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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2017 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
// A collection of functions for rendering and parsing hexadecimal strings
#ifndef OPENVPN_COMMON_HEXSTR_H
#define OPENVPN_COMMON_HEXSTR_H
#include <string>
#include <iomanip>
#include <sstream>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/string.hpp>
namespace openvpn {
/**
* Renders an integer value within the hexadecimal range (0-15)
* to a hexadecimal character.
*
* @param c Integer to render as a hexadecimal character.
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Returns a char with the hexadecimal representation of
* the input value. If the value is out-of-range (outside
* of 0-15), it will be replaced with a questionmark (?).
*/
inline char render_hex_char(const int c, const bool caps=false)
{
if (c < 10)
return '0' + c;
else if (c < 16)
return (caps ? 'A' : 'a') - 10 + c;
else
return '?';
}
/**
* Parses a character in the range {0..9,A-F,a-f} to an
* integer value. Used to convert hexadecimal character to integer.
* Only a single character is parsed by this function.
*
* @param c Character to be be parsed.
*
* @return Returns an integer value of the hexadecimal input. If the
* input character is invalid, outside of {0..9,A-F,a-f}, it will
* return -1.
*/
inline int parse_hex_char(const char c)
{
if (c >= '0' && c <= '9')
return c - '0';
else if (c >= 'a' && c <= 'f')
return c - 'a' + 10;
else if (c >= 'A' && c <= 'F')
return c - 'A' + 10;
else
return -1;
}
/**
* Class which Renders a single byte as hexadecimal
*/
class RenderHexByte
{
public:
/**
* Initializes a new object
*
* @param byte Unsigned char (one byte) to be processed
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*/
RenderHexByte(const unsigned char byte, const bool caps=false)
{
c[0] = render_hex_char(byte >> 4, caps);
c[1] = render_hex_char(byte & 0x0F, caps);
}
char char1() const { return c[0]; }
char char2() const { return c[1]; }
/**
* Retrieve the hexadecimal representation of the value.
* Warning: The result is a non-NULL terminated string.
*
* @return Returns a non-NULL terminated 2 byte string with the hexadecimal
* representation of the initial value. The return value is guaranteed
* to always be 2 bytes.
*/
const char *str2() const { return c; } // Note: length=2, NOT null terminated
private:
char c[2];
};
/**
* Render a byte buffer (unsigned char *) as a hexadecimal string.
*
* @param data Unsigned char pointer to buffer to render.
* @param size size_t of the number of bytes to parse from the buffer.
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Returns a std::string of the complete hexadecimal representation
*/
inline std::string render_hex(const unsigned char *data, size_t size, const bool caps=false)
{
if (!data)
return "NULL";
std::string ret;
ret.reserve(size*2+1);
while (size--)
{
const RenderHexByte b(*data++, caps);
ret += b.char1();
ret += b.char2();
}
return ret;
}
/**
* Render a byte buffer (void *) as a hexadecimal string.
*
* @param data Void pointer to buffer to render.
* @param size size_t of the number of bytes to parse from the buffer.
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Returns a std::string of the complete hexadecimal representation.
*/
inline std::string render_hex(const void *data, const size_t size, const bool caps=false)
{
return render_hex((const unsigned char *)data, size, caps);
}
/**
* Variant of @render_hex(const unsiged char *,...) which adds a
* separator between each byte
*
* @param data Unsigned char pointer to buffer to render.
* @param size size_t of the number of bytes to parse from the buffer.
* @param sep A single character to use as the separator.
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Returns a std::string of the complete hexadecimal representation
* with each byte separated by a given character.
*/
inline std::string render_hex_sep(const unsigned char *data, size_t size, const char sep, const bool caps=false)
{
if (!data)
return "NULL";
std::string ret;
ret.reserve(size*3);
bool prsep = false;
while (size--)
{
if (prsep)
ret += sep;
const RenderHexByte b(*data++, caps);
ret += b.char1();
ret += b.char2();
prsep = true;
}
return ret;
}
/**
* Variant of @render_hex(const void *,...) which adds a
* separator between each byte
* @param data Void pointer to buffer to render.
* @param size size_t of the number of bytes to parse from the buffer.
* @param sep A single character to use as the separator.
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Returns a std::string of the complete hexadecimal representation
* with each byte separated by a given character.
*/
inline std::string render_hex_sep(const void *data, const size_t size, const char sep, const bool caps=false)
{
return render_hex_sep((const unsigned char *)data, size, sep, caps);
}
/**
* Render a std::vector<T> container as a hexadecimal string.
* T must be a data type compatible with
* RenderHexByte(const unsigned char,...)
*
* @param data std::vector<T> containing the data to render
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Returns a std::string of the complete hexadecimal representation.
*/
template <typename V>
inline std::string render_hex_generic(const V& data, const bool caps=false)
{
std::string ret;
ret.reserve(data.size()*2+1);
for (size_t i = 0; i < data.size(); ++i)
{
const RenderHexByte b(data[i], caps);
ret += b.char1();
ret += b.char2();
}
return ret;
}
/**
* Renders a combined hexadecimal and character dump of a buffer,
* with the typical 16 bytes split between hexadecimal and character
* separation per line.
*
* @param data Unsigned char pointer to the buffer to dump.
* @param size Size of the buffer to render.
*
* @return Returns a string containing a preformatted output of the
* hexadecimal dump.
