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	/* @file parsecontroller.cpp
	* @brief Parse a mail and decrypt / verify accordingly
	*
	* Copyright (C) 2016 by Bundesamt für Sicherheit in der Informationstechnik
	* Software engineering by Intevation GmbH
	*
	* This file is part of GpgOL.
	*
	* GpgOL is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* GpgOL 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 Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public License
	* along with this program; if not, see <http://www.gnu.org/licenses/>.
	*/
	#include "config.h"

	#include "parsecontroller.h"
	#include "attachment.h"
	#include "mimedataprovider.h"

	#include "keycache.h"

	#include <gpgme++/context.h>
	#include <gpgme++/decryptionresult.h>
	#include <gpgme++/key.h>

	#include <sstream>

	#ifdef HAVE_W32_SYSTEM
	#include "common.h"
	/* We use UTF-8 internally. */
	#undef _
	# define _(a) utf8_gettext (a)
	#else
	# define _(a) a
	#endif



	const char decrypt_template_html[] = {
	"<html><head></head><body>"
	"<table border=\"0\" width=\"100%%\" cellspacing=\"1\" cellpadding=\"1\" bgcolor=\"#0069cc\">"
	"<tr>"
	"<td bgcolor=\"#0080ff\">"
	"<p><span style=\"font-weight:600; background-color:#0080ff;\"><center>%s %s</center><span></p></td></tr>"
	"<tr>"
	"<td bgcolor=\"#e0f0ff\">"
	"<center>"
	"<br/>%s"
	"</td></tr>"
	"</table></body></html>"};

	const char decrypt_template[] = {"%s %s\n\n%s"};

	using namespace GpgME;

	static bool
	expect_no_headers (msgtype_t type)
	{
	return type != MSGTYPE_GPGOL_MULTIPART_SIGNED;
	}

	static bool
	expect_no_mime (msgtype_t type)
	{
	return type == MSGTYPE_GPGOL_PGP_MESSAGE \|\|
	type == MSGTYPE_GPGOL_CLEAR_SIGNED;
	}

	#ifdef HAVE_W32_SYSTEM
	ParseController::ParseController(LPSTREAM instream, msgtype_t type):
	m_inputprovider (new MimeDataProvider(instream,
	expect_no_headers(type))),
	m_outputprovider (new MimeDataProvider(expect_no_mime(type))),
	m_type (type),
	m_block_html (false)
	{
	memdbg_ctor ("ParseController");
	log_mime_parser ("%s:%s: Creating parser for stream: %p of type %i"
	" expect no headers: %i expect no mime: %i",
	SRCNAME, __func__, instream, type,
	expect_no_headers (type), expect_no_mime (type));
	}
	#endif

	ParseController::ParseController(FILE *instream, msgtype_t type):
	m_inputprovider (new MimeDataProvider(instream,
	expect_no_headers(type))),
	m_outputprovider (new MimeDataProvider(expect_no_mime(type))),
	m_type (type),
	m_block_html (false)
	{
	memdbg_ctor ("ParseController");
	log_mime_parser ("%s:%s: Creating parser for stream: %p of type %i",
	SRCNAME, __func__, instream, type);
	}

	ParseController::~ParseController()
	{
	log_debug ("%s:%s", SRCNAME, __func__);
	memdbg_dtor ("ParseController");
	delete m_inputprovider;
	delete m_outputprovider;
	}

	static void
	operation_for_type(msgtype_t type, bool *decrypt,
	bool *verify)
	{
	*decrypt = false;
	*verify = false;
	switch (type)
	{
	case MSGTYPE_GPGOL_MULTIPART_ENCRYPTED:
	case MSGTYPE_GPGOL_PGP_MESSAGE:
	*decrypt = true;
	break;
	case MSGTYPE_GPGOL_MULTIPART_SIGNED:
	case MSGTYPE_GPGOL_CLEAR_SIGNED:
	*verify = true;
	break;
	case MSGTYPE_GPGOL_OPAQUE_SIGNED:
	*verify = true;
	break;
	case MSGTYPE_GPGOL_OPAQUE_ENCRYPTED:
	*decrypt = true;
	break;
	default:
	log_error ("%s:%s: Unknown data type: %i",
	SRCNAME, __func__, type);
	}
	}

	static bool
	is_smime (Data &data)
	{
	data.seek (0, SEEK_SET);
	auto id = data.type();
	data.seek (0, SEEK_SET);
	return id == Data::CMSSigned \|\| id == Data::CMSEncrypted;
	}

