1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 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.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 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24 #include "curl_setup.h"
25
26 #if defined(USE_OPENSSL) || \
27 defined(USE_GNUTLS) || \
28 defined(USE_WOLFSSL) || \
29 (defined(USE_NGTCP2) && defined(USE_NGHTTP3)) || \
30 defined(USE_QUICHE)
31
32 #include "keylog.h"
33 #include <curl/curl.h>
34
35 /* The last #include files should be: */
36 #include "curl_memory.h"
37 #include "memdebug.h"
38
39 #define KEYLOG_LABEL_MAXLEN (sizeof("CLIENT_HANDSHAKE_TRAFFIC_SECRET") - 1)
40
41 #define CLIENT_RANDOM_SIZE 32
42
43 /*
44 * The master secret in TLS 1.2 and before is always 48 bytes. In TLS 1.3, the
45 * secret size depends on the cipher suite's hash function which is 32 bytes
46 * for SHA-256 and 48 bytes for SHA-384.
47 */
48 #define SECRET_MAXLEN 48
49
50
51 /* The fp for the open SSLKEYLOGFILE, or NULL if not open */
52 static FILE *keylog_file_fp;
53
54 void
Curl_tls_keylog_open(void)55 Curl_tls_keylog_open(void)
56 {
57 char *keylog_file_name;
58
59 if(!keylog_file_fp) {
60 keylog_file_name = curl_getenv("SSLKEYLOGFILE");
61 if(keylog_file_name) {
62 keylog_file_fp = fopen(keylog_file_name, FOPEN_APPENDTEXT);
63 if(keylog_file_fp) {
64 #ifdef _WIN32
65 if(setvbuf(keylog_file_fp, NULL, _IONBF, 0))
66 #else
67 if(setvbuf(keylog_file_fp, NULL, _IOLBF, 4096))
68 #endif
69 {
70 fclose(keylog_file_fp);
71 keylog_file_fp = NULL;
72 }
73 }
74 Curl_safefree(keylog_file_name);
75 }
76 }
77 }
78
79 void
Curl_tls_keylog_close(void)80 Curl_tls_keylog_close(void)
81 {
82 if(keylog_file_fp) {
83 fclose(keylog_file_fp);
84 keylog_file_fp = NULL;
85 }
86 }
87
88 bool
Curl_tls_keylog_enabled(void)89 Curl_tls_keylog_enabled(void)
90 {
91 return keylog_file_fp != NULL;
92 }
93
94 bool
Curl_tls_keylog_write_line(const char * line)95 Curl_tls_keylog_write_line(const char *line)
96 {
97 /* The current maximum valid keylog line length LF and NUL is 195. */
98 size_t linelen;
99 char buf[256];
100
101 if(!keylog_file_fp || !line) {
102 return false;
103 }
104
105 linelen = strlen(line);
106 if(linelen == 0 || linelen > sizeof(buf) - 2) {
107 /* Empty line or too big to fit in a LF and NUL. */
108 return false;
109 }
110
111 memcpy(buf, line, linelen);
112 if(line[linelen - 1] != '\n') {
113 buf[linelen++] = '\n';
114 }
115 buf[linelen] = '\0';
116
117 /* Using fputs here instead of fprintf since libcurl's fprintf replacement
118 may not be thread-safe. */
119 fputs(buf, keylog_file_fp);
120 return true;
121 }
122
123 bool
Curl_tls_keylog_write(const char * label,const unsigned char client_random[CLIENT_RANDOM_SIZE],const unsigned char * secret,size_t secretlen)124 Curl_tls_keylog_write(const char *label,
125 const unsigned char client_random[CLIENT_RANDOM_SIZE],
126 const unsigned char *secret, size_t secretlen)
127 {
128 const char *hex = "0123456789ABCDEF";
129 size_t pos, i;
130 char line[KEYLOG_LABEL_MAXLEN + 1 + 2 * CLIENT_RANDOM_SIZE + 1 +
131 2 * SECRET_MAXLEN + 1 + 1];
132
133 if(!keylog_file_fp) {
134 return false;
135 }
136
137 pos = strlen(label);
138 if(pos > KEYLOG_LABEL_MAXLEN || !secretlen || secretlen > SECRET_MAXLEN) {
139 /* Should never happen - sanity check anyway. */
140 return false;
141 }
142
143 memcpy(line, label, pos);
144 line[pos++] = ' ';
145
146 /* Client Random */
147 for(i = 0; i < CLIENT_RANDOM_SIZE; i++) {
148 line[pos++] = hex[client_random[i] >> 4];
149 line[pos++] = hex[client_random[i] & 0xF];
150 }
151 line[pos++] = ' ';
152
153 /* Secret */
154 for(i = 0; i < secretlen; i++) {
155 line[pos++] = hex[secret[i] >> 4];
156 line[pos++] = hex[secret[i] & 0xF];
157 }
158 line[pos++] = '\n';
159 line[pos] = '\0';
160
161 /* Using fputs here instead of fprintf since libcurl's fprintf replacement
162 may not be thread-safe. */
163 fputs(line, keylog_file_fp);
164 return true;
165 }
166
167 #endif /* TLS or QUIC backend */
168
