JSDoc: Source: rpc.js

'use strict';
+
+var rpcRequestID = 1,
+    rpcSessionID = L.env.sessionid || '00000000000000000000000000000000',
+    rpcBaseURL = L.url('admin/ubus'),
+    rpcInterceptorFns = [];
+
+/**
+ * @class rpc
+ * @memberof LuCI
+ * @hideconstructor
+ * @classdesc
+ *
+ * The `LuCI.rpc` class provides high level ubus JSON-RPC abstractions
+ * and means for listing and invoking remove RPC methods.
+ */
+return L.Class.extend(/** @lends LuCI.rpc.prototype */ {
+	/* privates */
+	call: function(req, cb, nobatch) {
+		var q = '';
+
+		if (Array.isArray(req)) {
+			if (req.length == 0)
+				return Promise.resolve([]);
+
+			for (var i = 0; i < req.length; i++)
+				if (req[i].params)
+					q += '%s%s.%s'.format(
+						q ? ';' : '/',
+						req[i].params[1],
+						req[i].params[2]
+					);
+		}
+		else if (req.params) {
+			q += '/%s.%s'.format(req.params[1], req.params[2]);
+		}
+
+		return L.Request.post(rpcBaseURL + q, req, {
+			timeout: (L.env.rpctimeout || 20) * 1000,
+			nobatch: nobatch,
+			credentials: true
+		}).then(cb, cb);
+	},
+
+	parseCallReply: function(req, res) {
+		var msg = null;
+
+		if (res instanceof Error)
+			return req.reject(res);
+
+		try {
+			if (!res.ok)
+				L.raise('RPCError', 'RPC call to %s/%s failed with HTTP error %d: %s',
+					req.object, req.method, res.status, res.statusText || '?');
+
+			msg = res.json();
+		}
+		catch (e) {
+			return req.reject(e);
+		}
+
+		/*
+		 * The interceptor args are intentionally swapped.
+		 * Response is passed as first arg to align with Request class interceptors
+		 */
+		Promise.all(rpcInterceptorFns.map(function(fn) { return fn(msg, req) }))
+			.then(this.handleCallReply.bind(this, req, msg))
+			.catch(req.reject);
+	},
+
+	handleCallReply: function(req, msg) {
+		var type = Object.prototype.toString,
+		    ret = null;
+
+		try {
+			/* verify message frame */
+			if (!L.isObject(msg) || msg.jsonrpc != '2.0')
+				L.raise('RPCError', 'RPC call to %s/%s returned invalid message frame',
+					req.object, req.method);
+
+			/* check error condition */
+			if (L.isObject(msg.error) && msg.error.code && msg.error.message)
+				L.raise('RPCError', 'RPC call to %s/%s failed with error %d: %s',
+					req.object, req.method, msg.error.code, msg.error.message || '?');
+		}
+		catch (e) {
+			return req.reject(e);
+		}
+
+		if (!req.object && !req.method) {
+			ret = msg.result;
+		}
+		else if (Array.isArray(msg.result)) {
+			ret = (msg.result.length > 1) ? msg.result[1] : msg.result[0];
+		}
+
+		if (req.expect) {
+			for (var key in req.expect) {
+				if (ret != null && key != '')
+					ret = ret[key];
+
+				if (ret == null || type.call(ret) != type.call(req.expect[key]))
+					ret = req.expect[key];
+
+				break;
+			}
+		}
+
+		/* apply filter */
+		if (typeof(req.filter) == 'function') {
+			req.priv[0] = ret;
+			req.priv[1] = req.params;
+			ret = req.filter.apply(this, req.priv);
+		}
+
+		req.resolve(ret);
+	},
+
+	/**
+	 * Lists available remote ubus objects or the method signatures of
+	 * specific objects.
+	 *
+	 * This function has two signatures and is sensitive to the number of
+	 * arguments passed to it:
+	 *  - `list()` -
+	 *    Returns an array containing the names of all remote `ubus` objects
+	 *  - `list("objname", ...)`
+	 *    Returns method signatures for each given `ubus` object name.
+	 *
+	 * @param {...string} [objectNames]
+	 * If any object names are given, this function will return the method
+	 * signatures of each given object.
