/*
 *
 * (C) 2010-2020 Anope Team
 * Contact us at team@anope.org
 *
 * Please read COPYING and README for further details.
 */

/* RequiredLibraries: ssl,crypto */
/* RequiredWindowsLibraries: ssleay32,libeay32 */

#include "module.h"
#include "modules/ssl.h"

#define OPENSSL_NO_SHA512
#include <openssl/bio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/crypto.h>
#include <openssl/evp.h>

static SSL_CTX *server_ctx, *client_ctx;

class MySSLService : public SSLService
{
 public:
	MySSLService(Module *o, const Anope::string &n);

	/** Initialize a socket to use SSL
	 * @param s The socket
	 */
	void Init(Socket *s) anope_override;
};

class SSLSocketIO : public SocketIO
{
 public:
	/* The SSL socket for this socket */
	SSL *sslsock;

	/** Constructor
	 */
	SSLSocketIO();

	/** Really receive something from the buffer
	 * @param s The socket
	 * @param buf The buf to read to
	 * @param sz How much to read
	 * @return Number of bytes received
	 */
	int Recv(Socket *s, char *buf, size_t sz) anope_override;

	/** Write something to the socket
	 * @param s The socket
	 * @param buf The data to write
	 * @param size The length of the data
	 */
	int Send(Socket *s, const char *buf, size_t sz) anope_override;

	/** Accept a connection from a socket
	 * @param s The socket
	 * @return The new socket
	 */
	ClientSocket *Accept(ListenSocket *s) anope_override;

	/** Finished accepting a connection from a socket
	 * @param s The socket
	 * @return SF_ACCEPTED if accepted, SF_ACCEPTING if still in process, SF_DEAD on error
	 */
	SocketFlag FinishAccept(ClientSocket *cs) anope_override;

	/** Connect the socket
	 * @param s THe socket
	 * @param target IP to connect to
	 * @param port to connect to
	 */
	void Connect(ConnectionSocket *s, const Anope::string &target, int port) anope_override;

	/** Called to potentially finish a pending connection
	 * @param s The socket
	 * @return SF_CONNECTED on success, SF_CONNECTING if still pending, and SF_DEAD on error.
	 */
	SocketFlag FinishConnect(ConnectionSocket *s) anope_override;

	/** Called when the socket is destructing
	 */
	void Destroy() anope_override;
};

class SSLModule;
static SSLModule *me;
class SSLModule : public Module
{
	Anope::string certfile, keyfile;

 public:
	MySSLService service;

	SSLModule(const Anope::string &modname, const Anope::string &creator) : Module(modname, creator, EXTRA | VENDOR), service(this, "ssl")
	{
		me = this;

		this->SetPermanent(true);

		SSL_library_init();
		SSL_load_error_strings();

		client_ctx = SSL_CTX_new(SSLv23_client_method());
		server_ctx = SSL_CTX_new(SSLv23_server_method());

		if (!client_ctx || !server_ctx)
			throw ModuleException("Error initializing SSL CTX");

		long opts = SSL_OP_NO_SSLv2 | SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION | SSL_OP_CIPHER_SERVER_PREFERENCE;
		SSL_CTX_set_options(client_ctx, opts);
		SSL_CTX_set_options(server_ctx, opts);

		SSL_CTX_set_mode(client_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE | SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
		SSL_CTX_set_mode(server_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE | SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);

		Anope::string context_name = "Anope";
		SSL_CTX_set_session_id_context(client_ctx, reinterpret_cast<const unsigned char *>(context_name.c_str()), context_name.length());
		SSL_CTX_set_session_id_context(server_ctx, reinterpret_cast<const unsigned char *>(context_name.c_str()), context_name.length());
	}

	~SSLModule()
	{
		for (std::map<int, Socket *>::const_iterator it = SocketEngine::Sockets.begin(), it_end = SocketEngine::Sockets.end(); it != it_end;)
		{
			Socket *s = it->second;
			++it;

			if (dynamic_cast<SSLSocketIO *>(s->io))
				delete s;
		}

		SSL_CTX_free(client_ctx);
		SSL_CTX_free(server_ctx);
	}

	void OnReload(Configuration::Conf *conf) anope_override
	{
		Configuration::Block *config = conf->GetModule(this);

		this->certfile = config->Get<const Anope::string>("cert", "data/anope.crt");
		this->keyfile = config->Get<const Anope::string>("key", "data/anope.key");

