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/**
* TLS Record Reading
* (C) 2004-2010 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#include <botan/tls_record.h>
#include <botan/lookup.h>
#include <botan/loadstor.h>
#include <botan/internal/debug.h>
namespace Botan {
/**
* Reset the state
*/
void Record_Reader::reset()
{
cipher.reset();
mac.reset();
mac_size = 0;
block_size = 0;
iv_size = 0;
major = minor = 0;
seq_no = 0;
}
/**
* Set the version to use
*/
void Record_Reader::set_version(Version_Code version)
{
if(version != SSL_V3 && version != TLS_V10 && version != TLS_V11)
throw Invalid_Argument("Record_Reader: Invalid protocol version");
major = (version >> 8) & 0xFF;
minor = (version & 0xFF);
}
/**
* Set the keys for reading
*/
void Record_Reader::set_keys(const CipherSuite& suite, const SessionKeys& keys,
Connection_Side side)
{
cipher.reset();
mac.reset();
SymmetricKey mac_key, cipher_key;
InitializationVector iv;
if(side == CLIENT)
{
cipher_key = keys.server_cipher_key();
iv = keys.server_iv();
mac_key = keys.server_mac_key();
}
else
{
cipher_key = keys.client_cipher_key();
iv = keys.client_iv();
mac_key = keys.client_mac_key();
}
const std::string cipher_algo = suite.cipher_algo();
const std::string mac_algo = suite.mac_algo();
if(have_block_cipher(cipher_algo))
{
cipher.append(get_cipher(
cipher_algo + "/CBC/NoPadding",
cipher_key, iv, DECRYPTION)
);
block_size = block_size_of(cipher_algo);
if(major == 3 && minor >= 2)
iv_size = block_size;
else
iv_size = 0;
}
else if(have_stream_cipher(cipher_algo))
{
cipher.append(get_cipher(cipher_algo, cipher_key, DECRYPTION));
block_size = 0;
iv_size = 0;
}
else
throw Invalid_Argument("Record_Reader: Unknown cipher " + cipher_algo);
if(have_hash(mac_algo))
{
if(major == 3 && minor == 0)
mac.append(new MAC_Filter("SSL3-MAC(" + mac_algo + ")", mac_key));
else
mac.append(new MAC_Filter("HMAC(" + mac_algo + ")", mac_key));
mac_size = output_length_of(mac_algo);
}
else
throw Invalid_Argument("Record_Reader: Unknown hash " + mac_algo);
}
void Record_Reader::add_input(const byte input[], u32bit input_size)
{
input_queue.write(input, input_size);
}
/**
* Retrieve the next record
*/
u32bit Record_Reader::get_record(byte& msg_type,
MemoryRegion<byte>& output)
{
byte header[5] = { 0 };
const u32bit have_in_queue = input_queue.size();
if(have_in_queue < sizeof(header))
return (sizeof(header) - have_in_queue);
/*
* We peek first to make sure we have the full record
*/
input_queue.peek(header, sizeof(header));
const u16bit version = make_u16bit(header[1], header[2]);
const u16bit record_len = make_u16bit(header[3], header[4]);
if(major && (header[1] != major || header[2] != minor))
throw TLS_Exception(PROTOCOL_VERSION,
"Record_Reader: Got unexpected version");
// If insufficient data, return without doing anything
if(have_in_queue < (sizeof(header) + record_len))
return (sizeof(header) + record_len - have_in_queue);
SecureVector<byte> buffer(record_len);
input_queue.read(header, sizeof(header)); // pull off the header
input_queue.read(buffer, buffer.size());
/*
* We are handshaking, no crypto to do so return as-is
* TODO: Check msg_type to confirm a handshake?
*/
if(mac_size == 0)
{
msg_type = header[0];
output = buffer;
return 0; // got a full record
}
// Otherwise, decrypt, check MAC, return plaintext
cipher.process_msg(buffer);
SecureVector<byte> plaintext = cipher.read_all(Pipe::LAST_MESSAGE);
u32bit pad_size = 0;
if(block_size)
{
byte pad_value = plaintext[plaintext.size()-1];
pad_size = pad_value + 1;
if(version == SSL_V3)
{
if(pad_value > block_size)
throw TLS_Exception(BAD_RECORD_MAC,
"Record_Reader: Bad padding");
}
else
{
for(u32bit j = 0; j != pad_size; j++)
if(plaintext[plaintext.size()-j-1] != pad_value)
throw TLS_Exception(BAD_RECORD_MAC,
"Record_Reader: Bad padding");
}
}
if(plaintext.size() < mac_size + pad_size + iv_size)
throw Decoding_Error("Record_Reader: Record truncated");
const u32bit mac_offset = plaintext.size() - (mac_size + pad_size);
SecureVector<byte> recieved_mac(plaintext.begin() + mac_offset,
mac_size);
const u16bit plain_length = plaintext.size() - (mac_size + pad_size + iv_size);
mac.start_msg();
for(u32bit j = 0; j != 8; j++)
mac.write(get_byte(j, seq_no));
mac.write(header[0]); // msg_type
if(version != SSL_V3)
for(u32bit j = 0; j != 2; j++)
mac.write(get_byte(j, version));
for(u32bit j = 0; j != 2; j++)
mac.write(get_byte(j, plain_length));
mac.write(&plaintext[iv_size], plain_length);
mac.end_msg();
++seq_no;
SecureVector<byte> computed_mac = mac.read_all(Pipe::LAST_MESSAGE);
if(recieved_mac != computed_mac)
throw TLS_Exception(BAD_RECORD_MAC, "Record_Reader: MAC failure");
msg_type = header[0];
output.set(&plaintext[iv_size], plain_length);
return 0;
}
}
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