+	 *
+	 * @returns {Promise<Array<string>|Object<string, Object<string, Object<string, string>>>>}
+	 * When invoked without arguments, this function will return a promise
+	 * resolving to an array of `ubus` object names. When invoked with one or
+	 * more arguments, a promise resolving to an object describing the method
+	 * signatures of each requested `ubus` object name will be returned.
+	 */
+	list: function() {
+		var msg = {
+			jsonrpc: '2.0',
+			id:      rpcRequestID++,
+			method:  'list',
+			params:  arguments.length ? this.varargs(arguments) : undefined
+		};
+
+		return new Promise(L.bind(function(resolveFn, rejectFn) {
+			/* store request info */
+			var req = {
+				resolve: resolveFn,
+				reject:  rejectFn
+			};
+
+			/* call rpc */
+			this.call(msg, this.parseCallReply.bind(this, req));
+		}, this));
+	},
+
+	/**
+	 * @typedef {Object} DeclareOptions
+	 * @memberof LuCI.rpc
+	 *
+	 * @property {string} object
+	 * The name of the remote `ubus` object to invoke.
+	 *
+	 * @property {string} method
+	 * The name of the remote `ubus` method to invoke.
+	 *
+	 * @property {string[]} [params]
+	 * Lists the named parameters expected by the remote `ubus` RPC method.
+	 * The arguments passed to the resulting generated method call function
+	 * will be mapped to named parameters in the order they appear in this
+	 * array.
+	 *
+	 * Extraneous parameters passed to the generated function will not be
+	 * sent to the remote procedure but are passed to the
+	 * {@link LuCI.rpc~filterFn filter function} if one is specified.
+	 *
+	 * Examples:
+	 *  - `params: [ "foo", "bar" ]` -
+	 *    When the resulting call function is invoked with `fn(true, false)`,
+	 *    the corresponding args object sent to the remote procedure will be
+	 *    `{ foo: true, bar: false }`.
+	 *  - `params: [ "test" ], filter: function(reply, args, extra) { ... }` -
+	 *    When the resultung generated function is invoked with
+	 *    `fn("foo", "bar", "baz")` then `{ "test": "foo" }` will be sent as
+	 *    argument to the remote procedure and the filter function will be
+	 *    invoked with `filterFn(reply, [ "foo" ], "bar", "baz")`
+	 *
+	 * @property {Object<string,*>} [expect]
+	 * Describes the expected return data structure. The given object is
+	 * supposed to contain a single key selecting the value to use from
+	 * the returned `ubus` reply object. The value of the sole key within
+	 * the `expect` object is used to infer the expected type of the received
+	 * `ubus` reply data.
+	 *
+	 * If the received data does not contain `expect`'s key, or if the
+	 * type of the data differs from the type of the value in the expect
+	 * object, the expect object's value is returned as default instead.
+	 *
+	 * The key in the `expect` object may be an empty string (`''`) in which
+	 * case the entire reply object is selected instead of one of its subkeys.
+	 *
+	 * If the `expect` option is omitted, the received reply will be returned
+	 * as-is, regardless of its format or type.
+	 *
+	 * Examples:
+	 *  - `expect: { '': { error: 'Invalid response' } }` -
+	 *    This requires the entire `ubus` reply to be a plain JavaScript
+	 *    object. If the reply isn't an object but e.g. an array or a numeric
+	 *    error code instead, it will get replaced with
+	 *    `{ error: 'Invalid response' }` instead.
+	 *  - `expect: { results: [] }` -
+	 *    This requires the received `ubus` reply to be an object containing
+	 *    a key `results` with an array as value. If the received reply does
+	 *    not contain such a key, or if `reply.results` points to a non-array
+	 *    value, the empty array (`[]`) will be used instead.
+	 *  - `expect: { success: false }` -
+	 *    This requires the received `ubus` reply to be an object containing
+	 *    a key `success` with a boolean value. If the reply does not contain
+	 *    `success` or if `reply.success` is not a boolean value, `false` will
+	 *    be returned as default instead.