		if (Anope::IsFile(this->certfile.c_str()))
		{
			if (!SSL_CTX_use_certificate_chain_file(client_ctx, this->certfile.c_str()) || !SSL_CTX_use_certificate_chain_file(server_ctx, this->certfile.c_str()))
				throw ConfigException("Error loading certificate");
			else
				Log(LOG_DEBUG) << "m_ssl_openssl: Successfully loaded certificate " << this->certfile;
		}
		else
			Log() << "Unable to open certificate " << this->certfile;

		if (Anope::IsFile(this->keyfile.c_str()))
		{
			if (!SSL_CTX_use_PrivateKey_file(client_ctx, this->keyfile.c_str(), SSL_FILETYPE_PEM) || !SSL_CTX_use_PrivateKey_file(server_ctx, this->keyfile.c_str(), SSL_FILETYPE_PEM))
				throw ConfigException("Error loading private key");
			else
				Log(LOG_DEBUG) << "m_ssl_openssl: Successfully loaded private key " << this->keyfile;
		}
		else
		{
			if (Anope::IsFile(this->certfile.c_str()))
				throw ConfigException("Error loading private key " + this->keyfile + " - file not found");
			else
				Log() << "Unable to open private key " << this->keyfile;
		}

		// Allow disabling SSLv3
		if (!config->Get<Anope::string>("sslv3").empty())
		{
			if (config->Get<bool>("sslv3"))
			{
				SSL_CTX_clear_options(client_ctx, SSL_OP_NO_SSLv3);
				SSL_CTX_clear_options(server_ctx, SSL_OP_NO_SSLv3);
			}
			else
			{
				SSL_CTX_set_options(client_ctx, SSL_OP_NO_SSLv3);
				SSL_CTX_set_options(server_ctx, SSL_OP_NO_SSLv3);
			}
		}
	}

	void OnPreServerConnect() anope_override
	{
		Configuration::Block *config = Config->GetBlock("uplink", Anope::CurrentUplink);

		if (config->Get<bool>("ssl"))
		{
			this->service.Init(UplinkSock);
		}
	}
};

MySSLService::MySSLService(Module *o, const Anope::string &n) : SSLService(o, n)
{
}

void MySSLService::Init(Socket *s)
{
	if (s->io != &NormalSocketIO)
		throw CoreException("Socket initializing SSL twice");

	s->io = new SSLSocketIO();
}

SSLSocketIO::SSLSocketIO()
{
	this->sslsock = NULL;
}

int SSLSocketIO::Recv(Socket *s, char *buf, size_t sz)
{
	int i = SSL_read(this->sslsock, buf, sz);
	if (i > 0)
		TotalRead += i;
	else if (i < 0)
	{
		int err = SSL_get_error(this->sslsock, i);
		switch (err)
		{
			case SSL_ERROR_WANT_READ:
			case SSL_ERROR_WANT_WRITE:
				SocketEngine::SetLastError(EAGAIN);
		}
	}

	return i;
}

int SSLSocketIO::Send(Socket *s, const char *buf, size_t sz)
{
	int i = SSL_write(this->sslsock, buf, sz);
	if (i > 0)
		TotalWritten += i;
	else if (i < 0)
	{
		int err = SSL_get_error(this->sslsock, i);
		switch (err)
		{
			case SSL_ERROR_WANT_READ:
			case SSL_ERROR_WANT_WRITE:
				SocketEngine::SetLastError(EAGAIN);
		}
	}
	return i;
}

ClientSocket *SSLSocketIO::Accept(ListenSocket *s)
{
	if (s->io == &NormalSocketIO)
		throw SocketException("Attempting to accept on uninitialized socket with SSL");

	sockaddrs conaddr;

	socklen_t size = sizeof(conaddr);
	int newsock = accept(s->GetFD(), &conaddr.sa, &size);

#ifndef INVALID_SOCKET
	const int INVALID_SOCKET = -1;
#endif

	if (newsock < 0 || newsock == INVALID_SOCKET)
		throw SocketException("Unable to accept connection: " + Anope::LastError());

	ClientSocket *newsocket = s->OnAccept(newsock, conaddr);
	me->service.Init(newsocket);
	SSLSocketIO *io = anope_dynamic_static_cast<SSLSocketIO *>(newsocket->io);

	io->sslsock = SSL_new(server_ctx);
	if (!io->sslsock)
		throw SocketException("Unable to initialize SSL socket");

	SSL_set_accept_state(io->sslsock);

	if (!SSL_set_fd(io->sslsock, newsocket->GetFD()))
		throw SocketException("Unable to set SSL fd");

	newsocket->flags[SF_ACCEPTING] = true;
	this->FinishAccept(newsocket);

	return newsocket;
}

SocketFlag SSLSocketIO::FinishAccept(ClientSocket *cs)
{
	if (cs->io == &NormalSocketIO)
		throw SocketException("Attempting to finish connect uninitialized socket with SSL");
	else if (cs->flags[SF_ACCEPTED])
		return SF_ACCEPTED;
	else if (!cs->flags[SF_ACCEPTING])
		throw SocketException("SSLSocketIO::FinishAccept called for a socket not accepted nor accepting?");

