added wrapper for OpenSSL hashers

src/libstrongswan/plugins/openssl/openssl_hasher.c

@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2008 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil 
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ *
+ * $Id$
+ */
+
+#include "openssl_hasher.h"
+
+#include <openssl/evp.h>
+
+typedef struct private_openssl_hasher_t private_openssl_hasher_t;
+
+/**
+ * Private data of openssl_hasher_t
+ */
+struct private_openssl_hasher_t {
+	
+	/**
+	 * Public part of this class.
+	 */
+	openssl_hasher_t public;
+	
+	/**
+	 * data collected to hash
+	 */
+	chunk_t data;
+	
+	/*
+	 * the hasher to use
+	 */
+	const EVP_MD *hasher;
+};
+
+/**
+ * Mapping from the algorithms defined in IKEv2 to
+ * OpenSSL algorithm names
+ */
+typedef struct {
+	/**
+	 * Identifier specified in IKEv2
+	 */
+	int ikev2_id;
+	
+	/**
+	 * Name of the algorithm, as used in OpenSSL
+	 */
+	char *name;
+} openssl_algorithm_t;
+
+#define END_OF_LIST -1
+
+/**
+ * Algorithms for integrity
+ */
+static openssl_algorithm_t integrity_algs[] = {
+	{HASH_MD2,		"md2"},
+	{HASH_MD5,		"md5"},
+	{HASH_SHA1,		"sha1"},
+	{HASH_SHA256,	"sha256"},
+	{HASH_SHA384,	"sha384"},
+	{HASH_SHA512, 	"sha512"},
+	{END_OF_LIST, 	NULL},
+};
+
+/**
+ * Look up an OpenSSL algorithm name
+ */
+static char* lookup_algorithm(openssl_algorithm_t *openssl_algo, 
+					   u_int16_t ikev2_algo)
+{
+	while (openssl_algo->ikev2_id != END_OF_LIST)
+	{
+		if (ikev2_algo == openssl_algo->ikev2_id)
+		{
+			return openssl_algo->name;
+		}
+		openssl_algo++;
+	}
+	return NULL;
+}
+
+/**
+ * append data to the to-be-hashed buffer
+ */
+static void append_data(private_openssl_hasher_t *this, chunk_t data)
+{
+	this->data.ptr = realloc(this->data.ptr, this->data.len + data.len);
+	memcpy(this->data.ptr + this->data.len, data.ptr, data.len);
+	this->data.len += data.len;
+}
+
+/**
+ * hash a buffer of data
+ */
+static void hash_data(private_openssl_hasher_t *this, chunk_t data, u_int8_t *digest)
+{
+	EVP_MD_CTX ctx;
+	EVP_MD_CTX_init(&ctx);
+	EVP_DigestInit_ex(&ctx, this->hasher, NULL);
+	EVP_DigestUpdate(&ctx, data.ptr, data.len);
+	EVP_DigestFinal_ex(&ctx, digest, NULL);
+	EVP_MD_CTX_cleanup(&ctx);
+}
+
+/**
+ * Implementation of hasher_t.get_hash_size.
+ */
+static size_t get_hash_size(private_openssl_hasher_t *this)
+{
+	return this->hasher->md_size;
+}
+
+/**
+ * Implementation of hasher_t.reset.
+ */
+static void reset(private_openssl_hasher_t *this)
+{
+	chunk_free(&this->data);
+}
+
+/**
+ * Implementation of hasher_t.get_hash.
+ */
+static void get_hash(private_openssl_hasher_t *this, chunk_t chunk,
+					 u_int8_t *hash)
+{
+	if (hash)
+	{
+		if (this->data.len)
+		{
+			append_data(this, chunk);
+			hash_data(this, this->data, hash);
+		}
+		else
+		{   /* hash directly if no previous data found */   
+			hash_data(this, chunk, hash);
+		}
+		reset(this);
+	}
+	else
+	{
+		append_data(this, chunk);	
+	}
+}
+
+/**
+ * Implementation of hasher_t.allocate_hash.
+ */
+static void allocate_hash(private_openssl_hasher_t *this, chunk_t chunk,
+						  chunk_t *hash)
+{
+	if (hash)
+	{
+		*hash = chunk_alloc(get_hash_size(this));
+		get_hash(this, chunk, hash->ptr);
+	}
+	else
+	{
+		get_hash(this, chunk, NULL);	
+	}
+}
+
+/**
+ * Implementation of hasher_t.destroy.
+ */
+static void destroy (private_openssl_hasher_t *this)
+{
+	free(this->data.ptr);
+	free(this);
+}
+
+/*
+ * Described in header
+ */
+openssl_hasher_t *openssl_hasher_create(hash_algorithm_t algo)
+{
+	private_openssl_hasher_t *this;
+	
+	char* name = lookup_algorithm(integrity_algs, algo);
+	if (!name)
+	{
+		/* algo unavailable */
+		return NULL;
+	}
+
+	this = malloc_thing(private_openssl_hasher_t);
+	
+	this->hasher = EVP_get_digestbyname(name);
+	if (!this->hasher)
+	{
+		/* OpenSSL does not support the requested algo */
+		free(this);
+		return NULL;
+	}
+	
+	this->public.hasher_interface.get_hash = (void (*) (hasher_t*, chunk_t, u_int8_t*))get_hash;
+	this->public.hasher_interface.allocate_hash = (void (*) (hasher_t*, chunk_t, chunk_t*))allocate_hash;
+	this->public.hasher_interface.get_hash_size = (size_t (*) (hasher_t*))get_hash_size;
+	this->public.hasher_interface.reset = (void (*) (hasher_t*))reset;
+	this->public.hasher_interface.destroy = (void (*) (hasher_t*))destroy;
+	
+	this->data = chunk_empty;
+	
+	return &this->public;
+}