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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2022, 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.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
#include "curl_setup.h"
#include "keylog.h"
/* The last #include files should be: */
#include "curl_memory.h"
#include "memdebug.h"
#define KEYLOG_LABEL_MAXLEN (sizeof("CLIENT_HANDSHAKE_TRAFFIC_SECRET") - 1)
#define CLIENT_RANDOM_SIZE 32
/*
* The master secret in TLS 1.2 and before is always 48 bytes. In TLS 1.3, the
* secret size depends on the cipher suite's hash function which is 32 bytes
* for SHA-256 and 48 bytes for SHA-384.
*/
#define SECRET_MAXLEN 48
/* The fp for the open SSLKEYLOGFILE, or NULL if not open */
static FILE *keylog_file_fp;
void
Curl_tls_keylog_open(void)
{
char *keylog_file_name;
if(!keylog_file_fp) {
keylog_file_name = curl_getenv("SSLKEYLOGFILE");
if(keylog_file_name) {
keylog_file_fp = fopen(keylog_file_name, FOPEN_APPENDTEXT);
if(keylog_file_fp) {
#ifdef WIN32
if(setvbuf(keylog_file_fp, NULL, _IONBF, 0))
#else
if(setvbuf(keylog_file_fp, NULL, _IOLBF, 4096))
#endif
{
fclose(keylog_file_fp);
keylog_file_fp = NULL;
}
}
Curl_safefree(keylog_file_name);
}
}
}
void
Curl_tls_keylog_close(void)
{
if(keylog_file_fp) {
fclose(keylog_file_fp);
keylog_file_fp = NULL;
}
}
bool
Curl_tls_keylog_enabled(void)
{
return keylog_file_fp != NULL;
}
bool
Curl_tls_keylog_write_line(const char *line)
{
/* The current maximum valid keylog line length LF and NUL is 195. */
size_t linelen;
char buf[256];
if(!keylog_file_fp || !line) {
return false;
}
linelen = strlen(line);
if(linelen == 0 || linelen > sizeof(buf) - 2) {
/* Empty line or too big to fit in a LF and NUL. */
return false;
}
memcpy(buf, line, linelen);
if(line[linelen - 1] != '\n') {
buf[linelen++] = '\n';
}
buf[linelen] = '\0';
/* Using fputs here instead of fprintf since libcurl's fprintf replacement
may not be thread-safe. */
fputs(buf, keylog_file_fp);
return true;
}
bool
Curl_tls_keylog_write(const char *label,
const unsigned char client_random[CLIENT_RANDOM_SIZE],
const unsigned char *secret, size_t secretlen)
{
const char *hex = "0123456789ABCDEF";
size_t pos, i;
char line[KEYLOG_LABEL_MAXLEN + 1 + 2 * CLIENT_RANDOM_SIZE + 1 +
2 * SECRET_MAXLEN + 1 + 1];
if(!keylog_file_fp) {
return false;
}
pos = strlen(label);
if(pos > KEYLOG_LABEL_MAXLEN || !secretlen || secretlen > SECRET_MAXLEN) {
/* Should never happen - sanity check anyway. */
return false;
}
memcpy(line, label, pos);
line[pos++] = ' ';
/* Client Random */
for(i = 0; i < CLIENT_RANDOM_SIZE; i++) {
line[pos++] = hex[client_random[i] >> 4];
line[pos++] = hex[client_random[i] & 0xF];
}
line[pos++] = ' ';
/* Secret */
for(i = 0; i < secretlen; i++) {
line[pos++] = hex[secret[i] >> 4];
line[pos++] = hex[secret[i] & 0xF];
}
line[pos++] = '\n';
line[pos] = '\0';
/* Using fputs here instead of fprintf since libcurl's fprintf replacement
may not be thread-safe. */
fputs(line, keylog_file_fp);
return true;
}
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