	static std::string
	format_recipients(GpgME::DecryptionResult result, Protocol protocol)
	{
	std::string msg;
	for (const auto recipient: result.recipients())
	{
	auto ctx = Context::createForProtocol(protocol);
	Error e;
	if (!ctx) {
	/* Can't happen */
	TRACEPOINT;
	continue;
	}
	const auto key = ctx->key(recipient.keyID(), e, false);
	delete ctx;
	if (!key.isNull() && key.numUserIDs() && !e) {
	msg += std::string("<br/>") + key.userIDs()[0].id() + " (0x" + recipient.keyID() + ")";
	continue;
	}
	msg += std::string("<br/>") + _("Unknown Key:") + " 0x" + recipient.keyID();
	}
	return msg;
	}

	static std::string
	format_error(GpgME::DecryptionResult result, Protocol protocol)
	{
	char *buf;
	bool no_sec = false;
	std::string msg;

	if (result.error ().isCanceled () \|\|
	result.error ().code () == GPG_ERR_NO_SECKEY)
	{
	msg = _("Decryption canceled or timed out.");
	}

	if (result.error ().code () == GPG_ERR_DECRYPT_FAILED \|\|
	result.error ().code () == GPG_ERR_NO_SECKEY)
	{
	no_sec = true;
	for (const auto &recipient: result.recipients ()) {
	no_sec &= (recipient.status ().code () == GPG_ERR_NO_SECKEY);
	}
	}

	if (no_sec)
	{
	msg = _("No secret key found to decrypt the message. "
	"It is encrypted to the following keys:");
	msg += format_recipients (result, protocol);
	}
	else
	{
	msg = _("Could not decrypt the data: ");

	if (result.isNull ())
	{
	msg += _("Failed to parse the mail.");
	}
	else if (result.isLegacyCipherNoMDC())
	{
	msg += _("Data is not integrity protected. "
	"Decrypting it could be a security problem. (no MDC)");
	}
	else
	{
	msg += result.error().asString();
	}
	}

	if (gpgrt_asprintf (&buf, opt.prefer_html ? decrypt_template_html :
	decrypt_template,
	protocol == OpenPGP ? "OpenPGP" : "S/MIME",
	_("Encrypted message (decryption not possible)"),
	msg.c_str()) == -1)
	{
	log_error ("%s:%s:Failed to Format error.",
	SRCNAME, __func__);
	return "Failed to Format error.";
	}
	memdbg_alloc (buf);
	msg = buf;
	return msg;
	}

	void
	ParseController::setSender(const std::string &sender)
	{
	m_sender = sender;
	}

	static bool
	is_valid_chksum(const GpgME::Signature &sig)
	{
	const auto sum = sig.summary();
	static unsigned int valid_mask = (unsigned int) (
	GpgME::Signature::Valid \|
	GpgME::Signature::Green \|
	GpgME::Signature::KeyRevoked \|
	GpgME::Signature::KeyExpired \|
	GpgME::Signature::SigExpired \|
	GpgME::Signature::CrlMissing \|
	GpgME::Signature::CrlTooOld \|
	GpgME::Signature::TofuConflict );

	return sum & valid_mask;
	}


	/* Note on stability:

	Experiments have shown that we can have a crash if parse
	returns at time that is not good for the state of Outlook.

	This happend in my test instance after a delay of > 1s < 3s
	with a < 1% chance :-/

	So if you have really really bad luck this might still crash
	although it usually should be either much quicker or much slower
	(slower e.g. when pinentry is requrired).
	*/
	void
	ParseController::parse()
	{
	// Wrap the input stream in an attachment / GpgME Data
	Protocol protocol;
	bool decrypt, verify;

	Data input (m_inputprovider);

	auto inputType = input.type ();

	if (inputType == Data::Type::PGPSigned)
	{
	verify = true;
	decrypt = false;
	}
	else
	{
	operation_for_type (m_type, &decrypt, &verify);
	}

	if ((m_inputprovider->signature() && is_smime (*m_inputprovider->signature())) \|\|
	is_smime (input))
	{
	protocol = Protocol::CMS;
	}
	else
	{
	protocol = Protocol::OpenPGP;
	}
	auto ctx = std::unique_ptr<Context> (Context::createForProtocol (protocol));
	if (!ctx)
	{
	log_error ("%s:%s:Failed to create context. Installation broken.",
	SRCNAME, __func__);
	char *buf;
	const char *proto = protocol == OpenPGP ? "OpenPGP" : "S/MIME";
	if (gpgrt_asprintf (&buf, opt.prefer_html ? decrypt_template_html :
	decrypt_template,
	proto,
	_("Encrypted message (decryption not possible)"),
	_("Failed to find GnuPG please ensure that GnuPG or "
	"Gpg4win is properly installed.")) == -1)
	{
	log_error ("%s:%s:Failed format error.",
	SRCNAME, __func__);
	/* Should never happen */
	m_error = std::string("Bad installation");
	}
	memdbg_alloc (buf);
	m_error = buf;
	xfree (buf);
	return;
	}

