init

    pub fn init(r: []const u8) Error!DnsResponse {
        if (r.len < 12) return error.InvalidDnsPacket;
        if ((r[3] & 15) != 0) return .{ .bytes = r, .bytes_index = 3, .answers_remaining = 0 };
        var i: u32 = 12;
        var query_count = std.mem.readInt(u16, r[4..6], .big);
        while (query_count != 0) : (query_count -= 1) {
            while (i < r.len and r[i] -% 1 < 127) i += 1;
            if (r.len - i < 6) return error.InvalidDnsPacket;
            i = i + 5 + @intFromBool(r[i] != 0);
        }
        return .{
            .bytes = r,
            .bytes_index = i,
            .answers_remaining = std.mem.readInt(u16, r[6..8], .big),
        };
    }