A packet envelope sent/received over the mesh only payloadVariant is sent in the payload portion of the LORA packet. The other fields are either not sent at all, or sent in the special 16 byte LORA header.
(Usually) If set, this indicates the index in the secondary_channels table that this packet was sent/received on. If unset, packet was on the primary channel. A particular node might know only a subset of channels in use on the mesh. Therefore channel_index is inherently a local concept and meaningless to send between nodes. Very briefly, while sending and receiving deep inside the device Router code, this field instead contains the 'channel hash' instead of the index. This 'trick' is only used while the payloadVariant is an 'encrypted'.
The sending node number. Note: Our crypto implementation uses this field as well. See crypto for details. FIXME - really should be fixed32 instead, this encoding only hurts the ble link though.
If unset treated as zero (no forwarding, send to adjacent nodes only) if 1, allow hopping through one node, etc... For our usecase real world topologies probably have a max of about 3. This field is normally placed into a few of bits in the header.
A unique ID for this packet. Always 0 for no-ack packets or non broadcast packets (and therefore take zero bytes of space). Otherwise a unique ID for this packet, useful for flooding algorithms. ID only needs to be unique on a per sender basis, and it only needs to be unique for a few minutes (long enough to last for the length of any ACK or the completion of a mesh broadcast flood). Note: Our crypto implementation uses this id as well. See crypto for details. FIXME - really should be fixed32 instead, this encoding only hurts the ble link though.
The priority of this message for sending. See MeshPacket.Priority description for more details.
rssi of received packet. Only sent to phone for dispay purposes.
Never sent over the radio links. Set during reception to indicate the SNR of this packet. Used to collect statistics on current link quality.
The time this message was received by the esp32 (secs since 1970). Note: this field is never sent on the radio link itself (to save space) Times are typically not sent over the mesh, but they will be added to any Packet (chain of SubPacket) sent to the phone (so the phone can know exact time of reception)
The (immediatSee Priority description for more details.y should be fixed32 instead, this encoding only hurts the ble link though.
This packet is being sent as a reliable message, we would prefer it to arrive at the destination. We would like to receive a ack packet in response. Broadcasts messages treat this flag specially: Since acks for broadcasts would rapidly flood the channel, the normal ack behavior is suppressed. Instead, the original sender listens to see if at least one node is rebroadcasting this packet (because naive flooding algorithm). If it hears that the odds (given typical LoRa topologies) the odds are very high that every node should eventually receive the message. So FloodingRouter.cpp generates an implicit ack which is delivered to the original sender. If after some time we don't hear anyone rebroadcast our packet, we will timeout and retransmit, using the regular resend logic. Note: This flag is normally sent in a flag bit in the header when sent over the wire
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