#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
-#include <openssl/aes.h>
-#include <openssl/opensslv.h>
-#if OPENSSL_VERSION_NUMBER > 0x1010000fL && !defined LIBRESSL_VERSION_NUMBER
-// Older OpenSSL does not have CRYPTO_ctr128_encrypt. Before 1.1.0 the header
-// file did not have the necessary extern "C" wrapper. In 1.1.0, AES_ctr128_encrypt
-// was removed.
-#include <openssl/modes.h>
-#endif
-#include <iostream>
-#include <cstdlib>
-#include <cstring>
#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
#include <unistd.h>
-#include <sys/time.h>
-#include <limits>
-#include <stdexcept>
-#include <stdint.h>
+#include <stdlib.h>
+#include <string>
#include "dns_random.hh"
+#include "arguments.hh"
+#include "logger.hh"
+#include "boost/lexical_cast.hpp"
+
+#if defined(HAVE_RANDOMBYTES_STIR)
+#include <sodium.h>
+#endif
+#if defined(HAVE_RAND_BYTES)
+#include <openssl/rand.h>
+#endif
+#if defined(HAVE_GETRANDOM)
+#include <linux/random.h>
+#endif
-using namespace std;
+static enum DNS_RNG {
+ RNG_UNINITIALIZED = 0,
+ RNG_SODIUM,
+ RNG_OPENSSL,
+ RNG_GETRANDOM,
+ RNG_ARC4RANDOM,
+ RNG_URANDOM,
+ RNG_KISS,
+} chosen_rng = RNG_UNINITIALIZED;
-static AES_KEY aes_key;
-static unsigned int g_offset;
-static unsigned char g_counter[16], g_stream[16];
-static uint32_t g_in;
+static int urandom_fd = -1;
-static bool g_initialized;
+#if defined(HAVE_KISS_RNG)
+/* KISS is intended for development use only */
+static unsigned int kiss_seed;
+static uint32_t kiss_z, kiss_w, kiss_jsr, kiss_jcong;
-void dns_random_init(const char data[16])
+static void
+kiss_init(unsigned int seed)
{
- g_offset = 0;
- memset(&g_stream, 0, sizeof(g_stream));
- if (AES_set_encrypt_key((const unsigned char*)data, 128, &aes_key) < 0) {
- throw std::runtime_error("AES_set_encrypt_key failed");
+ kiss_seed = seed;
+ kiss_jsr = 0x5eed5eed; /* simply musn't be 0 */
+ kiss_z = 1 ^ (kiss_w = kiss_jcong = seed); /* w=z=0 is bad, see Rose */
+}
+
+static unsigned int
+kiss_rand(void)
+{
+ kiss_z = 36969 * (kiss_z&65535) + (kiss_z>>16);
+ kiss_w = 18000 * (kiss_w&65535) + (kiss_w>>16);
+ kiss_jcong = 69069 * kiss_jcong + 1234567;
+ kiss_jsr^=(kiss_jsr<<13); /* <<17, >>13 gives cycle length 2^28.2 max */
+ kiss_jsr^=(kiss_jsr>>17); /* <<13, >>17 gives maximal cycle length */
+ kiss_jsr^=(kiss_jsr<<5);
+ return (((kiss_z<<16) + kiss_w) ^ kiss_jcong) + kiss_jsr;
+}
+#endif
+
+static void dns_random_setup(void)
+{
+ string rdev;
+ string rng;
+ /* check if selection has been done */
+ if (chosen_rng > RNG_UNINITIALIZED)
+ return;
+
+/* XXX: A horrible hack to allow using dns_random in places where arguments are not available.
