Resolve DNS A record

Cargo.lock

@@ -902,6 +902,12 @@ version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "650eef8c711430f1a879fdd01d4745a7deea475becfb90269c06775983bbf086"
 
+[[package]]
+name = "no-std-net"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43794a0ace135be66a25d3ae77d41b91615fb68ae937f904090203e81f755b65"
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
@@ -1009,6 +1015,7 @@ dependencies = [
  "rand",
  "serde",
  "serde_yaml",
+ "sntpc",
  "static_cell",
 ]
 
@@ -1341,6 +1348,15 @@ dependencies = [
  "managed",
 ]
 
+[[package]]
+name = "sntpc"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de6292f240a2bf33ae7156cb354802bca8ecfacf96b820a6ec2f2e9f5c01f260"
+dependencies = [
+ "no-std-net",
+]
+
 [[package]]
 name = "ssmarshal"
 version = "1.0.0"

Cargo.toml

@@ -21,6 +21,7 @@ log ="*"
 panic-halt = "*"
 portable-atomic = { version = "*", features = ["critical-section"] }
 rand = { version = "*", default-features = false }
+sntpc = { version = "*", default-features = false }
 static_cell = "*"
 
 [profile.release]

src/main.rs

@@ -2,12 +2,17 @@
 #![no_std]
 #![no_main]
 
+mod picow_time;
+
 extern crate panic_halt;
 
 use cyw43::JoinOptions;
 use cyw43_pio::PioSpi;
 use embassy_executor::Spawner;
-use embassy_net::{Config, DhcpConfig, StackResources};
+use embassy_net::{
+    dns::{DnsQueryType, DnsSocket},
+    Config, DhcpConfig, IpAddress, StackResources,
+};
 use embassy_rp::{
     bind_interrupts,
     clocks::RoscRng,
@@ -18,15 +23,16 @@ use embassy_rp::{
 };
 use embassy_time::Timer;
 use log::info;
+use picow_time::PicowUDPBuffer;
 use rand::RngCore;
 use static_cell::StaticCell;
 
 const HOSTNAME: &str = "picow";
+const NTP_ENDPOINT: &str = "time.google.com";
+const WAIT_SECOND: u64 = 7;
 const WIRELESS_CREDENTIALS: &[(&str, &str)] =
     &include!(concat!(env!("OUT_DIR"), "/wireless-credentials.rs"));
 
-const WIRELESS_SCAN_PERIOD_SECOND: u64 = 7;
-
 bind_interrupts!(struct Irqs {
     PIO0_IRQ_0 => pio::InterruptHandler<PIO0>;
     USBCTRL_IRQ => usb::InterruptHandler<USB>;
@@ -107,11 +113,11 @@ async fn main(spawner: Spawner) -> ! {
         .set_power_management(cyw43::PowerManagementMode::PowerSave)
         .await;
 
-    // set hostname
+    // hostname
     let mut dhcpv4_config = DhcpConfig::default();
     dhcpv4_config.hostname = HOSTNAME.try_into().ok();
 
-    // setup network stack
+    // network stack
     static RESOURCES: StaticCell<StackResources<3>> = StaticCell::new();
     let (network_stack, network_runner) = embassy_net::new(
         network_device,
@@ -141,8 +147,8 @@ async fn main(spawner: Spawner) -> ! {
                 .0
         {
             info!("Unable to join any wireless network with provided credentials");
-            info!("Sleep for {WIRELESS_SCAN_PERIOD_SECOND} seconds before rescan");
-            Timer::after_secs(WIRELESS_SCAN_PERIOD_SECOND).await;
+            info!("Sleep for {WAIT_SECOND} seconds before rescan");
+            Timer::after_secs(WAIT_SECOND).await;
         }
     }
 
@@ -156,8 +162,37 @@ async fn main(spawner: Spawner) -> ! {
     // turn on led to indicate network connection
     wireless_control.gpio_set(0, true).await;
 
+    // dns client
+    let dns_client = DnsSocket::new(network_stack);
+
+    // udp client
+    // let mut udp_buffer = PicowUDPBuffer::default();
+    // let udp_client = udp_buffer.socket(network_stack);
+
     loop {
-        info!("System is idle");
-        Timer::after_secs(1).await;
+        let ntp_ipv4 = match dns_client.query(NTP_ENDPOINT, DnsQueryType::A).await {
+            Ok(address) => match address.first() {
+                Some(IpAddress::Ipv4(ipv4)) => ipv4.octets(),
+                None => {
+                    info!(
+                        "DNS A record lookup returned no IPv4 address: {}",
+                        NTP_ENDPOINT
+                    );
+                    continue;
+                }
+            },
+            Err(error) => {
+                info!(
+                    "DNS A record lookup returned error: {}, {:?}",
+                    NTP_ENDPOINT, error
+                );
+                continue;
+            }
+        };
+        info!(
+            "Resolved IPv4 address for {}: {}.{}.{}.{}",
+            NTP_ENDPOINT, ntp_ipv4[0], ntp_ipv4[1], ntp_ipv4[1], ntp_ipv4[3]
+        );
+        Timer::after_secs(WAIT_SECOND).await;
     }
 }

src/picow_time.rs

@@ -0,0 +1,67 @@
+use embassy_net::{
+    udp::{PacketMetadata, UdpSocket},
+    Stack,
+};
+use embassy_time::{Duration, Instant};
+use sntpc::NtpTimestampGenerator;
+
+const UDP_BUFFER_SIZE_BYTE: usize = 1 << 12;
+const UDP_METADATA_SIZE: usize = 1 << 3;
+
+#[derive(Copy, Clone)]
+pub struct PicowTimestampGenerator {
+    duration: Duration,
+}
+
+impl Default for PicowTimestampGenerator {
+    fn default() -> Self {
+        Self {
+            duration: Instant::now().duration_since(Instant::MIN),
+        }
+    }
+}
+
+impl NtpTimestampGenerator for PicowTimestampGenerator {
+    fn init(&mut self) {
+        self.duration = Instant::now().duration_since(Instant::MIN);
+    }
+
+    fn timestamp_sec(&self) -> u64 {
+        self.duration.as_secs()
+    }
+
+    fn timestamp_subsec_micros(&self) -> u32 {
+        (self.duration.as_micros() % 1000000) as u32
+    }
+}
+
+#[derive(Debug)]
+pub struct PicowUDPBuffer {
+    receive_buffer: [u8; UDP_BUFFER_SIZE_BYTE],
+    receive_metadata: [PacketMetadata; UDP_METADATA_SIZE],
+    transmit_buffer: [u8; UDP_BUFFER_SIZE_BYTE],
+    transmit_metadata: [PacketMetadata; UDP_METADATA_SIZE],
+}
+
+impl Default for PicowUDPBuffer {
+    fn default() -> Self {
+        Self {
+            receive_buffer: [0; UDP_BUFFER_SIZE_BYTE],
+            receive_metadata: [PacketMetadata::EMPTY; UDP_METADATA_SIZE],
+            transmit_buffer: [0; UDP_BUFFER_SIZE_BYTE],
+            transmit_metadata: [PacketMetadata::EMPTY; UDP_METADATA_SIZE],
+        }
+    }
+}
+
+impl PicowUDPBuffer {
+    pub fn socket<'me>(&'me mut self, network_stack: Stack<'me>) -> UdpSocket<'me> {
+        UdpSocket::new(
+            network_stack,
+            &mut self.receive_metadata,
+            &mut self.receive_buffer,
+            &mut self.transmit_metadata,
+            &mut self.transmit_buffer,
+        )
+    }
+}