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 | } |
187 | |