+	 *
+	 * @property {LuCI.rpc~filterFn} [filter]
+	 * Specfies an optional filter function which is invoked to transform the
+	 * received reply data before it is returned to the caller.
+	 *
+	 */
+
+	/**
+	 * The filter function is invoked to transform a received `ubus` RPC call
+	 * reply before returning it to the caller.
+	 *
+	 * @callback LuCI.rpc~filterFn
+	 *
+	 * @param {*} data
+	 * The received `ubus` reply data or a subset of it as described in the
+	 * `expect` option of the RPC call declaration. In case of remote call
+	 * errors, `data` is numeric `ubus` error code instead.
+	 *
+	 * @param {Array<*>} args
+	 * The arguments the RPC method has been invoked with.
+	 *
+	 * @param {...*} extraArgs
+	 * All extraneous arguments passed to the RPC method exceeding the number
+	 * of arguments describes in the RPC call declaration.
+	 *
+	 * @return {*}
+	 * The return value of the filter function will be returned to the caller
+	 * of the RPC method as-is.
+	 */
+
+	/**
+	 * The generated invocation function is returned by
+	 * {@link LuCI.rpc#declare rpc.declare()} and encapsulates a single
+	 * RPC method call.
+	 *
+	 * Calling this function will execute a remote `ubus` HTTP call request
+	 * using the arguments passed to it as arguments and return a promise
+	 * resolving to the received reply values.
+	 *
+	 * @callback LuCI.rpc~invokeFn
+	 *
+	 * @param {...*} params
+	 * The parameters to pass to the remote procedure call. The given
+	 * positional arguments will be named to named RPC parameters according
+	 * to the names specified in the `params` array of the method declaration.
+	 *
+	 * Any additional parameters exceeding the amount of arguments in the
+	 * `params` declaration are passed as private extra arguments to the
+	 * declared filter function.
+	 *
+	 * @return {Promise<*>}
+	 * Returns a promise resolving to the result data of the remote `ubus`
+	 * RPC method invocation, optionally substituted and filtered according
+	 * to the `expect` and `filter` declarations.
+	 */
+
+	/**
+	 * Describes a remote RPC call procedure and returns a function
+	 * implementing it.
+	 *
+	 * @param {LuCI.rpc.DeclareOptions} options
+	 * If any object names are given, this function will return the method
+	 * signatures of each given object.
+	 *
+	 * @returns {LuCI.rpc~invokeFn}
+	 * Returns a new function implementing the method call described in
+	 * `options`.
+	 */
+	declare: function(options) {
+		return Function.prototype.bind.call(function(rpc, options) {
+			var args = this.varargs(arguments, 2);
+			return new Promise(function(resolveFn, rejectFn) {
+				/* build parameter object */
+				var p_off = 0;
+				var params = { };
+				if (Array.isArray(options.params))
+					for (p_off = 0; p_off < options.params.length; p_off++)
+						params[options.params[p_off]] = args[p_off];
+
+				/* all remaining arguments are private args */
+				var priv = [ undefined, undefined ];
+				for (; p_off < args.length; p_off++)
+					priv.push(args[p_off]);
+
+				/* store request info */
+				var req = {
+					expect:  options.expect,
+					filter:  options.filter,
+					resolve: resolveFn,
+					reject:  rejectFn,
+					params:  params,
+					priv:    priv,
+					object:  options.object,
+					method:  options.method
+				};
+
+				/* build message object */
+				var msg = {
+					jsonrpc: '2.0',
+					id:      rpcRequestID++,
+					method:  'call',
+					params:  [
+						rpcSessionID,
+						options.object,
+						options.method,
+						params
+					]
+				};
+
+				/* call rpc */
+				rpc.call(msg, rpc.parseCallReply.bind(rpc, req), options.nobatch);
+			});
+		}, this, this, options);
+	},
+
+	/**
+	 * Returns the current RPC session id.
+	 *
+	 * @returns {string}
+	 * Returns the 32 byte session ID string used for authenticating remote
+	 * requests.
+	 */
+	getSessionID: function() {
+		return rpcSessionID;
+	},
+
+	/**
+	 * Set the RPC session id to use.
