mirror of
https://github.com/didyouexpectthat/zerotierone.git
synced 2024-09-19 04:10:20 -07:00
258 lines
6.8 KiB
C++
258 lines
6.8 KiB
C++
/*
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* ZeroTier One - Network Virtualization Everywhere
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* Copyright (C) 2011-2016 ZeroTier, Inc. https://www.zerotier.com/
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <time.h>
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#include <sys/stat.h>
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#include "Constants.hpp"
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#ifdef __UNIX_LIKE__
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/uio.h>
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#include <dirent.h>
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#endif
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#ifdef __WINDOWS__
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#include <wincrypt.h>
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#endif
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#include "Utils.hpp"
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#include "Mutex.hpp"
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#include "Salsa20.hpp"
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namespace ZeroTier {
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const char Utils::HEXCHARS[16] = { '0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f' };
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// Crazy hack to force memory to be securely zeroed in spite of the best efforts of optimizing compilers.
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static void _Utils_doBurn(volatile uint8_t *ptr,unsigned int len)
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{
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volatile uint8_t *const end = ptr + len;
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while (ptr != end) *(ptr++) = (uint8_t)0;
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}
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static void (*volatile _Utils_doBurn_ptr)(volatile uint8_t *,unsigned int) = _Utils_doBurn;
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void Utils::burn(void *ptr,unsigned int len) { (_Utils_doBurn_ptr)((volatile uint8_t *)ptr,len); }
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std::string Utils::hex(const void *data,unsigned int len)
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{
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std::string r;
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r.reserve(len * 2);
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for(unsigned int i=0;i<len;++i) {
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r.push_back(HEXCHARS[(((const unsigned char *)data)[i] & 0xf0) >> 4]);
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r.push_back(HEXCHARS[((const unsigned char *)data)[i] & 0x0f]);
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}
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return r;
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}
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std::string Utils::unhex(const char *hex,unsigned int maxlen)
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{
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int n = 1;
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unsigned char c,b = 0;
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const char *eof = hex + maxlen;
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std::string r;
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if (!maxlen)
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return r;
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while ((c = (unsigned char)*(hex++))) {
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if ((c >= 48)&&(c <= 57)) { // 0..9
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if ((n ^= 1))
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r.push_back((char)(b | (c - 48)));
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else b = (c - 48) << 4;
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} else if ((c >= 65)&&(c <= 70)) { // A..F
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if ((n ^= 1))
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r.push_back((char)(b | (c - (65 - 10))));
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else b = (c - (65 - 10)) << 4;
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} else if ((c >= 97)&&(c <= 102)) { // a..f
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if ((n ^= 1))
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r.push_back((char)(b | (c - (97 - 10))));
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else b = (c - (97 - 10)) << 4;
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}
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if (hex == eof)
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break;
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}
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return r;
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}
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unsigned int Utils::unhex(const char *hex,unsigned int maxlen,void *buf,unsigned int len)
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{
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int n = 1;
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unsigned char c,b = 0;
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unsigned int l = 0;
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const char *eof = hex + maxlen;
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if (!maxlen)
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return 0;
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while ((c = (unsigned char)*(hex++))) {
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if ((c >= 48)&&(c <= 57)) { // 0..9
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if ((n ^= 1)) {
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if (l >= len) break;
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((unsigned char *)buf)[l++] = (b | (c - 48));
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} else b = (c - 48) << 4;
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} else if ((c >= 65)&&(c <= 70)) { // A..F
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if ((n ^= 1)) {
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if (l >= len) break;
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((unsigned char *)buf)[l++] = (b | (c - (65 - 10)));
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} else b = (c - (65 - 10)) << 4;
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} else if ((c >= 97)&&(c <= 102)) { // a..f
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if ((n ^= 1)) {
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if (l >= len) break;
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((unsigned char *)buf)[l++] = (b | (c - (97 - 10)));
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} else b = (c - (97 - 10)) << 4;
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}
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if (hex == eof)
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break;
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}
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return l;
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}
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void Utils::getSecureRandom(void *buf,unsigned int bytes)
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{
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static Mutex globalLock;
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static Salsa20 s20;
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static bool s20Initialized = false;
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static uint8_t randomBuf[65536];
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static unsigned int randomPtr = sizeof(randomBuf);
