hasher: Add function to determine length of hashes

src/libstrongswan/crypto/hashers/hasher.c

@@ -56,6 +56,44 @@ ENUM_NEXT(hash_algorithm_short_names, HASH_UNKNOWN, HASH_SHA3_512, HASH_IDENTITY
 	"sha3_512");
 ENUM_END(hash_algorithm_short_names, HASH_SHA3_512);
 
+/*
+ * Described in header
+ */
+size_t hasher_hash_size(hash_algorithm_t alg)
+{
+	switch (alg)
+	{
+		case HASH_SHA1:
+			return HASH_SIZE_SHA1;
+		case HASH_SHA256:
+			return HASH_SIZE_SHA256;
+		case HASH_SHA384:
+			return HASH_SIZE_SHA384;
+		case HASH_SHA512:
+			return HASH_SIZE_SHA512;
+		case HASH_MD2:
+			return HASH_SIZE_MD2;
+		case HASH_MD4:
+			return HASH_SIZE_MD4;
+		case HASH_MD5:
+			return HASH_SIZE_MD5;
+		case HASH_SHA224:
+			return HASH_SIZE_SHA224;
+		case HASH_SHA3_224:
+			return HASH_SIZE_SHA224;
+		case HASH_SHA3_256:
+			return HASH_SIZE_SHA256;
+		case HASH_SHA3_384:
+			return HASH_SIZE_SHA384;
+		case HASH_SHA3_512:
+			return HASH_SIZE_SHA512;
+		case HASH_IDENTITY:
+		case HASH_UNKNOWN:
+			break;
+	}
+	return 0;
+}
+
 /*
  * Described in header.
  */

src/libstrongswan/crypto/hashers/hasher.h

@@ -130,6 +130,14 @@ struct hasher_t {
 	void (*destroy)(hasher_t *this);
 };
 
+/**
+ * Returns the size of the hash for the given algorithm.
+ *
+ * @param alg			hash algorithm
+ * @return				size of hash or 0 if unknown
+ */
+size_t hasher_hash_size(hash_algorithm_t alg);
+
 /**
  * Conversion of ASN.1 OID to hash algorithm.
  *