Module udp 

The Semtech packet forwarder protocol, both sides.

A gateway and a network server exchange six kinds of UDP datagram, described by PROTOCOL.TXT in Semtech’s packet_forwarder. Each begins with the same three bytes, a protocol version of 2 and a random token, then an identifier that says which kind it is:

• The gateway sends PUSH_DATA with the packets it heard, and the server answers PUSH_ACK with the same token.
• The gateway sends PULL_DATA to hold a route open through whatever network address translation sits in front of it, and the server answers PULL_ACK.
• The server sends PULL_RESP with a packet to transmit, and the gateway answers TX_ACK saying whether it accepted it.

The protocol has no authentication and no retries, which is why it belongs on a private network or behind a tunnel. Packet builds and parses every kind, and the objects they carry are in Rxpk, Stat, Txpk, and TxStatus.

Examples

A server reads a forwarded packet and answers it.

use pamoja_gateway::udp::{Eui, Packet, PacketKind, Rxpk, Uplink};
use pamoja_lora::LinkSettings;

let gateway = Eui::new([0xB8, 0x27, 0xEB, 0xFF, 0xFE, 0x01, 0x02, 0x03]);
let datagram = Packet::PushData {
    token: 0x0102,
    gateway,
    uplink: Uplink::from(Rxpk::new(
        868_100_000,
        LinkSettings::new(7, 125_000),
        b"hello".to_vec(),
    )),
}
.to_bytes();

let packet = Packet::parse(&datagram)?;
assert_eq!(packet.kind(), PacketKind::PushData);
assert_eq!(packet.gateway(), Some(gateway));
assert_eq!(packet.acknowledgment().map(|ack| ack.to_bytes()), Some(vec![2, 0x01, 0x02, 0x01]));

Structs

Eui

A gateway’s unique identifier, the eight bytes it puts in every datagram it sends.

Rxpk

A packet the gateway heard, with the metadata the protocol carries beside it.

Stat

The gateway’s own status report.

Txpk

A packet the server asks the gateway to transmit.

Uplink

What a PUSH_DATA carries: the packets heard, and the gateway’s own report.

Enums

CrcStatus

What the CRC of a received packet said.

Modulation

How a packet was modulated.

Packet

One datagram of the protocol.

PacketKind

Which kind of datagram, as its fourth byte says.

ProtocolError

Why a datagram is not one this protocol defines.

TxStatus

What became of a downlink the server asked for.

Constants

EUI_LEN

The length of a gateway’s unique identifier.

HEADER_LEN

The bytes before a datagram’s payload: the version, the token, and the identifier.

PROTOCOL_VERSION

The protocol version every datagram starts with.