peer.c

Linux下的多协议即时通讯程序源代码

	if (read < 0)
	{
		if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
			/* No worries */
			return;

		peer_connection_destroy(conn,
				OSCAR_DISCONNECT_LOST_CONNECTION, strerror(errno));
		return;
	}

	conn->lastactivity = time(NULL);
	conn->buffer_incoming.offset += read;
	if (conn->buffer_incoming.offset < conn->buffer_incoming.len)
		/* Waiting for more data to arrive */
		return;

	/* We have a complete ODC/OFT frame!  Handle it and continue reading */
	byte_stream_rewind(&conn->buffer_incoming);
	if (conn->type == OSCAR_CAPABILITY_DIRECTIM)
	{
		peer_odc_recv_frame(conn, &conn->buffer_incoming);
	}
	else if (conn->type == OSCAR_CAPABILITY_SENDFILE)
	{
		peer_oft_recv_frame(conn, &conn->buffer_incoming);
	}

	g_free(conn->buffer_incoming.data);
	conn->buffer_incoming.data = NULL;

	conn->header_received = 0;
}

/*******************************************************************/
/* End code for receiving data on a peer connection                */
/*******************************************************************/

/*******************************************************************/
/* Begin code for sending data on a peer connection                */
/*******************************************************************/

static void
send_cb(gpointer data, gint source, PurpleInputCondition cond)
{
	PeerConnection *conn;
	gsize writelen;
	ssize_t wrotelen;

	conn = data;
	writelen = purple_circ_buffer_get_max_read(conn->buffer_outgoing);

	if (writelen == 0)
	{
		purple_input_remove(conn->watcher_outgoing);
		conn->watcher_outgoing = 0;
		return;
	}

	wrotelen = send(conn->fd, conn->buffer_outgoing->outptr, writelen, 0);
	if (wrotelen <= 0)
	{
		if (wrotelen < 0 && ((errno == EAGAIN) || (errno == EWOULDBLOCK)))
			/* No worries */
			return;

		if (conn->ready)
		{
			purple_input_remove(conn->watcher_outgoing);
			conn->watcher_outgoing = 0;
			close(conn->fd);
			conn->fd = -1;
			peer_connection_schedule_destroy(conn,
					OSCAR_DISCONNECT_LOST_CONNECTION, NULL);
		}
		else
		{
			/*
			 * This could happen when unable to send a negotiation
			 * frame to a peer proxy server.
			 */
			peer_connection_trynext(conn);
		}
		return;
	}

	purple_circ_buffer_mark_read(conn->buffer_outgoing, wrotelen);
	conn->lastactivity = time(NULL);
}

/**
 * This should be called by OFT/ODC code to send a standard OFT or ODC
 * frame across the peer connection along with some payload data.  Or
 * maybe a file.  Anything, really.
 */
void
peer_connection_send(PeerConnection *conn, ByteStream *bs)
{
	/* Add everything to our outgoing buffer */
	purple_circ_buffer_append(conn->buffer_outgoing, bs->data, bs->len);

	/* If we haven't already started writing stuff, then start the cycle */
	if ((conn->watcher_outgoing == 0) && (conn->fd >= 0))
	{
		conn->watcher_outgoing = purple_input_add(conn->fd,
				PURPLE_INPUT_WRITE, send_cb, conn);
		send_cb(conn, conn->fd, 0);
	}
}

/*******************************************************************/
/* End code for sending data on a peer connection                  */
/*******************************************************************/

/*******************************************************************/
/* Begin code for establishing a peer connection                   */
/*******************************************************************/

void
peer_connection_finalize_connection(PeerConnection *conn)
{
	conn->watcher_incoming = purple_input_add(conn->fd,
			PURPLE_INPUT_READ, peer_connection_recv_cb, conn);

	if (conn->type == OSCAR_CAPABILITY_DIRECTIM)
	{
		/*
		 * If we are connecting to them then send our cookie so they
		 * can verify who we are.  Note: This doesn't seem to be
		 * necessary, but it also doesn't seem to hurt.
		 */
		if (!(conn->flags & PEER_CONNECTION_FLAG_IS_INCOMING))
			peer_odc_send_cookie(conn);
	}
	else if (conn->type == OSCAR_CAPABILITY_SENDFILE)
	{
		if (purple_xfer_get_type(conn->xfer) == PURPLE_XFER_SEND)
		{
			peer_oft_send_prompt(conn);
		}
	}

	/*
	 * Tell the remote user that we're connected (which may also imply
	 * that we've accepted their request).
	 */
	if (!(conn->flags & PEER_CONNECTION_FLAG_IS_INCOMING))
		aim_im_sendch2_connected(conn);
}

/**
 * We tried to make an outgoing connection to a remote user.  It
 * either connected or failed to connect.
 */
static void
peer_connection_common_established_cb(gpointer data, gint source, const gchar *error_message, gboolean verified)
{
	PeerConnection *conn;

	conn = data;

	if (verified)
		conn->verified_connect_data = NULL;
	else
		conn->client_connect_data = NULL;

	if (source < 0)
	{
		if ((conn->verified_connect_data == NULL) &&
			(conn->client_connect_data == NULL))
		{
			/* Our parallel connection attemps have both failed. */
			peer_connection_trynext(conn);
		}
		return;
	}

	purple_timeout_remove(conn->connect_timeout_timer);
	conn->connect_timeout_timer = 0;

	if (conn->client_connect_data != NULL)
	{
		purple_proxy_connect_cancel(conn->client_connect_data);
		conn->client_connect_data = NULL;
	}

	if (conn->verified_connect_data != NULL)
	{
		purple_proxy_connect_cancel(conn->verified_connect_data);
		conn->verified_connect_data = NULL;
	}

	conn->fd = source;

	peer_connection_finalize_connection(conn);
}

static void
peer_connection_verified_established_cb(gpointer data, gint source, const gchar *error_message)
{
	peer_connection_common_established_cb(data, source, error_message, TRUE);
}

static void
peer_connection_client_established_cb(gpointer data, gint source, const gchar *error_message)
{
	peer_connection_common_established_cb(data, source, error_message, FALSE);
}

