text: /*
   * Copyright 2017 Facebook, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #pragma once
  
  #include <folly/Range.h>
  #include <folly/io/IOBuf.h>
  #include <folly/portability/OpenSSL.h>
  #include <folly/ssl/OpenSSLPtrTypes.h>
  
  namespace folly {
  namespace ssl {
  
  /// Warning:
  /// These functions are not thread-safe unless you initialize OpenSSL.
  class OpenSSLHash {
   public:
    class Digest {
     public:
      Digest() : ctx_(EVP_MD_CTX_new()) {}
  
      Digest(const Digest& other) {
        ctx_ = EvpMdCtxUniquePtr(EVP_MD_CTX_new());
        if (other.md_ != nullptr) {
          hash_init(other.md_);
          check_libssl_result(
              1, EVP_MD_CTX_copy_ex(ctx_.get(), other.ctx_.get()));
        }
      }
  
      Digest& operator=(const Digest& other) {
        this->~Digest();
        return *new (this) Digest(other);
      }
  
      void hash_init(const EVP_MD* md) {
        md_ = md;
        check_libssl_result(1, EVP_DigestInit_ex(ctx_.get(), md, nullptr));
      }
      void hash_update(ByteRange data) {
        check_libssl_result(
            1, EVP_DigestUpdate(ctx_.get(), data.data(), data.size()));
      }
      void hash_update(const IOBuf& data) {
        for (auto r : data) {
          hash_update(r);
        }
      }
      void hash_final(MutableByteRange out) {
        const auto size = EVP_MD_size(md_);
        check_out_size(size_t(size), out);
        unsigned int len = 0;
        check_libssl_result(1, EVP_DigestFinal_ex(ctx_.get(), out.data(), &len));
        check_libssl_result(size, int(len));
        md_ = nullptr;
      }
  
     private:
      const EVP_MD* md_ = nullptr;
      EvpMdCtxUniquePtr ctx_{nullptr};
    };
  
    static void hash(MutableByteRange out, const EVP_MD* md, ByteRange data) {
      Digest hash;
      hash.hash_init(md);
      hash.hash_update(data);
      hash.hash_final(out);
    }
    static void hash(MutableByteRange out, const EVP_MD* md, const IOBuf& data) {
      Digest hash;
      hash.hash_init(md);
      hash.hash_update(data);
      hash.hash_final(out);
    }
    static void sha1(MutableByteRange out, ByteRange data) {
      hash(out, EVP_sha1(), data);
    }
    static void sha1(MutableByteRange out, const IOBuf& data) {
      hash(out, EVP_sha1(), data);
    }
    static void sha256(MutableByteRange out, ByteRange data) {
      hash(out, EVP_sha256(), data);
    }
    static void sha256(MutableByteRange out, const IOBuf& data) {
      hash(out, EVP_sha256(), data);
    }
  
    class Hmac {
     public:
      Hmac() : ctx_(HMAC_CTX_new()) {}
  
      void hash_init(const EVP_MD* md, ByteRange key) {
        md_ = md;
        check_libssl_result(
            1,
            HMAC_Init_ex(ctx_.get(), key.data(), int(key.size()), md_, nullptr));
      }
      void hash_update(ByteRange data) {
        check_libssl_result(1, HMAC_Update(ctx_.get(), data.data(), data.size()));
      }
      void hash_update(const IOBuf& data) {
        for (auto r : data) {
          hash_update(r);
        }
      }
      void hash_final(MutableByteRange out) {
        const auto size = EVP_MD_size(md_);
        check_out_size(size_t(size), out);
        unsigned int len = 0;
        check_libssl_result(1, HMAC_Final(ctx_.get(), out.data(), &len));
        check_libssl_result(size, int(len));
        md_ = nullptr;
      }
  
     private:
      const EVP_MD* md_ = nullptr;
      HmacCtxUniquePtr ctx_{nullptr};
    };
  
    static void
    hmac(MutableByteRange out, const EVP_MD* md, ByteRange key, ByteRange data) {
      Hmac hmac;
      hmac.hash_init(md, key);
      hmac.hash_update(data);
      hmac.hash_final(out);
    }
    static void hmac(
        MutableByteRange out,
        const EVP_MD* md,
        ByteRange key,
        const IOBuf& data) {
      Hmac hmac;
      hmac.hash_init(md, key);
      hmac.hash_update(data);
      hmac.hash_final(out);
    }
    static void hmac_sha1(MutableByteRange out, ByteRange key, ByteRange data) {
      hmac(out, EVP_sha1(), key, data);
    }
    static void
    hmac_sha1(MutableByteRange out, ByteRange key, const IOBuf& data) {
      hmac(out, EVP_sha1(), key, data);
    }
    static void hmac_sha256(MutableByteRange out, ByteRange key, ByteRange data) {
      hmac(out, EVP_sha256(), key, data);
    }
    static void
    hmac_sha256(MutableByteRange out, ByteRange key, const IOBuf& data) {
      hmac(out, EVP_sha256(), key, data);
    }
  
   private:
    static inline void check_out_size(size_t size, MutableByteRange out) {
      if (LIKELY(size == out.size())) {
        return;
      }
      check_out_size_throw(size, out);
    }
    [[noreturn]] static void check_out_size_throw(
        size_t size,
        MutableByteRange out);
  
    static inline void check_libssl_result(int expected, int result) {
      if (LIKELY(result == expected)) {
        return;
      }
      check_libssl_result_throw();
    }
    [[noreturn]] static void check_libssl_result_throw();
  };
  }
  }
  