	/* Maybe a different option for this ? */
	if (opt.autoresolve)
	{
	ctx->setFlag("auto-key-retrieve", "1");
	}

	ctx->setArmor(true);

	if (!m_sender.empty())
	{
	ctx->setSender(m_sender.c_str());
	}

	Data output (m_outputprovider);
	log_debug ("%s:%s:%p decrypt: %i verify: %i with protocol: %s sender: %s type: %i",
	SRCNAME, __func__, this,
	decrypt, verify,
	protocol == OpenPGP ? "OpenPGP" :
	protocol == CMS ? "CMS" : "Unknown",
	m_sender.empty() ? "none" : m_sender.c_str(), inputType);
	if (decrypt)
	{
	input.seek (0, SEEK_SET);
	auto combined_result = ctx->decryptAndVerify(input, output);
	log_debug ("%s:%s:%p decrypt / verify done.",
	SRCNAME, __func__, this);
	m_decrypt_result = combined_result.first;
	m_verify_result = combined_result.second;

	if ((!m_decrypt_result.error () &&
	m_verify_result.signatures ().empty() &&
	m_outputprovider->signature ()) \|\|
	is_smime (output) \|\|
	output.type() == Data::Type::PGPSigned)
	{
	/* There is a signature in the output. So we have
	to verify it now as an extra step. */
	input = Data (m_outputprovider);
	delete m_inputprovider;
	m_inputprovider = m_outputprovider;
	m_outputprovider = new MimeDataProvider();
	output = Data(m_outputprovider);
	verify = true;
	}
	else
	{
	verify = false;
	}
	if (m_decrypt_result.error () \|\| m_decrypt_result.isNull () \|\|
	m_decrypt_result.error ().isCanceled ())
	{
	m_error = format_error (m_decrypt_result, protocol);
	}
	}
	if (verify)
	{
	const auto sig = m_inputprovider->signature();
	input.seek (0, SEEK_SET);
	if (sig)
	{
	sig->seek (0, SEEK_SET);
	m_verify_result = ctx->verifyDetachedSignature(*sig, input);
	log_debug ("%s:%s:%p verify done.",
	SRCNAME, __func__, this);
	/* Copy the input to output to do a mime parsing. */
	char buf[4096];
	input.seek (0, SEEK_SET);
	output.seek (0, SEEK_SET);
	size_t nread;
	while ((nread = input.read (buf, 4096)) > 0)
	{
	output.write (buf, nread);
	}
	}
	else
	{
	m_verify_result = ctx->verifyOpaqueSignature(input, output);

	const auto sigs = m_verify_result.signatures();
	bool allBad = sigs.size();
	for (const auto s :sigs)
	{
	if (!(s.summary() & Signature::Red))
	{
	allBad = false;
	break;
	}
	}
	#ifdef HAVE_W32_SYSTEM
	if (allBad)
	{
	log_debug ("%s:%s:%p inline verify error trying native to utf8.",
	SRCNAME, __func__, this);


	/* The proper solution would be to take the encoding from
	the mail / headers. Then convert the wchar body to that
	encoding. Verify, and convert it after verifcation to
	UTF-8 which the rest of the code expects.

	Or native_body from native ACP to InternetCodepage, then
	verify and convert the output back to utf8 as the rest
	expects.

	But as this is clearsigned and we don't really want that.
	Meh.
	*/
	char *utf8 = native_to_utf8 (input.toString().c_str());
	if (utf8)
	{
	// Try again after conversion.
	ctx = std::unique_ptr<Context> (Context::createForProtocol (protocol));
	ctx->setArmor (true);
	if (!m_sender.empty())
	{
	ctx->setSender(m_sender.c_str());
	}

	input = Data (utf8, strlen (utf8));
	xfree (utf8);

	// Use a fresh output
	auto provider = new MimeDataProvider (true);

	// Warning: The dtor of the Data object touches
	// the provider. So we have to delete it after
	// the assignment.
	output = Data (provider);
	delete m_outputprovider;
	m_outputprovider = provider;

	// Try again
	m_verify_result = ctx->verifyOpaqueSignature(input, output);
	}
	}
	#endif
	}
	}
	log_debug ("%s:%s:%p: decrypt err: %i verify err: %i",
	SRCNAME, __func__, this, m_decrypt_result.error().code(),
	m_verify_result.error().code());

	bool has_valid_encrypted_checksum = false;
	/* Ensure that the Keys for the signatures are available
	and if it has a valid encrypted checksum. */
	bool ultimate_keys_queried = false;
	for (const auto sig: m_verify_result.signatures())
	{
	has_valid_encrypted_checksum = is_valid_chksum (sig);

