channels.c

C＋＋编写

	char buf[16384], *remote_ipaddr;
	int remote_port;

	if (FD_ISSET(c->sock, readset)) {
		debug("X11 connection requested.");
		addrlen = sizeof(addr);
		newsock = accept(c->sock, &addr, &addrlen);
		if (c->single_connection) {
			debug("single_connection: closing X11 listener.");
			channel_close_fd(&c->sock);
			chan_mark_dead(c);
		}
		if (newsock < 0) {
			error("accept: %.100s", strerror(errno));
			return;
		}
		set_nodelay(newsock);
		remote_ipaddr = get_peer_ipaddr(newsock);
		remote_port = get_peer_port(newsock);
		snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
		    remote_ipaddr, remote_port);

		nc = channel_new("accepted x11 socket",
		    SSH_CHANNEL_OPENING, newsock, newsock, -1,
		    c->local_window_max, c->local_maxpacket,
		    0, xstrdup(buf), 1);
		if (compat20) {
			packet_start(SSH2_MSG_CHANNEL_OPEN);
			packet_put_cstring("x11");
			packet_put_int(nc->self);
			packet_put_int(nc->local_window_max);
			packet_put_int(nc->local_maxpacket);
			/* originator ipaddr and port */
			packet_put_cstring(remote_ipaddr);
			if (datafellows & SSH_BUG_X11FWD) {
				debug("ssh2 x11 bug compat mode");
			} else {
				packet_put_int(remote_port);
			}
			packet_send();
		} else {
			packet_start(SSH_SMSG_X11_OPEN);
			packet_put_int(nc->self);
			if (packet_get_protocol_flags() &
			    SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
				packet_put_cstring(buf);
			packet_send();
		}
		xfree(remote_ipaddr);
	}
}

static void
port_open_helper(Channel *c, char *rtype)
{
	int direct;
	char buf[1024];
	char *remote_ipaddr = get_peer_ipaddr(c->sock);
	u_short remote_port = get_peer_port(c->sock);

	direct = (strcmp(rtype, "direct-tcpip") == 0);

	snprintf(buf, sizeof buf,
	    "%s: listening port %d for %.100s port %d, "
	    "connect from %.200s port %d",
	    rtype, c->listening_port, c->path, c->host_port,
	    remote_ipaddr, remote_port);

	xfree(c->remote_name);
	c->remote_name = xstrdup(buf);

	if (compat20) {
		packet_start(SSH2_MSG_CHANNEL_OPEN);
		packet_put_cstring(rtype);
		packet_put_int(c->self);
		packet_put_int(c->local_window_max);
		packet_put_int(c->local_maxpacket);
		if (direct) {
			/* target host, port */
			packet_put_cstring(c->path);
			packet_put_int(c->host_port);
		} else {
			/* listen address, port */
			packet_put_cstring(c->path);
			packet_put_int(c->listening_port);
		}
		/* originator host and port */
		packet_put_cstring(remote_ipaddr);
		packet_put_int(remote_port);
		packet_send();
	} else {
		packet_start(SSH_MSG_PORT_OPEN);
		packet_put_int(c->self);
		packet_put_cstring(c->path);
		packet_put_int(c->host_port);
		if (packet_get_protocol_flags() &
		    SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
			packet_put_cstring(c->remote_name);
		packet_send();
	}
	xfree(remote_ipaddr);
}

/*
 * This socket is listening for connections to a forwarded TCP/IP port.
 */
static void
channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
{
	Channel *nc;
	struct sockaddr addr;
	int newsock, nextstate;
	socklen_t addrlen;
	char *rtype;

	if (FD_ISSET(c->sock, readset)) {
		debug("Connection to port %d forwarding "
		    "to %.100s port %d requested.",
		    c->listening_port, c->path, c->host_port);

		if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
			nextstate = SSH_CHANNEL_OPENING;
			rtype = "forwarded-tcpip";
		} else {
			if (c->host_port == 0) {
				nextstate = SSH_CHANNEL_DYNAMIC;
				rtype = "dynamic-tcpip";
			} else {
				nextstate = SSH_CHANNEL_OPENING;
				rtype = "direct-tcpip";
			}
		}

