ardupilot/libraries/GCS_MAVLink/MAVLink_routing.cpp

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/// @file MAVLink_routing.h
/// @brief handle routing of MAVLink packets by sysid/componentid
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#include <stdio.h>
#include <AP_HAL/AP_HAL.h>
#include <AP_Common/AP_Common.h>
#include "GCS.h"
#include "MAVLink_routing.h"
extern const AP_HAL::HAL& hal;
#define ROUTING_DEBUG 0
// constructor
MAVLink_routing::MAVLink_routing(void) : num_routes(0) {}
/*
forward a MAVLink message to the right port. This also
automatically learns the route for the sender if it is not
already known.
This returns true if the message should be processed locally
Theory of MAVLink routing:
When a flight controller receives a message it should process it
locally if any of these conditions hold:
1a) the message has no target_system field
1b) the message has a target_system of zero
1c) the message has the flight controllers target system and has no
target_component field
1d) the message has the flight controllers target system and has
the flight controllers target_component
1e) the message has the flight controllers target system and the
flight controller has not seen any messages on any of its links
from a system that has the messages
target_system/target_component combination
When a flight controller receives a message it should forward it
onto another different link if any of these conditions hold for that
link:
2a) the message has no target_system field
2b) the message has a target_system of zero
2c) the message does not have the flight controllers target_system
and the flight controller has seen a message from the messages
target_system on the link
2d) the message has the flight controllers target_system and has a
target_component field and the flight controllers has seen a
message from the target_system/target_component combination on
the link
Note: This proposal assumes that ground stations will not send command
packets to a non-broadcast destination (sysid/compid combination)
until they have received at least one package from that destination
over the link. This is essential to prevent a flight controller from
acting on a message that is not meant for it. For example, a PARAM_SET
cannot be sent to a specific sysid/compid combination until the GCS
has seen a packet from that sysid/compid combination on the link.
The GCS must also reset what sysid/compid combinations it has seen on
a link when it sees a SYSTEM_TIME message with a decrease in
time_boot_ms from a particular sysid/compid. That is essential to
detect a reset of the flight controller, which implies a reset of its
routing table.
*/
bool MAVLink_routing::check_and_forward(mavlink_channel_t in_channel, const mavlink_message_t* msg)
{
// handle the case of loopback of our own messages, due to
// incorrect serial configuration.
if (msg->sysid == mavlink_system.sysid &&
msg->compid == mavlink_system.compid) {
return true;
}
// learn new routes
learn_route(in_channel, msg);
if (msg->msgid == MAVLINK_MSG_ID_RADIO ||
msg->msgid == MAVLINK_MSG_ID_RADIO_STATUS) {
// don't forward RADIO packets
return true;
}
if (msg->msgid == MAVLINK_MSG_ID_HEARTBEAT) {
// heartbeat needs special handling
handle_heartbeat(in_channel, msg);
return true;
}
if (msg->msgid == MAVLINK_MSG_ID_ADSB_VEHICLE) {
// ADSB packets are not forwarded, they have their own stream rate
return true;
}
// extract the targets for this packet
int16_t target_system = -1;
int16_t target_component = -1;
get_targets(msg, target_system, target_component);
bool broadcast_system = (target_system == 0 || target_system == -1);
bool broadcast_component = (target_component == 0 || target_component == -1);
bool match_system = broadcast_system || (target_system == mavlink_system.sysid);
bool match_component = match_system && (broadcast_component ||
(target_component == mavlink_system.compid));
bool process_locally = match_system && match_component;
if (process_locally && !broadcast_system && !broadcast_component) {
// nothing more to do - it can only be for us
return true;
}
// forward on any channels matching the targets
bool forwarded = false;
bool sent_to_chan[MAVLINK_COMM_NUM_BUFFERS];
memset(sent_to_chan, 0, sizeof(sent_to_chan));
for (uint8_t i=0; i<num_routes; i++) {
if (broadcast_system || (target_system == routes[i].sysid &&
(broadcast_component ||
target_component == routes[i].compid ||
!match_system))) {
if (in_channel != routes[i].channel && !sent_to_chan[routes[i].channel]) {
if (comm_get_txspace(routes[i].channel) >= ((uint16_t)msg->len) +
GCS_MAVLINK::packet_overhead_chan(routes[i].channel)) {
#if ROUTING_DEBUG
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::printf("fwd msg %u from chan %u on chan %u sysid=%d compid=%d\n",
msg->msgid,
(unsigned)in_channel,
(unsigned)routes[i].channel,
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(int)target_system,
