Allow checking ssl files are readable (check_ssl_files)

- adds a new check_path_exists() method to path_util
- move code checking if SSL-related files exist with assertions (thus
  causing a fatal error) to a new check_ssl_files() method, allowing for
  soft or hard fail modes

This will allow for non-fatal checks of SSL files existence on reload.

Signed-off-by: Loïc Gomez <bip@animanova.fr>

src/connection.c

@@ -34,6 +34,7 @@ extern char *conf_client_ciphers;
 extern char *conf_client_dh_file;
 static int SSLize(connection_t *cn, int *nc);
 static SSL_CTX *SSL_init_context(char *ciphers);
+SSL_CTX *get_ssl_context(void);
 /* SSH like trust management */
 int link_add_untrusted(void *ls, X509 *cert);
 #endif
@@ -1231,6 +1232,77 @@ static int ctx_set_dh(SSL_CTX *ctx)
             conf_client_dh_file);
 	return 1;
 }
+
+int set_ssl_context(int force)
+{
+	SSL_CTX *newctx = NULL;
+	if (sslctx) {
+		if (force == SSLCTX_FORCE_UPDATE) {
+			mylog(LOG_DEBUG, "SSL context already set, forcing update");
+		} else {
+			mylog(LOG_DEBUG, "SSL context is already set, not updating");
+			return 0;
+		}
+	} else {
+		mylog(LOG_DEBUG, "Initializing SSL context for accepted connections");
+	}
+
+	newctx = get_ssl_context();
+	if (!newctx) {
+		mylog(LOG_ERROR, "Failed to get new SSL context");
+		if (sslctx)
+			mylog(LOG_WARN, "Keeping old SSL context");
+		return 0;
+	}
+	sslctx = newctx;
+	return 1;
+}
+
+SSL_CTX *get_ssl_context(void)
+{
+	SSL_CTX *newctx = NULL;
+	if (!(newctx = SSL_init_context(conf_client_ciphers))) {
+		mylog(LOG_ERROR, "SSL context initialization failed");
+		return NULL;
+	}
+
+	if (!conf_client_dh_file) {
+		// try with a default path but don't fail if it doesn't exist
+		conf_client_dh_file = default_path(conf_biphome, "dh.pem",
+					 "DH parameters");
+
+		struct stat st_buf;
+		if (stat(conf_client_dh_file, &st_buf) != 0) {
+			free(conf_client_dh_file);
+			conf_client_dh_file = NULL;
+		}
+	}
+
+	if (conf_client_dh_file) {
+		if (!ctx_set_dh(newctx)) {
+			SSL_CTX_free(newctx);
+			mylog(LOG_ERROR, "SSL Unable to load DH parameters");
+			return NULL;
+		}
+	}
+
+	mylog(LOG_DEBUG, "Loading SSL cert from %s", conf_ssl_certfile);
+	if (!SSL_CTX_use_certificate_chain_file(newctx, conf_ssl_certfile)) {
+		mylog(LOG_WARN, "SSL: Unable to load certificate file");
+		SSL_CTX_free(newctx);
+		return NULL;
+	}
+
+	mylog(LOG_DEBUG, "Loading SSL key from %s", conf_ssl_certfile);
+	if (!SSL_CTX_use_PrivateKey_file(newctx, conf_ssl_certfile,
+					 SSL_FILETYPE_PEM)) {
+		mylog(LOG_WARN, "SSL: Unable to load key file");
+		SSL_CTX_free(newctx);
+		return NULL;
+	}
+
+	return newctx;
+}
 #endif
 
 connection_t *accept_new(connection_t *cn)
@@ -1266,52 +1338,11 @@ connection_t *accept_new(connection_t *cn)
 	conn->client = 1;
 #ifdef HAVE_LIBSSL
 	if (cn->ssl) {
+		if (!sslctx)
+			set_ssl_context(SSLCTX_NO_REPLACE);
 		if (!sslctx) {
-			mylog(LOG_DEBUG,
-			      "No SSL context available for "
-			      "accepted connections. "
-			      "Initializing...");
-			if (!(sslctx = SSL_init_context(conf_client_ciphers))) {
-				mylog(LOG_ERROR,
-				      "SSL context initialization "
-				      "failed");
-				connection_free(conn);
-				return NULL;
-			}
-
-			if (!conf_client_dh_file) {
-				// try with a default path but don't fail if it
-				// doesn't exist
-				conf_client_dh_file =
-					default_path(conf_biphome, "dh.pem",
-						     "DH parameters");
-
-				struct stat st_buf;
-				if (stat(conf_client_dh_file, &st_buf) != 0) {
-					free(conf_client_dh_file);
-					conf_client_dh_file = NULL;
-				}
-			}
-
-			if (conf_client_dh_file) {
-				if (!ctx_set_dh(sslctx)) {
-					mylog(LOG_ERROR,
-					      "SSL Unable to load DH "
-					      "parameters");
-					connection_free(conn);
-					return NULL;
-				}
-			}
-
-			if (!SSL_CTX_use_certificate_chain_file(
-				    sslctx, conf_ssl_certfile))
-				mylog(LOG_WARN,
-				      "SSL: Unable to load "
-				      "certificate file");
-			if (!SSL_CTX_use_PrivateKey_file(sslctx,
-							 conf_ssl_certfile,
-							 SSL_FILETYPE_PEM))
-				mylog(LOG_WARN, "SSL: Unable to load key file");
+			connection_free(conn);
+			return NULL;
 		}
 
 		conn->ssl_h = SSL_new(sslctx);

src/connection.h

@@ -60,6 +60,9 @@
 #define SSL_CHECK_NONE (0)
 #define SSL_CHECK_BASIC (1)
 #define SSL_CHECK_CA (2)
+
+#define SSLCTX_NO_REPLACE 0
+#define SSLCTX_FORCE_UPDATE 1
 #endif
 
 struct connecting_data;
@@ -113,4 +116,9 @@ uint16_t connection_localport(connection_t *cn);
 uint16_t connection_remoteport(connection_t *cn);
 char *connection_localip(connection_t *cn);
 char *connection_remoteip(connection_t *cn);
+#ifdef HAVE_LIBSSL
+/* Set SSL context, force update if already set and force is 1
+ * Return 1 if SSL context has been set */
+int set_ssl_context(int force);
+#endif
 #endif