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Mutex::Lock _l(globalLock);
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/* Just for posterity we Salsa20 encrypt the result of whatever system
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* CSPRNG we use. There have been several bugs at the OS or OS distribution
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* level in the past that resulted in systematically weak or predictable
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* keys due to random seeding problems. This mitigates that by grabbing
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* a bit of extra entropy and further randomizing the result, and comes
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* at almost no cost and with no real downside if the random source is
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* good. */
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if (!s20Initialized) {
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s20Initialized = true;
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uint64_t s20Key[4];
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s20Key[0] = (uint64_t)time(0); // system clock
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s20Key[1] = (uint64_t)buf; // address of buf
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s20Key[2] = (uint64_t)s20Key; // address of s20Key[]
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s20Key[3] = (uint64_t)&s20; // address of s20
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s20.init(s20Key,s20Key);
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}
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#ifdef __WINDOWS__
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static HCRYPTPROV cryptProvider = NULL;
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for(unsigned int i=0;i<bytes;++i) {
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if (randomPtr >= sizeof(randomBuf)) {
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if (cryptProvider == NULL) {
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if (!CryptAcquireContextA(&cryptProvider,NULL,NULL,PROV_RSA_FULL,CRYPT_VERIFYCONTEXT|CRYPT_SILENT)) {
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fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to obtain WinCrypt context!\r\n");
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exit(1);
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}
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}
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if (!CryptGenRandom(cryptProvider,(DWORD)sizeof(randomBuf),(BYTE *)randomBuf)) {
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fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() CryptGenRandom failed!\r\n");
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exit(1);
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}
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randomPtr = 0;
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s20.crypt12(randomBuf,randomBuf,sizeof(randomBuf));
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s20.init(randomBuf,randomBuf);
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}
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((uint8_t *)buf)[i] = randomBuf[randomPtr++];
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}
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#else // not __WINDOWS__
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static int devURandomFd = -1;
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if (devURandomFd < 0) {
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devURandomFd = ::open("/dev/urandom",O_RDONLY);
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if (devURandomFd < 0) {
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fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to open /dev/urandom\n");
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exit(1);
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return;
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}
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}
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for(unsigned int i=0;i<bytes;++i) {
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if (randomPtr >= sizeof(randomBuf)) {
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for(;;) {
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if ((int)::read(devURandomFd,randomBuf,sizeof(randomBuf)) != (int)sizeof(randomBuf)) {
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::close(devURandomFd);
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devURandomFd = ::open("/dev/urandom",O_RDONLY);
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if (devURandomFd < 0) {
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fprintf(stderr,"FATAL ERROR: Utils::getSecureRandom() unable to open /dev/urandom\n");
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exit(1);
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return;
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}
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} else break;
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}
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randomPtr = 0;
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s20.crypt12(randomBuf,randomBuf,sizeof(randomBuf));
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s20.init(randomBuf,randomBuf);
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}
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((uint8_t *)buf)[i] = randomBuf[randomPtr++];
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}
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#endif // __WINDOWS__ or not
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}
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bool Utils::scopy(char *dest,unsigned int len,const char *src)
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{
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if (!len)
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return false; // sanity check
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if (!src) {
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*dest = (char)0;
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return true;
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}
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char *end = dest + len;
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while ((*dest++ = *src++)) {
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if (dest == end) {
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*(--dest) = (char)0;
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return false;
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}
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}
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return true;
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}
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unsigned int Utils::snprintf(char *buf,unsigned int len,const char *fmt,...)
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throw(std::length_error)
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{
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va_list ap;
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va_start(ap,fmt);
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int n = (int)vsnprintf(buf,len,fmt,ap);
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va_end(ap);
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if ((n >= (int)len)||(n < 0)) {
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if (len)
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buf[len - 1] = (char)0;
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throw std::length_error("buf[] overflow in Utils::snprintf");
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}
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return (unsigned int)n;
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}
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} // namespace ZeroTier
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