WIP: Mavlink file server

1 files changed, 377 insertions, 0 deletions

diff --git a/src/modules/mavlink/mavlink_ftp.cpp b/src/modules/mavlink/mavlink_ftp.cpp
new file mode 100644
index 000000000..4cb31640e
--- /dev/null
+++ b/src/modules/mavlink/mavlink_ftp.cpp
@@ -0,0 +1,377 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2014 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#include <crc32.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "mavlink_ftp.h"
+
+MavlinkFTP *MavlinkFTP::_server;
+
+MavlinkFTP *
+MavlinkFTP::getServer()
+{
+	// XXX this really cries out for some locking...
+	if (_server == nullptr) {
+		_server = new MavlinkFTP;
+	}
+	return _server;
+}
+
+MavlinkFTP::MavlinkFTP()
+{
+	// initialise the request freelist
+	dq_init(&_workFree);
+	sem_init(&_lock, 0, 1);
+
+	// drop work entries onto the free list
+	for (unsigned i = 0; i < kRequestQueueSize; i++) {
+		_qFree(&_workBufs[i]);
+	}
+
+}
+
+void
+MavlinkFTP::handle_message(mavlink_message_t *msg, mavlink_channel_t channel)
+{
+	// get a free request
+	auto req = _dqFree();
+
+	// if we couldn't get a request slot, just drop it
+	if (req != nullptr) {
+
+		// decode the request
+		req->decode(channel, msg);
+
+		// and queue it for the worker
+		work_queue(LPWORK, &req->work, &MavlinkFTP::_workerTrampoline, req, 0);
+	}
+}
+
+void
+MavlinkFTP::_workerTrampoline(void *arg)
+{
+	auto req = reinterpret_cast<Request *>(arg);
+	auto server = MavlinkFTP::getServer();
+
+	// call the server worker with the work item
+	server->_worker(req);
+}
+
+void
+MavlinkFTP::_worker(Request *req)
+{
+	auto hdr = req->header();
+	ErrorCode errorCode = kErrNone;
+	uint32_t messageCRC;
+
+	// basic sanity checks; must validate length before use
+	if ((hdr->magic != kProtocolMagic) || (hdr->size > kMaxDataLength)) {
+		errorCode = kErrNoRequest;
+		goto out;
+	}
+
+	// check request CRC to make sure this is one of ours
+	messageCRC = hdr->crc32;
+	hdr->crc32 = 0;
+	if (crc32(req->data(), req->dataSize()) != messageCRC) {
+		errorCode = kErrNoRequest;
+		goto out;
+	}
+
+	switch (hdr->opcode) {
+	case kCmdNone:
+		break;
+
+	case kCmdTerminate:
+		if (!Session::terminate(hdr->session)) {
+			errorCode = kErrNoRequest;
+		}
+		break;
+
+	case kCmdReset:
+		Session::reset();
+		break;
+
+	case kCmdList:
+		errorCode = _workList(req);
+		break;
+
+	case kCmdOpen:
+		errorCode = _workOpen(req, false);
+		break;
+
+	case kCmdCreate:
+		errorCode = _workOpen(req, true);
+		break;
+
+	case kCmdRead:
+		errorCode = _workRead(req);
+		break;
+
+	case kCmdWrite:
+		errorCode = _workWrite(req);
+		break;
+
+	case kCmdRemove:
+		errorCode = _workRemove(req);
+		break;
+
+	default:
+		errorCode = kErrNoRequest;
+		break;	
+	}
+
+out:
+	// handle success vs. error
+	if (errorCode == kErrNone) {
+		hdr->opcode = kRspAck;
+	} else {
+		hdr->opcode = kRspNak;
+		hdr->size = 1;
+		hdr->data[0] = errorCode;
+	}
+
+	// respond to the request
+	_reply(req);
+
+	// free the request buffer back to the freelist
+	_qFree(req);
+}
+
+void
+MavlinkFTP::_reply(Request *req)
+{
+	auto hdr = req->header();
+
+	// message is assumed to be already constructed in the request buffer, so generate the CRC
+	hdr->crc32 = 0;
+	hdr->crc32 = crc32(req->data(), req->dataSize());
+
+	// then pack and send the reply back to the request source
+	mavlink_msg_encapsulated_data_send(req->channel, req->sequence(), req->data());
+}
+
+MavlinkFTP::ErrorCode
+MavlinkFTP::_workList(Request *req)
