clientloop.c

OpenSSH 是 SSH （Secure SHell） 协议的免费开源实现。它用安全、加密的网络连接工具代替了 telnet、ftp、 rlogin、rsh 和 rcp 工具。OpenSSH 支持

	/* Clear and free any buffers. */
	memset(buf, 0, sizeof(buf));
	buffer_free(&stdin_buffer);
	buffer_free(&stdout_buffer);
	buffer_free(&stderr_buffer);

	/* Report bytes transferred, and transfer rates. */
	total_time = get_current_time() - start_time;
	debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds",
	    stdin_bytes, stdout_bytes, stderr_bytes, total_time);
	if (total_time > 0)
		debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f",
		    stdin_bytes / total_time, stdout_bytes / total_time,
		    stderr_bytes / total_time);

	/* Return the exit status of the program. */
	debug("Exit status %d", exit_status);
	return exit_status;
}

/*********/

static void
client_input_stdout_data(int type, u_int32_t seq, void *ctxt)
{
	u_int data_len;
	char *data = packet_get_string(&data_len);
	packet_check_eom();
	buffer_append(&stdout_buffer, data, data_len);
	memset(data, 0, data_len);
	xfree(data);
}
static void
client_input_stderr_data(int type, u_int32_t seq, void *ctxt)
{
	u_int data_len;
	char *data = packet_get_string(&data_len);
	packet_check_eom();
	buffer_append(&stderr_buffer, data, data_len);
	memset(data, 0, data_len);
	xfree(data);
}
static void
client_input_exit_status(int type, u_int32_t seq, void *ctxt)
{
	exit_status = packet_get_int();
	packet_check_eom();
	/* Acknowledge the exit. */
	packet_start(SSH_CMSG_EXIT_CONFIRMATION);
	packet_send();
	/*
	 * Must wait for packet to be sent since we are
	 * exiting the loop.
	 */
	packet_write_wait();
	/* Flag that we want to exit. */
	quit_pending = 1;
}
static void
client_input_agent_open(int type, u_int32_t seq, void *ctxt)
{
	Channel *c = NULL;
	int remote_id, sock;

	/* Read the remote channel number from the message. */
	remote_id = packet_get_int();
	packet_check_eom();

	/*
	 * Get a connection to the local authentication agent (this may again
	 * get forwarded).
	 */
	sock = ssh_get_authentication_socket();

	/*
	 * If we could not connect the agent, send an error message back to
	 * the server. This should never happen unless the agent dies,
	 * because authentication forwarding is only enabled if we have an
	 * agent.
	 */
	if (sock >= 0) {
		c = channel_new("", SSH_CHANNEL_OPEN, sock, sock,
		    -1, 0, 0, 0, "authentication agent connection", 1);
		c->remote_id = remote_id;
		c->force_drain = 1;
	}
	if (c == NULL) {
		packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
		packet_put_int(remote_id);
	} else {
		/* Send a confirmation to the remote host. */
		debug("Forwarding authentication connection.");
		packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
		packet_put_int(remote_id);
		packet_put_int(c->self);
	}
	packet_send();
}

static Channel *
client_request_forwarded_tcpip(const char *request_type, int rchan)
{
	Channel *c = NULL;
	char *listen_address, *originator_address;
	int listen_port, originator_port;
	int sock;

	/* Get rest of the packet */
	listen_address = packet_get_string(NULL);
	listen_port = packet_get_int();
	originator_address = packet_get_string(NULL);
	originator_port = packet_get_int();
	packet_check_eom();

	debug("client_request_forwarded_tcpip: listen %s port %d, originator %s port %d",
	    listen_address, listen_port, originator_address, originator_port);

	sock = channel_connect_by_listen_address(listen_port);
	if (sock < 0) {
		xfree(originator_address);
		xfree(listen_address);
		return NULL;
	}
	c = channel_new("forwarded-tcpip",
	    SSH_CHANNEL_CONNECTING, sock, sock, -1,
	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
	    originator_address, 1);
	xfree(originator_address);
	xfree(listen_address);
	return c;
}

