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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
// Wrap the OpenSSL HMAC API defined in <openssl/hmac.h> so
// that it can be used as part of the crypto layer of the OpenVPN core.
#ifndef OPENVPN_OPENSSL_CRYPTO_HMAC_H
#define OPENVPN_OPENSSL_CRYPTO_HMAC_H
#include <string>
#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/openssl/crypto/digest.hpp>
#include <openvpn/openssl/compat.hpp>
namespace openvpn::OpenSSLCrypto {
class HMACContext
{
public:
HMACContext(const HMACContext &) = delete;
HMACContext &operator=(const HMACContext &) = delete;
HMACContext &operator=(HMACContext &&rhs)
{
erase();
ctx = rhs.ctx;
rhs.ctx = nullptr;
return *this;
}
OPENVPN_SIMPLE_EXCEPTION(openssl_hmac_uninitialized);
OPENVPN_EXCEPTION(openssl_hmac_error);
enum
{
MAX_HMAC_SIZE = EVP_MAX_MD_SIZE
};
HMACContext() = default;
HMACContext(const CryptoAlgs::Type digest, const unsigned char *key, const size_t key_size)
{
init(digest, key, key_size);
}
~HMACContext()
{
erase();
}
void init(const CryptoAlgs::Type digest, const unsigned char *key, const size_t key_size)
{
erase();
ctx = HMAC_CTX_new();
if (!HMAC_Init_ex(ctx, key, int(key_size), DigestContext::digest_type(digest, nullptr), nullptr))
{
openssl_clear_error_stack();
HMAC_CTX_free(ctx);
ctx = nullptr;
throw openssl_hmac_error("HMAC_Init_ex (init)");
}
}
void reset()
{
check_initialized();
if (!HMAC_Init_ex(ctx, nullptr, 0, nullptr, nullptr))
{
openssl_clear_error_stack();
throw openssl_hmac_error("HMAC_Init_ex (reset)");
}
}
void update(const unsigned char *in, const size_t size)
{
check_initialized();
if (!HMAC_Update(ctx, in, int(size)))
{
openssl_clear_error_stack();
throw openssl_hmac_error("HMAC_Update");
}
}
size_t final(unsigned char *out)
{
check_initialized();
unsigned int outlen;
if (!HMAC_Final(ctx, out, &outlen))
{
openssl_clear_error_stack();
throw openssl_hmac_error("HMAC_Final");
}
return outlen;
}
size_t size() const
{
check_initialized();
return size_();
}
bool is_initialized() const
{
return ctx != nullptr;
}
private:
void erase()
{
HMAC_CTX_free(ctx);
ctx = nullptr;
}
size_t size_() const
{
return HMAC_size(ctx);
}
void check_initialized() const
{
#ifdef OPENVPN_ENABLE_ASSERT
if (!ctx)
throw openssl_hmac_uninitialized();
#endif
}
HMAC_CTX *ctx = nullptr;
};
} // namespace openvpn::OpenSSLCrypto
#endif
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