		addrlen = sizeof(addr);
		newsock = accept(c->sock, &addr, &addrlen);
		if (newsock < 0) {
			error("accept: %.100s", strerror(errno));
			return;
		}
		set_nodelay(newsock);
		nc = channel_new(rtype,
		    nextstate, newsock, newsock, -1,
		    c->local_window_max, c->local_maxpacket,
		    0, xstrdup(rtype), 1);
		nc->listening_port = c->listening_port;
		nc->host_port = c->host_port;
		strlcpy(nc->path, c->path, sizeof(nc->path));

		if (nextstate == SSH_CHANNEL_DYNAMIC) {
			/*
			 * do not call the channel_post handler until
			 * this flag has been reset by a pre-handler.
			 * otherwise the FD_ISSET calls might overflow
			 */
			nc->delayed = 1;
		} else {
			port_open_helper(nc, rtype);
		}
	}
}

/*
 * This is the authentication agent socket listening for connections from
 * clients.
 */
static void
channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
{
	Channel *nc;
	char *name;
	int newsock;
	struct sockaddr addr;
	socklen_t addrlen;

	if (FD_ISSET(c->sock, readset)) {
		addrlen = sizeof(addr);
		newsock = accept(c->sock, &addr, &addrlen);
		if (newsock < 0) {
			error("accept from auth socket: %.100s", strerror(errno));
			return;
		}
		name = xstrdup("accepted auth socket");
		nc = channel_new("accepted auth socket",
		    SSH_CHANNEL_OPENING, newsock, newsock, -1,
		    c->local_window_max, c->local_maxpacket,
		    0, name, 1);
		if (compat20) {
			packet_start(SSH2_MSG_CHANNEL_OPEN);
			packet_put_cstring("[e-mail]");
			packet_put_int(nc->self);
			packet_put_int(c->local_window_max);
			packet_put_int(c->local_maxpacket);
		} else {
			packet_start(SSH_SMSG_AGENT_OPEN);
			packet_put_int(nc->self);
		}
		packet_send();
	}
}

static void
channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
{
	int err = 0;
	socklen_t sz = sizeof(err);

	if (FD_ISSET(c->sock, writeset)) {
		if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
			err = errno;
			error("getsockopt SO_ERROR failed");
		}
		if (err == 0) {
			debug("channel %d: connected", c->self);
			c->type = SSH_CHANNEL_OPEN;
			if (compat20) {
				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);
			} else {
				packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
				packet_put_int(c->remote_id);
				packet_put_int(c->self);
			}
		} else {
			debug("channel %d: not connected: %s",
			    c->self, strerror(err));
			if (compat20) {
				packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
				packet_put_int(c->remote_id);
				packet_put_int(SSH2_OPEN_CONNECT_FAILED);
				if (!(datafellows & SSH_BUG_OPENFAILURE)) {
					packet_put_cstring(strerror(err));
					packet_put_cstring("");
				}
			} else {
				packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
				packet_put_int(c->remote_id);
			}
			chan_mark_dead(c);
		}
		packet_send();
	}
}

static int
channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
{
	char buf[16*1024];
	int len;

	if (c->rfd != -1 &&
	    FD_ISSET(c->rfd, readset)) {
		len = read(c->rfd, buf, sizeof(buf));
		if (len < 0 && (errno == EINTR || errno == EAGAIN))
			return 1;
		if (len <= 0) {
			debug("channel %d: read<=0 rfd %d len %d",
			    c->self, c->rfd, len);
			if (c->type != SSH_CHANNEL_OPEN) {
				debug("channel %d: not open", c->self);
				chan_mark_dead(c);
				return -1;
			} else if (compat13) {
				buffer_clear(&c->output);
				c->type = SSH_CHANNEL_INPUT_DRAINING;
				debug("channel %d: input draining.", c->self);
			} else {
				chan_read_failed(c);
			}
			return -1;
		}
		if (c->input_filter != NULL) {
			if (c->input_filter(c, buf, len) == -1) {
				debug("channel %d: filter stops", c->self);
				chan_read_failed(c);
			}
		} else {
			buffer_append(&c->input, buf, len);
		}
	}
	return 1;
}
static int
channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
{
	struct termios tio;
	u_char *data;
	u_int dlen;
	int len;

