Annotation of embedaddon/curl/lib/rand.c, revision 1.1.1.1
1.1 misho 1: /***************************************************************************
2: * _ _ ____ _
3: * Project ___| | | | _ \| |
4: * / __| | | | |_) | |
5: * | (__| |_| | _ <| |___
6: * \___|\___/|_| \_\_____|
7: *
8: * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
9: *
10: * This software is licensed as described in the file COPYING, which
11: * you should have received as part of this distribution. The terms
12: * are also available at https://curl.haxx.se/docs/copyright.html.
13: *
14: * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15: * copies of the Software, and permit persons to whom the Software is
16: * furnished to do so, under the terms of the COPYING file.
17: *
18: * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19: * KIND, either express or implied.
20: *
21: ***************************************************************************/
22:
23: #include "curl_setup.h"
24:
25: #ifdef HAVE_FCNTL_H
26: #include <fcntl.h>
27: #endif
28:
29: #include <curl/curl.h>
30: #include "vtls/vtls.h"
31: #include "sendf.h"
32: #include "rand.h"
33:
34: /* The last 3 #include files should be in this order */
35: #include "curl_printf.h"
36: #include "curl_memory.h"
37: #include "memdebug.h"
38:
39: static CURLcode randit(struct Curl_easy *data, unsigned int *rnd)
40: {
41: unsigned int r;
42: CURLcode result = CURLE_OK;
43: static unsigned int randseed;
44: static bool seeded = FALSE;
45:
46: #ifdef CURLDEBUG
47: char *force_entropy = getenv("CURL_ENTROPY");
48: if(force_entropy) {
49: if(!seeded) {
50: unsigned int seed = 0;
51: size_t elen = strlen(force_entropy);
52: size_t clen = sizeof(seed);
53: size_t min = elen < clen ? elen : clen;
54: memcpy((char *)&seed, force_entropy, min);
55: randseed = ntohl(seed);
56: seeded = TRUE;
57: }
58: else
59: randseed++;
60: *rnd = randseed;
61: return CURLE_OK;
62: }
63: #endif
64:
65: /* data may be NULL! */
66: result = Curl_ssl_random(data, (unsigned char *)rnd, sizeof(*rnd));
67: if(result != CURLE_NOT_BUILT_IN)
68: /* only if there is no random function in the TLS backend do the non crypto
69: version, otherwise return result */
70: return result;
71:
72: /* ---- non-cryptographic version following ---- */
73:
74: #ifdef RANDOM_FILE
75: if(!seeded) {
76: /* if there's a random file to read a seed from, use it */
77: int fd = open(RANDOM_FILE, O_RDONLY);
78: if(fd > -1) {
79: /* read random data into the randseed variable */
80: ssize_t nread = read(fd, &randseed, sizeof(randseed));
81: if(nread == sizeof(randseed))
82: seeded = TRUE;
83: close(fd);
84: }
85: }
86: #endif
87:
88: if(!seeded) {
89: struct curltime now = Curl_now();
90: infof(data, "WARNING: Using weak random seed\n");
91: randseed += (unsigned int)now.tv_usec + (unsigned int)now.tv_sec;
92: randseed = randseed * 1103515245 + 12345;
93: randseed = randseed * 1103515245 + 12345;
94: randseed = randseed * 1103515245 + 12345;
95: seeded = TRUE;
96: }
97:
98: /* Return an unsigned 32-bit pseudo-random number. */
99: r = randseed = randseed * 1103515245 + 12345;
100: *rnd = (r << 16) | ((r >> 16) & 0xFFFF);
101: return CURLE_OK;
102: }
103:
104: /*
105: * Curl_rand() stores 'num' number of random unsigned integers in the buffer
106: * 'rndptr' points to.
107: *
108: * If libcurl is built without TLS support or with a TLS backend that lacks a
109: * proper random API (Gskit or mbedTLS), this function will use "weak" random.
110: *
111: * When built *with* TLS support and a backend that offers strong random, it
112: * will return error if it cannot provide strong random values.
113: *
114: * NOTE: 'data' may be passed in as NULL when coming from external API without
115: * easy handle!
116: *
117: */
118:
119: CURLcode Curl_rand(struct Curl_easy *data, unsigned char *rnd, size_t num)
120: {
121: CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
122:
123: DEBUGASSERT(num > 0);
124:
125: while(num) {
126: unsigned int r;
127: size_t left = num < sizeof(unsigned int) ? num : sizeof(unsigned int);
128:
129: result = randit(data, &r);
130: if(result)
131: return result;
132:
133: while(left) {
134: *rnd++ = (unsigned char)(r & 0xFF);
135: r >>= 8;
136: --num;
137: --left;
138: }
139: }
140:
141: return result;
142: }
143:
144: /*
145: * Curl_rand_hex() fills the 'rnd' buffer with a given 'num' size with random
146: * hexadecimal digits PLUS a zero terminating byte. It must be an odd number
147: * size.
148: */
149:
150: CURLcode Curl_rand_hex(struct Curl_easy *data, unsigned char *rnd,
151: size_t num)
152: {
153: CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
154: const char *hex = "0123456789abcdef";
155: unsigned char buffer[128];
156: unsigned char *bufp = buffer;
157: DEBUGASSERT(num > 1);
158:
159: #ifdef __clang_analyzer__
160: /* This silences a scan-build warning about accessing this buffer with
161: uninitialized memory. */
162: memset(buffer, 0, sizeof(buffer));
163: #endif
164:
165: if((num/2 >= sizeof(buffer)) || !(num&1))
166: /* make sure it fits in the local buffer and that it is an odd number! */
167: return CURLE_BAD_FUNCTION_ARGUMENT;
168:
169: num--; /* save one for zero termination */
170:
171: result = Curl_rand(data, buffer, num/2);
172: if(result)
173: return result;
174:
175: while(num) {
176: /* clang-tidy warns on this line without this comment: */
177: /* NOLINTNEXTLINE(clang-analyzer-core.UndefinedBinaryOperatorResult) */
178: *rnd++ = hex[(*bufp & 0xF0)>>4];
179: *rnd++ = hex[*bufp & 0x0F];
180: bufp++;
181: num -= 2;
182: }
183: *rnd = 0;
184:
185: return result;
186: }
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