+ Forces /dev/urandom usage
+*/
+#if defined(USE_URANDOM_ONLY)
+ chosen_rng = RNG_URANDOM;
+ rdev = "/dev/urandom";
+#else
+ rng = ::arg()["rng"];
+ rdev = ::arg()["entropy-source"];
+ if (rng == "auto") {
+# if defined(HAVE_GETRANDOM)
+ chosen_rng = RNG_GETRANDOM;
+# elif defined(HAVE_ARC4RANDOM)
+ chosen_rng = RNG_ARC4RANDOM;
+# elif defined(HAVE_RANDOMBYTES_STIR)
+ chosen_rng = RNG_SODIUM;
+# elif defined(HAVE_RAND_BYTES)
+ chosen_rng = RNG_OPENSSL;
+# else
+ chosen_rng = RNG_URANDOM;
+# endif
+# if defined(HAVE_RANDOMBYTES_STIR)
+ } else if (rng == "sodium") {
+ chosen_rng = RNG_SODIUM;
+# endif
+# if defined(HAVE_RAND_BYTES)
+ } else if (rng == "openssl") {
+ chosen_rng = RNG_OPENSSL;
+# endif
+# if defined(HAVE_GETRANDOM)
+ } else if (rng == "getrandom") {
+ chosen_rng = RNG_GETRANDOM;
+# endif
+# if defined(HAVE_ARC4RANDOM)
+ } else if (rng == "arc4random") {
+ chosen_rng = RNG_ARC4RANDOM;
+# endif
+ } else if (rng == "urandom") {
+ chosen_rng = RNG_URANDOM;
+#if defined(HAVE_KISS_RNG)
+ } else if (rng == "kiss") {
+ chosen_rng = RNG_KISS;
+ L<<Logger::Warning<<"kiss rng should not be used in production environment"<<std::endl;
+#endif
+ } else {
+ throw PDNSException("Unsupported rng '" + rng + "'");
}
- struct timeval now;
- gettimeofday(&now, 0);
+# if defined(HAVE_RANDOMBYTES_STIR)
+ if (chosen_rng == RNG_SODIUM) {
+ if (sodium_init() == -1)
+ throw PDNSException("Unable to initialize sodium crypto library");
+ /* make sure it's set up */
+ randombytes_stir();
+ }
+# endif
- static_assert(sizeof(g_counter) >= (sizeof(now.tv_usec) + sizeof(now.tv_sec)), "g_counter must be large enough to get tv_sec + tv_usec");
- memcpy(g_counter, &now.tv_usec, sizeof(now.tv_usec));
- memcpy(g_counter+sizeof(now.tv_usec), &now.tv_sec, sizeof(now.tv_sec));
- g_in = getpid() | (getppid()<<16);
+# if defined(HAVE_GETRANDOM)
+ if (chosen_rng == RNG_GETRANDOM) {
+ char buf[1];
+ // some systems define getrandom but it does not really work, e.g. because it's
+ // not present in kernel.
+ if (getrandom(buf, sizeof(buf), 0) == -1) {
+ L<<Logger::Warning<<"getrandom() failed: "<<strerror(errno)<<", falling back to " + rdev<<std::endl;
+ chosen_rng = RNG_URANDOM;
+ }
+ }
+# endif
- g_initialized = true;
- srandom(dns_random(numeric_limits<uint32_t>::max()));
+# if defined(HAVE_RAND_BYTES)
+ if (chosen_rng == RNG_OPENSSL) {
+ int ret;
+ unsigned char buf[1];
+ if ((ret = RAND_bytes(buf, sizeof(buf))) == -1)
+ throw PDNSException("RAND_bytes not supported by current SSL engine");
+ if (ret == 0)
+ throw PDNSException("Openssl RNG was not seeded");
+ }
+# endif
+#endif /* USE_URANDOM_ONLY */
+ if (chosen_rng == RNG_URANDOM) {
+ urandom_fd = open(rdev.c_str(), O_RDONLY);
+ if (urandom_fd == -1)
+ throw PDNSException("Cannot open " + rdev + ": " + std::string(strerror(errno)));
+ }
+#if defined(HAVE_KISS_RNG)
+ if (chosen_rng == RNG_KISS) {
+ unsigned int seed;
+ urandom_fd = open(rdev.c_str(), O_RDONLY);
+ if (urandom_fd == -1)
+ throw PDNSException("Cannot open " + rdev + ": " + std::string(strerror(errno)));
+ if (read(urandom_fd, &seed, sizeof(seed)) < 0) {
+ (void)close(urandom_fd);
+ throw PDNSException("Cannot read random device");
+ }
+ kiss_init(seed);
+ (void)close(urandom_fd);
+ }
+#endif
}
-unsigned int dns_random(unsigned int n)
-{
- if(!g_initialized)
- abort();
- uint32_t out;
-#if OPENSSL_VERSION_NUMBER > 0x1010000fL && !defined LIBRESSL_VERSION_NUMBER
- CRYPTO_ctr128_encrypt((const unsigned char*)&g_in, (unsigned char*) &out, sizeof(g_in), &aes_key, g_counter, g_stream, &g_offset, (block128_f) AES_encrypt);
-#else
- AES_ctr128_encrypt((const unsigned char*)&g_in, (unsigned char*) &out, sizeof(g_in), &aes_key, g_counter, g_stream, &g_offset);
+void dns_random_init(const string& data __attribute__((unused))) {
+ dns_random_setup();
+ (void)dns_random(1);
+ // init should occur already in dns_random_setup
+ // this interface is only for KISS
+#if defined(HAVE_KISS_RNG)
+ unsigned int seed;
+ if (chosen_rng != RNG_KISS)
+ return;
+ if (data.size() != 16)
+ throw PDNSException("invalid seed");
+ seed = (data[0] + (data[1]<<8) + (data[2]<<16) + (data[3]<<24)) ^
+ (data[4] + (data[5]<<8) + (data[6]<<16) + (data[7]<<24)) ^
+ (data[8] + (data[9]<<8) + (data[10]<<16) + (data[11]<<24)) ^
+ (data[12] + (data[13]<<8) + (data[14]<<16) + (data[15]<<24));
+ kiss_init(seed);
#endif
- return out % n;
}
-#if 0
-int main()
-{
- dns_random_init("0123456789abcdef");
+/* Parts of this code come from arc4random_uniform */
+unsigned int dns_random(unsigned int upper_bound) {
+ if (chosen_rng == RNG_UNINITIALIZED)
+ dns_random_setup();
- for(int n = 0; n < 16; n++)
- cerr<<dns_random(16384)<<endl;
-}
+ unsigned int min;
+ if (upper_bound < 2)
+ return 0;
+ /* To avoid "modulo bias" for some methods, calculate
+ minimum acceptable value for random number to improve
+ uniformity.
