1 files changed, 98 insertions, 0 deletions
diff --git a/src/dns_updater.rs b/src/dns_updater.rs
new file mode 100644
index 0000000..06ba408
--- /dev/null
+++ b/src/dns_updater.rs
@@ -0,0 +1,98 @@
+use std::net::{Ipv4Addr, Ipv6Addr};
+use std::sync::Arc;
+
+use anyhow::{anyhow, bail, Result};
+use log::*;
+use tokio::select;
+use tokio::sync::watch;
+
+use crate::dns_config::*;
+use crate::provider::DnsProvider;
+
+pub async fn dns_updater_task(
+    mut rx_dns_config: watch::Receiver<Arc<DnsConfig>>,
+    provider: Box<dyn DnsProvider>,
+    allowed_domains: Vec<String>,
+    mut must_exit: watch::Receiver<bool>,
+) {
+    let mut config = Arc::new(DnsConfig::new());
+    while !*must_exit.borrow() {
+        select!(
+            c = rx_dns_config.changed() => {
+                if c.is_err() {
+                    break;
+                }
+            }
+            _ = must_exit.changed() => continue,
+        );
+        let new_config: Arc<DnsConfig> = rx_dns_config.borrow().clone();
+
+        for (k, v) in new_config.entries.iter() {
+            if config.entries.get(k) != Some(v) {
+                let fulldomain = format!("{}.{}", k.subdomain, k.domain);
+                if !allowed_domains.iter().any(|d| fulldomain.ends_with(d)) {
+                    error!(
+                        "Got an entry for domain {} which is not in allowed list",
+                        k.domain
+                    );
+                    continue;
+                }
+
+                info!("Updating {} {}", k, v);
+                if let Err(e) = update_dns_entry(k, v, provider.as_ref()).await {
+                    error!("Unable to update entry {} {}: {}", k, v, e);
+                }
+            }
+        }
+
+        config = new_config;
+    }
+}
+
+async fn update_dns_entry(
+    key: &DnsEntryKey,
+    value: &DnsEntryValue,
+    provider: &dyn DnsProvider,
+) -> Result<()> {
+    if value.targets.is_empty() {
+        bail!("zero targets (internal error)");
+    }
+
+    match key.record_type {
+        DnsRecordType::A => {
+            let mut targets = vec![];
+            for tgt in value.targets.iter() {
+                targets.push(
+                    tgt.parse::<Ipv4Addr>()
+                        .map_err(|_| anyhow!("Invalid ipv4 address: {}", tgt))?,
+                );
+            }
+            provider
+                .update_a(&key.domain, &key.subdomain, &targets)
+                .await?;
+        }
+        DnsRecordType::AAAA => {
+            let mut targets = vec![];
+            for tgt in value.targets.iter() {
+                targets.push(
+                    tgt.parse::<Ipv6Addr>()
+                        .map_err(|_| anyhow!("Invalid ipv6 address: {}", tgt))?,
+                );
+            }
+            provider
+                .update_aaaa(&key.domain, &key.subdomain, &targets)
+                .await?;
+        }
+        DnsRecordType::CNAME => {
+            let mut targets = value.targets.iter().cloned().collect::<Vec<_>>();
+            if targets.len() > 1 {
+                targets.sort();
+                warn!("Several CNAME targets for {}: {:?}. Taking first one in alphabetical order. Consider switching to a single global target instead.", key, targets);
+            }
+            provider
+                .update_cname(&key.domain, &key.subdomain, &targets[0])
+                .await?;
+        }
+    }
+    Ok(())
+}