+
+// PortableDataHash computes the portable data hash of the given
+// manifest.
+func PortableDataHash(mt string) string {
+ // To calculate the PDH, we write the manifest to an md5 hash
+ // func, except we skip the "extra" part of block tokens that
+ // look like "abcdef0123456789abcdef0123456789+12345+extra".
+ //
+ // This code is simplified by the facts that (A) all block
+ // tokens -- even the first and last in a stream -- are
+ // preceded and followed by a space character; and (B) all
+ // non-block tokens either start with '.' or contain ':'.
+ //
+ // A regexp-based approach (like the one this replaced) would
+ // be more readable, but very slow.
+ h := md5.New()
+ size := 0
+ todo := []byte(mt)
+ for len(todo) > 0 {
+ // sp is the end of the current token (note that if
+ // the current token is the last file token in a
+ // stream, we'll also include the \n and the dirname
+ // token on the next line, which is perfectly fine for
+ // our purposes).
+ sp := bytes.IndexByte(todo, ' ')
+ if sp < 0 {
+ // Last token of the manifest, which is never
+ // a block token.
+ n, _ := h.Write(todo)
+ size += n
+ break
+ }
+ if sp >= 34 && todo[32] == '+' && bytes.IndexByte(todo[:32], ':') == -1 && todo[0] != '.' {
+ // todo[:sp] is a block token.
+ sizeend := bytes.IndexByte(todo[33:sp], '+')
+ if sizeend < 0 {
+ // "hash+size"
+ sizeend = sp
+ } else {
+ // "hash+size+extra"
+ sizeend += 33
+ }
+ n, _ := h.Write(todo[:sizeend])
+ h.Write([]byte{' '})
+ size += n + 1
+ } else {
+ // todo[:sp] is not a block token.
+ n, _ := h.Write(todo[:sp+1])
+ size += n
+ }
+ todo = todo[sp+1:]
+ }
+ return fmt.Sprintf("%x+%d", h.Sum(nil), size)
+}
+
+// CollectionIDFromDNSName returns a UUID or PDH if s begins with a
+// UUID or URL-encoded PDH; otherwise "".
+func CollectionIDFromDNSName(s string) string {
+ // Strip domain.
+ if i := strings.IndexRune(s, '.'); i >= 0 {
+ s = s[:i]
+ }
+ // Names like {uuid}--collections.example.com serve the same
+ // purpose as {uuid}.collections.example.com but can reduce
+ // cost/effort of using [additional] wildcard certificates.
+ if i := strings.Index(s, "--"); i >= 0 {
+ s = s[:i]
+ }
+ if UUIDMatch(s) {
+ return s
+ }
+ if pdh := strings.Replace(s, "-", "+", 1); PDHMatch(pdh) {
+ return pdh
+ }
+ return ""
+}