static Channel *
client_request_x11(const char *request_type, int rchan)
{
	Channel *c = NULL;
	char *originator;
	int originator_port;
	int sock;

	if (!options.forward_x11) {
		error("Warning: ssh server tried X11 forwarding.");
		error("Warning: this is probably a break in attempt by a malicious server.");
		return NULL;
	}
	originator = packet_get_string(NULL);
	if (datafellows & SSH_BUG_X11FWD) {
		debug2("buggy server: x11 request w/o originator_port");
		originator_port = 0;
	} else {
		originator_port = packet_get_int();
	}
	packet_check_eom();
	/* XXX check permission */
	debug("client_request_x11: request from %s %d", originator,
	    originator_port);
	xfree(originator);
	sock = x11_connect_display();
	if (sock < 0)
		return NULL;
	c = channel_new("x11",
	    SSH_CHANNEL_X11_OPEN, sock, sock, -1,
	    CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
	c->force_drain = 1;
	return c;
}

static Channel *
client_request_agent(const char *request_type, int rchan)
{
	Channel *c = NULL;
	int sock;

	if (!options.forward_agent) {
		error("Warning: ssh server tried agent forwarding.");
		error("Warning: this is probably a break in attempt by a malicious server.");
		return NULL;
	}
	sock =  ssh_get_authentication_socket();
	if (sock < 0)
		return NULL;
	c = channel_new("authentication agent connection",
	    SSH_CHANNEL_OPEN, sock, sock, -1,
	    CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
	    "authentication agent connection", 1);
	c->force_drain = 1;
	return c;
}

/* XXXX move to generic input handler */
static void
client_input_channel_open(int type, u_int32_t seq, void *ctxt)
{
	Channel *c = NULL;
	char *ctype;
	int rchan;
	u_int rmaxpack, rwindow, len;

	ctype = packet_get_string(&len);
	rchan = packet_get_int();
	rwindow = packet_get_int();
	rmaxpack = packet_get_int();

	debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
	    ctype, rchan, rwindow, rmaxpack);

	if (strcmp(ctype, "forwarded-tcpip") == 0) {
		c = client_request_forwarded_tcpip(ctype, rchan);
	} else if (strcmp(ctype, "x11") == 0) {
		c = client_request_x11(ctype, rchan);
	} else if (strcmp(ctype, "[e-mail]") == 0) {
		c = client_request_agent(ctype, rchan);
	}
/* XXX duplicate : */
	if (c != NULL) {
		debug("confirm %s", ctype);
		c->remote_id = rchan;
		c->remote_window = rwindow;
		c->remote_maxpacket = rmaxpack;
		if (c->type != SSH_CHANNEL_CONNECTING) {
			packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
			packet_put_int(c->remote_id);
			packet_put_int(c->self);
			packet_put_int(c->local_window);
			packet_put_int(c->local_maxpacket);
			packet_send();
		}
	} else {
		debug("failure %s", ctype);
		packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
		packet_put_int(rchan);
		packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
		if (!(datafellows & SSH_BUG_OPENFAILURE)) {
			packet_put_cstring("open failed");
			packet_put_cstring("");
		}
		packet_send();
	}
	xfree(ctype);
}
static void
client_input_channel_req(int type, u_int32_t seq, void *ctxt)
{
	Channel *c = NULL;
	int exitval, id, reply, success = 0;
	char *rtype;

	id = packet_get_int();
	rtype = packet_get_string(NULL);
	reply = packet_get_char();

	debug("client_input_channel_req: channel %d rtype %s reply %d",
	    id, rtype, reply);

	if (id == -1) {
		error("client_input_channel_req: request for channel -1");
	} else if ((c = channel_lookup(id)) == NULL) {
		error("client_input_channel_req: channel %d: unknown channel", id);
	} else if (strcmp(rtype, "exit-status") == 0) {
		exitval = packet_get_int();
		if (id == session_ident) {
			success = 1;
			exit_status = exitval;
		} else if (c->ctl_fd == -1) {
			error("client_input_channel_req: unexpected channel %d",
			    session_ident);
		} else {
			atomicio(vwrite, c->ctl_fd, &exitval, sizeof(exitval));
			success = 1;
		}
		packet_check_eom();
	}
	if (reply) {
		packet_start(success ?
		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
		packet_put_int(id);
		packet_send();
	}
	xfree(rtype);
}
static void
client_input_global_request(int type, u_int32_t seq, void *ctxt)
{
	char *rtype;
	int want_reply;
	int success = 0;

