tor: add a new response reader for tor controller

This commit adds a new response reader which replaces the old
textproto.Reader.ReadResponse. The older reader cannot handle the case
when the reply from Tor server contains a data reply line, which uses
the symbol "+" to signal such a case.

tor/controller_test.go

@@ -1,6 +1,12 @@
 package tor
 
-import "testing"
+import (
+	"net"
+	"net/textproto"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
 
 // TestParseTorVersion is a series of tests for different version strings that
 // check the correctness of determining whether they support creating v3 onion
@@ -74,3 +80,199 @@ func TestParseTorVersion(t *testing.T) {
 		}
 	}
 }
+
+// testProxy emulates a Tor daemon and contains the info used for the tor
+// controller to make connections.
+type testProxy struct {
+	// server is the proxy listener.
+	server net.Listener
+
+	// serverConn is the established connection from the server side.
+	serverConn net.Conn
+
+	// serverAddr is the tcp address the proxy is listening on.
+	serverAddr string
+
+	// clientConn is the established connection from the client side.
+	clientConn *textproto.Conn
+}
+
+// cleanUp is used after each test to properly close the ports/connections.
+func (tp *testProxy) cleanUp() {
+	// Don't bother cleanning if there's no a server created.
+	if tp.server == nil {
+		return
+	}
+
+	if err := tp.clientConn.Close(); err != nil {
+		log.Errorf("closing client conn got err: %v", err)
+	}
+	if err := tp.server.Close(); err != nil {
+		log.Errorf("closing proxy server got err: %v", err)
+	}
+}
+
+// createTestProxy creates a proxy server to listen on a random address,
+// creates a server and a client connection, and initializes a testProxy using
+// these params.
+func createTestProxy(t *testing.T) *testProxy {
+	// Set up the proxy to listen on given port.
+	//
+	// NOTE: we use a port 0 here to indicate we want a free port selected
+	// by the system.
+	proxy, err := net.Listen("tcp", ":0")
+	require.NoError(t, err, "failed to create proxy")
+
+	t.Logf("created proxy server to listen on address: %v", proxy.Addr())
+
+	// Accept the connection inside a goroutine.
+	serverChan := make(chan net.Conn, 1)
+	go func(result chan net.Conn) {
+		conn, err := proxy.Accept()
+		require.NoError(t, err, "failed to accept")
+
+		result <- conn
+	}(serverChan)
+
+	// Create the connection using tor controller.
+	client, err := textproto.Dial("tcp", proxy.Addr().String())
+	require.NoError(t, err, "failed to create connection")
+
+	tc := &testProxy{
+		server:     proxy,
+		serverConn: <-serverChan,
+		serverAddr: proxy.Addr().String(),
+		clientConn: client,
+	}
+
+	return tc
+}
+
+// TestReadResponse contructs a series of possible responses returned by Tor
+// and asserts the readResponse can handle them correctly.
+func TestReadResponse(t *testing.T) {
+	// Create mock server and client connection.
+	proxy := createTestProxy(t)
+	defer proxy.cleanUp()
+	server := proxy.serverConn
+
+	// Create a dummy tor controller.
+	c := &Controller{conn: proxy.clientConn}
+
+	testCase := []struct {
+		name       string
+		serverResp string
+
+		// expectedReply is the reply we expect the readResponse to
+		// return.
+		expectedReply string
+
+		// expectedCode is the code we expect the server to return.
+		expectedCode int
+
+		// returnedCode is the code we expect the readResponse to
+		// return.
+		returnedCode int
+
+		// expectedErr is the error we expect the readResponse to
+		// return.
+		expectedErr error
+	}{
+		{
+			// Test a simple response.
+			name:          "succeed on 250",
+			serverResp:    "250 OK\n",
+			expectedReply: "OK",
+			expectedCode:  250,
+			returnedCode:  250,
+			expectedErr:   nil,
+		},
+		{
+			// Test a mid reply(-) response.
+			name: "succeed on mid reply line",
+			serverResp: "250-field=value\n" +
+				"250 OK\n",
+			expectedReply: "field=value\nOK",
+			expectedCode:  250,
+			returnedCode:  250,
+			expectedErr:   nil,
+		},
+		{
+			// Test a data reply(+) response.
+			name: "succeed on data reply line",
+			serverResp: "250+field=\n" +
+				"line1\n" +
+				"line2\n" +
+				".\n" +
+				"250 OK\n",
+			expectedReply: "field=line1,line2\nOK",
+			expectedCode:  250,
+			returnedCode:  250,
+			expectedErr:   nil,
+		},
+		{
+			// Test a mixed reply response.
+			name: "succeed on mixed reply line",
+			serverResp: "250-field=value\n" +
+				"250+field=\n" +
+				"line1\n" +
+				"line2\n" +
+				".\n" +
+				"250 OK\n",
+			expectedReply: "field=value\nfield=line1,line2\nOK",
+			expectedCode:  250,
+			returnedCode:  250,
+			expectedErr:   nil,
+		},
+		{
+			// Test unexpected code.
+			name:          "fail on codes not matched",
+			serverResp:    "250 ERR\n",
+			expectedReply: "ERR",
+			expectedCode:  500,
+			returnedCode:  250,
+			expectedErr:   errCodeNotMatch,
+		},
+		{
+			// Test short response error.
+			name:          "fail on short response",
+			serverResp:    "123\n250 OK\n",
+			expectedReply: "",
+			expectedCode:  250,
+			returnedCode:  0,
+			expectedErr: textproto.ProtocolError(
+				"short line: 123"),
+		},
+		{
+			// Test short response error.
+			name:          "fail on invalid response",
+			serverResp:    "250?OK\n",
+			expectedReply: "",
+			expectedCode:  250,
+			returnedCode:  250,
+			expectedErr: textproto.ProtocolError(
+				"invalid line: 250?OK"),
+		},
+	}
+
+	for _, tc := range testCase {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+
+			// Let the server mocks a given response.
+			_, err := server.Write([]byte(tc.serverResp))
+			require.NoError(t, err, "server failed to write")
+
+			// Read the response and checks all expectations
+			// satisfied.
+			code, reply, err := c.readResponse(tc.expectedCode)
+			require.Equal(t, tc.expectedErr, err)
+			require.Equal(t, tc.returnedCode, code)
+			require.Equal(t, tc.expectedReply, reply)
+
+			// Check that the read buffer is cleaned.
+			require.Zero(t, c.conn.R.Buffered(),
+				"read buffer not empty")
+		})
+	}
+}