#pragma once

#include <atomic>

#include <fstream>

#include <map>

#include <memory>

#include <optional>

#include <string>

#include <vector>

#include <optional>

#include "config.h"

#include "circular_buffer.hh"

#include "lock.hh"

#include "misc.hh"

enum class LibsslTLSVersion : uint8_t { Unknown, TLS10, TLS11, TLS12, TLS13 };

struct TLSCertKeyPair

{

  std::string d_cert;

  std::optional<std::string> d_key;

  std::optional<std::string> d_password;

  explicit TLSCertKeyPair(const std::string& cert, std::optional<std::string> key = std::nullopt, std::optional<std::string> password = std::nullopt):

    d_cert(cert), d_key(std::move(key)), d_password(std::move(password)) {

  }

};

class TLSConfig

{

public:

  std::vector<TLSCertKeyPair> d_certKeyPairs;

  std::vector<std::string> d_ocspFiles;

  std::string d_ciphers;

  std::string d_ciphers13;

  std::string d_ticketKeyFile;

  std::string d_keyLogFile;

  size_t d_maxStoredSessions{20480};

  time_t d_sessionTimeout{0};

  time_t d_ticketsKeyRotationDelay{43200};

  uint8_t d_numberOfTicketsKeys{5};

  LibsslTLSVersion d_minTLSVersion{LibsslTLSVersion::TLS10};

  bool d_preferServerCiphers{true};

  bool d_enableTickets{true};

  /* whether OpenSSL will release I/O buffers when the connection

     becomes idle, saving memory */

  bool d_releaseBuffers{true};

  /* whether so-called secure renegotiation should be allowed for TLS < 1.3 */

  bool d_enableRenegotiation{false};

  /* enable TLS async mode, if supported by any engine */

  bool d_asyncMode{false};

  /* enable kTLS mode, if supported */

  bool d_ktls{false};

  /* set read ahead mode, if supported */

  bool d_readAhead{true};

};

struct TLSErrorCounters

{

  std::atomic<uint64_t> d_dhKeyTooSmall{0}; /* the other side sent a DH value that is not large enough */

  std::atomic<uint64_t> d_inappropriateFallBack{0}; /* SCSV indicates that the client previously tried a higher version,

                                                       something bad is happening */

  std::atomic<uint64_t> d_noSharedCipher{0}; /* we could not agree on a cipher to use */

  std::atomic<uint64_t> d_unknownCipherType{0}; /* unknown cipher type */

  std::atomic<uint64_t> d_unknownKeyExchangeType{0}; /* * unknown exchange type, weird */

  std::atomic<uint64_t> d_unknownProtocol{0}; /* unknown protocol (SSLv2 or TLS 1.4, who knows? */

  std::atomic<uint64_t> d_unsupportedEC{0}; /* unsupported elliptic curve */

  std::atomic<uint64_t> d_unsupportedProtocol{0}; /* we don't accept this TLS version, sorry */

};

#ifdef HAVE_LIBSSL

#include <openssl/ssl.h>

void registerOpenSSLUser();

void unregisterOpenSSLUser();

/* From rfc5077 Section 4. Recommended Ticket Construction */

#define TLS_TICKETS_KEY_NAME_SIZE (16)

/* AES-256 */

#define TLS_TICKETS_CIPHER_KEY_SIZE (32)

#define TLS_TICKETS_CIPHER_ALGO (EVP_aes_256_cbc)

/* HMAC SHA-256 */

#define TLS_TICKETS_MAC_KEY_SIZE (32)

#define TLS_TICKETS_MAC_ALGO (EVP_sha256)

class OpenSSLTLSTicketKey

{

public:

  OpenSSLTLSTicketKey();

  OpenSSLTLSTicketKey(std::ifstream& file);

  OpenSSLTLSTicketKey(const std::string& key);

  ~OpenSSLTLSTicketKey();

  bool nameMatches(const unsigned char name[TLS_TICKETS_KEY_NAME_SIZE]) const;

#if OPENSSL_VERSION_MAJOR >= 3

  int encrypt(unsigned char keyName[TLS_TICKETS_KEY_NAME_SIZE], unsigned char* iv, EVP_CIPHER_CTX* ectx, EVP_MAC_CTX* hctx) const;

  bool decrypt(const unsigned char* iv, EVP_CIPHER_CTX* ectx, EVP_MAC_CTX* hctx) const;

#else

  int encrypt(unsigned char keyName[TLS_TICKETS_KEY_NAME_SIZE], unsigned char* iv, EVP_CIPHER_CTX* ectx, HMAC_CTX* hctx) const;

  bool decrypt(const unsigned char* iv, EVP_CIPHER_CTX* ectx, HMAC_CTX* hctx) const;

