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Diffstat (limited to 'src/tls/tls_reader.h')
| -rw-r--r-- | src/tls/tls_reader.h | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/src/tls/tls_reader.h b/src/tls/tls_reader.h new file mode 100644 index 000000000..f6b0d4088 --- /dev/null +++ b/src/tls/tls_reader.h @@ -0,0 +1,233 @@ +/* +* TLS Data Reader +* (C) 2010-2011 Jack Lloyd +* +* Released under the terms of the Botan license +*/ + +#ifndef BOTAN_TLS_READER_H__ +#define BOTAN_TLS_READER_H__ + +#include <botan/exceptn.h> +#include <botan/secmem.h> +#include <botan/loadstor.h> +#include <string> +#include <vector> +#include <stdexcept> + +namespace Botan { + +namespace TLS { + +/** +* Helper class for decoding TLS protocol messages +*/ +class TLS_Data_Reader + { + public: + TLS_Data_Reader(const MemoryRegion<byte>& buf_in) : + buf(buf_in), offset(0) {} + + void assert_done() const + { + if(has_remaining()) + throw Decoding_Error("Extra bytes at end of message"); + } + + size_t remaining_bytes() const + { + return buf.size() - offset; + } + + bool has_remaining() const + { + return (remaining_bytes() > 0); + } + + void discard_next(size_t bytes) + { + assert_at_least(bytes); + offset += bytes; + } + + u16bit get_u32bit() + { + assert_at_least(4); + u16bit result = make_u32bit(buf[offset ], buf[offset+1], + buf[offset+2], buf[offset+3]); + offset += 4; + return result; + } + + u16bit get_u16bit() + { + assert_at_least(2); + u16bit result = make_u16bit(buf[offset], buf[offset+1]); + offset += 2; + return result; + } + + byte get_byte() + { + assert_at_least(1); + byte result = buf[offset]; + offset += 1; + return result; + } + + template<typename T, typename Container> + Container get_elem(size_t num_elems) + { + assert_at_least(num_elems * sizeof(T)); + + Container result(num_elems); + + for(size_t i = 0; i != num_elems; ++i) + result[i] = load_be<T>(&buf[offset], i); + + offset += num_elems * sizeof(T); + + return result; + } + + template<typename T> + SecureVector<T> get_range(size_t len_bytes, + size_t min_elems, + size_t max_elems) + { + const size_t num_elems = + get_num_elems(len_bytes, sizeof(T), min_elems, max_elems); + + return get_elem<T, SecureVector<T> >(num_elems); + } + + template<typename T> + std::vector<T> get_range_vector(size_t len_bytes, + size_t min_elems, + size_t max_elems) + { + const size_t num_elems = + get_num_elems(len_bytes, sizeof(T), min_elems, max_elems); + + return get_elem<T, std::vector<T> >(num_elems); + } + + std::string get_string(size_t len_bytes, + size_t min_bytes, + size_t max_bytes) + { + std::vector<byte> v = + get_range_vector<byte>(len_bytes, min_bytes, max_bytes); + + return std::string(reinterpret_cast<char*>(&v[0]), v.size()); + } + + template<typename T> + SecureVector<T> get_fixed(size_t size) + { + return get_elem<T, SecureVector<T> >(size); + } + + private: + size_t get_length_field(size_t len_bytes) + { + assert_at_least(len_bytes); + + if(len_bytes == 1) + return get_byte(); + else if(len_bytes == 2) + return get_u16bit(); + + throw Decoding_Error("TLS_Data_Reader: Bad length size"); + } + + size_t get_num_elems(size_t len_bytes, + size_t T_size, + size_t min_elems, + size_t max_elems) + { + const size_t byte_length = get_length_field(len_bytes); + + if(byte_length % T_size != 0) + throw Decoding_Error("TLS_Data_Reader: Size isn't multiple of T"); + + const size_t num_elems = byte_length / T_size; + + if(num_elems < min_elems || num_elems > max_elems) + throw Decoding_Error("TLS_Data_Reader: Range outside paramaters"); + + return num_elems; + } + + void assert_at_least(size_t n) const + { + if(buf.size() - offset < n) + { + throw Decoding_Error("TLS_Data_Reader: Expected " + to_string(n) + + " bytes remaining, only " + to_string(buf.size()-offset) + + " left"); + } + } + + const MemoryRegion<byte>& buf; + size_t offset; + }; + +/** +* Helper function for encoding length-tagged vectors +*/ +template<typename T> +void append_tls_length_value(MemoryRegion<byte>& buf, + const T* vals, + size_t vals_size, + size_t tag_size) + { + const size_t T_size = sizeof(T); + const size_t val_bytes = T_size * vals_size; + + if(tag_size != 1 && tag_size != 2) + throw std::invalid_argument("append_tls_length_value: invalid tag size"); + + if((tag_size == 1 && val_bytes > 255) || + (tag_size == 2 && val_bytes > 65535)) + throw std::invalid_argument("append_tls_length_value: value too large"); + + for(size_t i = 0; i != tag_size; ++i) + buf.push_back(get_byte(sizeof(val_bytes)-tag_size+i, val_bytes)); + + for(size_t i = 0; i != vals_size; ++i) + for(size_t j = 0; j != T_size; ++j) + buf.push_back(get_byte(j, vals[i])); + } + +template<typename T> +void append_tls_length_value(MemoryRegion<byte>& buf, + const MemoryRegion<T>& vals, + size_t tag_size) + { + append_tls_length_value(buf, &vals[0], vals.size(), tag_size); + } + +template<typename T> +void append_tls_length_value(MemoryRegion<byte>& buf, + const std::vector<T>& vals, + size_t tag_size) + { + append_tls_length_value(buf, &vals[0], vals.size(), tag_size); + } + +inline void append_tls_length_value(MemoryRegion<byte>& buf, + const std::string& str, + size_t tag_size) + { + append_tls_length_value(buf, + reinterpret_cast<const byte*>(&str[0]), + str.size(), + tag_size); + } + +} + +} + +#endif |