+	 *
+	 * @param {string} sid
+	 * Sets the 32 byte session ID string used for authenticating remote
+	 * requests.
+	 */
+	setSessionID: function(sid) {
+		rpcSessionID = sid;
+	},
+
+	/**
+	 * Returns the current RPC base URL.
+	 *
+	 * @returns {string}
+	 * Returns the RPC URL endpoint to issue requests against.
+	 */
+	getBaseURL: function() {
+		return rpcBaseURL;
+	},
+
+	/**
+	 * Set the RPC base URL to use.
+	 *
+	 * @param {string} sid
+	 * Sets the RPC URL endpoint to issue requests against.
+	 */
+	setBaseURL: function(url) {
+		rpcBaseURL = url;
+	},
+
+	/**
+	 * Translates a numeric `ubus` error code into a human readable
+	 * description.
+	 *
+	 * @param {number} statusCode
+	 * The numeric status code.
+	 *
+	 * @returns {string}
+	 * Returns the textual description of the code.
+	 */
+	getStatusText: function(statusCode) {
+		switch (statusCode) {
+		case 0: return _('Command OK');
+		case 1: return _('Invalid command');
+		case 2: return _('Invalid argument');
+		case 3: return _('Method not found');
+		case 4: return _('Resource not found');
+		case 5: return _('No data received');
+		case 6: return _('Permission denied');
+		case 7: return _('Request timeout');
+		case 8: return _('Not supported');
+		case 9: return _('Unspecified error');
+		case 10: return _('Connection lost');
+		default: return _('Unknown error code');
+		}
+	},
+
+	/**
+	 * Registered interceptor functions are invoked before the standard reply
+	 * parsing and handling logic.
+	 *
+	 * By returning rejected promises, interceptor functions can cause the
+	 * invocation function to fail, regardless of the received reply.
+	 *
+	 * Interceptors may also modify their message argument in-place to
+	 * rewrite received replies before they're processed by the standard
+	 * response handling code.
+	 *
+	 * A common use case for such functions is to detect failing RPC replies
+	 * due to expired authentication in order to trigger a new login.
+	 *
+	 * @callback LuCI.rpc~interceptorFn
+	 *
+	 * @param {*} msg
+	 * The unprocessed, JSON decoded remote RPC method call reply.
+	 *
+	 * Since interceptors run before the standard parsing logic, the reply
+	 * data is not verified for correctness or filtered according to
+	 * `expect` and `filter` specifications in the declarations.
+	 *
+	 * @param {Object} req
+	 * The related request object which is an extended variant of the
+	 * declaration object, allowing access to internals of the invocation
+	 * function such as `filter`, `expect` or `params` values.
+	 *
+	 * @return {Promise<*>|*}
+	 * Interceptor functions may return a promise to defer response
+	 * processing until some delayed work completed. Any values the returned
+	 * promise resolves to are ignored.
+	 *
+	 * When the returned promise rejects with an error, the invocation
+	 * function will fail too, forwarding the error to the caller.
+	 */
+
+	/**
+	 * Registers a new interceptor function.
+	 *
+	 * @param {LuCI.rpc~interceptorFn} interceptorFn
+	 * The inteceptor function to register.
+	 *
+	 * @returns {LuCI.rpc~interceptorFn}
+	 * Returns the given function value.
+	 */
+	addInterceptor: function(interceptorFn) {
+		if (typeof(interceptorFn) == 'function')
+			rpcInterceptorFns.push(interceptorFn);
+		return interceptorFn;
+	},
+
+	/**
+	 * Removes a registered interceptor function.
+	 *
+	 * @param {LuCI.rpc~interceptorFn} interceptorFn
+	 * The inteceptor function to remove.
+	 *
+	 * @returns {boolean}
+	 * Returns `true` if the given function has been removed or `false`
+	 * if it has not been found.
+	 */
+	removeInterceptor: function(interceptorFn) {
+		var oldlen = rpcInterceptorFns.length, i = oldlen;
+		while (i--)
+			if (rpcInterceptorFns[i] === interceptorFn)
+				rpcInterceptorFns.splice(i, 1);
+		return (rpcInterceptorFns.length < oldlen);
+	}
+});
+