//========================================================================
//
// SecurityHandler.cc
//
// Copyright 2004 Glyph & Cog, LLC
//
//========================================================================

//========================================================================
//
// Modified under the Poppler project - http://poppler.freedesktop.org
//
// All changes made under the Poppler project to this file are licensed
// under GPL version 2 or later
//
// Copyright (C) 2010, 2012, 2015, 2017, 2018, 2020 Albert Astals Cid <aacid@kde.org>
// Copyright (C) 2013 Adrian Johnson <ajohnson@redneon.com>
// Copyright (C) 2014 Fabio D'Urso <fabiodurso@hotmail.it>
// Copyright (C) 2016 Alok Anand <alok4nand@gmail.com>
//
// To see a description of the changes please see the Changelog file that
// came with your tarball or type make ChangeLog if you are building from git
//
//========================================================================

#include <config.h>

#include "GooString.h"
#include "PDFDoc.h"
#include "Decrypt.h"
#include "Error.h"
#include "GlobalParams.h"
#include "SecurityHandler.h"

#include <climits>

//------------------------------------------------------------------------
// SecurityHandler
//------------------------------------------------------------------------

SecurityHandler *SecurityHandler::make(PDFDoc *docA, Object *encryptDictA)
{
    SecurityHandler *secHdlr;

    Object filterObj = encryptDictA->dictLookup("Filter");
    if (filterObj.isName("Standard")) {
        secHdlr = new StandardSecurityHandler(docA, encryptDictA);
    } else if (filterObj.isName()) {
        error(errSyntaxError, -1, "Couldn't find the '{0:s}' security handler", filterObj.getName());
        secHdlr = nullptr;
    } else {
        error(errSyntaxError, -1, "Missing or invalid 'Filter' entry in encryption dictionary");
        secHdlr = nullptr;
    }
    return secHdlr;
}

SecurityHandler::SecurityHandler(PDFDoc *docA)
{
    doc = docA;
}

SecurityHandler::~SecurityHandler() { }

bool SecurityHandler::checkEncryption(const GooString *ownerPassword, const GooString *userPassword)
{
    void *authData;

    if (ownerPassword || userPassword) {
        authData = makeAuthData(ownerPassword, userPassword);
    } else {
        authData = nullptr;
    }
    const bool ok = authorize(authData);
    if (authData) {
        freeAuthData(authData);
    }
    if (!ok) {
        if (!ownerPassword && !userPassword) {
            GooString dummy;
            return checkEncryption(&dummy, &dummy);
        } else {
            error(errCommandLine, -1, "Incorrect password");
        }
    }
    return ok;
}

//------------------------------------------------------------------------
// StandardSecurityHandler
//------------------------------------------------------------------------

class StandardAuthData
{
public:
    StandardAuthData(GooString *ownerPasswordA, GooString *userPasswordA)
    {
        ownerPassword = ownerPasswordA;
        userPassword = userPasswordA;
    }

    ~StandardAuthData()
    {
        if (ownerPassword) {
            delete ownerPassword;
        }
        if (userPassword) {
            delete userPassword;
        }
    }

    StandardAuthData(const StandardAuthData &) = delete;
    StandardAuthData &operator=(const StandardAuthData &) = delete;

    GooString *ownerPassword;
    GooString *userPassword;
};

StandardSecurityHandler::StandardSecurityHandler(PDFDoc *docA, Object *encryptDictA) : SecurityHandler(docA)
{
    ok = false;
    fileID = nullptr;
    ownerKey = nullptr;
    userKey = nullptr;
    ownerEnc = nullptr;
    userEnc = nullptr;
    fileKeyLength = 0;
    encAlgorithm = cryptNone;

