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/*
* TLS Extensions
* (C) 2011 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#include <botan/internal/tls_extensions.h>
#include <botan/internal/tls_reader.h>
#include <botan/tls_exceptn.h>
namespace Botan {
namespace {
TLS_Extension* make_extension(TLS_Data_Reader& reader,
u16bit code,
u16bit size)
{
if(code == TLSEXT_SERVER_NAME_INDICATION)
return new Server_Name_Indicator(reader, size);
else if(code == TLSEXT_MAX_FRAGMENT_LENGTH)
return new Maximum_Fragment_Length(reader, size);
else if(code == TLSEXT_SRP_IDENTIFIER)
return new SRP_Identifier(reader, size);
else if(code == TLSEXT_SAFE_RENEGOTIATION)
return new Renegotation_Extension(reader, size);
else
return 0; // not known
}
}
TLS_Extensions::TLS_Extensions(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();
TLS_Extension* extn = make_extension(reader,
extension_code,
extension_size);
if(extn)
extensions.push_back(extn);
else // unknown/unhandled extension
reader.discard_next(extension_size);
}
}
}
MemoryVector<byte> TLS_Extensions::serialize() const
{
MemoryVector<byte> buf(2); // 2 bytes for length field
for(size_t i = 0; i != extensions.size(); ++i)
{
if(extensions[i]->empty())
continue;
const u16bit extn_code = extensions[i]->type();
MemoryVector<byte> extn_val = extensions[i]->serialize();
buf.push_back(get_byte(0, extn_code));
buf.push_back(get_byte(1, extn_code));
buf.push_back(get_byte<u16bit>(0, extn_val.size()));
buf.push_back(get_byte<u16bit>(1, extn_val.size()));
buf += extn_val;
}
const u16bit extn_size = buf.size() - 2;
buf[0] = get_byte(0, extn_size);
buf[1] = get_byte(1, extn_size);
// avoid sending a completely empty extensions block
if(buf.size() == 2)
return MemoryVector<byte>();
return buf;
}
TLS_Extensions::~TLS_Extensions()
{
for(size_t i = 0; i != extensions.size(); ++i)
delete extensions[i];
extensions.clear();
}
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
{
sni_host_name = reader.get_string(2, 1, 65535);
name_bytes -= (2 + sni_host_name.size());
}
else // some other unknown name type
{
reader.discard_next(name_bytes);
name_bytes = 0;
}
}
}
MemoryVector<byte> Server_Name_Indicator::serialize() const
{
MemoryVector<byte> buf;
size_t name_len = sni_host_name.size();
buf.push_back(get_byte<u16bit>(0, name_len+3));
buf.push_back(get_byte<u16bit>(1, name_len+3));
buf.push_back(0); // DNS
buf.push_back(get_byte<u16bit>(0, name_len));
buf.push_back(get_byte<u16bit>(1, name_len));
buf += std::make_pair(
reinterpret_cast<const byte*>(sni_host_name.data()),
sni_host_name.size());
return buf;
}
SRP_Identifier::SRP_Identifier(TLS_Data_Reader& reader,
u16bit extension_size)
{
srp_identifier = reader.get_string(1, 1, 255);
if(srp_identifier.size() + 1 != extension_size)
throw Decoding_Error("Bad encoding for SRP identifier extension");
}
MemoryVector<byte> SRP_Identifier::serialize() const
{
MemoryVector<byte> buf;
const byte* srp_bytes =
reinterpret_cast<const byte*>(srp_identifier.data());
append_tls_length_value(buf, srp_bytes, srp_identifier.size(), 1);
return buf;
}
Renegotation_Extension::Renegotation_Extension(TLS_Data_Reader& reader,
u16bit extension_size)
{
reneg_data = reader.get_range<byte>(1, 0, 255);
if(reneg_data.size() + 1 != extension_size)
throw Decoding_Error("Bad encoding for secure renegotiation extn");
}
MemoryVector<byte> Renegotation_Extension::serialize() const
{
MemoryVector<byte> buf;
append_tls_length_value(buf, reneg_data, 1);
return buf;
}
size_t Maximum_Fragment_Length::fragment_size() const
{
switch(val)
{
case 1:
return 512;
case 2:
return 1024;
case 3:
return 2048;
case 4:
return 4096;
default:
throw TLS_Exception(ILLEGAL_PARAMETER,
"Bad value in maximum fragment extension");
}
}
Maximum_Fragment_Length::Maximum_Fragment_Length(size_t max_fragment)
{
if(max_fragment == 512)
val = 1;
else if(max_fragment == 1024)
val = 2;
else if(max_fragment == 2048)
val = 3;
else if(max_fragment == 4096)
val = 4;
else
throw std::invalid_argument("Bad setting " + to_string(max_fragment) +
" for maximum fragment size");
}
Maximum_Fragment_Length::Maximum_Fragment_Length(TLS_Data_Reader& reader,
u16bit extension_size)
{
if(extension_size != 1)
throw Decoding_Error("Bad size for maximum fragment extension");
val = reader.get_byte();
}
}
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