diff options
Diffstat (limited to 'model/utils.go')
-rw-r--r-- | model/utils.go | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/model/utils.go b/model/utils.go index 9f8ef90e1..892f8c278 100644 --- a/model/utils.go +++ b/model/utils.go @@ -536,3 +536,57 @@ func checkNowhereNil(t *testing.T, name string, value interface{}) bool { return true } } + +// Copied from https://golang.org/src/net/dnsclient.go#L119 +func IsDomainName(s string) bool { + // See RFC 1035, RFC 3696. + // Presentation format has dots before every label except the first, and the + // terminal empty label is optional here because we assume fully-qualified + // (absolute) input. We must therefore reserve space for the first and last + // labels' length octets in wire format, where they are necessary and the + // maximum total length is 255. + // So our _effective_ maximum is 253, but 254 is not rejected if the last + // character is a dot. + l := len(s) + if l == 0 || l > 254 || l == 254 && s[l-1] != '.' { + return false + } + + last := byte('.') + ok := false // Ok once we've seen a letter. + partlen := 0 + for i := 0; i < len(s); i++ { + c := s[i] + switch { + default: + return false + case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || c == '_': + ok = true + partlen++ + case '0' <= c && c <= '9': + // fine + partlen++ + case c == '-': + // Byte before dash cannot be dot. + if last == '.' { + return false + } + partlen++ + case c == '.': + // Byte before dot cannot be dot, dash. + if last == '.' || last == '-' { + return false + } + if partlen > 63 || partlen == 0 { + return false + } + partlen = 0 + } + last = c + } + if last == '-' || partlen > 63 { + return false + } + + return ok +} |