Add Command type

Adds the `Command` type which allows projects to generate a properly formatted
gvproxy command in the form of a string slice without hard-coding it. Adds the
functionality to convert `Command` to a format in which os/exec can directly
execute it.

Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me>

pkg/types/command.go

@@ -0,0 +1,187 @@
+package types
+
+import (
+	"fmt"
+	"os/exec"
+)
+
+type Command struct {
+	// Print packets on stderr
+	Debug bool
+
+	// Length of packet
+	// Larger packets means less packets to exchange for the same amount of data (and less protocol overhead)
+	MTU int
+
+	// Values passed in by forward-xxx flags in commandline (forward-xxx:info)
+	forwardInfo map[string][]string
+
+	// List of endpoints the user wants to listen to
+	Endpoints []string
+
+	// Map of different sockets provided by user (socket-type flag:socket)
+	sockets map[string]string
+
+	// File where gvproxy's pid is stored
+	Pidfile string
+
+	// SSHPort to access the guest VM
+	SSHPort int
+}
+
+func NewCommand() Command {
+	return Command{
+		MTU:         1500,
+		SSHPort:     2222,
+		forwardInfo: map[string][]string{},
+		sockets:     map[string]string{},
+	}
+}
+
+func (c *Command) checkSocketsInitialized() {
+	if len(c.sockets) < 1 {
+		c.sockets = map[string]string{}
+	}
+}
+
+func (c *Command) checkForwardInfoInitialized() {
+	if len(c.forwardInfo) < 1 {
+		c.forwardInfo = map[string][]string{}
+	}
+}
+
+func (c *Command) AddVpnkitSocket(socket string) {
+	c.checkSocketsInitialized()
+	c.sockets["listen-vpnkit"] = socket
+}
+
+func (c *Command) AddQemuSocket(socket string) {
+	c.checkSocketsInitialized()
+	c.sockets["listen-qemu"] = socket
+}
+
+func (c *Command) AddBessSocket(socket string) {
+	c.checkSocketsInitialized()
+	c.sockets["listen-bess"] = socket
+}
+
+func (c *Command) AddStdioSocket(socket string) {
+	c.checkSocketsInitialized()
+	c.sockets["listen-stdio"] = socket
+}
+
+func (c *Command) AddVfkitSocket(socket string) {
+	c.checkSocketsInitialized()
+	c.sockets["listen-vfkit"] = socket
+}
+
+func (c *Command) addForwardInfo(flag, value string) {
+	if _, ok := c.forwardInfo[flag]; ok {
+		c.forwardInfo[flag] = append(c.forwardInfo[flag], value)
+	} else {
+		c.forwardInfo[flag] = []string{value}
+	}
+}
+
+func (c *Command) AddForwardSock(socket string) {
+	c.checkForwardInfoInitialized()
+	c.addForwardInfo("forward-sock", socket)
+}
+
+func (c *Command) AddForwardDest(dest string) {
+	c.checkForwardInfoInitialized()
+	c.addForwardInfo("forward-dest", dest)
+}
+
+func (c *Command) AddForwardUser(user string) {
+	c.checkForwardInfoInitialized()
+	c.addForwardInfo("forward-user", user)
+}
+
+func (c *Command) AddForwardIdentity(identity string) {
+	c.checkForwardInfoInitialized()
+	c.addForwardInfo("forward-identity", identity)
+}
+
+// socketsToCmdline converts Command.Sockets to a commandline format
+func (c *Command) socketsToCmdline() ([]string, error) {
+	args := []string{}
+
+	for socketFlag, socket := range c.sockets {
+		if socket != "" {
+			args = append(args, fmt.Sprintf("-%s %s", socketFlag, socket))
+		}
+	}
+
+	return args, nil
+}
+
+// forwardInfoToCmdline converts Command.ForwardInfo to a command line format
+func (c *Command) forwardInfoToCmdline() ([]string, error) {
+	args := []string{}
+
+	for forwardInfoFlag, forwardInfo := range c.forwardInfo {
+		for _, i := range forwardInfo {
+			if i != "" {
+				args = append(args, fmt.Sprintf("-%s %s", forwardInfoFlag, i))
+			}
+		}
+	}
+
+	return args, nil
+}
+
+// ToCmdline converts Command to a properly formatted command for gvproxy based
+// on its fields
+func (c *Command) ToCmdline() ([]string, error) {
+	args := []string{}
+
+	// listen (endpoints)
+	for _, endpoint := range c.Endpoints {
+		args = append(args, "-listen "+endpoint)
+	}
+
+	// debug
+	if c.Debug {
+		args = append(args, "-debug")
+	}
+
+	// mtu
+	args = append(args, fmt.Sprintf("-mtu %d", c.MTU))
+
+	// ssh-port
+	args = append(args, fmt.Sprintf("-ssh-port %d", c.SSHPort))
+
+	// sockets
+	socketArgs, err := c.socketsToCmdline()
+	if err != nil {
+		return nil, err
+	}
+	args = append(args, socketArgs...)
+
+	// forward info
+	forwardInfoArgs, err := c.forwardInfoToCmdline()
+	if err != nil {
+		return nil, err
+	}
+	args = append(args, forwardInfoArgs...)
+
+	// pid-file
+	if c.Pidfile != "" {
+		args = append(args, "-pid-file "+c.Pidfile)
+	}
+
+	return args, nil
+}
+
+// Cmd converts Command to a commandline format and returns an exec.Cmd which
+// can be executed by os/exec
+func (c *Command) Cmd(gvproxyPath string) (*exec.Cmd, error) {
+	args, err := c.ToCmdline()
+	if err != nil {
+		return nil, err
+	}
+
+	cmd := exec.Command(gvproxyPath, args...)
+	return cmd, nil
+}

test/basic_test.go

@@ -196,3 +196,26 @@ var _ = Describe("dns", func() {
 		Expect(string(out)).To(ContainSubstring("Address: 192.168.127.1"))
 	})
 })
+
+var _ = Describe("command-line format", func() {
+	It("should convert Command to command line format", func() {
+		command := types.NewCommand()
+		command.Endpoints = []string{"unix:///tmp/network.sock"}
+		command.Debug = true
+		command.AddQemuSocket("tcp://0.0.0.0:1234")
+		command.Pidfile = "~/gv-pidfile.txt"
+        command.AddForwardUser("demouser")
+
+		cmd, err := command.ToCmdline()
+		Expect(err).ShouldNot(HaveOccurred())
+		Expect(cmd).To(Equal([]string{
+			"-listen unix:///tmp/network.sock",
+			"-debug",
+			"-mtu 1500",
+			"-ssh-port 2222",
+			"-listen-qemu tcp://0.0.0.0:1234",
+			"-forward-user demouser",
+			"-pid-file ~/gv-pidfile.txt",
+		}))
+	})
+})