    Object versionObj = encryptDictA->dictLookup("V");
    Object revisionObj = encryptDictA->dictLookup("R");
    Object lengthObj = encryptDictA->dictLookup("Length");
    Object ownerKeyObj = encryptDictA->dictLookup("O");
    Object userKeyObj = encryptDictA->dictLookup("U");
    Object ownerEncObj = encryptDictA->dictLookup("OE");
    Object userEncObj = encryptDictA->dictLookup("UE");
    Object permObj = encryptDictA->dictLookup("P");
    if (permObj.isInt64()) {
        unsigned int permUint = permObj.getInt64();
        int perms = permUint - UINT_MAX - 1;
        permObj = Object(perms);
    }
    Object fileIDObj = doc->getXRef()->getTrailerDict()->dictLookup("ID");
    if (versionObj.isInt() && revisionObj.isInt() && permObj.isInt() && ownerKeyObj.isString() && userKeyObj.isString()) {
        encVersion = versionObj.getInt();
        encRevision = revisionObj.getInt();
        if ((encRevision <= 4 && ownerKeyObj.getString()->getLength() == 32 && userKeyObj.getString()->getLength() == 32)
            || ((encRevision == 5 || encRevision == 6) &&
                // the spec says 48 bytes, but Acrobat pads them out longer
                ownerKeyObj.getString()->getLength() >= 48 && userKeyObj.getString()->getLength() >= 48 && ownerEncObj.isString() && ownerEncObj.getString()->getLength() == 32 && userEncObj.isString()
                && userEncObj.getString()->getLength() == 32)) {
            encAlgorithm = cryptRC4;
            // revision 2 forces a 40-bit key - some buggy PDF generators
            // set the Length value incorrectly
            if (encRevision == 2 || !lengthObj.isInt()) {
                fileKeyLength = 5;
            } else {
                fileKeyLength = lengthObj.getInt() / 8;
            }
            encryptMetadata = true;
            //~ this currently only handles a subset of crypt filter functionality
            //~ (in particular, it ignores the EFF entry in encryptDictA, and
            //~ doesn't handle the case where StmF, StrF, and EFF are not all the
            //~ same)
            if ((encVersion == 4 || encVersion == 5) && (encRevision == 4 || encRevision == 5 || encRevision == 6)) {
                Object cryptFiltersObj = encryptDictA->dictLookup("CF");
                Object streamFilterObj = encryptDictA->dictLookup("StmF");
                Object stringFilterObj = encryptDictA->dictLookup("StrF");
                if (cryptFiltersObj.isDict() && streamFilterObj.isName() && stringFilterObj.isName() && !strcmp(streamFilterObj.getName(), stringFilterObj.getName())) {
                    if (!strcmp(streamFilterObj.getName(), "Identity")) {
                        // no encryption on streams or strings
                        encVersion = encRevision = -1;
                    } else {
                        Object cryptFilterObj = cryptFiltersObj.dictLookup(streamFilterObj.getName());
                        if (cryptFilterObj.isDict()) {
                            Object cfmObj = cryptFilterObj.dictLookup("CFM");
                            if (cfmObj.isName("V2")) {
                                encVersion = 2;
                                encRevision = 3;
                                Object cfLengthObj = cryptFilterObj.dictLookup("Length");
                                if (cfLengthObj.isInt()) {
                                    //~ according to the spec, this should be cfLengthObj / 8
                                    fileKeyLength = cfLengthObj.getInt();
                                }
                            } else if (cfmObj.isName("AESV2")) {
                                encVersion = 2;
                                encRevision = 3;
                                encAlgorithm = cryptAES;
                                Object cfLengthObj = cryptFilterObj.dictLookup("Length");
                                if (cfLengthObj.isInt()) {
                                    //~ according to the spec, this should be cfLengthObj / 8
                                    fileKeyLength = cfLengthObj.getInt();
                                }
                            } else if (cfmObj.isName("AESV3")) {
                                encVersion = 5;
                                // let encRevision be 5 or 6
                                encAlgorithm = cryptAES256;
                                Object cfLengthObj = cryptFilterObj.dictLookup("Length");
                                if (cfLengthObj.isInt()) {
                                    //~ according to the spec, this should be cfLengthObj / 8
                                    fileKeyLength = cfLengthObj.getInt();
                                }
                            }
                        }
                    }
                }
                Object encryptMetadataObj = encryptDictA->dictLookup("EncryptMetadata");
                if (encryptMetadataObj.isBool()) {
                    encryptMetadata = encryptMetadataObj.getBool();
                }
            }
            permFlags = permObj.getInt();
            ownerKey = ownerKeyObj.getString()->copy();
            userKey = userKeyObj.getString()->copy();
            if (encVersion >= 1 && encVersion <= 2 && encRevision >= 2 && encRevision <= 3) {
                if (fileIDObj.isArray()) {
                    Object fileIDObj1 = fileIDObj.arrayGet(0);
                    if (fileIDObj1.isString()) {
                        fileID = fileIDObj1.getString()->copy();
                    } else {
                        fileID = new GooString();
                    }
                } else {
                    fileID = new GooString();
                }
                if (fileKeyLength > 16 || fileKeyLength < 0) {
                    fileKeyLength = 16;
                }
                ok = true;
            } else if (encVersion == 5 && (encRevision == 5 || encRevision == 6)) {
                fileID = new GooString(); // unused for V=R=5
                if (ownerEncObj.isString() && userEncObj.isString()) {
                    ownerEnc = ownerEncObj.getString()->copy();
                    userEnc = userEncObj.getString()->copy();
                    if (fileKeyLength > 32 || fileKeyLength < 0) {
                        fileKeyLength = 32;
                    }
                    ok = true;
                } else {
                    error(errSyntaxError, -1, "Weird encryption owner/user info");
                }
            } else if (!(encVersion == -1 && encRevision == -1)) {
                error(errUnimplemented, -1, "Unsupported version/revision ({0:d}/{1:d}) of Standard security handler", encVersion, encRevision);
            }
        } else {
            error(errSyntaxError, -1, "Invalid encryption key length");
        }
    } else {
        error(errSyntaxError, -1, "Weird encryption info");
    }
}

StandardSecurityHandler::~StandardSecurityHandler()
{
    if (fileID) {
        delete fileID;
    }
    if (ownerKey) {
        delete ownerKey;
    }
    if (userKey) {
        delete userKey;
    }
    if (ownerEnc) {
        delete ownerEnc;
    }
    if (userEnc) {
        delete userEnc;
    }
}

bool StandardSecurityHandler::isUnencrypted() const
{
    if (!ok) {
        return true;
    }
    return encVersion == -1 && encRevision == -1;
}

void *StandardSecurityHandler::makeAuthData(const GooString *ownerPassword, const GooString *userPassword)
{
    return new StandardAuthData(ownerPassword ? ownerPassword->copy() : nullptr, userPassword ? userPassword->copy() : nullptr);
}

void StandardSecurityHandler::freeAuthData(void *authData)
{
    delete (StandardAuthData *)authData;
}

bool StandardSecurityHandler::authorize(void *authData)
{
    GooString *ownerPassword, *userPassword;

    if (!ok) {
        return false;
    }
    if (authData) {
        ownerPassword = ((StandardAuthData *)authData)->ownerPassword;
        userPassword = ((StandardAuthData *)authData)->userPassword;
    } else {
        ownerPassword = nullptr;
        userPassword = nullptr;
    }
    if (!Decrypt::makeFileKey(encVersion, encRevision, fileKeyLength, ownerKey, userKey, ownerEnc, userEnc, permFlags, fileID, ownerPassword, userPassword, fileKey, encryptMetadata, &ownerPasswordOk)) {
        return false;
    }
    return true;
}