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// Copyright (c) 2006, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "common/linux/eintr_wrapper.h"
#include "common/linux/guid_creator.h"
#include <assert.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#if defined(HAVE_SYS_RANDOM_H)
#include <sys/random.h>
#endif
//
// GUIDGenerator
//
// This class is used to generate random GUID.
// Currently use random number to generate a GUID since Linux has
// no native GUID generator. This should be OK since we don't expect
// crash to happen very offen.
//
class GUIDGenerator {
public:
static uint32_t BytesToUInt32(const uint8_t bytes[]) {
return ((uint32_t) bytes[0]
| ((uint32_t) bytes[1] << 8)
| ((uint32_t) bytes[2] << 16)
| ((uint32_t) bytes[3] << 24));
}
static void UInt32ToBytes(uint8_t bytes[], uint32_t n) {
bytes[0] = n & 0xff;
bytes[1] = (n >> 8) & 0xff;
bytes[2] = (n >> 16) & 0xff;
bytes[3] = (n >> 24) & 0xff;
}
static bool CreateGUID(GUID *guid) {
#if defined(HAVE_ARC4RANDOM) // Android, BSD, ...
CreateGuidFromArc4Random(guid);
#else // Linux
bool success = false;
#if defined(HAVE_SYS_RANDOM_H) && defined(HAVE_GETRANDOM)
success = CreateGUIDFromGetrandom(guid);
#endif // HAVE_SYS_RANDOM_H && HAVE_GETRANDOM
if (!success) {
success = CreateGUIDFromDevUrandom(guid);
}
if (!success) {
CreateGUIDFromRand(guid);
success = true;
}
#endif
// Put in the version according to RFC 4122.
guid->data3 &= 0x0fff;
guid->data3 |= 0x4000;
// Put in the variant according to RFC 4122.
guid->data4[0] &= 0x3f;
guid->data4[0] |= 0x80;
return true;
}
private:
#ifdef HAVE_ARC4RANDOM
static void CreateGuidFromArc4Random(GUID *guid) {
char *buf = reinterpret_cast<char *>(guid);
for (size_t i = 0; i < sizeof(GUID); i += sizeof(uint32_t)) {
uint32_t random_data = arc4random();
memcpy(buf + i, &random_data, sizeof(uint32_t));
}
}
#else
static void InitOnce() {
pthread_once(&once_control, &InitOnceImpl);
}
static void InitOnceImpl() {
// time(NULL) is a very poor seed, so lacking anything better mix an
// address into it. We drop the four rightmost bits as they're likely to
// be 0 on almost all architectures.
srand(time(NULL) | ((uintptr_t)&once_control >> 4));
}
static pthread_once_t once_control;
#if defined(HAVE_SYS_RANDOM_H) && defined(HAVE_GETRANDOM)
static bool CreateGUIDFromGetrandom(GUID *guid) {
char *buf = reinterpret_cast<char *>(guid);
int read_bytes = getrandom(buf, sizeof(GUID), GRND_NONBLOCK);
return (read_bytes == static_cast<int>(sizeof(GUID)));
}
#endif // HAVE_SYS_RANDOM_H && HAVE_GETRANDOM
// Populate the GUID using random bytes read from /dev/urandom, returns false
// if the GUID wasn't fully populated with random data.
static bool CreateGUIDFromDevUrandom(GUID *guid) {
char *buf = reinterpret_cast<char *>(guid);
int fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
if (fd == -1) {
return false;
}
ssize_t read_bytes = HANDLE_EINTR(read(fd, buf, sizeof(GUID)));
close(fd);
return (read_bytes == static_cast<ssize_t>(sizeof(GUID)));
}
// Populate the GUID using a stream of random bytes obtained from rand().
static void CreateGUIDFromRand(GUID *guid) {
char *buf = reinterpret_cast<char *>(guid);
InitOnce();
for (size_t i = 0; i < sizeof(GUID); i++) {
buf[i] = rand();
}
}
#endif
};
#ifndef HAVE_ARC4RANDOM
pthread_once_t GUIDGenerator::once_control = PTHREAD_ONCE_INIT;
#endif
bool CreateGUID(GUID *guid) {
return GUIDGenerator::CreateGUID(guid);
}
// Parse guid to string.
bool GUIDToString(const GUID *guid, char *buf, int buf_len) {
// Should allow more space the the max length of GUID.
assert(buf_len > kGUIDStringLength);
int num = snprintf(buf, buf_len, kGUIDFormatString,
guid->data1, guid->data2, guid->data3,
GUIDGenerator::BytesToUInt32(&(guid->data4[0])),
GUIDGenerator::BytesToUInt32(&(guid->data4[4])));
if (num != kGUIDStringLength)
return false;
buf[num] = '\0';
return true;
}
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