#endif

  [[nodiscard]] std::string content() const;

private:

  unsigned char d_name[TLS_TICKETS_KEY_NAME_SIZE];

  unsigned char d_cipherKey[TLS_TICKETS_CIPHER_KEY_SIZE];

  unsigned char d_hmacKey[TLS_TICKETS_MAC_KEY_SIZE];

};

class OpenSSLTLSTicketKeysRing

{

public:

  OpenSSLTLSTicketKeysRing(size_t capacity);

  ~OpenSSLTLSTicketKeysRing();

  std::shared_ptr<OpenSSLTLSTicketKey> getEncryptionKey();

  std::shared_ptr<OpenSSLTLSTicketKey> getDecryptionKey(unsigned char name[TLS_TICKETS_KEY_NAME_SIZE], bool& activeKey);

  size_t getKeysCount();

  void loadTicketsKeys(const std::string& keyFile);

  void loadTicketsKey(const std::string& key);

  void rotateTicketsKey(time_t now);

private:

  void addKey(std::shared_ptr<OpenSSLTLSTicketKey>&& newKey);

  SharedLockGuarded<boost::circular_buffer<std::shared_ptr<OpenSSLTLSTicketKey> > > d_ticketKeys;

};

void* libssl_get_ticket_key_callback_data(SSL* s);

void libssl_set_ticket_key_callback_data(SSL_CTX* ctx, void* data);

#if OPENSSL_VERSION_MAJOR >= 3

int libssl_ticket_key_callback(SSL* s, OpenSSLTLSTicketKeysRing& keyring, unsigned char keyName[TLS_TICKETS_KEY_NAME_SIZE], unsigned char* iv, EVP_CIPHER_CTX* ectx, EVP_MAC_CTX* hctx, int enc);

#else

int libssl_ticket_key_callback(SSL* s, OpenSSLTLSTicketKeysRing& keyring, unsigned char keyName[TLS_TICKETS_KEY_NAME_SIZE], unsigned char* iv, EVP_CIPHER_CTX* ectx, HMAC_CTX* hctx, int enc);

#endif

#ifndef DISABLE_OCSP_STAPLING

int libssl_ocsp_stapling_callback(SSL* ssl, const std::map<int, std::string>& ocspMap);

#ifdef HAVE_OCSP_BASIC_SIGN

bool libssl_generate_ocsp_response(const std::string& certFile, const std::string& caCert, const std::string& caKey, const std::string& outFile, int ndays, int nmin);

#endif

#endif /* DISABLE_OCSP_STAPLING */

void libssl_set_error_counters_callback(std::unique_ptr<SSL_CTX, decltype(&SSL_CTX_free)>& ctx, TLSErrorCounters* counters);

LibsslTLSVersion libssl_tls_version_from_string(const std::string& str);

const std::string& libssl_tls_version_to_string(LibsslTLSVersion version);

bool libssl_set_min_tls_version(std::unique_ptr<SSL_CTX, decltype(&SSL_CTX_free)>& ctx, LibsslTLSVersion version);

/* return the created context, and a list of warning messages for issues not severe enough

   to trigger raising an exception, like failing to load an OCSP response file */

std::pair<std::unique_ptr<SSL_CTX, decltype(&SSL_CTX_free)>, std::vector<std::string>> libssl_init_server_context(const TLSConfig& config,

                                                                                                            std::map<int, std::string>& ocspResponses);

pdns::UniqueFilePtr libssl_set_key_log_file(std::unique_ptr<SSL_CTX, decltype(&SSL_CTX_free)>& ctx, const std::string& logFile);

/* called in a server context, to select an ALPN value advertised by the client if any */

void libssl_set_alpn_select_callback(SSL_CTX* ctx, int (*cb)(SSL* s, const unsigned char** out, unsigned char* outlen, const unsigned char* in, unsigned int inlen, void* arg), void* arg);

/* set the supported ALPN protos in client context */

bool libssl_set_alpn_protos(SSL_CTX* ctx, const std::vector<std::vector<uint8_t>>& protos);

std::string libssl_get_error_string();

#if defined(HAVE_LIBSSL) && OPENSSL_VERSION_MAJOR >= 3 && defined(HAVE_TLS_PROVIDERS)

std::pair<bool, std::string> libssl_load_provider(const std::string& engineName);

#endif /* HAVE_LIBSSL && OPENSSL_VERSION_MAJOR >= 3 && HAVE_TLS_PROVIDERS */

#if defined(HAVE_LIBSSL) && !defined(HAVE_TLS_PROVIDERS)

std::pair<bool, std::string> libssl_load_engine(const std::string& engineName, const std::optional<std::string>& defaultString);

#endif /* HAVE_LIBSSL && !HAVE_TLS_PROVIDERS */

#endif /* HAVE_LIBSSL */