	rtype = packet_get_string(NULL);
	want_reply = packet_get_char();
	debug("client_input_global_request: rtype %s want_reply %d",
	    rtype, want_reply);
	if (want_reply) {
		packet_start(success ?
		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
		packet_send();
		packet_write_wait();
	}
	xfree(rtype);
}

void
client_session2_setup(int id, int want_tty, int want_subsystem,
    const char *term, struct termios *tiop, int in_fd, Buffer *cmd, char **env,
    dispatch_fn *subsys_repl)
{
	int len;
	Channel *c = NULL;

	debug2("%s: id %d", __func__, id);

	if ((c = channel_lookup(id)) == NULL)
		fatal("client_session2_setup: channel %d: unknown channel", id);

	if (want_tty) {
		struct winsize ws;
		struct termios tio;

		/* Store window size in the packet. */
		if (ioctl(in_fd, TIOCGWINSZ, &ws) < 0)
			memset(&ws, 0, sizeof(ws));

		channel_request_start(id, "pty-req", 0);
		packet_put_cstring(term != NULL ? term : "");
		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(-1, tiop != NULL ? tiop : &tio);
		packet_send();
		/* XXX wait for reply */
		c->client_tty = 1;
	}

	/* Transfer any environment variables from client to server */
	if (options.num_send_env != 0 && env != NULL) {
		int i, j, matched;
		char *name, *val;

		debug("Sending environment.");
		for (i = 0; env[i] != NULL; i++) {
			/* Split */
			name = xstrdup(env[i]);
			if ((val = strchr(name, '=')) == NULL) {
				free(name);
				continue;
			}
			*val++ = '\0';

			matched = 0;
			for (j = 0; j < options.num_send_env; j++) {
				if (match_pattern(name, options.send_env[j])) {
					matched = 1;
					break;
				}
			}
			if (!matched) {
				debug3("Ignored env %s", name);
				free(name);
				continue;
			}

			debug("Sending env %s = %s", name, val);
			channel_request_start(id, "env", 0);
			packet_put_cstring(name);
			packet_put_cstring(val);
			packet_send();
			free(name);
		}
	}

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

static void
client_init_dispatch_20(void)
{
	dispatch_init(&dispatch_protocol_error);

	dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
	dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
	dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
	dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
	dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);

	/* rekeying */
	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);

	/* global request reply messages */
	dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
	dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
}
static void
client_init_dispatch_13(void)
{
	dispatch_init(NULL);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
	dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
	dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
	dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
	dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
	dispatch_set(SSH_SMSG_EXITSTATUS, &client_input_exit_status);
	dispatch_set(SSH_SMSG_STDERR_DATA, &client_input_stderr_data);
	dispatch_set(SSH_SMSG_STDOUT_DATA, &client_input_stdout_data);

	dispatch_set(SSH_SMSG_AGENT_OPEN, options.forward_agent ?
	    &client_input_agent_open : &deny_input_open);
	dispatch_set(SSH_SMSG_X11_OPEN, options.forward_x11 ?
	    &x11_input_open : &deny_input_open);
}
static void
client_init_dispatch_15(void)
{
	client_init_dispatch_13();
	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, & channel_input_oclose);
}
static void
client_init_dispatch(void)
{
	if (compat20)
		client_init_dispatch_20();
	else if (compat13)
		client_init_dispatch_13();
	else
		client_init_dispatch_15();
}

/* client specific fatal cleanup */
void
cleanup_exit(int i)
{
	leave_raw_mode();
	leave_non_blocking();
	if (options.control_path != NULL && control_fd != -1)
		unlink(options.control_path);
	_exit(i);
}