ssh.c

C＋＋编写

	/* Initiate local TCP/IP port forwardings. */
	for (i = 0; i < options.num_local_forwards; i++) {
		debug("Connections to local port %d forwarded to remote address %.200s:%d",
		    options.local_forwards[i].port,
		    options.local_forwards[i].host,
		    options.local_forwards[i].host_port);
		success += channel_setup_local_fwd_listener(
		    options.local_forwards[i].port,
		    options.local_forwards[i].host,
		    options.local_forwards[i].host_port,
		    options.gateway_ports);
	}
	if (i > 0 && success == 0)
		error("Could not request local forwarding.");

	/* Initiate remote TCP/IP port forwardings. */
	for (i = 0; i < options.num_remote_forwards; i++) {
		debug("Connections to remote port %d forwarded to local address %.200s:%d",
		    options.remote_forwards[i].port,
		    options.remote_forwards[i].host,
		    options.remote_forwards[i].host_port);
		channel_request_remote_forwarding(
		    options.remote_forwards[i].port,
		    options.remote_forwards[i].host,
		    options.remote_forwards[i].host_port);
	}
}

static void
check_agent_present(void)
{
	if (options.forward_agent) {
		/* Clear agent forwarding if we don\'t have an agent. */
		if (!ssh_agent_present())
			options.forward_agent = 0;
	}
}

static int
ssh_session(void)
{
	int type;
	int interactive = 0;
	int have_tty = 0;
	struct winsize ws;
	char *cp;

	/* Enable compression if requested. */
	if (options.compression) {
		debug("Requesting compression at level %d.", options.compression_level);

		if (options.compression_level < 1 || options.compression_level > 9)
			fatal("Compression level must be from 1 (fast) to 9 (slow, best).");

		/* Send the request. */
		packet_start(SSH_CMSG_REQUEST_COMPRESSION);
		packet_put_int(options.compression_level);
		packet_send();
		packet_write_wait();
		type = packet_read();
		if (type == SSH_SMSG_SUCCESS)
			packet_start_compression(options.compression_level);
		else if (type == SSH_SMSG_FAILURE)
			log("Warning: Remote host refused compression.");
		else
			packet_disconnect("Protocol error waiting for compression response.");
	}
	/* Allocate a pseudo tty if appropriate. */
	if (tty_flag) {
		debug("Requesting pty.");

		/* Start the packet. */
		packet_start(SSH_CMSG_REQUEST_PTY);

		/* Store TERM in the packet.  There is no limit on the
		   length of the string. */
		cp = getenv("TERM");
		if (!cp)
			cp = "";
		packet_put_cstring(cp);

		/* Store window size in the packet. */
		if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
			memset(&ws, 0, sizeof(ws));
		packet_put_int(ws.ws_row);
		packet_put_int(ws.ws_col);
		packet_put_int(ws.ws_xpixel);
		packet_put_int(ws.ws_ypixel);

		/* Store tty modes in the packet. */
		tty_make_modes(fileno(stdin), NULL);

		/* Send the packet, and wait for it to leave. */
		packet_send();
		packet_write_wait();

		/* Read response from the server. */
		type = packet_read();
		if (type == SSH_SMSG_SUCCESS) {
			interactive = 1;
			have_tty = 1;
		} else if (type == SSH_SMSG_FAILURE)
			log("Warning: Remote host failed or refused to allocate a pseudo tty.");
		else
			packet_disconnect("Protocol error waiting for pty request response.");
	}
	/* Request X11 forwarding if enabled and DISPLAY is set. */
	if (options.forward_x11 && getenv("DISPLAY") != NULL) {
		char *proto, *data;
		/* Get reasonable local authentication information. */
		x11_get_proto(&proto, &data);
		/* Request forwarding with authentication spoofing. */
		debug("Requesting X11 forwarding with authentication spoofing.");
		x11_request_forwarding_with_spoofing(0, proto, data);

