1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
/*
* TLS Data Reader
* (C) 2010 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#ifndef BOTAN_TLS_READER_H__
#define BOTAN_TLS_READER_H__
#include <botan/secmem.h>
#include <botan/loadstor.h>
namespace Botan {
/**
* 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) {}
u32bit remaining_bytes() const
{
return buf.size() - offset;
}
bool has_remaining() const
{
return (remaining_bytes() > 0);
}
void discard_next(u32bit bytes)
{
assert_at_least(bytes);
offset += bytes;
}
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(u32bit num_elems)
{
assert_at_least(num_elems * sizeof(T));
Container result(num_elems);
for(u32bit 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(u32bit len_bytes,
u32bit min_elems,
u32bit max_elems)
{
const u32bit 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(u32bit len_bytes,
u32bit min_elems,
u32bit max_elems)
{
const u32bit num_elems =
get_num_elems(len_bytes, sizeof(T), min_elems, max_elems);
return get_elem<T, std::vector<T> >(num_elems);
}
template<typename T>
SecureVector<T> get_fixed(u32bit size)
{
return get_elem<T, SecureVector<T> >(size);
}
private:
u32bit get_length_field(u32bit 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");
}
u32bit get_num_elems(u32bit len_bytes,
u32bit T_size,
u32bit min_elems,
u32bit max_elems)
{
const u32bit 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 u32bit 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(u32bit n) const
{
if(buf.size() - offset < n)
throw Decoding_Error("TLS_Data_Reader: Corrupt packet");
}
const MemoryRegion<byte>& buf;
u32bit offset;
};
/**
* Helper function for encoding length-tagged vectors
*/
template<typename T>
void append_tls_length_value(MemoryRegion<byte>& buf,
const T* vals,
u32bit vals_size,
u32bit tag_size)
{
const u32bit T_size = sizeof(T);
const u32bit 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(u32bit i = 0; i != tag_size; ++i)
buf.push_back(get_byte(4-tag_size+i, val_bytes));
for(u32bit i = 0; i != vals_size; ++i)
for(u32bit 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,
u32bit 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,
u32bit tag_size)
{
append_tls_length_value(buf, &vals[0], vals.size(), tag_size);
}
}
#endif
|
