fix(dns): fix tmux dns resolver

Kieran Klukas created 1 month ago

Change summary

internal/dns/android.go | 41 +++++++++++++++++++++++++++++++++++++++++
main.go                 |  1 +
2 files changed, 42 insertions(+)

Detailed changes

internal/dns/android.go

@@ -0,0 +1,41 @@
+// Package dns configures Go's DNS resolver for Termux/Android where
+// Go's pure-Go resolver reads /etc/resolv.conf which points to
+// non-functional loopback nameservers.
+// The package uses runtime detection — no build tags required.
+package dns
+
+import (
+	"context"
+	"net"
+	"os"
+)
+
+func init() {
+	if os.Getenv("TERMUX_VERSION") == "" {
+		return
+	}
+
+	net.DefaultResolver = &net.Resolver{
+		PreferGo: true,
+		Dial:     dialWithFallback([]string{"8.8.8.8:53", "1.1.1.1:53"}),
+	}
+}
+
+// dialWithFallback returns a resolver Dial func that tries each
+// nameserver in order, falling through on failure.
+func dialWithFallback(nameservers []string) func(context.Context, string, string) (net.Conn, error) {
+	return func(ctx context.Context, network, _ string) (net.Conn, error) {
+		var lastErr error
+		d := net.Dialer{
+			Resolver: nil,
+		}
+		for _, ns := range nameservers {
+			conn, err := d.DialContext(ctx, network, ns)
+			if err == nil {
+				return conn, nil
+			}
+			lastErr = err
+		}
+		return nil, lastErr
+	}
+}

main.go

@@ -17,6 +17,7 @@ import (
 	"os"
 
 	"github.com/charmbracelet/crush/internal/cmd"
+	_ "github.com/charmbracelet/crush/internal/dns"
 	_ "github.com/joho/godotenv/autoload"
 )