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/*
* Copyright (c) 2020, Michael Raitza. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of New Artisans LLC nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <system.hh>
#include "gpgme.h"
#include "utils.h"
#include <iostream>
#include <sstream>
#include <cerrno>
#include <gpgme++/context.h>
#include <gpgme++/decryptionresult.h>
namespace ledger {
using GpgME::Context;
using GpgME::Data;
using GpgME::Protocol;
using namespace std;
using std::shared_ptr;
using std::unique_ptr;
constexpr static unsigned int _bufsize = 4096;
data_streambuffer_t::data_streambuffer_t(Data& _data) :
data(_data),
bufsize(_bufsize),
cbuf(unique_ptr<char[]>(new char[_bufsize])) {}
streambuf::int_type data_streambuffer_t::underflow() {
if (this->gptr() == this->egptr()) {
auto buf = cbuf.get();
auto size = data.read(buf, bufsize);
if (size < 0)
throw_(runtime_error, _f("Reading decrypted data: GPGME: %1%") % strerror(errno));
else if (size == 0)
return char_traits<char>::eof();
this->setg(buf, buf, buf + size);
}
return this->gptr() == this->egptr()
? char_traits<char>::eof()
: char_traits<char>::to_int_type(*this->gptr());
}
streambuf::pos_type data_streambuffer_t::seekpos(streambuf::pos_type sp, ios_base::openmode which = ios_base::in) {
return this->seekoff(static_cast<streambuf::off_type>(sp), ios::beg, which);
}
streambuf::pos_type data_streambuffer_t::seekoff(streambuf::off_type off,
ios_base::seekdir dir,
ios_base::openmode which = ios_base::in) {
streamoff pos = -1;
if (dir == ios::beg)
pos = static_cast<streambuf::pos_type>(data.seek(static_cast<streamoff>(off), SEEK_SET));
else if (dir == ios::end)
pos = static_cast<streambuf::pos_type>(data.seek(static_cast<streamoff>(off), SEEK_END));
else if (dir == ios::cur)
pos = static_cast<streambuf::pos_type>(data.seek(static_cast<streamoff>(off), SEEK_CUR));
if (pos == -1)
throw runtime_error("Unable to seek to position");
auto buf = cbuf.get();
// Trigger underflow on next read
this->setg(buf, buf+1, buf+1);
return pos;
}
FILE * decrypted_stream_t::open_file(const path& filename) {
FILE * f = fopen(filename.c_str(), "rb");
if (!f)
throw_(runtime_error, _f("Could not open file: %1%") % strerror(errno));
return f;
}
shared_ptr<Data> decrypted_stream_t::setup_cipher_buffer(FILE * f) {
auto enc_d = make_shared<Data>(f);
if (!enc_d)
throw runtime_error("Unable to create cipher text buffer");
if (enc_d->type() != Data::PGPEncrypted
&& enc_d->type() != Data::CMSEncrypted
&& enc_d->type() != Data::Unknown
&& enc_d->type() != Data::Invalid)
throw_(runtime_error, _f("Unsupported encryption type: %1%") % enc_d->type());
return enc_d;
}
static bool is_encrypted(shared_ptr<Data> enc_d) {
if (enc_d->type() == Data::Unknown
|| enc_d->type() == Data::Invalid)
return false;
else
return true;
}
shared_ptr<Data> decrypted_stream_t::decrypt(shared_ptr<Data> enc_d) {
unique_ptr<Context> ctx;
shared_ptr<Data> dec_d;
if (enc_d->type() == Data::Unknown
|| enc_d->type() == Data::Invalid) {
ctx = nullptr;
dec_d = enc_d;
} else {
ctx = Context::create(enc_d->type() == Data::PGPEncrypted
? Protocol::OpenPGP
: Protocol::CMS);
if (!ctx)
throw runtime_error("Unable to establish decryption context");
ctx->setOffline(true);
dec_d = make_shared<Data>();
if (!dec_d)
throw runtime_error("Unable to create plain text buffer");
auto res = ctx->decrypt(*enc_d.get(), *dec_d.get());
if (res.error())
throw_(runtime_error, _f("Decryption error: %1%: %2%") % res.error().source() % res.error().asString());
}
return dec_d;
}
static inline void init_lib() {
auto err = GpgME::initializeLibrary(0);
if (err.code() != GPG_ERR_NO_ERROR)
throw_(runtime_error, _f("%1%: %2%") % err.source() % err.asString());
}
istream* decrypted_stream_t::open_stream(const path& filename) {
init_lib();
unique_ptr<FILE, decltype(&fclose)> file(open_file(filename), &fclose);
auto enc_d = setup_cipher_buffer(file.get());
if (is_encrypted(enc_d)) {
auto dec_d = decrypt(enc_d);
dec_d.get()->rewind();
return new decrypted_stream_t(dec_d);
}
return new ifstream(filename);
}
decrypted_stream_t::decrypted_stream_t(path& filename)
: istream(new data_streambuffer_t(*new Data())) {
init_lib();
file = open_file(filename);
auto enc_d = setup_cipher_buffer(file);
dec_d = decrypt(enc_d);
dec_d.get()->rewind();
if (is_encrypted(enc_d)) {
fclose(file);
file = nullptr;
}
set_rdbuf(new data_streambuffer_t(*dec_d.get()));
clear();
}
decrypted_stream_t::decrypted_stream_t(shared_ptr<Data> dec_d)
: istream(new data_streambuffer_t(*dec_d.get())),
dec_d(dec_d),
file(nullptr) {
clear();
}
decrypted_stream_t::~decrypted_stream_t() {
if (file)
fclose(file);
}
} // namespace ledger
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