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/*
* Phusion Passenger - http://www.modrails.com/
* Copyright (c) 2010 Phusion
*
* "Phusion Passenger" is a trademark of Hongli Lai & Ninh Bui.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef _PASSENGER_RANDOM_GENERATOR_H_
#define _PASSENGER_RANDOM_GENERATOR_H_
#include <string>
#include <boost/noncopyable.hpp>
#include <boost/shared_ptr.hpp>
#include <oxt/system_calls.hpp>
#include "StaticString.h"
#include "Exceptions.h"
#include "Utils/StrIntUtils.h"
/**
* A random
*/
namespace Passenger {
using namespace std;
using namespace boost;
using namespace oxt;
/**
* A random data generator. Data is generated using /dev/urandom, and
* is cryptographically secure. Unlike rand() and friends,
* RandomGenerator does not require seeding.
*
* The reason why RandomGenerator isn't a singleton is because opening
* /dev/urandom is *very* slow on Mac OS X and OpenBSD. Each object of
* this class caches the /dev/urandom file handle.
*
* This class is thread-safe as long as there are no concurrent
* calls to reopen() or close().
*/
class RandomGenerator: public boost::noncopyable {
private:
FILE *handle;
public:
RandomGenerator(bool open = true) {
handle = NULL;
if (open) {
reopen();
}
}
~RandomGenerator() {
this_thread::disable_syscall_interruption dsi;
close();
}
void reopen() {
close();
handle = syscalls::fopen("/dev/urandom", "r");
if (handle == NULL) {
throw FileSystemException("Cannot open /dev/urandom",
errno, "/dev/urandom");
}
}
void close() {
if (handle != NULL) {
syscalls::fclose(handle);
handle = NULL;
}
}
StaticString generateBytes(void *buf, unsigned int size) {
size_t ret = syscalls::fread(buf, 1, size, handle);
if (ret != size) {
throw IOException("Cannot read sufficient data from /dev/urandom");
}
return StaticString((const char *) buf, size);
}
string generateByteString(unsigned int size) {
char buf[size];
generateBytes(buf, size);
return string(buf, size);
}
string generateHexString(unsigned int size) {
char buf[size];
generateBytes(buf, size);
return toHex(StaticString(buf, size));
}
/**
* Generates a random string of <em>size</em> bytes which is also
* valid ASCII. The result consists only of the characters A-Z,
* a-z and 0-9, and therefore the total number of possibilities
* given a size of N is 62**N. However not every character has an
* equal chance of being chosen: a-i have 5/256 chance of being
* chosen, while other characters have 4/256 chance of being chosen.
* Therefore, to match the entropy of a random binary string of
* size N, one should choose a <em>size</em> which yields slightly
* more possibilities than 2**N.
*/
string generateAsciiString(unsigned int size) {
char buf[size];
generateAsciiString(buf, size);
return string(buf, size);
}
void generateAsciiString(char *_buf, unsigned int size) {
static const char chars[] = {
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'
};
unsigned char *buf = (unsigned char *) _buf;
generateBytes(buf, size);
for (unsigned int i = 0; i < size; i++) {
buf[i] = chars[buf[i] % sizeof(chars)];
}
}
int generateInt() {
int ret;
generateBytes(&ret, sizeof(ret));
return ret;
}
unsigned int generateUint() {
return (unsigned int) generateInt();
}
};
typedef shared_ptr<RandomGenerator> RandomGeneratorPtr;
} // namespace Passenger
#endif /* _PASSENGER_RANDOM_GENERATOR_H_ */
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