	SSLSocketIO *io = anope_dynamic_static_cast<SSLSocketIO *>(cs->io);

	int ret = SSL_accept(io->sslsock);
	if (ret <= 0)
	{
		int error = SSL_get_error(io->sslsock, ret);
		if (ret == -1 && (error == SSL_ERROR_WANT_READ || error == SSL_ERROR_WANT_WRITE))
		{
			SocketEngine::Change(cs, error == SSL_ERROR_WANT_WRITE, SF_WRITABLE);
			SocketEngine::Change(cs, error == SSL_ERROR_WANT_READ, SF_READABLE);
			return SF_ACCEPTING;
		}
		else
		{
			cs->OnError(ERR_error_string(ERR_get_error(), NULL));
			cs->flags[SF_DEAD] = true;
			cs->flags[SF_ACCEPTING] = false;
			return SF_DEAD;
		}
	}
	else
	{
		cs->flags[SF_ACCEPTED] = true;
		cs->flags[SF_ACCEPTING] = false;
		SocketEngine::Change(cs, false, SF_WRITABLE);
		SocketEngine::Change(cs, true, SF_READABLE);
		cs->OnAccept();
		return SF_ACCEPTED;
	}
}

void SSLSocketIO::Connect(ConnectionSocket *s, const Anope::string &target, int port)
{
	if (s->io == &NormalSocketIO)
		throw SocketException("Attempting to connect uninitialized socket with SSL");

	s->flags[SF_CONNECTING] = s->flags[SF_CONNECTED] = false;

	s->conaddr.pton(s->IsIPv6() ? AF_INET6 : AF_INET, target, port);
	int c = connect(s->GetFD(), &s->conaddr.sa, s->conaddr.size());
	if (c == -1)
	{
		if (Anope::LastErrorCode() != EINPROGRESS)
		{
			s->OnError(Anope::LastError());
			s->flags[SF_DEAD] = true;
			return;
		}
		else
		{
			SocketEngine::Change(s, true, SF_WRITABLE);
			s->flags[SF_CONNECTING] = true;
			return;
		}
	}
	else
	{
		s->flags[SF_CONNECTING] = true;
		this->FinishConnect(s);
	}
}

SocketFlag SSLSocketIO::FinishConnect(ConnectionSocket *s)
{
	if (s->io == &NormalSocketIO)
		throw SocketException("Attempting to finish connect uninitialized socket with SSL");
	else if (s->flags[SF_CONNECTED])
		return SF_CONNECTED;
	else if (!s->flags[SF_CONNECTING])
		throw SocketException("SSLSocketIO::FinishConnect called for a socket not connected nor connecting?");

	SSLSocketIO *io = anope_dynamic_static_cast<SSLSocketIO *>(s->io);

	if (io->sslsock == NULL)
	{
		io->sslsock = SSL_new(client_ctx);
		if (!io->sslsock)
			throw SocketException("Unable to initialize SSL socket");

		if (!SSL_set_fd(io->sslsock, s->GetFD()))
			throw SocketException("Unable to set SSL fd");
	}

	int ret = SSL_connect(io->sslsock);
	if (ret <= 0)
	{
		int error = SSL_get_error(io->sslsock, ret);
		if (ret == -1 && (error == SSL_ERROR_WANT_READ || error == SSL_ERROR_WANT_WRITE))
		{
			SocketEngine::Change(s, error == SSL_ERROR_WANT_WRITE, SF_WRITABLE);
			SocketEngine::Change(s, error == SSL_ERROR_WANT_READ, SF_READABLE);
			return SF_CONNECTING;
		}
		else
		{
			s->OnError(ERR_error_string(ERR_get_error(), NULL));
			s->flags[SF_CONNECTING] = false;
			s->flags[SF_DEAD] = true;
			return SF_DEAD;
		}
	}
	else
	{
		s->flags[SF_CONNECTING] = false;
		s->flags[SF_CONNECTED] = true;
		SocketEngine::Change(s, false, SF_WRITABLE);
		SocketEngine::Change(s, true, SF_READABLE);
		s->OnConnect();
		return SF_CONNECTED;
	}
}

void SSLSocketIO::Destroy()
{
	if (this->sslsock)
	{
		SSL_shutdown(this->sslsock);
		SSL_free(this->sslsock);
	}

	delete this;
}

MODULE_INIT(SSLModule)
