Add subdomain constructor

src/hosts.zig

@@ -62,14 +62,26 @@ fn append_new(tmp_hosts: std.fs.File, addr: std.net.Address) !void {
     const writer = tmp_hosts.writer();
     var buff = [_]u8{0x00} ** 50;
 
+    // write output
     const header_len = hosts_header.*.len;
     @memcpy(buff[0..header_len], hosts_header);
     try writer.writeAll(buff[0..header_len]);
     try writer.writeByte('\n');
 
+    var subdomains = try get_subdomains();
+    const domain = try util.getenv("TARGET_DOMAIN");
+    while (subdomains.next()) |subdomain| {
+        std.debug.print("{s}.{s}\n", .{ subdomain, domain });
+    }
+    // add extra final newline
     try writer.writeByte('\n');
 }
 
+fn get_subdomains() !std.mem.SplitIterator(u8, .scalar) {
+    const subdomain_list = try util.getenv("SUBDOMAIN_LIST");
+    return std.mem.splitScalar(u8, std.mem.span(subdomain_list), ' ');
+}
+
 fn create_tmp_hosts(ip: util.IP) !void {
     var old_hosts = try std.fs.openFileAbsoluteZ(try util.getenv("OLD_HOSTS_PATH"), .{ .mode = .read_only });
     defer old_hosts.close();

src/util.zig

@@ -64,7 +64,7 @@ fn check_domain(domain_str: [:0]const u8) !Domain {
         .name = domain_str,
         .labels = [_][]const u8{&[_]u8{}} ** 5,
     };
-    var labels = std.mem.split(u8, domain_str, ".");
+    var labels = std.mem.splitScalar(u8, domain_str, '.');
     var last: []const u8 = "";
     var i: usize = 0;
     while (labels.next()) |segment| {