Fix handling of dnames

Add support for escaped dots. Only thing to fix is the
fqdn-ness of user defined names.

defaults.go

@@ -198,7 +198,7 @@ func (dns *Msg) IsEdns0() (ok bool) {
 
 // IsDomainName checks if s is a valid domainname, it returns
 // true and a length, when a domain name is valid. When false
-// is return the length isn't specified.
+// ithe returned length isn't specified.
 func IsDomainName(s string) (bool, int) { // copied from net package.
 	// See RFC 1035, RFC 3696.
 	if len(s) == 0 {
@@ -224,6 +224,8 @@ func IsDomainName(s string) (bool, int) { // copied from net package.
 			ok = true
 			partlen++
                         n++
+                case c == '\\':
+                        // Ok
 		case '0' <= c && c <= '9':
 			// fine
 			partlen++
@@ -239,6 +241,11 @@ func IsDomainName(s string) (bool, int) { // copied from net package.
 			if last == '.' || last == '-' {
 				return false, 0
 			}
+                        if last == '\\' { // Ok, escaped dot.
+                                partlen++
+                                n++
+                                break
+                        }
 			if partlen > 63 || partlen == 0 {
 				return false, 0
 			}

parse_test.go

@@ -130,6 +130,30 @@ z3.miek.nl.  IN      NSEC    miek.nl. TXT RRSIG NSEC`
 	}
 }
 
+func TestDomainName(t *testing.T) {
+        tests := []string{"r\\.gieben.miek.nl."}
+        dbuff := make([]byte, 40)
+
+
+        for _, ts := range tests {
+                if _, ok := PackDomainName(ts, dbuff, 0); !ok {
+                        t.Log("Not a valid domain name")
+                        t.Fail()
+                        continue
+                }
+                n, _, ok := UnpackDomainName(dbuff, 0)
+                if !ok {
+                        t.Log("Failed to unpack packed domain name")
+                        t.Fail()
+                        continue;
+                }
+                if ts != n {
+                        t.Logf("Must be equal: in: %s, out: %s\n", ts, n)
+                        t.Fail()
+                }
+        }
+}
+
 func TestParseBrace(t *testing.T) {
 	tests := map[string]string{
 		"(miek.nl.) 3600 IN A 127.0.0.1":                 "miek.nl.\t3600\tIN\tA\t127.0.0.1",