From 3ae9e3e24a57effb107acea96719955db9f699c8 Mon Sep 17 00:00:00 2001
From: Scott Mabin <scott@mabez.dev>
Date: Thu, 20 Jul 2023 12:13:09 +0100
Subject: [PATCH] Replace the hardcoded ip address with a dns lookup

---
 Cargo.toml  |  2 +-
 src/main.rs | 12 ++++++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 5e825a3..bd2c453 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,7 +15,7 @@ heapless = "0.7.16"
 esp-backtrace = { version = "0.7.0", features = ["esp32c3", "panic-handler", "exception-handler", "print-uart"] }
 esp-println       = { version = "0.5.0", features = ["esp32c3","log"] }
 embedded-svc = { version = "0.25.0", default-features = false}
-embassy-net = { version = "0.1.0", features = ["nightly", "tcp", "udp", "dhcpv4", "medium-ethernet", "proto-ipv6", "log"] }
+embassy-net = { version = "0.1.0", features = ["nightly", "tcp", "udp", "dhcpv4", "medium-ethernet", "proto-ipv6", "log", "dns"] }
 embassy-executor  = { version = "0.2.0", features = ["nightly", "integrated-timers", "arch-riscv32", "executor-thread"] }
 embassy-time       = { version = "0.1.1", features = ["nightly"] }
 embedded-hal       = { version = "0.2.7", features = ["unproven"] }
diff --git a/src/main.rs b/src/main.rs
index cad3638..06a3b12 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -28,7 +28,7 @@ use embassy_time::{Duration, Timer};
 
 use embassy_executor::_export::StaticCell;
 use embassy_net::tcp::TcpSocket;
-use embassy_net::{Config, Ipv4Address, Stack, StackResources};
+use embassy_net::{Config, Stack, StackResources, dns::DnsQueryType};
 
 use heapless::String;
 use core::fmt::Write;
@@ -124,7 +124,15 @@ async fn task(stack: &'static Stack<WifiDevice<'static>>, i2c: I2C<'static, I2C0
 
         socket.set_timeout(Some(embassy_time::Duration::from_secs(10)));
 
-        let remote_endpoint = (Ipv4Address::new(52, 57, 158, 144), 1883);
+        let address = match stack.dns_query("broker.hivemq.com", DnsQueryType::A).await.map(|a| a[0]) {
+            Ok(address) => address,
+            Err(e) => {
+                println!("DNS lookup error: {e:?}");
+                continue
+            }
+        };
+
+        let remote_endpoint = (address, 1883);
         println!("connecting...");
         let connection = socket.connect(remote_endpoint).await;
         if let Err(e) = connection {