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Encode high codepoints as surrogates to safely transport wchar_t over network

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fixes #7643
This commit is contained in:
sfan5 2021-01-29 15:24:07 +01:00
parent c834d2ab25
commit 674d67f312
5 changed files with 80 additions and 26 deletions
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51
src/network/networkpacket.cpp
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@ -50,7 +50,7 @@ void NetworkPacket::checkReadOffset(u32 from_offset, u32 field_size)
}
}
void NetworkPacket::putRawPacket(u8 *data, u32 datasize, session_t peer_id)
void NetworkPacket::putRawPacket(const u8 *data, u32 datasize, session_t peer_id)
{
// If a m_command is already set, we are rewriting on same packet
// This is not permitted
@ -145,6 +145,8 @@ void NetworkPacket::putLongString(const std::string &src)
putRawString(src.c_str(), msgsize);
}
static constexpr bool NEED_SURROGATE_CODING = sizeof(wchar_t) > 2;
NetworkPacket& NetworkPacket::operator>>(std::wstring& dst)
{
checkReadOffset(m_read_offset, 2);
@ -160,9 +162,16 @@ NetworkPacket& NetworkPacket::operator>>(std::wstring& dst)
checkReadOffset(m_read_offset, strLen * 2);
dst.reserve(strLen);
for(u16 i=0; i<strLen; i++) {
wchar_t c16 = readU16(&m_data[m_read_offset]);
dst.append(&c16, 1);
for (u16 i = 0; i < strLen; i++) {
wchar_t c = readU16(&m_data[m_read_offset]);
if (NEED_SURROGATE_CODING && c >= 0xD800 && c < 0xDC00 && i+1 < strLen) {
i++;
m_read_offset += sizeof(u16);
wchar_t c2 = readU16(&m_data[m_read_offset]);
c = 0x10000 + ( ((c & 0x3ff) << 10) | (c2 & 0x3ff) );
}
dst.push_back(c);
m_read_offset += sizeof(u16);
}
@ -175,15 +184,37 @@ NetworkPacket& NetworkPacket::operator<<(const std::wstring &src)
throw PacketError("String too long");
}
u16 msgsize = src.size();
if (!NEED_SURROGATE_CODING || src.size() == 0) {
*this << static_cast<u16>(src.size());
for (u16 i = 0; i < src.size(); i++)
*this << static_cast<u16>(src[i]);
*this << msgsize;
// Write string
for (u16 i=0; i<msgsize; i++) {
*this << (u16) src[i];
return *this;
}
// write dummy value, to be overwritten later
const u32 len_offset = m_read_offset;
u32 written = 0;
*this << static_cast<u16>(0xfff0);
for (u16 i = 0; i < src.size(); i++) {
wchar_t c = src[i];
if (c > 0xffff) {
// Encode high code-points as surrogate pairs
u32 n = c - 0x10000;
*this << static_cast<u16>(0xD800 | (n >> 10))
<< static_cast<u16>(0xDC00 | (n & 0x3ff));
written += 2;
} else {
*this << static_cast<u16>(c);
written++;
}
}
if (written > WIDE_STRING_MAX_LEN)
throw PacketError("String too long");
writeU16(&m_data[len_offset], written);
return *this;
}