
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* already authenticated as the right user.
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*
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* If you're sitting at one end of such a channel and want to type
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* commands into the other end, the most obvious thing to do is to run
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* a terminal session directly over it. But if you run psusan at one
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* end, and a PuTTY (or compatible) client at the other end, then you
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* not only get a single terminal session: you get all the other SSH
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* amenities, like the ability to spawn extra terminal sessions,
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* forward ports or X11 connections, even forward an SSH agent.
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*
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* There are a surprising number of channels of that kind; see the man
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* page for some examples.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <assert.h>
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#include <stdarg.h>
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#include <signal.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <termios.h>
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#include <pwd.h>
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#include <sys/ioctl.h>
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#include <sys/time.h>
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#include "putty.h"
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#include "mpint.h"
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#include "ssh.h"
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#include "ssh/server.h"
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const char *const appname = "psusan";
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void modalfatalbox(const char *p, ...)
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{
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va_list ap;
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fprintf(stderr, "FATAL ERROR: ");
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va_start(ap, p);
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vfprintf(stderr, p, ap);
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va_end(ap);
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fputc('\n', stderr);
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exit(1);
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}
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void nonfatal(const char *p, ...)
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{
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va_list ap;
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fprintf(stderr, "ERROR: ");
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va_start(ap, p);
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vfprintf(stderr, p, ap);
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va_end(ap);
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fputc('\n', stderr);
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}
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char *platform_default_s(const char *name)
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{
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return NULL;
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}
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bool platform_default_b(const char *name, bool def)
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{
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return def;
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}
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int platform_default_i(const char *name, int def)
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{
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return def;
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}
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FontSpec *platform_default_fontspec(const char *name)
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{
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return fontspec_new("");
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}
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Filename *platform_default_filename(const char *name)
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{
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return filename_from_str("");
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}
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char *x_get_default(const char *key)
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{
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return NULL; /* this is a stub */
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}
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void old_keyfile_warning(void) { }
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void timer_change_notify(unsigned long next)
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{
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}
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char *platform_get_x_display(void) { return NULL; }
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void make_unix_sftp_filehandle_key(void *vdata, size_t size)
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{
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/* psusan runs without a random number generator, so we can't make
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* this up by random_read. Fortunately, psusan is also
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* non-adversarial, so it's safe to generate this trivially. */
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unsigned char *data = (unsigned char *)vdata;
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for (size_t i = 0; i < size; i++)
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data[i] = (unsigned)rand() / ((unsigned)RAND_MAX / 256);
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}
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static bool verbose;
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struct server_instance {
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unsigned id;
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LogPolicy logpolicy;
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};
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static void log_to_stderr(unsigned id, const char *msg)
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{
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if (!verbose)
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return;
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if (id != (unsigned)-1)
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fprintf(stderr, "#%u: ", id);
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fputs(msg, stderr);
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fputc('\n', stderr);
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fflush(stderr);
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}
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static void server_eventlog(LogPolicy *lp, const char *event)
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{
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struct server_instance *inst = container_of(
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lp, struct server_instance, logpolicy);
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if (verbose)
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log_to_stderr(inst->id, event);
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}
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static void server_logging_error(LogPolicy *lp, const char *event)
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{
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struct server_instance *inst = container_of(
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lp, struct server_instance, logpolicy);
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log_to_stderr(inst->id, event); /* unconditional */
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}
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static int server_askappend(
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LogPolicy *lp, Filename *filename,
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void (*callback)(void *ctx, int result), void *ctx)
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{
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return 2; /* always overwrite (FIXME: could make this a cmdline option) */
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}
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static const LogPolicyVtable server_logpolicy_vt = {
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.eventlog = server_eventlog,
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.askappend = server_askappend,