	/* Send buffered output data to the socket. */
	if (c->wfd != -1 &&
	    FD_ISSET(c->wfd, writeset) &&
	    buffer_len(&c->output) > 0) {
		data = buffer_ptr(&c->output);
		dlen = buffer_len(&c->output);
		len = write(c->wfd, data, dlen);
		if (len < 0 && (errno == EINTR || errno == EAGAIN))
			return 1;
		if (len <= 0) {
			if (c->type != SSH_CHANNEL_OPEN) {
				debug("channel %d: not open", c->self);
				chan_mark_dead(c);
				return -1;
			} else if (compat13) {
				buffer_clear(&c->output);
				debug("channel %d: input draining.", c->self);
				c->type = SSH_CHANNEL_INPUT_DRAINING;
			} else {
				chan_write_failed(c);
			}
			return -1;
		}
		if (compat20 && c->isatty && dlen >= 1 && data[0] != '\r') {
			if (tcgetattr(c->wfd, &tio) == 0 &&
			    !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
				/*
				 * Simulate echo to reduce the impact of
				 * traffic analysis. We need to match the
				 * size of a SSH2_MSG_CHANNEL_DATA message
				 * (4 byte channel id + data)
				 */
				packet_send_ignore(4 + len);
				packet_send();
			}
		}
		buffer_consume(&c->output, len);
		if (compat20 && len > 0) {
			c->local_consumed += len;
		}
	}
	return 1;
}
static int
channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
{
	char buf[16*1024];
	int len;

/** XXX handle drain efd, too */
	if (c->efd != -1) {
		if (c->extended_usage == CHAN_EXTENDED_WRITE &&
		    FD_ISSET(c->efd, writeset) &&
		    buffer_len(&c->extended) > 0) {
			len = write(c->efd, buffer_ptr(&c->extended),
			    buffer_len(&c->extended));
			debug2("channel %d: written %d to efd %d",
			    c->self, len, c->efd);
			if (len < 0 && (errno == EINTR || errno == EAGAIN))
				return 1;
			if (len <= 0) {
				debug2("channel %d: closing write-efd %d",
				    c->self, c->efd);
				channel_close_fd(&c->efd);
			} else {
				buffer_consume(&c->extended, len);
				c->local_consumed += len;
			}
		} else if (c->extended_usage == CHAN_EXTENDED_READ &&
		    FD_ISSET(c->efd, readset)) {
			len = read(c->efd, buf, sizeof(buf));
			debug2("channel %d: read %d from efd %d",
			    c->self, len, c->efd);
			if (len < 0 && (errno == EINTR || errno == EAGAIN))
				return 1;
			if (len <= 0) {
				debug2("channel %d: closing read-efd %d",
				    c->self, c->efd);
				channel_close_fd(&c->efd);
			} else {
				buffer_append(&c->extended, buf, len);
			}
		}
	}
	return 1;
}
static int
channel_check_window(Channel *c)
{
	if (c->type == SSH_CHANNEL_OPEN &&
	    !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
	    c->local_window < c->local_window_max/2 &&
	    c->local_consumed > 0) {
		packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
		packet_put_int(c->remote_id);
		packet_put_int(c->local_consumed);
		packet_send();
		debug2("channel %d: window %d sent adjust %d",
		    c->self, c->local_window,
		    c->local_consumed);
		c->local_window += c->local_consumed;
		c->local_consumed = 0;
	}
	return 1;
}

static void
channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
{
	if (c->delayed)
		return;
	channel_handle_rfd(c, readset, writeset);
	channel_handle_wfd(c, readset, writeset);
	if (!compat20)
		return;
	channel_handle_efd(c, readset, writeset);
	channel_check_window(c);
}

static void
channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
{
	int len;

