ZeroTierOne/node/Utils.cpp
2017-02-06 11:49:41 -08:00

263 lines
6.8 KiB
C++

/*
* ZeroTier One - Network Virtualization Everywhere
* Copyright (C) 2011-2016 ZeroTier, Inc. https://www.zerotier.com/
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <time.h>
#include <sys/stat.h>
#include "Constants.hpp"
#ifdef __UNIX_LIKE__
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <dirent.h>
#endif
#ifdef __WINDOWS__
#include <wincrypt.h>
#endif
#include "Utils.hpp"
#include "Mutex.hpp"
#include "Salsa20.hpp"
namespace ZeroTier {
const char Utils::HEXCHARS[16] = { '0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f' };
static void _Utils_doBurn(char *ptr,unsigned int len)
{
for(unsigned int i=0;i<len;++i)
ptr[i] = (char)0;
}
void (*volatile _Utils_doBurn_ptr)(char *,unsigned int) = _Utils_doBurn;
void Utils::burn(void *ptr,unsigned int len)
throw()
{
// Ridiculous hack: call _doBurn() via a volatile function pointer to
// hold down compiler optimizers and beat them mercilessly until they
// cry and mumble something about never eliding secure memory zeroing
// again.
(_Utils_doBurn_ptr)((char *)ptr,len);
}
std::string Utils::hex(const void *data,unsigned int len)
{
std::string r;
r.reserve(len * 2);
for(unsigned int i=0;i<len;++i) {
r.push_back(HEXCHARS[(((const unsigned char *)data)[i] & 0xf0) >> 4]);
r.push_back(HEXCHARS[((const unsigned char *)data)[i] & 0x0f]);
}
return r;
}
std::string Utils::unhex(const char *hex,unsigned int maxlen)
{
int n = 1;
unsigned char c,b = 0;
const char *eof = hex + maxlen;
std::string r;
if (!maxlen)
return r;
while ((c = (unsigned char)*(hex++))) {
if ((c >= 48)&&(c <= 57)) { // 0..9
if ((n ^= 1))
r.push_back((char)(b | (c - 48)));
else b = (c - 48) << 4;
} else if ((c >= 65)&&(c <= 70)) { // A..F
if ((n ^= 1))
r.push_back((char)(b | (c - (65 - 10))));
else b = (c - (65 - 10)) << 4;
} else if ((c >= 97)&&(c <= 102)) { // a..f
if ((n ^= 1))
r.push_back((char)(b | (c - (97 - 10))));
else b = (c - (97 - 10)) << 4;
}
if (hex == eof)
break;
}
return r;
}
unsigned int Utils::unhex(const char *hex,unsigned int maxlen,void *buf,unsigned int len)
{
int n = 1;
unsigned char c,b = 0;
unsigned int l = 0;
const char *eof = hex + maxlen;
if (!maxlen)
return 0;
while ((c = (unsigned char)*(hex++))) {
if ((c >= 48)&&(c <= 57)) { // 0..9
if ((n ^= 1)) {
if (l >= len) break;
((unsigned char *)buf)[l++] = (b | (c - 48));
} else b = (c - 48) << 4;
} else if ((c >= 65)&&(c <= 70)) { // A..F
if ((n ^= 1)) {
if (l >= len) break;
((unsigned char *)buf)[l++] = (b | (c - (65 - 10)));
} else b = (c - (65 - 10)) << 4;
} else if ((c >= 97)&&(c <= 102)) { // a..f
if ((n ^= 1)) {
if (l >= len) break;
((unsigned char *)buf)[l++] = (b | (c - (97 - 10)));
} else b = (c - (97 - 10)) << 4;
}
if (hex == eof)
break;
}
return l;
}
void Utils::getSecureRandom(void *buf,unsigned int bytes)
{
static Mutex globalLock;
static Salsa20 s20;
static bool s20Initialized = false;
static uint8_t randomBuf[65536];
static unsigned int randomPtr = sizeof(randomBuf);
Mutex::Lock _l(globalLock);
/* Just for posterity we Salsa20 encrypt the result of whatever system
* CSPRNG we use. There have been several bugs at the OS or OS distribution
* level in the past that resulted in systematically weak or predictable
* keys due to random seeding problems. This mitigates that by grabbing
* a bit of extra entropy and further randomizing the result, and comes
* at almost no cost and with no real downside if the random source is
* good. */
if (!s20Initialized) {
s20Initialized = true;
uint64_t s20Key[4];
s20Key[0] = (uint64_t)time(0); // system clock
s20Key[1] = (uint64_t)buf; // address of buf
s20Key[2] = (uint64_t)s20Key; // address of s20Key[]
s20Key[3] = (uint64_t)&s20; // address of s20
s20.init(s20Key,256,s20Key);
}
#ifdef __WINDOWS__
static HCRYPTPROV cryptProvider = NULL;
for(unsigned int i=0;i<bytes;++i) {
if (randomPtr >= sizeof(randomBuf)) {
if (cryptProvider == NULL) {
if (!CryptAcquireContextA(&cryptProvider,NULL,NULL,PROV_RSA_FULL,CRYPT_VERIFYCONTEXT|CRYPT_SILENT)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to obtain WinCrypt context!\r\n");
exit(1);
}
}
if (!CryptGenRandom(cryptProvider,(DWORD)sizeof(randomBuf),(BYTE *)randomBuf)) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() CryptGenRandom failed!\r\n");
exit(1);
}
randomPtr = 0;
s20.crypt12(randomBuf,randomBuf,sizeof(randomBuf));
}
((uint8_t *)buf)[i] = randomBuf[randomPtr++];
}
#else // not __WINDOWS__
static int devURandomFd = -1;
if (devURandomFd < 0) {
devURandomFd = ::open("/dev/urandom",O_RDONLY);
if (devURandomFd < 0) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to open /dev/urandom\n");
exit(1);
return;
}
}
for(unsigned int i=0;i<bytes;++i) {
if (randomPtr >= sizeof(randomBuf)) {
for(;;) {
if ((int)::read(devURandomFd,randomBuf,sizeof(randomBuf)) != (int)sizeof(randomBuf)) {
::close(devURandomFd);
devURandomFd = ::open("/dev/urandom",O_RDONLY);
if (devURandomFd < 0) {
fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to open /dev/urandom\n");
exit(1);
return;
}
} else break;
}
randomPtr = 0;
s20.crypt12(randomBuf,randomBuf,sizeof(randomBuf));
}
((uint8_t *)buf)[i] = randomBuf[randomPtr++];
}
#endif // __WINDOWS__ or not
}
bool Utils::scopy(char *dest,unsigned int len,const char *src)
{
if (!len)
return false; // sanity check
if (!src) {
*dest = (char)0;
return true;
}
char *end = dest + len;
while ((*dest++ = *src++)) {
if (dest == end) {
*(--dest) = (char)0;
return false;
}
}
return true;
}
unsigned int Utils::snprintf(char *buf,unsigned int len,const char *fmt,...)
throw(std::length_error)
{
va_list ap;
va_start(ap,fmt);
int n = (int)vsnprintf(buf,len,fmt,ap);
va_end(ap);
if ((n >= (int)len)||(n < 0)) {
if (len)
buf[len - 1] = (char)0;
throw std::length_error("buf[] overflow in Utils::snprintf");
}
return (unsigned int)n;
}
} // namespace ZeroTier