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.logging_error = server_logging_error,
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.verbose = null_lp_verbose_no,
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};
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static void show_help(FILE *fp)
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{
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fputs("usage: psusan [options]\n"
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"options: --listen SOCKETPATH listen for connections on a Unix-domain socket\n"
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" --listen-once (with --listen) stop after one connection\n"
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" --verbose print log messages to standard error\n"
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" --sessiondir DIR cwd for session subprocess (default $HOME)\n"
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" --sshlog FILE write ssh-connection packet log to FILE\n"
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" --sshrawlog FILE write packets and raw data log to FILE\n"
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"also: psusan --help show this text\n"
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" psusan --version show version information\n", fp);
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}
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static void show_version_and_exit(void)
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{
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char *buildinfo_text = buildinfo("\n");
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printf("%s: %s\n%s\n", appname, ver, buildinfo_text);
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sfree(buildinfo_text);
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exit(0);
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}
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const bool buildinfo_gtk_relevant = false;
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static bool listening = false, listen_once = false;
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static bool finished = false;
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void server_instance_terminated(LogPolicy *lp)
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{
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struct server_instance *inst = container_of(
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lp, struct server_instance, logpolicy);
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if (listening && !listen_once) {
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log_to_stderr(inst->id, "connection terminated");
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} else {
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finished = true;
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}
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sfree(inst);
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}
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bool psusan_continue(void *ctx, bool fd, bool cb)
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{
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return !finished;
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}
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static bool longoptarg(const char *arg, const char *expected,
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const char **val, int *argcp, char ***argvp)
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{
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int len = strlen(expected);
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if (memcmp(arg, expected, len))
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return false;
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if (arg[len] == '=') {
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*val = arg + len + 1;
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return true;
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} else if (arg[len] == '\0') {
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if (--*argcp > 0) {
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*val = *++*argvp;
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return true;
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} else {
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fprintf(stderr, "%s: option %s expects an argument\n",
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appname, expected);
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exit(1);
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}
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}
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return false;
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}
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static bool longoptnoarg(const char *arg, const char *expected)
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{
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int len = strlen(expected);
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if (memcmp(arg, expected, len))
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return false;
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if (arg[len] == '=') {
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fprintf(stderr, "%s: option %s expects no argument\n",
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appname, expected);
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exit(1);
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} else if (arg[len] == '\0') {
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return true;
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}
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return false;
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}
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struct server_config {
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Conf *conf;
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const SshServerConfig *ssc;
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unsigned next_id;
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Socket *listening_socket;
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Plug listening_plug;
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};
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static Plug *server_conn_plug(
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struct server_config *cfg, struct server_instance **inst_out)
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{
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struct server_instance *inst = snew(struct server_instance);
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memset(inst, 0, sizeof(*inst));
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inst->id = cfg->next_id++;
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inst->logpolicy.vt = &server_logpolicy_vt;
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if (inst_out)
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*inst_out = inst;
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return ssh_server_plug(
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cfg->conf, cfg->ssc, NULL, 0, NULL, NULL,
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&inst->logpolicy, &unix_live_sftpserver_vt);
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}
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static void server_log(Plug *plug, PlugLogType type, SockAddr *addr, int port,
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const char *error_msg, int error_code)
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{
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log_to_stderr(-1, error_msg);
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}
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static void server_closing(Plug *plug, const char *error_msg, int error_code,
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bool calling_back)
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{
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log_to_stderr(-1, error_msg);
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}
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static int server_accepting(Plug *p, accept_fn_t constructor, accept_ctx_t ctx)
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{
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struct server_config *cfg = container_of(
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p, struct server_config, listening_plug);
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Socket *s;
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const char *err;
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struct server_instance *inst;
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if (listen_once) {
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if (!cfg->listening_socket) /* in case of rapid double-accept */
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return 1;
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sk_close(cfg->listening_socket);
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cfg->listening_socket = NULL;