	/* Send buffered output data to the socket. */
	if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
		len = write(c->sock, buffer_ptr(&c->output),
			    buffer_len(&c->output));
		if (len <= 0)
			buffer_clear(&c->output);
		else
			buffer_consume(&c->output, len);
	}
}

static void
channel_handler_init_20(void)
{
	channel_pre[SSH_CHANNEL_OPEN] =			&channel_pre_open;
	channel_pre[SSH_CHANNEL_X11_OPEN] =		&channel_pre_x11_open;
	channel_pre[SSH_CHANNEL_PORT_LISTENER] =	&channel_pre_listener;
	channel_pre[SSH_CHANNEL_RPORT_LISTENER] =	&channel_pre_listener;
	channel_pre[SSH_CHANNEL_X11_LISTENER] =		&channel_pre_listener;
	channel_pre[SSH_CHANNEL_AUTH_SOCKET] =		&channel_pre_listener;
	channel_pre[SSH_CHANNEL_CONNECTING] =		&channel_pre_connecting;
	channel_pre[SSH_CHANNEL_DYNAMIC] =		&channel_pre_dynamic;

	channel_post[SSH_CHANNEL_OPEN] =		&channel_post_open;
	channel_post[SSH_CHANNEL_PORT_LISTENER] =	&channel_post_port_listener;
	channel_post[SSH_CHANNEL_RPORT_LISTENER] =	&channel_post_port_listener;
	channel_post[SSH_CHANNEL_X11_LISTENER] =	&channel_post_x11_listener;
	channel_post[SSH_CHANNEL_AUTH_SOCKET] =		&channel_post_auth_listener;
	channel_post[SSH_CHANNEL_CONNECTING] =		&channel_post_connecting;
	channel_post[SSH_CHANNEL_DYNAMIC] =		&channel_post_open;
}

static void
channel_handler_init_13(void)
{
	channel_pre[SSH_CHANNEL_OPEN] =			&channel_pre_open_13;
	channel_pre[SSH_CHANNEL_X11_OPEN] =		&channel_pre_x11_open_13;
	channel_pre[SSH_CHANNEL_X11_LISTENER] =		&channel_pre_listener;
	channel_pre[SSH_CHANNEL_PORT_LISTENER] =	&channel_pre_listener;
	channel_pre[SSH_CHANNEL_AUTH_SOCKET] =		&channel_pre_listener;
	channel_pre[SSH_CHANNEL_INPUT_DRAINING] =	&channel_pre_input_draining;
	channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =	&channel_pre_output_draining;
	channel_pre[SSH_CHANNEL_CONNECTING] =		&channel_pre_connecting;
	channel_pre[SSH_CHANNEL_DYNAMIC] =		&channel_pre_dynamic;

	channel_post[SSH_CHANNEL_OPEN] =		&channel_post_open;
	channel_post[SSH_CHANNEL_X11_LISTENER] =	&channel_post_x11_listener;
	channel_post[SSH_CHANNEL_PORT_LISTENER] =	&channel_post_port_listener;
	channel_post[SSH_CHANNEL_AUTH_SOCKET] =		&channel_post_auth_listener;
	channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =	&channel_post_output_drain_13;
	channel_post[SSH_CHANNEL_CONNECTING] =		&channel_post_connecting;
	channel_post[SSH_CHANNEL_DYNAMIC] =		&channel_post_open;
}

static void
channel_handler_init_15(void)
{
	channel_pre[SSH_CHANNEL_OPEN] =			&channel_pre_open;
	channel_pre[SSH_CHANNEL_X11_OPEN] =		&channel_pre_x11_open;
	channel_pre[SSH_CHANNEL_X11_LISTENER] =		&channel_pre_listener;
	channel_pre[SSH_CHANNEL_PORT_LISTENER] =	&channel_pre_listener;
	channel_pre[SSH_CHANNEL_AUTH_SOCKET] =		&channel_pre_listener;
	channel_pre[SSH_CHANNEL_CONNECTING] =		&channel_pre_connecting;
	channel_pre[SSH_CHANNEL_DYNAMIC] =		&channel_pre_dynamic;

	channel_post[SSH_CHANNEL_X11_LISTENER] =	&channel_post_x11_listener;
	channel_post[SSH_CHANNEL_PORT_LISTENER] =	&channel_post_port_listener;
	channel_post[SSH_CHANNEL_AUTH_SOCKET] =		&channel_post_auth_listener;
	channel_post[SSH_CHANNEL_OPEN] =		&channel_post_open;
	channel_post[SSH_CHANNEL_CONNECTING] =		&channel_post_connecting;
	channel_post[SSH_CHANNEL_DYNAMIC] =		&channel_post_open;
}

static void
channel_handler_init(void)
{
	int i;

	for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {