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/*
Copyright (C) 2024-2025 Selwin van Dijk
This file is part of signalbackup-tools.
signalbackup-tools is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
signalbackup-tools 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with signalbackup-tools. If not, see <https://www.gnu.org/licenses/>.
*/
#include "signalbackup.ih"
#include <regex>
bool SignalBackup::unescapeXmlString(std::string *s) const
{
//std::cout << " IN: " << *s << std::endl;
if (s->find('&') == std::string::npos)
return true;
bepaald::replaceAll(s, "&", "&");
bepaald::replaceAll(s, "'", "'");
bepaald::replaceAll(s, """, "\"");
bepaald::replaceAll(s, "<", "<");
bepaald::replaceAll(s, ">", ">");
std::regex entity_regex("&#(x?[0-9a-fA-F]+);");
std::smatch m;
std::string searchstr(*s);
int codepointcomplete = 0;
uint32_t unicode_codepoint = 0;
int match_position = 0;
int match_length = 0;
while (std::regex_search(searchstr, m, entity_regex))
{
// digits
std::string utf16str(m[1]); // value-part of the match
uint32_t utf16 = 0;
if (codepointcomplete == 1) // we're here because we need more data
match_length += m.length(0);
else
{
match_position = m.position(0); // pos and length of entire
match_length = m.length(0); // match (including &#;)
}
// check leading x, interpret as hex...
if (utf16str[0] == 'x') [[unlikely]] // I dont think this exists in Signal plaintext
{ // backups but it does in SMS Backup & Restore
utf16str = utf16str.substr(1);
utf16 = bepaald::toNumberFromHex<uint32_t>(utf16str);
}
else
utf16 = bepaald::toNumber<uint32_t>(utf16str);
//std::cout << "found utf16: " << utf16 << " (" << utf16str << ")" << std::endl;
if (utf16 > 0xFFFF) [[unlikely]] // SMS Backup & Restore stores as unicode32
{
codepointcomplete = 0;
unicode_codepoint = utf16;
}
else
codepointcomplete = utf16ToUnicodeCodepoint(utf16, &unicode_codepoint);
if (codepointcomplete == 1)
{
//std::cout << "requested more" << std::endl;
searchstr = m.suffix();
continue;
}
if (codepointcomplete == -1) [[unlikely]]
{
Logger::warning("Failed to fully un-escape XML string: '", *s, "'");
return false;
}
//std::cout << "Codepoint: " << unicode_codepoint << " UTF8: ";
std::string utf8(unicodeToUtf8(unicode_codepoint));
//std::cout << bepaald::bytesToHexString(reinterpret_cast<unsigned char *>(utf8.data()), utf8.size()) << std::endl;
// codepointcomplete == 0 : do the replace... start search at top...
s->replace(match_position, match_length, unicodeToUtf8(unicode_codepoint));
unicode_codepoint = 0;
searchstr = *s;
}
if (codepointcomplete != 0)
{
Logger::warning("Failed fully to un-escape XML string: '", *s, "'");
return false;
}
//std::cout << "OUT: " << *s << std::endl;
return true;
}
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