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}
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Plug *plug = server_conn_plug(cfg, &inst);
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s = constructor(ctx, plug);
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if ((err = sk_socket_error(s)) != NULL)
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return 1;
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SocketPeerInfo *pi = sk_peer_info(s);
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char *msg = dupprintf("new connection from %s", pi->log_text);
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log_to_stderr(inst->id, msg);
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sfree(msg);
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sk_free_peer_info(pi);
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sk_set_frozen(s, false);
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ssh_server_start(plug, s);
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return 0;
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}
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static const PlugVtable server_plugvt = {
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.log = server_log,
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.closing = server_closing,
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.accepting = server_accepting,
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};
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unsigned auth_methods(AuthPolicy *ap)
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{ return 0; }
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bool auth_none(AuthPolicy *ap, ptrlen username)
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{ return false; }
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int auth_password(AuthPolicy *ap, ptrlen username, ptrlen password,
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ptrlen *new_password_opt)
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{ return 0; }
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bool auth_publickey(AuthPolicy *ap, ptrlen username, ptrlen public_blob)
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{ return false; }
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RSAKey *auth_publickey_ssh1(
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AuthPolicy *ap, ptrlen username, mp_int *rsa_modulus)
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{ return NULL; }
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AuthKbdInt *auth_kbdint_prompts(AuthPolicy *ap, ptrlen username)
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{ return NULL; }
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int auth_kbdint_responses(AuthPolicy *ap, const ptrlen *responses)
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{ return -1; }
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char *auth_ssh1int_challenge(AuthPolicy *ap, unsigned method, ptrlen username)
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{ return NULL; }
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bool auth_ssh1int_response(AuthPolicy *ap, ptrlen response)
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{ return false; }
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bool auth_successful(AuthPolicy *ap, ptrlen username, unsigned method)
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{ return false; }
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int main(int argc, char **argv)
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{
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const char *listen_socket = NULL;
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SshServerConfig ssc;
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Conf *conf = make_ssh_server_conf();
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memset(&ssc, 0, sizeof(ssc));
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ssc.application_name = "PSUSAN";
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ssc.session_starting_dir = getenv("HOME");
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ssc.bare_connection = true;
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while (--argc > 0) {
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const char *arg = *++argv;
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const char *val;
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if (longoptnoarg(arg, "--help")) {
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show_help(stdout);
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exit(0);
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} else if (longoptnoarg(arg, "--version")) {
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show_version_and_exit();
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} else if (longoptnoarg(arg, "--verbose") || !strcmp(arg, "-v")) {
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verbose = true;
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} else if (longoptarg(arg, "--sessiondir", &val, &argc, &argv)) {
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ssc.session_starting_dir = val;
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} else if (longoptarg(arg, "--sshlog", &val, &argc, &argv) ||
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longoptarg(arg, "-sshlog", &val, &argc, &argv)) {
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Filename *logfile = filename_from_str(val);
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conf_set_filename(conf, CONF_logfilename, logfile);
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filename_free(logfile);
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conf_set_int(conf, CONF_logtype, LGTYP_PACKETS);
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conf_set_int(conf, CONF_logxfovr, LGXF_OVR);
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} else if (longoptarg(arg, "--sshrawlog", &val, &argc, &argv) ||
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longoptarg(arg, "-sshrawlog", &val, &argc, &argv)) {
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Filename *logfile = filename_from_str(val);
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conf_set_filename(conf, CONF_logfilename, logfile);
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filename_free(logfile);
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conf_set_int(conf, CONF_logtype, LGTYP_SSHRAW);
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conf_set_int(conf, CONF_logxfovr, LGXF_OVR);
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} else if (longoptarg(arg, "--listen", &val, &argc, &argv)) {
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listen_socket = val;
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} else if (!strcmp(arg, "--listen-once")) {
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listen_once = true;
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} else {
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fprintf(stderr, "%s: unrecognised option '%s'\n", appname, arg);
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exit(1);
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}
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}
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sk_init();
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uxsel_init();
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struct server_config scfg;
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scfg.conf = conf;
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scfg.ssc = &ssc;
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scfg.next_id = 0;
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if (listen_socket) {
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listening = true;
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scfg.listening_plug.vt = &server_plugvt;
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SockAddr *addr = unix_sock_addr(listen_socket);
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scfg.listening_socket = new_unix_listener(addr, &scfg.listening_plug);
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char *msg = dupprintf("listening on Unix socket %s", listen_socket);
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log_to_stderr(-1, msg);
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sfree(msg);
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} else {
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struct server_instance *inst;
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Plug *plug = server_conn_plug(&scfg, &inst);
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ssh_server_start(plug, make_fd_socket(0, 1, -1, plug));
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log_to_stderr(inst->id, "running directly on stdio");
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}
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cli_main_loop(cliloop_no_pw_setup, cliloop_no_pw_check,
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psusan_continue, NULL);
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return 0;
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}
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