(int)target_component);
#endif
_mavlink_resend_uart(routes[i].channel, msg);
}
sent_to_chan[routes[i].channel] = true;
forwarded = true;
}
}
}
if (!forwarded && match_system) {
process_locally = true;
}
return process_locally;
}
/*
send a MAVLink message to all components with this vehicle's system id
This is a no-op if no routes to components have been learned
*/
void MAVLink_routing::send_to_components(const mavlink_message_t* msg)
{
bool sent_to_chan[MAVLINK_COMM_NUM_BUFFERS];
memset(sent_to_chan, 0, sizeof(sent_to_chan));
// check learned routes
for (uint8_t i=0; i<num_routes; i++) {
if ((routes[i].sysid == mavlink_system.sysid) && !sent_to_chan[routes[i].channel]) {
if (comm_get_txspace(routes[i].channel) >= ((uint16_t)msg->len) +
GCS_MAVLINK::packet_overhead_chan(routes[i].channel)) {
#if ROUTING_DEBUG
::printf("send msg %u on chan %u sysid=%u compid=%u\n",
msg->msgid,
(unsigned)routes[i].channel,
(unsigned)routes[i].sysid,
(unsigned)routes[i].compid);
#endif
_mavlink_resend_uart(routes[i].channel, msg);
sent_to_chan[routes[i].channel] = true;
}
}
}
}
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/*
search for the first vehicle or component in the routing table with given mav_type and retrieve it's sysid, compid and channel
returns true if a match is found
*/
bool MAVLink_routing::find_by_mavtype(uint8_t mavtype, uint8_t &sysid, uint8_t &compid, mavlink_channel_t &channel)
{
// check learned routes
for (uint8_t i=0; i<num_routes; i++) {
if (routes[i].mavtype == mavtype) {
sysid = routes[i].sysid;
compid = routes[i].compid;
channel = routes[i].channel;
return true;
}
}
// if we've reached we have not found the component
return false;
}
/*
see if the message is for a new route and learn it
*/
void MAVLink_routing::learn_route(mavlink_channel_t in_channel, const mavlink_message_t* msg)
{
uint8_t i;
if (msg->sysid == 0 ||
(msg->sysid == mavlink_system.sysid &&
msg->compid == mavlink_system.compid)) {
return;
}
for (i=0; i<num_routes; i++) {
if (routes[i].sysid == msg->sysid &&
routes[i].compid == msg->compid &&
routes[i].channel == in_channel) {
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if (routes[i].mavtype == 0 && msg->msgid == MAVLINK_MSG_ID_HEARTBEAT) {
routes[i].mavtype = mavlink_msg_heartbeat_get_type(msg);
}
break;
}
}
if (i == num_routes && i<MAVLINK_MAX_ROUTES) {
routes[i].sysid = msg->sysid;
routes[i].compid = msg->compid;
routes[i].channel = in_channel;
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if (msg->msgid == MAVLINK_MSG_ID_HEARTBEAT) {
routes[i].mavtype = mavlink_msg_heartbeat_get_type(msg);
}
num_routes++;
#if ROUTING_DEBUG
::printf("learned route %u %u via %u\n",
(unsigned)msg->sysid,
(unsigned)msg->compid,
(unsigned)in_channel);
#endif
}
}
/*
special handling for heartbeat messages. To ensure routing
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propagation heartbeat messages need to be forwarded on all channels
except channels where the sysid/compid of the heartbeat could come from
*/
void MAVLink_routing::handle_heartbeat(mavlink_channel_t in_channel, const mavlink_message_t* msg)
{
uint16_t mask = GCS_MAVLINK::active_channel_mask();
// don't send on the incoming channel. This should only matter if
// the routing table is full
mask &= ~(1U<<(in_channel-MAVLINK_COMM_0));
// mask out channels that do not want the heartbeat to be forwarded
mask &= ~no_route_mask;
// mask out channels that are known sources for this sysid/compid
for (uint8_t i=0; i<num_routes; i++) {
if (routes[i].sysid == msg->sysid && routes[i].compid == msg->compid) {
mask &= ~(1U<<((unsigned)(routes[i].channel-MAVLINK_COMM_0)));
}
}
if (mask == 0) {
// nothing to send to
return;
}
// send on the remaining channels
for (uint8_t i=0; i<MAVLINK_COMM_NUM_BUFFERS; i++) {
if (mask & (1U<<i)) {
mavlink_channel_t channel = (mavlink_channel_t)(MAVLINK_COMM_0 + i);
if (comm_get_txspace(channel) >= ((uint16_t)msg->len) +
GCS_MAVLINK::packet_overhead_chan(channel)) {
#if ROUTING_DEBUG
::printf("fwd HB from chan %u on chan %u from sysid=%u compid=%u\n",
(unsigned)in_channel,
(unsigned)channel,
(unsigned)msg->sysid,
(unsigned)msg->compid);
#endif
_mavlink_resend_uart(channel, msg);
}
}
}
}
/*
extract target sysid and compid from a message. int16_t is used so
that the caller can set them to -1 and know when a sysid or compid
target is found in the message
*/
void MAVLink_routing::get_targets(const mavlink_message_t* msg, int16_t &sysid, int16_t &compid)
{
const mavlink_msg_entry_t *msg_entry = mavlink_get_msg_entry(msg->msgid);
if (msg_entry == nullptr) {
return;
}
if (msg_entry->flags & MAV_MSG_ENTRY_FLAG_HAVE_TARGET_SYSTEM) {
sysid = _MAV_RETURN_uint8_t(msg, msg_entry->target_system_ofs);
}
if (msg_entry->flags & MAV_MSG_ENTRY_FLAG_HAVE_TARGET_COMPONENT) {
compid = _MAV_RETURN_uint8_t(msg, msg_entry->target_component_ofs);
}
}