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https://git.tartarus.org/simon/putty.git
synced 2025-07-01 11:32:48 -05:00
New application: 'psusan', the PROT_SSHCONN server end.
In the previous commit I introduced the ability for PuTTY to talk to a server speaking the bare ssh-connection protocol, and listed several applications for that ability. But none of those applications is any use without a server that speaks the same protocol. Until now, the only such server has been the Unix-domain socket presented by an upstream connection-sharing PuTTY - and we already had a way to connect to that. So here's the missing piece: by reusing code that already existed for the testing SSH server Uppity, I've created a program that will speak the bare ssh-connection protocol on its standard I/O channels. If you want to get a shell session over any of the transports I mentioned in the last commit, this is the program you need to run at the far end of it. I have yet to write the documentation, but just in case I forget, the name stands for 'Pseudo Ssh for Untappable, Separately Authenticated Networks'.
This commit is contained in:
Simon Tatham
305
unix/uxpsusan.c
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305
unix/uxpsusan.c
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/*
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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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* the server end of the bare ssh-connection protocol used by PuTTY's
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* connection sharing.
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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 "sshserver.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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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 (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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server_eventlog,
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server_askappend,
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server_logging_error,
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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: --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 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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finished = true;
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sfree(inst);
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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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};
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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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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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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.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 (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 {
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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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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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cli_main_loop(cliloop_no_pw_setup, cliloop_no_pw_check,
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cliloop_always_continue, NULL);
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return 0;
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}
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