/**
 * This is the watcher callback for any listening socket that is
 * waiting for a peer to connect.  When a peer connects we set the
 * input watcher to start reading data from the peer.
 *
 * To make sure that the connection is with the intended person and
 * not with a malicious middle man, we don't send anything until we've
 * received a peer frame from the remote user and have verified that
 * the cookie in the peer frame matches the cookie that was exchanged
 * in the channel 2 ICBM.
 */
void
peer_connection_listen_cb(gpointer data, gint source, PurpleInputCondition cond)
{
	PeerConnection *conn;
	OscarData *od;
	PurpleConnection *gc;
	struct sockaddr addr;
	socklen_t addrlen = sizeof(addr);

	conn = data;
	od = conn->od;
	gc = od->gc;

	purple_debug_info("oscar", "Accepting connection on listener socket.\n");

	conn->fd = accept(conn->listenerfd, &addr, &addrlen);
	if (conn->fd < 0)
	{
		if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
			/* No connection yet--no worries */
			/* TODO: Hmm, but they SHOULD be connected if we're here, right? */
			return;

		peer_connection_trynext(conn);
		return;
	}

	if ((addr.sa_family != PF_INET) && (addr.sa_family != PF_INET6))
	{
		/* Invalid connection type?!  Continue waiting. */
		close(conn->fd);
		return;
	}

	fcntl(conn->fd, F_SETFL, O_NONBLOCK);
	purple_input_remove(conn->watcher_incoming);

	peer_connection_finalize_connection(conn);
}

/**
 * We've just opened a listener socket, so we send the remote
 * user an ICBM and ask them to connect to us.
 */
static void
peer_connection_establish_listener_cb(int listenerfd, gpointer data)
{
	PeerConnection *conn;
	OscarData *od;
	PurpleConnection *gc;
	PurpleAccount *account;
	PurpleConversation *conv;
	char *tmp;
	FlapConnection *bos_conn;
	const char *listener_ip;
	unsigned short listener_port;

	conn = data;
	conn->listen_data = NULL;

	if (listenerfd < 0)
	{
		/* Could not open listener socket */
		peer_connection_trynext(conn);
		return;
	}

	od = conn->od;
	gc = od->gc;
	account = purple_connection_get_account(gc);
	conn->listenerfd = listenerfd;

	/* Send the "please connect to me!" ICBM */
	bos_conn = flap_connection_findbygroup(od, SNAC_FAMILY_ICBM);
	if (bos_conn == NULL)
	{
		/* Not good */
		peer_connection_trynext(conn);
		return;
	}

	listener_ip = purple_network_get_my_ip(bos_conn->fd);
	listener_port = purple_network_get_port_from_fd(conn->listenerfd);
	if (conn->type == OSCAR_CAPABILITY_DIRECTIM)
	{
		aim_im_sendch2_odc_requestdirect(od,
				conn->cookie, conn->sn, purple_network_ip_atoi(listener_ip),
				listener_port, ++conn->lastrequestnumber);

		/* Print a message to a local conversation window */
		conv = purple_conversation_new(PURPLE_CONV_TYPE_IM, account, conn->sn);
		tmp = g_strdup_printf(_("Asking %s to connect to us at %s:%hu for "
				"Direct IM."), conn->sn, listener_ip, listener_port);
		purple_conversation_write(conv, NULL, tmp, PURPLE_MESSAGE_SYSTEM, time(NULL));
		g_free(tmp);
	}
	else if (conn->type == OSCAR_CAPABILITY_SENDFILE)
	{
		aim_im_sendch2_sendfile_requestdirect(od,
				conn->cookie, conn->sn,
				purple_network_ip_atoi(listener_ip),
				listener_port, ++conn->lastrequestnumber,
				(const gchar *)conn->xferdata.name,
				conn->xferdata.size, conn->xferdata.totfiles);
	}
}

/**
 * This is a callback function used when we're connecting to a peer
 * using either the client IP or the verified IP and the connection
 * took longer than 5 seconds to complete.  We do this because
 * waiting for the OS to time out the connection attempt is not
 * practical--the default timeout on many OSes can be 3 minutes or
 * more, and users are impatient.
 *
 * Worst case scenario: the user is connected to the Internet using
 * a modem with severe lag.  The peer connections fail and Purple falls
 * back to using a proxied connection.  The lower bandwidth
 * limitations imposed by the proxied connection won't matter because
 * the user is using a modem.
 *
 * I suppose this line of thinking is discriminatory against people
 * with very high lag but decent throughput who are transferring
 * large files.  But we don't care about those people.
 *
 * I (Sean) changed the timeout from 15 to 5 seconds, as 60 seconds is
 * too long for a user to wait to send a file. I'm also parallelizing
 * requests when possible. The longest we should have to wait now is 10
 * seconds. We shouldn't make it shorter than this.
 */
static gboolean
peer_connection_tooktoolong(gpointer data)
{
	PeerConnection *conn;

	conn = data;

	purple_debug_info("oscar", "Peer connection timed out after 5 seconds.  "
			"Trying next method...\n");

	peer_connection_trynext(conn);