| // 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 <string.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; |
| } |