/*
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)
{
// learn new routes
learn_route(in_channel, msg);
if (msg->msgid == MAVLINK_MSG_ID_HEARTBEAT) {
// heartbeat needs special handling
handle_heartbeat(in_channel, msg);
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;
for (uint8_t i=0; i<num_routes; i++) {
if (broadcast_system || (target_system == routes[i].sysid &&
(broadcast_component ||
target_component == routes[i].compid))) {
if (in_channel != routes[i].channel) {
if (comm_get_txspace(routes[i].channel) >=
((uint16_t)msg->len) + MAVLINK_NUM_NON_PAYLOAD_BYTES) {
#if ROUTING_DEBUG
::printf("fwd msg %u from chan %u on chan %u sysid=%u compid=%u\n",
msg->msgid,
(unsigned)in_channel,
(unsigned)routes[i].channel,
(unsigned)target_system,
(unsigned)target_component);
#endif
_mavlink_resend_uart(routes[i].channel, msg);
}
forwarded = true;
}
}
}
if (!forwarded && match_system) {
process_locally = true;
}
return process_locally;
}
/*
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;
}
// 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
::printf("fwd msg %u from chan %u on chan %u sysid=%d compid=%d\n",
msg->msgid,
(unsigned)in_channel,
(unsigned)routes[i].channel,
(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;
}
