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#include "keylog.h"
27#include <curl/curl.h>
28
29/* The last #include files should be: */
30#include "curl_memory.h"
31#include "memdebug.h"
32
33#define KEYLOG_LABEL_MAXLEN (sizeof("CLIENT_HANDSHAKE_TRAFFIC_SECRET") - 1)
34
35#define CLIENT_RANDOM_SIZE 32
36
37/*
38 * The master secret in TLS 1.2 and before is always 48 bytes. In TLS 1.3, the
39 * secret size depends on the cipher suite's hash function which is 32 bytes
40 * for SHA-256 and 48 bytes for SHA-384.
41 */
42#define SECRET_MAXLEN 48
43
44
45/* The fp for the open SSLKEYLOGFILE, or NULL if not open */
46static FILE *keylog_file_fp;
47
48void
49Curl_tls_keylog_open(void)
50{
51 char *keylog_file_name;
52
53 if(!keylog_file_fp) {
54 keylog_file_name = curl_getenv(variable: "SSLKEYLOGFILE");
55 if(keylog_file_name) {
56 keylog_file_fp = fopen(filename: keylog_file_name, FOPEN_APPENDTEXT);
57 if(keylog_file_fp) {
58#ifdef WIN32
59 if(setvbuf(keylog_file_fp, NULL, _IONBF, 0))
60#else
61 if(setvbuf(stream: keylog_file_fp, NULL, _IOLBF, n: 4096))
62#endif
63 {
64 fclose(stream: keylog_file_fp);
65 keylog_file_fp = NULL;
66 }
67 }
68 Curl_safefree(keylog_file_name);
69 }
70 }
71}
72
73void
74Curl_tls_keylog_close(void)
75{
76 if(keylog_file_fp) {
77 fclose(stream: keylog_file_fp);
78 keylog_file_fp = NULL;
79 }
80}
81
82bool
83Curl_tls_keylog_enabled(void)
84{
85 return keylog_file_fp != NULL;
86}
87
88bool
89Curl_tls_keylog_write_line(const char *line)
90{
91 /* The current maximum valid keylog line length LF and NUL is 195. */
92 size_t linelen;
93 char buf[256];
94
95 if(!keylog_file_fp || !line) {
96 return false;
97 }
98
99 linelen = strlen(s: line);
100 if(linelen == 0 || linelen > sizeof(buf) - 2) {
101 /* Empty line or too big to fit in a LF and NUL. */
102 return false;
103 }
104
105 memcpy(dest: buf, src: line, n: linelen);
106 if(line[linelen - 1] != '\n') {
107 buf[linelen++] = '\n';
108 }
109 buf[linelen] = '\0';
110
111 /* Using fputs here instead of fprintf since libcurl's fprintf replacement
112 may not be thread-safe. */
113 fputs(s: buf, stream: keylog_file_fp);
114 return true;
115}
116
117bool
118Curl_tls_keylog_write(const char *label,
119 const unsigned char client_random[CLIENT_RANDOM_SIZE],
120 const unsigned char *secret, size_t secretlen)
121{
122 const char *hex = "0123456789ABCDEF";
123 size_t pos, i;
124 char line[KEYLOG_LABEL_MAXLEN + 1 + 2 * CLIENT_RANDOM_SIZE + 1 +
125 2 * SECRET_MAXLEN + 1 + 1];
126
127 if(!keylog_file_fp) {
128 return false;
129 }
130
131 pos = strlen(s: label);
132 if(pos > KEYLOG_LABEL_MAXLEN || !secretlen || secretlen > SECRET_MAXLEN) {
133 /* Should never happen - sanity check anyway. */
134 return false;
135 }
136
137 memcpy(dest: line, src: label, n: pos);
138 line[pos++] = ' ';
139
140 /* Client Random */
141 for(i = 0; i < CLIENT_RANDOM_SIZE; i++) {
142 line[pos++] = hex[client_random[i] >> 4];
143 line[pos++] = hex[client_random[i] & 0xF];
144 }
145 line[pos++] = ' ';
146
147 /* Secret */
148 for(i = 0; i < secretlen; i++) {
149 line[pos++] = hex[secret[i] >> 4];
150 line[pos++] = hex[secret[i] & 0xF];
151 }
152 line[pos++] = '\n';
153 line[pos] = '\0';
154
155 /* Using fputs here instead of fprintf since libcurl's fprintf replacement
156 may not be thread-safe. */
157 fputs(s: line, stream: keylog_file_fp);
158 return true;
159}
160