+
+ On applicable rngs, we loop until the rng spews out
+ value larger than min, and then take modulo out of that.
+ */
+#if (ULONG_MAX > 0xffffffffUL)
+ min = 0x100000000UL % upper_bound;
+#else
+ /* Calculate (2**32 % upper_bound) avoiding 64-bit math */
+ if (upper_bound > 0x80000000)
+ min = 1 + ~upper_bound; /* 2**32 - upper_bound */
+ else {
+ /* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
+ min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
+ }
#endif
+
+ switch(chosen_rng) {
+ case RNG_UNINITIALIZED:
+ throw PDNSException("Unreachable at " __FILE__ ":" + boost::lexical_cast<std::string>(__LINE__)); // cannot be reached
+ case RNG_SODIUM:
+#if defined(HAVE_RANDOMBYTES_STIR) && !defined(USE_URANDOM_ONLY)
+ return static_cast<unsigned int>(randombytes_uniform(static_cast<uint32_t>(upper_bound)));
+#else
+ throw PDNSException("Unreachable at " __FILE__ ":" + boost::lexical_cast<std::string>(__LINE__)); // cannot be reached
+#endif /* RND_SODIUM */
+ case RNG_OPENSSL: {
+#if defined(HAVE_RAND_BYTES) && !defined(USE_URANDOM_ONLY)
+ unsigned int num=0;
+ while(num < min) {
+ if (RAND_bytes(reinterpret_cast<unsigned char*>(&num), sizeof(num)) < 1)
+ throw PDNSException("Openssl RNG was not seeded");
+ }
+ return num % upper_bound;
+#else
+ throw PDNSException("Unreachable at " __FILE__ ":" + boost::lexical_cast<std::string>(__LINE__)); // cannot be reached
+#endif /* RNG_OPENSSL */
+ }
+ case RNG_GETRANDOM: {
+#if defined(HAVE_GETRANDOM) && !defined(USE_URANDOM_ONLY)
+ unsigned int num=0;
+ while(num < min) {
+ if (getrandom(&num, sizeof(num), 0) != 0)
+ throw PDNSException("getrandom() failed: " + std::string(strerror(errno)));
+ }
+ return num % upper_bound;
+#else
+ throw PDNSException("Unreachable at " __FILE__ ":" + boost::lexical_cast<std::string>(__LINE__)); // cannot be reached
+#endif
+ }
+ case RNG_ARC4RANDOM:
+#if defined(HAVE_ARC4RANDOM) && !defined(USE_URANDOM_ONLY)
+ return static_cast<unsigned int>(arc4random_uniform(static_cast<uint32_t>(upper_bound)));
+#else
+ throw PDNSException("Unreachable at " __FILE__ ":" + boost::lexical_cast<std::string>(__LINE__)); // cannot be reached
+#endif
+ case RNG_URANDOM: {
+ unsigned int num = 0;
+ while(num < min) {
+ if (read(urandom_fd, &num, sizeof(num)) < 0) {
+ (void)close(urandom_fd);
+ throw PDNSException("Cannot read random device");
+ }
+ }
+ return num % upper_bound;
+ }
+#if defined(HAVE_KISS_RNG)
+ case RNG_KISS: {
+ unsigned int num = 0;
+ while(num < min)
+ num = kiss_rand();
+ return num % upper_bound;
+ }
+#endif
+ default:
+ throw PDNSException("Unreachable at " __FILE__ ":" + boost::lexical_cast<std::string>(__LINE__)); // cannot be reached
+ };
+}
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