attempt to improve ssl error handling (again)

the error queue may contain multiple errors, so make sure to drain it
completely. also, don't try to fall back to errno in case of
SSL_ERROR_SSL.

src/common.h

@@ -33,6 +33,7 @@
 typedef unsigned char uchar;
 typedef unsigned short ushort;
 typedef unsigned int uint;
+typedef unsigned long ulong;
 
 #define as(ar) (sizeof(ar)/sizeof(ar[0]))
 

src/socket.c

@@ -63,6 +63,34 @@ socket_fail( conn_t *conn )
 }
 
 #ifdef HAVE_LIBSSL
+static void ATTR_PRINTFLIKE(1, 2)
+print_ssl_errors( const char *fmt, ... )
+{
+	char *action;
+	va_list va;
+	ulong err;
+
+	va_start( va, fmt );
+	nfvasprintf( &action, fmt, va );
+	va_end( va );
+	while ((err = ERR_get_error()))
+		error( "Error while %s: %s\n", action, ERR_error_string( err, 0 ) );
+	free( action );
+}
+
+static int
+print_ssl_socket_errors( const char *func, conn_t *conn )
+{
+	ulong err;
+	int num = 0;
+
+	while ((err = ERR_get_error())) {
+		error( "Socket error: secure %s %s: %s\n", func, conn->name, ERR_error_string( err, 0 ) );
+		num++;
+	}
+	return num;
+}
+
 static int
 ssl_return( const char *func, conn_t *conn, int ret )
 {
@@ -76,20 +104,20 @@ ssl_return( const char *func, conn_t *conn, int ret )
 		FALLTHROUGH
 	case SSL_ERROR_WANT_READ:
 		return 0;
-	case SSL_ERROR_SYSCALL:
 	case SSL_ERROR_SSL:
-		if (!(err = ERR_get_error())) {
-			if (ret == 0) {
+		print_ssl_socket_errors( func, conn );
+		break;
+	case SSL_ERROR_SYSCALL:
+		if (print_ssl_socket_errors( func, conn ))
+			break;
+		if (ret == 0) {
 	case SSL_ERROR_ZERO_RETURN:
-				/* Callers take the short path out, so signal higher layers from here. */
-				conn->state = SCK_EOF;
-				conn->read_callback( conn->callback_aux );
-				return -1;
-			}
-			sys_error( "Socket error: secure %s %s", func, conn->name );
-		} else {
-			error( "Socket error: secure %s %s: %s\n", func, conn->name, ERR_error_string( err, 0 ) );
+			/* Callers take the short path out, so signal higher layers from here. */
+			conn->state = SCK_EOF;
+			conn->read_callback( conn->callback_aux );
+			return -1;
 		}
+		sys_error( "Socket error: secure %s %s", func, conn->name );
 		break;
 	default:
 		error( "Socket error: secure %s %s: unhandled SSL error %d\n", func, conn->name, err );
@@ -233,25 +261,24 @@ init_ssl_ctx( const server_conf_t *conf )
 	SSL_CTX_set_options( mconf->SSLContext, options );
 
 	if (conf->cert_file && !SSL_CTX_load_verify_locations( mconf->SSLContext, conf->cert_file, 0 )) {
-		error( "Error while loading certificate file '%s': %s\n",
-		       conf->cert_file, ERR_error_string( ERR_get_error(), 0 ) );
+		print_ssl_errors( "loading certificate file '%s'", conf->cert_file );
 		return 0;
 	}
 	mconf->trusted_certs = (_STACK *)sk_X509_OBJECT_dup( X509_STORE_get0_objects( SSL_CTX_get_cert_store( mconf->SSLContext ) ) );
-	if (mconf->system_certs && !SSL_CTX_set_default_verify_paths( mconf->SSLContext ))
-		warn( "Warning: Unable to load default certificate files: %s\n",
-		      ERR_error_string( ERR_get_error(), 0 ) );
+	if (mconf->system_certs && !SSL_CTX_set_default_verify_paths( mconf->SSLContext )) {
+		ulong err;
+		while ((err = ERR_get_error()))
+			warn( "Warning: Unable to load default certificate files: %s\n", ERR_error_string( err, 0 ) );
+	}
 
 	SSL_CTX_set_verify( mconf->SSLContext, SSL_VERIFY_NONE, NULL );
 
 	if (conf->client_certfile && !SSL_CTX_use_certificate_chain_file( mconf->SSLContext, conf->client_certfile)) {
-		error( "Error while loading client certificate file '%s': %s\n",
-		       conf->client_certfile, ERR_error_string( ERR_get_error(), 0 ) );
+		print_ssl_errors( "loading client certificate file '%s'", conf->client_certfile );
 		return 0;
 	}
 	if (conf->client_keyfile && !SSL_CTX_use_PrivateKey_file( mconf->SSLContext, conf->client_keyfile, SSL_FILETYPE_PEM)) {
-		error( "Error while loading client private key '%s': %s\n",
-		       conf->client_keyfile, ERR_error_string( ERR_get_error(), 0 ) );
+		print_ssl_errors( "loading client private key '%s'", conf->client_keyfile );
 		return 0;
 	}