	KeyCache::instance ()->update (sig.fingerprint (), protocol);

	if (!ultimate_keys_queried &&
	(sig.validity() == Signature::Validity::Full \|\|
	sig.validity() == Signature::Validity::Ultimate))
	{
	/* Ensure that we have the keys with ultimate
	trust cached for the ui. */

	// TODO this is something for the keycache
	get_ultimate_keys ();
	ultimate_keys_queried = true;
	}
	}

	if (protocol == Protocol::CMS && decrypt && !m_decrypt_result.error() &&
	!has_valid_encrypted_checksum)
	{
	log_debug ("%s:%s:%p Encrypted S/MIME without checksum. Block HTML.",
	SRCNAME, __func__, this);
	m_block_html = true;
	}

	if (opt.enable_debug)
	{
	std::stringstream ss;
	ss << m_decrypt_result << '\n' << m_verify_result;
	for (const auto sig: m_verify_result.signatures())
	{
	const auto key = sig.key();
	if (key.isNull())
	{
	ss << '\n' << "Cached key:\n" << KeyCache::instance()->getByFpr(
	sig.fingerprint(), false);
	}
	else
	{
	ss << '\n' << key;
	}
	}
	log_debug ("Decrypt / Verify result: %s", ss.str().c_str());
	}
	TRACEPOINT;

	return;
	}

	const std::string
	ParseController::get_html_body () const
	{
	if (m_outputprovider)
	{
	return m_outputprovider->get_html_body ();
	}
	else
	{
	return std::string();
	}
	}

	const std::string
	ParseController::get_body () const
	{
	if (m_outputprovider)
	{
	return m_outputprovider->get_body ();
	}
	else
	{
	return std::string();
	}
	}

	const std::string
	ParseController::get_body_charset() const
	{
	if (m_outputprovider)
	{
	return m_outputprovider->get_body_charset();
	}
	else
	{
	return std::string();
	}
	}

	const std::string
	ParseController::get_html_charset() const
	{
	if (m_outputprovider)
	{
	return m_outputprovider->get_html_charset();
	}
	else
	{
	return std::string();
	}
	}

	std::vector<std::shared_ptr<Attachment> >
	ParseController::get_attachments() const
	{
	if (m_outputprovider)
	{
	return m_outputprovider->get_attachments();
	}
	else
	{
	return std::vector<std::shared_ptr<Attachment> >();
	}
	}

	GPGRT_LOCK_DEFINE(keylist_lock);
	/* static */
	std::vector<Key>
	ParseController::get_ultimate_keys()
	{
	static bool s_keys_listed;
	static std::vector<Key> s_ultimate_keys;
	gpgrt_lock_lock (&keylist_lock);
	if (s_keys_listed)
	{
	gpgrt_lock_unlock (&keylist_lock);
	return s_ultimate_keys;
	}
	log_debug ("%s:%s: Starting keylisting.",
	SRCNAME, __func__);
	auto ctx = std::unique_ptr<Context> (Context::createForProtocol (OpenPGP));
	if (!ctx)
	{
	/* Maybe PGP broken and not S/MIME */
	log_error ("%s:%s: broken installation no ctx.",
	SRCNAME, __func__);
	gpgrt_lock_unlock (&keylist_lock);
	return s_ultimate_keys;
	}
	ctx->setKeyListMode (KeyListMode::Local);
	Error err;
	TRACEPOINT;
	if ((err = ctx->startKeyListing ()))
	{
	log_error ("%s:%s: Failed to start keylisting err: %i: %s",
	SRCNAME, __func__, err.code (), err.asString());
	gpgrt_lock_unlock (&keylist_lock);
	return s_ultimate_keys;
	}
	TRACEPOINT;
	while (!err)
	{
	const auto key = ctx->nextKey(err);
	if (err \|\| key.isNull())
	{
	TRACEPOINT;
	break;
	}
	if (key.isInvalid ())
	{
	log_debug ("%s:%s: skipping invalid key.",
	SRCNAME, __func__);
	continue;
	}
	for (const auto uid: key.userIDs())
	{
	if (uid.validity() == UserID::Validity::Ultimate &&
	uid.id())
	{
	s_ultimate_keys.push_back (key);
	log_debug ("%s:%s: Adding ultimate uid.",
	SRCNAME, __func__);
	log_mime_parser ("%s:%s: Added uid %s.",
	SRCNAME, __func__, uid.id());
	break;
	}
	}
	}
	TRACEPOINT;
	log_debug ("%s:%s: keylisting done.",
	SRCNAME, __func__);

	s_keys_listed = true;
	gpgrt_lock_unlock (&keylist_lock);
	return s_ultimate_keys;
	}

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