		/* Read response from the server. */
		type = packet_read();
		if (type == SSH_SMSG_SUCCESS) {
			interactive = 1;
		} else if (type == SSH_SMSG_FAILURE) {
			log("Warning: Remote host denied X11 forwarding.");
		} else {
			packet_disconnect("Protocol error waiting for X11 forwarding");
		}
	}
	/* Tell the packet module whether this is an interactive session. */
	packet_set_interactive(interactive);

	/* Request authentication agent forwarding if appropriate. */
	check_agent_present();

	if (options.forward_agent) {
		debug("Requesting authentication agent forwarding.");
		auth_request_forwarding();

		/* Read response from the server. */
		type = packet_read();
		packet_check_eom();
		if (type != SSH_SMSG_SUCCESS)
			log("Warning: Remote host denied authentication agent forwarding.");
	}

	/* Initiate port forwardings. */
	ssh_init_forwarding();

	/* If requested, let ssh continue in the background. */
	if (fork_after_authentication_flag)
		if (daemon(1, 1) < 0)
			fatal("daemon() failed: %.200s", strerror(errno));

	/*
	 * If a command was specified on the command line, execute the
	 * command now. Otherwise request the server to start a shell.
	 */
	if (buffer_len(&command) > 0) {
		int len = buffer_len(&command);
		if (len > 900)
			len = 900;
		debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
		packet_start(SSH_CMSG_EXEC_CMD);
		packet_put_string(buffer_ptr(&command), buffer_len(&command));
		packet_send();
		packet_write_wait();
	} else {
		debug("Requesting shell.");
		packet_start(SSH_CMSG_EXEC_SHELL);
		packet_send();
		packet_write_wait();
	}

	/* Enter the interactive session. */
	return client_loop(have_tty, tty_flag ?
	    options.escape_char : SSH_ESCAPECHAR_NONE, 0);
}

static void
client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
{
	int id, len;

	id = packet_get_int();
	len = buffer_len(&command);
	if (len > 900)
		len = 900;
	packet_check_eom();
	if (type == SSH2_MSG_CHANNEL_FAILURE)
		fatal("Request for subsystem '%.*s' failed on channel %d",
		    len, (u_char *)buffer_ptr(&command), id);
}

void
client_global_request_reply(int type, u_int32_t seq, void *ctxt)
{
	int i;

	i = client_global_request_id++;
	if (i >= options.num_remote_forwards) {
		debug("client_global_request_reply: too many replies %d > %d",
		    i, options.num_remote_forwards);
		return;
	}
	debug("remote forward %s for: listen %d, connect %s:%d",
	    type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
	    options.remote_forwards[i].port,
	    options.remote_forwards[i].host,
	    options.remote_forwards[i].host_port);
	if (type == SSH2_MSG_REQUEST_FAILURE)
		log("Warning: remote port forwarding failed for listen port %d",
		    options.remote_forwards[i].port);
}

/* request pty/x11/agent/tcpfwd/shell for channel */
static void
ssh_session2_setup(int id, void *arg)
{
	int len;
	int interactive = 0;
	struct termios tio;

	debug2("ssh_session2_setup: id %d", id);

	if (tty_flag) {
		struct winsize ws;
		char *cp;
		cp = getenv("TERM");
		if (!cp)
			cp = "";
		/* Store window size in the packet. */
		if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
			memset(&ws, 0, sizeof(ws));

		channel_request_start(id, "pty-req", 0);
		packet_put_cstring(cp);
		packet_put_int(ws.ws_col);
		packet_put_int(ws.ws_row);
		packet_put_int(ws.ws_xpixel);
		packet_put_int(ws.ws_ypixel);
		tio = get_saved_tio();
		tty_make_modes(/*ignored*/ 0, &tio);
		packet_send();
		interactive = 1;
		/* XXX wait for reply */
	}
	if (options.forward_x11 &&
	    getenv("DISPLAY") != NULL) {
		char *proto, *data;
		/* Get reasonable local authentication information. */
		x11_get_proto(&proto, &data);
		/* Request forwarding with authentication spoofing. */
		debug("Requesting X11 forwarding with authentication spoofing.");
		x11_request_forwarding_with_spoofing(id, proto, data);
		interactive = 1;
		/* XXX wait for reply */
	}

