/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
#include "curl_setup.h"
#include <limits.h>
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#include <curl/curl.h>
#include "urldata.h"
#include "vtls/vtls.h"
#include "sendf.h"
#include "timeval.h"
#include "rand.h"
#include "escape.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
#ifdef _WIN32
#if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600 && \
!defined(CURL_WINDOWS_APP)
# define HAVE_WIN_BCRYPTGENRANDOM
# include <bcrypt.h>
# ifdef _MSC_VER
# pragma comment(lib, "bcrypt.lib")
# endif
# ifndef BCRYPT_USE_SYSTEM_PREFERRED_RNG
# define BCRYPT_USE_SYSTEM_PREFERRED_RNG 0x00000002
# endif
# ifndef STATUS_SUCCESS
# define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
# endif
#elif defined(USE_WIN32_CRYPTO)
# include <wincrypt.h>
# ifdef _MSC_VER
# pragma comment(lib, "advapi32.lib")
# endif
#endif
CURLcode Curl_win32_random(unsigned char *entropy, size_t length)
{
memset(entropy, 0, length);
#if defined(HAVE_WIN_BCRYPTGENRANDOM)
if(BCryptGenRandom(NULL, entropy, (ULONG)length,
BCRYPT_USE_SYSTEM_PREFERRED_RNG) != STATUS_SUCCESS)
return CURLE_FAILED_INIT;
return CURLE_OK;
#elif defined(USE_WIN32_CRYPTO)
{
HCRYPTPROV hCryptProv = 0;
if(!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
return CURLE_FAILED_INIT;
if(!CryptGenRandom(hCryptProv, (DWORD)length, entropy)) {
CryptReleaseContext(hCryptProv, 0UL);
return CURLE_FAILED_INIT;
}
CryptReleaseContext(hCryptProv, 0UL);
}
return CURLE_OK;
#else
return CURLE_NOT_BUILT_IN;
#endif
}
#endif
#if !defined(USE_SSL) || defined(USE_RUSTLS)
/* ---- possibly non-cryptographic version following ---- */
CURLcode Curl_weak_random(struct Curl_easy *data,
unsigned char *entropy,
size_t length) /* always 4, size of int */
{
unsigned int r;
DEBUGASSERT(length == sizeof(int));
/* Trying cryptographically secure functions first */
#ifdef _WIN32
(void)data;
{
CURLcode result = Curl_win32_random(entropy, length);
if(result != CURLE_NOT_BUILT_IN)
return result;
}
#endif
#if defined(HAVE_ARC4RANDOM)
(void)data;
r = (unsigned int)arc4random();
memcpy(entropy, &r, length);
#else
infof(data, "WARNING: using weak random seed");
{
static unsigned int randseed;
static bool seeded = FALSE;
unsigned int rnd;
if(!seeded) {
struct curltime now = Curl_now();
randseed += (unsigned int)now.tv_usec + (unsigned int)now.tv_sec;
randseed = randseed * 1103515245 + 12345;
randseed = randseed * 1103515245 + 12345;
randseed = randseed * 1103515245 + 12345;
seeded = TRUE;
}
/* Return an unsigned 32-bit pseudo-random number. */
r = randseed = randseed * 1103515245 + 12345;
rnd = (r << 16) | ((r >> 16) & 0xFFFF);
memcpy(entropy, &rnd, length);
}
#endif
return CURLE_OK;
}
#endif
#ifdef USE_SSL
#define _random(x,y,z) Curl_ssl_random(x,y,z)
#else
#define _random(x,y,z) Curl_weak_random(x,y,z)
#endif
static CURLcode randit(struct Curl_easy *data, unsigned int *rnd,
bool env_override)
{
#ifdef DEBUGBUILD
if(env_override) {
char *force_entropy = getenv("CURL_ENTROPY");
if(force_entropy) {
static unsigned int randseed;
static bool seeded = FALSE;
if(!seeded) {
unsigned int seed = 0;
size_t elen = strlen(force_entropy);
size_t clen = sizeof(seed);
size_t min = elen < clen ? elen : clen;
memcpy((char *)&seed, force_entropy, min);
randseed = ntohl(seed);
seeded = TRUE;
}
else
randseed++;
*rnd = randseed;
return CURLE_OK;
}
}
#else
(void)env_override;
#endif
/* data may be NULL! */
return _random(data, (unsigned char *)rnd, sizeof(*rnd));
}
/*
* Curl_rand() stores 'num' number of random unsigned characters in the buffer
* 'rnd' points to.
*
* If libcurl is built without TLS support or with a TLS backend that lacks a
* proper random API (Rustls or mbedTLS), this function will use "weak"
* random.
*
* When built *with* TLS support and a backend that offers strong random, it
* will return error if it cannot provide strong random values.
*
* NOTE: 'data' may be passed in as NULL when coming from external API without
* easy handle!
*
*/
CURLcode Curl_rand_bytes(struct Curl_easy *data,
#ifdef DEBUGBUILD
bool env_override,
#endif
unsigned char *rnd, size_t num)
{
CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
#ifndef DEBUGBUILD
const bool env_override = FALSE;
#endif
DEBUGASSERT(num);
while(num) {
unsigned int r;
size_t left = num < sizeof(unsigned int) ? num : sizeof(unsigned int);
result = randit(data, &r, env_override);
if(result)
return result;
while(left) {
*rnd++ = (unsigned char)(r & 0xFF);
r >>= 8;
--num;
--left;
}
}
return result;
}
/*
* Curl_rand_hex() fills the 'rnd' buffer with a given 'num' size with random
* hexadecimal digits PLUS a null-terminating byte. It must be an odd number
* size.
*/
CURLcode Curl_rand_hex(struct Curl_easy *data, unsigned char *rnd,
size_t num)
{
CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
unsigned char buffer[128];
DEBUGASSERT(num > 1);
#ifdef __clang_analyzer__
/* This silences a scan-build warning about accessing this buffer with
uninitialized memory. */
memset(buffer, 0, sizeof(buffer));
#endif
if((num/2 >= sizeof(buffer)) || !(num&1)) {
/* make sure it fits in the local buffer and that it is an odd number! */
DEBUGF(infof(data, "invalid buffer size with Curl_rand_hex"));
return CURLE_BAD_FUNCTION_ARGUMENT;
}
num--; /* save one for null-termination */
result = Curl_rand(data, buffer, num/2);
if(result)
return result;
Curl_hexencode(buffer, num/2, rnd, num + 1);
return result;
}
/*
* Curl_rand_alnum() fills the 'rnd' buffer with a given 'num' size with random
* alphanumerical chars PLUS a null-terminating byte.
*/
static const char alnum[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
CURLcode Curl_rand_alnum(struct Curl_easy *data, unsigned char *rnd,
size_t num)
{
CURLcode result = CURLE_OK;
const unsigned int alnumspace = sizeof(alnum) - 1;
unsigned int r;
DEBUGASSERT(num > 1);
num--; /* save one for null-termination */
while(num) {
do {
result = randit(data, &r, TRUE);
if(result)
return result;
} while(r >= (UINT_MAX - UINT_MAX % alnumspace));
*rnd++ = (unsigned char)alnum[r % alnumspace];
num--;
}
*rnd = 0;
return result;
}