+{
+	auto hdr = req->header();
+
+	// open directory
+
+	// seek in directory
+
+	// read entries until buffer is full
+
+	// send reply
+
+	return kErrNone;
+}
+
+MavlinkFTP::ErrorCode
+MavlinkFTP::_workOpen(Request *req, bool create)
+{
+	auto hdr = req->header();
+
+	// allocate session ID
+	int session = Session::allocate();
+	if (session < 0) {
+		return kErrNoSession;
+	}
+
+	// get the session to open the file
+	if (!Session::get(session)->open(req->dataAsCString(), create)) {
+		return create ? kErrPerm : kErrNotFile;
+	}
+
+	// save the session ID in the reply
+	hdr->session = session;
+	hdr->size = 0;
+
+	return kErrNone;
+}
+
+MavlinkFTP::ErrorCode
+MavlinkFTP::_workRead(Request *req)
+{
+	auto hdr = req->header();
+
+	// look up session
+	auto session = Session::get(hdr->session);
+	if (session == nullptr) {
+		return kErrNoSession;
+	}
+
+	// read from file
+	int result = session->read(hdr->offset, &hdr->data[0], hdr->size);
+
+	if (result < 0) {
+		return kErrIO;
+	}
+	hdr->size = result;
+	return kErrNone;
+}
+
+MavlinkFTP::ErrorCode
+MavlinkFTP::_workWrite(Request *req)
+{
+	auto hdr = req->header();
+
+	// look up session
+	auto session = Session::get(hdr->session);
+	if (session == nullptr) {
+		return kErrNoSession;
+	}
+
+	// append to file
+	int result = session->append(hdr->offset, &hdr->data[0], hdr->size);
+
+	if (result < 0) {
+		// XXX might also be no space, I/O, etc.
+		return kErrNotAppend;
+	}
+
+	hdr->size = result;
+	return kErrNone;
+}
+
+MavlinkFTP::ErrorCode
+MavlinkFTP::_workRemove(Request *req)
+{
+	auto hdr = req->header();
+
+	// for now, send error reply
+	return kErrPerm;
+}
+
+MavlinkFTP::Session MavlinkFTP::Session::_sessions[MavlinkFTP::Session::kMaxSession];
+
+int
+MavlinkFTP::Session::allocate()
+{
+	for (unsigned i = 0; i < kMaxSession; i++) {
+		if (_sessions[i]._fd < 0) {
+			return i;
+		}
+	}
+	return -1;
+}
+
+MavlinkFTP::Session *
+MavlinkFTP::Session::get(unsigned index)
+{
+	if ((index >= kMaxSession) || (_sessions[index]._fd < 0)) {
+		return nullptr;
+	}
+	return &_sessions[index];
+}
+
+void
+MavlinkFTP::Session::terminate()
+{
+	// clean up aborted transfers?
+	if (_fd >= 0) {
+		close(_fd);
+		_fd = -1;
+	}
+}
+
+bool
+MavlinkFTP::Session::terminate(unsigned index)
+ {
+	Session *session = get(index);
+
+	if (session == nullptr) {
+		return false;
+	}
+
+	session->terminate();
+	return true;
+}
+
+void
+MavlinkFTP::Session::reset()
+{
+	for (unsigned i = 0; i < kMaxSession; i++) {
+		terminate(i);
+	}
+}
+
+bool
+MavlinkFTP::Session::open(const char *path, bool create)
+{
+	int oflag = create ? (O_CREAT | O_EXCL | O_APPEND) : O_RDONLY;
+
+	_fd = open(path, oflag);
+	if (_fd < 0) {
+		return false;
+	}
+	return true;
+}
+
+int
+MavlinkFTP::Session::read(off_t offset, uint8_t *buf, uint8_t count)
+{
+	// can we seek to the location?
+	if (lseek(_fd, offset, SEEK_SET) < 0) {
+		return -1;
+	}
+
+	return read(_fd, buf, count);
+}
+
+int
+MavlinkFTP::Session::append(off_t offset, uint8_t *buf, uint8_t count)
+{
+	// make sure that the requested offset matches our current position
+	off_t pos = lseek(_fd, 0, SEEK_CUR);
+	if (pos != offset) {
+		return -1;
+	}
+	return write(_fd, buf, count);
+}
+
+char *
+MavlinkFTP::Request::dataAsCString()
+{
+	// guarantee nul termination
+	if (header()->size < kMaxDataLength) {
+		data()[header()->size] = '\0';
+	} else {
+		data()[kMaxDataLength - 1] = '\0';
+	}
+
+	// and return data
+	return (char *)data();
+}