	check_agent_present();
	if (options.forward_agent) {
		debug("Requesting authentication agent forwarding.");
		channel_request_start(id, "[e-mail]", 0);
		packet_send();
	}

	len = buffer_len(&command);
	if (len > 0) {
		if (len > 900)
			len = 900;
		if (subsystem_flag) {
			debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
			channel_request_start(id, "subsystem", /*want reply*/ 1);
			/* register callback for reply */
			/* XXX we assume that client_loop has already been called */
			dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
			dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
		} else {
			debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
			channel_request_start(id, "exec", 0);
		}
		packet_put_string(buffer_ptr(&command), buffer_len(&command));
		packet_send();
	} else {
		channel_request_start(id, "shell", 0);
		packet_send();
	}

	packet_set_interactive(interactive);
}

/* open new channel for a session */
static int
ssh_session2_open(void)
{
	Channel *c;
	int window, packetmax, in, out, err;

	if (stdin_null_flag) {
		in = open(_PATH_DEVNULL, O_RDONLY);
	} else {
		in = dup(STDIN_FILENO);
	}
	out = dup(STDOUT_FILENO);
	err = dup(STDERR_FILENO);

	if (in < 0 || out < 0 || err < 0)
		fatal("dup() in/out/err failed");

	/* enable nonblocking unless tty */
	if (!isatty(in))
		set_nonblock(in);
	if (!isatty(out))
		set_nonblock(out);
	if (!isatty(err))
		set_nonblock(err);

	window = CHAN_SES_WINDOW_DEFAULT;
	packetmax = CHAN_SES_PACKET_DEFAULT;
	if (tty_flag) {
		window >>= 1;
		packetmax >>= 1;
	}
	c = channel_new(
	    "session", SSH_CHANNEL_OPENING, in, out, err,
	    window, packetmax, CHAN_EXTENDED_WRITE,
	    xstrdup("client-session"), /*nonblock*/0);

	debug3("ssh_session2_open: channel_new: %d", c->self);

	channel_send_open(c->self);
	if (!no_shell_flag)
		channel_register_confirm(c->self, ssh_session2_setup);

	return c->self;
}

static int
ssh_session2(void)
{
	int id = -1;

	/* XXX should be pre-session */
	ssh_init_forwarding();

	if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
		id = ssh_session2_open();

	/* If requested, let ssh continue in the background. */
	if (fork_after_authentication_flag)
		if (daemon(1, 1) < 0)
			fatal("daemon() failed: %.200s", strerror(errno));

	return client_loop(tty_flag, tty_flag ?
	    options.escape_char : SSH_ESCAPECHAR_NONE, id);
}

static void
load_public_identity_files(void)
{
	char *filename;
	int i = 0;
	Key *public;
#ifdef SMARTCARD
	Key **keys;

	if (options.smartcard_device != NULL &&
	    options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
	    (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
		int count = 0;
		for (i = 0; keys[i] != NULL; i++) {
			count++;
			memmove(&options.identity_files[1], &options.identity_files[0],
			    sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
			memmove(&options.identity_keys[1], &options.identity_keys[0],
			    sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
			options.num_identity_files++;
			options.identity_keys[0] = keys[i];
			options.identity_files[0] = xstrdup("smartcard key");;
		}
		if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
			options.num_identity_files = SSH_MAX_IDENTITY_FILES;
		i = count;
		xfree(keys);
	}
#endif /* SMARTCARD */
	for (; i < options.num_identity_files; i++) {
		filename = tilde_expand_filename(options.identity_files[i],
		    original_real_uid);
		public = key_load_public(filename, NULL);
		debug("identity file %s type %d", filename,
		    public ? public->type : -1);
		xfree(options.identity_files[i]);
		options.identity_files[i] = filename;
		options.identity_keys[i] = public;
	}
}