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feat: enable TLS key logging via SSLKEYLOGFILE env #3173

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Merged
chenBright merged 2 commits into from
Jan 5, 2026
+47 −0
Merged

feat: enable TLS key logging via SSLKEYLOGFILE env #3173

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1e6bba1
feat: enable TLS key logging via SSLKEYLOGFILE env
Dec 16, 2025
6ea77c7
fix
Dec 24, 2025
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42 changes: 42 additions & 0 deletions src/brpc/details/ssl_helper.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,9 @@
#ifndef USE_MESALINK

#include <sys/socket.h> // recv
#include <pthread.h> // pthread_once
#include <stdio.h> // fopen
#include <stdlib.h> // getenv
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/x509.h>
Expand Down Expand Up @@ -185,6 +188,43 @@ static void SSLMessageCallback(int write_p, int version, int content_type,
#endif // TLS1_RT_HEARTBEAT
}

#if defined(OPENSSL_IS_BORINGSSL) || (OPENSSL_VERSION_NUMBER >= 0x10101000L)
static pthread_once_t g_ssl_keylog_once = PTHREAD_ONCE_INIT;
static FILE* g_ssl_keylog_file = NULL;

static void InitSSLKeyLogFile() {
const char* path = getenv("SSLKEYLOGFILE");
if (path == NULL || path[0] == '\0') {
return;
}
g_ssl_keylog_file = fopen(path, "a");
if (g_ssl_keylog_file == NULL) {
PLOG(WARNING) << "Fail to open SSLKEYLOGFILE=" << path;
}
}

static void SSLKeyLogCallback(const SSL* ssl, const char* line) {
(void)ssl;
if (line == NULL) {
return;
}
// Write the full key log line with newline in one call to keep output atomic.
fprintf(g_ssl_keylog_file, "%s\n", line);
fflush(g_ssl_keylog_file);
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Copilot AI Dec 16, 2025

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The fprintf and fflush operations on g_ssl_keylog_file are not thread-safe. The SSLKeyLogCallback can be invoked concurrently from multiple SSL connections, and without synchronization, concurrent writes could interleave or corrupt the output. Consider adding a mutex to protect the file write operations or use flockfile/funlockfile for atomic writes.

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}

static void MaybeSetKeyLogCallback(SSL_CTX* ctx) {
pthread_once(&g_ssl_keylog_once, InitSSLKeyLogFile);
if (ctx != NULL && g_ssl_keylog_file != NULL) {
SSL_CTX_set_keylog_callback(ctx, SSLKeyLogCallback);
}
}
Comment on lines 196 to 226
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Copilot AI Dec 16, 2025

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The InitSSLKeyLogFile, SSLKeyLogCallback, and MaybeSetKeyLogCallback functions lack documentation explaining their purpose, the SSLKEYLOGFILE format expectations, and any security implications of enabling this feature. Adding comments would help other developers understand when and how this debugging feature should be used, especially since it exposes sensitive cryptographic material.

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#else
static void MaybeSetKeyLogCallback(SSL_CTX* ctx) {
(void)ctx;
}
#endif

#ifndef OPENSSL_NO_DH
static DH* SSLGetDHCallback(SSL* ssl, int exp, int keylen) {
(void)exp;
Expand Down Expand Up @@ -494,6 +534,7 @@ SSL_CTX* CreateClientSSLContext(const ChannelSSLOptions& options) {
LOG(ERROR) << "Fail to new SSL_CTX: " << SSLError(ERR_get_error());
return NULL;
}
MaybeSetKeyLogCallback(ssl_ctx.get());

if (!options.client_cert.certificate.empty()
&& LoadCertificate(ssl_ctx.get(),
Expand Down Expand Up @@ -532,6 +573,7 @@ SSL_CTX* CreateServerSSLContext(const std::string& certificate,
LOG(ERROR) << "Fail to new SSL_CTX: " << SSLError(ERR_get_error());
return NULL;
}
MaybeSetKeyLogCallback(ssl_ctx.get());

if (LoadCertificate(ssl_ctx.get(), certificate,
private_key, hostnames) != 0) {
Expand Down
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