Allow dumping SSL session keys on TRACE_SESSION_KEY

This dumps SSL session keys to a log file specified by the
SSLKEYLOGFILE environment variable.

This permits decrypting SSL trafic in wireshark with a tcpdump
capture for example.
cf.
https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format
https://security.stackexchange.com/questions/35639/decrypting-tls-in-wireshark-when-using-dhe-rsa-ciphersuites/42350#42350
https://wiki.wireshark.org/SSL#Using_the_.28Pre.29-Master-Secret
https://jimshaver.net/2015/02/11/decrypting-tls-browser-traffic-with-wireshark-the-easy-way/

Looks like we miss the required function from SSL...
SSL_SESSION_print_keylog is only in 1.1.0.
Also added dumping of client_random as it's required by wireshark.

src/kits/network/libnetapi/SecureSocket.cpp

@@ -11,6 +11,7 @@
 
 #ifdef OPENSSL_ENABLED
 #	include <openssl/ssl.h>
+#	include <openssl/ssl3.h> // for TRACE_SESSION_KEY only
 #	include <openssl/err.h>
 #endif
 
@@ -32,9 +33,94 @@
 #	define TRACE(x...) ;
 #endif
 
+//#define TRACE_SESSION_KEY
+
 
 #ifdef OPENSSL_ENABLED
 
+#ifdef TRACE_SESSION_KEY
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+/*
+ * print session id and master key in NSS keylog format (RSA
+ * Session-ID:<session id> Master-Key:<master key>)
+ */
+int SSL_SESSION_print_keylog(BIO *bp, const SSL_SESSION *x)
+{
+    size_t i;
+
+    if (x == NULL)
+        goto err;
+    if (x->session_id_length == 0 || x->master_key_length == 0)
+        goto err;
+
+    /*
+     * the RSA prefix is required by the format's definition although there's
+     * nothing RSA-specific in the output, therefore, we don't have to check if
+     * the cipher suite is based on RSA
+     */
+    if (BIO_puts(bp, "RSA ") <= 0)
+        goto err;
+
+    if (BIO_puts(bp, "Session-ID:") <= 0)
+        goto err;
+    for (i = 0; i < x->session_id_length; i++) {
+        if (BIO_printf(bp, "%02X", x->session_id[i]) <= 0)
+            goto err;
+    }
+    if (BIO_puts(bp, " Master-Key:") <= 0)
+        goto err;
+    for (i = 0; i < (size_t)x->master_key_length; i++) {
+        if (BIO_printf(bp, "%02X", x->master_key[i]) <= 0)
+            goto err;
+    }
+    if (BIO_puts(bp, "\n") <= 0)
+        goto err;
+
+    return (1);
+ err:
+    return (0);
+}
+#endif /* OPENSSL_VERSION_NUMBER < 0x10100000L */
+/*
+ * print client random id and master key in NSS keylog format
+ * as session ID is not enough.
+ */
+int SSL_SESSION_print_client_random(BIO *bp, const SSL *ssl)
+{
+	const SSL_SESSION *x = SSL_get_session(ssl);
+    size_t i;
+
+    if (x == NULL)
+        goto err;
+    if (x->session_id_length == 0 || x->master_key_length == 0)
+        goto err;
+
+    /*
+     * the RSA prefix is required by the format's definition although there's
+     * nothing RSA-specific in the output, therefore, we don't have to check if
+     * the cipher suite is based on RSA
+     */
+    if (BIO_puts(bp, "CLIENT_RANDOM ") <= 0)
+        goto err;
+
+    for (i = 0; i < sizeof(ssl->s3->client_random); i++) {
+        if (BIO_printf(bp, "%02X", ssl->s3->client_random[i]) <= 0)
+            goto err;
+    }
+    if (BIO_puts(bp, " ") <= 0)
+        goto err;
+    for (i = 0; i < (size_t)x->master_key_length; i++) {
+        if (BIO_printf(bp, "%02X", x->master_key[i]) <= 0)
+            goto err;
+    }
+    if (BIO_puts(bp, "\n") <= 0)
+        goto err;
+
+    return (1);
+ err:
+    return (0);
+}
+#endif /* TRACE_SESSION_KEY */
 
 class BSecureSocket::Private {
 public:
@@ -59,6 +145,11 @@ private:
 	static	SSL_CTX*			sContext;
 		// FIXME When do we SSL_CTX_free it?
 	static	pthread_once_t		sInitOnce;
+#ifdef TRACE_SESSION_KEY
+public:
+	static	BIO*				sKeyLogBIO;
+#endif
+
 };
 
 
@@ -66,6 +157,9 @@ private:
 /* static */ int BSecureSocket::Private::sDataIndex;
 /* static */ pthread_once_t BSecureSocket::Private::sInitOnce
 	= PTHREAD_ONCE_INIT;
+#ifdef TRACE_SESSION_KEY
+/* static */ BIO* BSecureSocket::Private::sKeyLogBIO = NULL;
+#endif
 
 
 BSecureSocket::Private::Private()
@@ -286,6 +380,17 @@ BSecureSocket::Private::_CreateContext()
 	// Get an unique index number for storing application data in SSL
 	// structs. We will store a pointer to the BSecureSocket class there.
 	sDataIndex = SSL_get_ex_new_index(0, NULL, NULL, NULL, NULL);
+
+#ifdef TRACE_SESSION_KEY
+	FILE *keylog = NULL;
+	const char *logpath = getenv("SSLKEYLOGFILE");
+	if (logpath)
+		keylog = fopen(logpath, "w+");
+	if (keylog) {
+		fprintf(keylog, "# Key Log File generated by Haiku Network Kit\n");
+		sKeyLogBIO = BIO_new_fp(keylog, BIO_NOCLOSE);
+	}
+#endif
 }
 
 
@@ -477,6 +582,7 @@ BSecureSocket::_SetupCommon(const char* host)
 			SSL_set_tlsext_host_name(fPrivate->fSSL, host);
 	}
 
+
 	return B_OK;
 }
 
@@ -495,6 +601,14 @@ BSecureSocket::_SetupConnect(const char* host)
 		return fPrivate->ErrorCode(returnValue);
 	}
 
+#ifdef TRACE_SESSION_KEY
+	fprintf(stderr, "SSL SESSION INFO:\n");
+	//SSL_SESSION_print_fp(stderr, SSL_get_session(fPrivate->fSSL));
+	SSL_SESSION_print_keylog(fPrivate->sKeyLogBIO, SSL_get_session(fPrivate->fSSL));
+	SSL_SESSION_print_client_random(fPrivate->sKeyLogBIO, fPrivate->fSSL);
+	fprintf(stderr, "\n");
+#endif
+
 	return B_OK;
 }