void Extensions::deserialize(TLS_Data_Reader& reader)
{
if(reader.has_remaining())
{
const u16bit all_extn_size = reader.get_u16bit();
if(reader.remaining_bytes() != all_extn_size)
throw Decoding_Error("Bad extension size");
while(reader.has_remaining())
{
const u16bit extension_code = reader.get_u16bit();
const u16bit extension_size = reader.get_u16bit();
Extension* extn = make_extension(reader,
extension_code,
extension_size);
if(extn)
this->add(extn);
else // unknown/unhandled extension
reader.discard_next(extension_size);
}
}
}
Application_Layer_Protocol_Notification::Application_Layer_Protocol_Notification(TLS_Data_Reader& reader,
u16bit extension_size)
{
if(extension_size == 0)
return; // empty extension
const u16bit name_bytes = reader.get_u16bit();
size_t bytes_remaining = extension_size - 2;
if(name_bytes != bytes_remaining)
throw Decoding_Error("Bad encoding of ALPN extension, bad length field");
while(bytes_remaining)
{
const std::string p = reader.get_string(1, 0, 255);
if(bytes_remaining < p.size() + 1)
throw Decoding_Error("Bad encoding of ALPN, length field too long");
bytes_remaining -= (p.size() + 1);
m_protocols.push_back(p);
}
}
Server_Name_Indicator::Server_Name_Indicator(TLS_Data_Reader& reader,
u16bit extension_size)
{
/*
* This is used by the server to confirm that it knew the name
*/
if(extension_size == 0)
return;
u16bit name_bytes = reader.get_u16bit();
if(name_bytes + 2 != extension_size)
throw Decoding_Error("Bad encoding of SNI extension");
while(name_bytes)
{
byte name_type = reader.get_byte();
name_bytes--;
if(name_type == 0) // DNS
{
m_sni_host_name = reader.get_string(2, 1, 65535);
name_bytes -= (2 + m_sni_host_name.size());
}
else // some other unknown name type
{
reader.discard_next(name_bytes);
name_bytes = 0;
}
}
}
Supported_Elliptic_Curves::Supported_Elliptic_Curves(TLS_Data_Reader& reader,
u16bit extension_size)
{
u16bit len = reader.get_u16bit();
if(len + 2 != extension_size)
throw Decoding_Error("Inconsistent length field in elliptic curve list");
if(len % 2 == 1)
throw Decoding_Error("Elliptic curve list of strange size");
len /= 2;
for(size_t i = 0; i != len; ++i)
{
const u16bit id = reader.get_u16bit();
const std::string name = curve_id_to_name(id);
if(!name.empty())
m_curves.push_back(name);
}
}
Signature_Algorithms::Signature_Algorithms(TLS_Data_Reader& reader,
u16bit extension_size)
{
u16bit len = reader.get_u16bit();
if(len + 2 != extension_size)
throw Decoding_Error("Bad encoding on signature algorithms extension");
while(len)
{
const std::string hash_code = hash_algo_name(reader.get_byte());
const std::string sig_code = sig_algo_name(reader.get_byte());
len -= 2;
// If not something we know, ignore it completely
if(hash_code.empty() || sig_code.empty())
continue;
m_supported_algos.push_back(std::make_pair(hash_code, sig_code));
}
}