package hostess import ( "fmt" "net" "regexp" "strings" ) var ipv4Pattern = regexp.MustCompile(`^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$`) var ipv6Pattern = regexp.MustCompile(`^[a-z0-9:]+$`) // LooksLikeIPv4 returns true if the IP looks like it's IPv4. This does not // validate whether the string is a valid IP address. func LooksLikeIPv4(ip string) bool { return ipv4Pattern.MatchString(ip) } // LooksLikeIPv6 returns true if the IP looks like it's IPv6. This does not // validate whether the string is a valid IP address. func LooksLikeIPv6(ip string) bool { if !strings.Contains(ip, ":") { return false } return ipv6Pattern.MatchString(ip) } // Hostname represents a hosts file entry, including a Domain, IP, whether the // Hostname is enabled (uncommented in the hosts file), and whether the IP is // in the IPv6 format. You should always create these with NewHostname(). Note: // when using Hostnames in the context of a Hostlist, you should not change the // Hostname fields except through the Hostlist's aggregate methods. Doing so // can cause unexpected behavior. Instead, use Hostlist's Add, Remove, Enable, // and Disable methods. type Hostname struct { Domain string IP net.IP Enabled bool IPv6 bool } // NewHostname creates a new Hostname struct and automatically sets the IPv6 // field based on the IP you pass in. func NewHostname(domain, ip string, enabled bool) (hostname *Hostname) { IP := net.ParseIP(ip) hostname = &Hostname{domain, IP, enabled, LooksLikeIPv6(ip)} return } // Equal compares two Hostnames. Note that only the Domain and IP fields are // compared because Enabled is transient state, and IPv6 should be set // automatically based on IP. func (h *Hostname) Equal(n *Hostname) bool { return h.Domain == n.Domain && h.IP.Equal(n.IP) } // EqualIP compares an IP against this Hostname. func (h *Hostname) EqualIP(ip net.IP) bool { return h.IP.Equal(ip) } // IsValid does a spot-check on the domain and IP to make sure they aren't blank func (h *Hostname) IsValid() bool { return h.Domain != "" && h.IP != nil } // Format outputs the Hostname as you'd see it in a hosts file, with a comment // if it is disabled. E.g. // # 127.0.0.1 blah.example.com func (h *Hostname) Format() string { r := fmt.Sprintf("%s %s", h.IP.String(), h.Domain) if !h.Enabled { r = "# " + r } return r } // FormatEnabled displays Hostname.Enabled as (On) or (Off) func (h *Hostname) FormatEnabled() string { if h.Enabled { return "(On)" } return "(Off)" } // FormatHuman outputs the Hostname in a more human-readable format: // blah.example.com -> 127.0.0.1 (Off) func (h *Hostname) FormatHuman() string { return fmt.Sprintf("%s -> %s %s", h.Domain, h.IP, h.FormatEnabled()) }