*/
inline std::string dump_hex(const unsigned char *data, size_t size)
{
if (!data)
return "NULL\n";
const unsigned int mask = 0x0F; // N bytes per line - 1
std::ostringstream os;
os << std::hex;
std::string chars;
size_t i;
for (i = 0; i < size; ++i)
{
if (!(i & mask))
{
if (i)
{
os << " " << chars << std::endl;
chars.clear();
}
os << std::setfill(' ') << std::setw(8) << i << ":";
}
const unsigned char c = data[i];
os << ' ' << std::setfill('0') << std::setw(2) << (unsigned int)c;
if (string::is_printable(c))
chars += c;
else
chars += '.';
}
if (i)
os << string::spaces(2 + (((i-1) & mask) ^ mask) * 3) << chars << std::endl;
return os.str();
}
/**
* Renders a combined hexadecimal and character dump of a buffer,
* with the typical 16 bytes split between hexadecimal and character
* separation per line.
*
* @param data Void pointer to the buffer to dump.
* @param size Size of the buffer to render.
*
* @return Returns a string containing a preformatted output of the
* hexadecimal dump.
*/
inline std::string dump_hex(void* data, size_t size)
{
return dump_hex((const unsigned char *)data, size);
}
/**
* Renders a combined hexadecimal and character dump of a std::string buffer,
* with the typical 16 bytes split between hexadecimal and character
* separation per line.
*
* @param data std::string containing the buffer to render
*
* @return Returns a string containing a preformatted output of the
* hexadecimal dump.
*/
inline std::string dump_hex(const std::string& str)
{
return dump_hex((const unsigned char *)str.c_str(), str.length());
}
/**
* Renders a combined hexadecimal and character dump of a std::vector<T>
* based buffer, with the typical 16 bytes split between hexadecimal and
* character separation per line.
*
* @param data std::vector<T> containing the buffer to render
*
* @return Returns a string containing a preformatted output of the
* hexadecimal dump.
*/
template <typename V>
inline std::string dump_hex(const V& data)
{
return dump_hex(data.c_data(), data.size());
}
/**
* Declaration of a hexadecimal parsing error exception class
*/
OPENVPN_SIMPLE_EXCEPTION(parse_hex_error);
/**
* Parses a std::string containing a hexadecimal value into
* a std::vector<T>.
*
* @param dest std::vector<T> destination buffer to use.
* @param str std::string& containing the hexadecimal string to parse.
*
* @return Returns nothing on success. Will throw a parse_hex_error
* exception if the input is invalid/not parseable as a hexadecimal
* number.
*/
template <typename V>
inline void parse_hex(V& dest, const std::string& str)
{
const int len = int(str.length());
int i;
for (i = 0; i <= len - 2; i += 2)
{
const int high = parse_hex_char(str[i]);
const int low = parse_hex_char(str[i+1]);
if (high == -1 || low == -1)
throw parse_hex_error();
dest.push_back((high<<4) + low);
}
if (i != len)
throw parse_hex_error(); // straggler char
}
/**
* Parses a char buffer (C string) containing a hexadecimal
* string into a templated (T) variable. The input buffer
* MUST be NULL terminated.
*
* WARNING: There are _NO_ overflow checks.
*
* @param str Char pointer (char *) to the buffer to be parsed.
* @param retval Return buffer where the parsed value is stored.
*
* @return Returns true on successful parsing, otherwise false.
*/
template <typename T>
inline bool parse_hex_number(const char *str, T& retval)
{
if (!str[0])
return false; // empty string
size_t i = 0;
T ret = T(0);
while (true)
{
const char c = str[i++];
const int hd = parse_hex_char(c);
if (hd >= 0)
{
ret *= T(16);
ret += T(hd);
}
else if (!c)
{
retval = ret;
return true;
}
else
return false; // non-hex-digit
}
}
/**
* Variant of @parse_hex_number(const char *, ...) which takes a std::string
* as the input.
*
* @param str std::string containing the hexadecimal string to be parsed.
* @param retval Return buffer where the parsed value is stored.
*
* @return Returns true on successful parsing, otherwise false.
*/
template <typename T>
inline bool parse_hex_number(const std::string& str, T& retval)
{
return parse_hex_number(str.c_str(), retval);
}
/**
* Parses a std::string containing a hexadecimal
* string into a templated (T) variable.
*
* NOTE: Currently doesn't detect overflow
*
* @param str std::string containing the hexadecimal
* string to be parsed.
*
* @return Returns a template T variable containing the
* parsed value on success. Will throw the parse_hex_error
* exception on parsing errors.
*
*/
template <typename T>
inline T parse_hex_number(const std::string& str)
{
T ret;
if (!parse_hex_number<T>(str.c_str(), ret))
throw parse_hex_error();
return ret;
}
/**
* Renders a templated T variable containing a numeric value
* into a std::string containing a hexadecimal representation.
*
* @param value Numeric (T) value to represent as hexadecimal.
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Retuns a std::string containing the hexadecimal
* representation on succes. Will throw a parse_hex_error
* exception on parsing errors.
*/
template <typename T>
std::string render_hex_number(T value, const bool caps=false)
{
unsigned char buf[sizeof(T)];
for (size_t i = sizeof(T); i --> 0 ;)
{
buf[i] = value & 0xFF;
value >>= 8;
}
return render_hex(buf, sizeof(T), caps);
}
/**
* Renders a single byte as a hexadecimal string
*
* @param value Unsigned char (byte) to be represented as hexadecimal.
* @param caps Boolean (default false) which sets the outout to
* be either lower case (false) or upper case (true).
*
* @return Returns a std::string with the hexadecimal representation
* of the input value. The result will always contain only
* two characters.
*/
inline std::string render_hex_number(unsigned char uc, const bool caps=false)
{
RenderHexByte b(uc, caps);
return std::string(b.str2(), 2);
}
} // namespace openvpn
#endif // OPENVPN_COMMON_HEXSTR_H