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package plugin
import (
"fmt"
"net"
"strconv"
"strings"
"github.com/coredns/coredns/plugin/pkg/parse"
"github.com/miekg/dns"
)
// See core/dnsserver/address.go - we should unify these two impls.
// Zones respresents a lists of zone names.
type Zones []string
// Matches checks if qname is a subdomain of any of the zones in z. The match
// will return the most specific zones that matches. The empty string
// signals a not found condition.
func (z Zones) Matches(qname string) string {
zone := ""
for _, zname := range z {
if dns.IsSubDomain(zname, qname) {
// We want the *longest* matching zone, otherwise we may end up in a parent
if len(zname) > len(zone) {
zone = zname
}
}
}
return zone
}
// Normalize fully qualifies all zones in z. The zones in Z must be domain names, without
// a port or protocol prefix.
func (z Zones) Normalize() {
for i := range z {
z[i] = Name(z[i]).Normalize()
}
}
// Name represents a domain name.
type Name string
// Matches checks to see if other is a subdomain (or the same domain) of n.
// This method assures that names can be easily and consistently matched.
func (n Name) Matches(child string) bool {
if dns.Name(n) == dns.Name(child) {
return true
}
return dns.IsSubDomain(string(n), child)
}
// Normalize lowercases and makes n fully qualified.
func (n Name) Normalize() string { return strings.ToLower(dns.Fqdn(string(n))) }
type (
// Host represents a host from the Corefile, may contain port.
Host string
)
// Normalize will return the host portion of host, stripping
// of any port or transport. The host will also be fully qualified and lowercased.
func (h Host) Normalize() string {
s := string(h)
_, s = parse.Transport(s)
// The error can be ignore here, because this function is called after the corefile has already been vetted.
host, _, _, _ := SplitHostPort(s)
return Name(host).Normalize()
}
// SplitHostPort splits s up in a host and port portion, taking reverse address notation into account.
// String the string s should *not* be prefixed with any protocols, i.e. dns://. The returned ipnet is the
// *net.IPNet that is used when the zone is a reverse and a netmask is given.
func SplitHostPort(s string) (host, port string, ipnet *net.IPNet, err error) {
// If there is: :[0-9]+ on the end we assume this is the port. This works for (ascii) domain
// names and our reverse syntax, which always needs a /mask *before* the port.
// So from the back, find first colon, and then check if its a number.
host = s
colon := strings.LastIndex(s, ":")
if colon == len(s)-1 {
return "", "", nil, fmt.Errorf("expecting data after last colon: %q", s)
}
if colon != -1 {
if p, err := strconv.Atoi(s[colon+1:]); err == nil {
port = strconv.Itoa(p)
host = s[:colon]
}
}
// TODO(miek): this should take escaping into account.
if len(host) > 255 {
return "", "", nil, fmt.Errorf("specified zone is too long: %d > 255", len(host))
}
_, d := dns.IsDomainName(host)
if !d {
return "", "", nil, fmt.Errorf("zone is not a valid domain name: %s", host)
}
// Check if it parses as a reverse zone, if so we use that. Must be fully specified IP and mask.
ip, n, err := net.ParseCIDR(host)
ones, bits := 0, 0
if err == nil {
if rev, e := dns.ReverseAddr(ip.String()); e == nil {
ones, bits = n.Mask.Size()
// get the size, in bits, of each portion of hostname defined in the reverse address. (8 for IPv4, 4 for IPv6)
sizeDigit := 8
if len(n.IP) == net.IPv6len {
sizeDigit = 4
}
// Get the first lower octet boundary to see what encompassing zone we should be authoritative for.
mod := (bits - ones) % sizeDigit
nearest := (bits - ones) + mod
offset := 0
var end bool
for i := 0; i < nearest/sizeDigit; i++ {
offset, end = dns.NextLabel(rev, offset)
if end {
break
}
}
host = rev[offset:]
}
}
return host, port, n, nil
}
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