添加 github.com/pion/dtls 代码

dtls-2.0.9/pkg/crypto/fingerprint/hash.go

@@ -0,0 +1,37 @@
+package fingerprint
+
+import (
+	"crypto"
+	"errors"
+)
+
+var errInvalidHashAlgorithm = errors.New("fingerprint: invalid hash algorithm")
+
+func nameToHash() map[string]crypto.Hash {
+	return map[string]crypto.Hash{
+		"md5":     crypto.MD5,    // [RFC3279]
+		"sha-1":   crypto.SHA1,   // [RFC3279]
+		"sha-224": crypto.SHA224, // [RFC4055]
+		"sha-256": crypto.SHA256, // [RFC4055]
+		"sha-384": crypto.SHA384, // [RFC4055]
+		"sha-512": crypto.SHA512, // [RFC4055]
+	}
+}
+
+// HashFromString allows looking up a hash algorithm by it's string representation
+func HashFromString(s string) (crypto.Hash, error) {
+	if h, ok := nameToHash()[s]; ok {
+		return h, nil
+	}
+	return 0, errInvalidHashAlgorithm
+}
+
+// StringFromHash allows looking up a string representation of the crypto.Hash.
+func StringFromHash(hash crypto.Hash) (string, error) {
+	for s, h := range nameToHash() {
+		if h == hash {
+			return s, nil
+		}
+	}
+	return "", errInvalidHashAlgorithm
+}