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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2021, 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.
*
***************************************************************************/
#include "curl_setup.h"
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#include <curl/curl.h>
#include "vtls/vtls.h"
#include "sendf.h"
#include "rand.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
static CURLcode randit(struct Curl_easy *data, unsigned int *rnd)
{
unsigned int r;
CURLcode result = CURLE_OK;
static unsigned int randseed;
static bool seeded = FALSE;
#ifdef CURLDEBUG
char *force_entropy = getenv("CURL_ENTROPY");
if(force_entropy) {
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;
}
#endif
/* data may be NULL! */
result = Curl_ssl_random(data, (unsigned char *)rnd, sizeof(*rnd));
if(result != CURLE_NOT_BUILT_IN)
/* only if there is no random function in the TLS backend do the non crypto
version, otherwise return result */
return result;
/* ---- non-cryptographic version following ---- */
#ifdef RANDOM_FILE
if(!seeded) {
/* if there's a random file to read a seed from, use it */
int fd = open(RANDOM_FILE, O_RDONLY);
if(fd > -1) {
/* read random data into the randseed variable */
ssize_t nread = read(fd, &randseed, sizeof(randseed));
if(nread == sizeof(randseed))
seeded = TRUE;
close(fd);
}
}
#endif
if(!seeded) {
struct curltime now = Curl_now();
infof(data, "WARNING: Using weak random seed");
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);
return CURLE_OK;
}
/*
* Curl_rand() stores 'num' number of random unsigned integers in the buffer
* 'rndptr' points to.
*
* If libcurl is built without TLS support or with a TLS backend that lacks a
* proper random API (Gskit 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(struct Curl_easy *data, unsigned char *rnd, size_t num)
{
CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
DEBUGASSERT(num > 0);
while(num) {
unsigned int r;
size_t left = num < sizeof(unsigned int) ? num : sizeof(unsigned int);
result = randit(data, &r);
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 zero 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;
const char *hex = "0123456789abcdef";
unsigned char buffer[128];
unsigned char *bufp = buffer;
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! */
return CURLE_BAD_FUNCTION_ARGUMENT;
num--; /* save one for zero termination */
result = Curl_rand(data, buffer, num/2);
if(result)
return result;
while(num) {
/* clang-tidy warns on this line without this comment: */
/* NOLINTNEXTLINE(clang-analyzer-core.UndefinedBinaryOperatorResult) */
*rnd++ = hex[(*bufp & 0xF0)>>4];
*rnd++ = hex[*bufp & 0x0F];
bufp++;
num -= 2;
}
*rnd = 0;
return result;
}
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