add scaffolding for configuration file

hypd/cmd/defaultconfig.go

@@ -0,0 +1,33 @@
+/*
+Copyright © 2024 Steven Polley <himself@stevenpolley.net>
+*/
+package cmd
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"deadbeef.codes/steven/hyp/hypd/configuration"
+	"github.com/spf13/cobra"
+)
+
+// defaultconfigCmd represents the defaultconfig command
+var defaultconfigCmd = &cobra.Command{
+	Use:   "defaultconfig",
+	Short: "Prints the default configuration to stdout",
+	Long: `The default configuration is used if one is not set.  The default configuration
+	can be used as a reference to build your own.  `,
+	Run: func(cmd *cobra.Command, args []string) {
+		config := configuration.DefaultConfig()
+		b, err := json.MarshalIndent(config, "", "    ")
+		if err != nil {
+			panic(fmt.Errorf("failed to marshal default configuration to json (this should never happen): %v", err))
+		}
+		fmt.Println(string(b))
+	},
+}
+
+func init() {
+	generateCmd.AddCommand(defaultconfigCmd)
+
+}

hypd/cmd/server.go

@@ -6,6 +6,7 @@ package cmd
 import (
 	"fmt"
 
+	"deadbeef.codes/steven/hyp/hypd/configuration"
 	"deadbeef.codes/steven/hyp/hypd/server"
 	"github.com/spf13/cobra"
 )
@@ -30,7 +31,16 @@ Example Usage:
 
 	`,
 	Run: func(cmd *cobra.Command, args []string) {
-		err := server.PacketServer(args[0])
+		configFile, err := cmd.Flags().GetString("configfile")
+		if err != nil {
+			panic(fmt.Errorf("failed to get configfile flag: %w", err))
+		}
+		hypdConfiguration, err := configuration.LoadConfiguration(configFile)
+		if err != nil {
+			panic(fmt.Errorf("failed to start packet server: %w", err))
+		}
+
+		err = server.PacketServer(args[0], hypdConfiguration)
 		if err != nil {
 			panic(fmt.Errorf("failed to start packet server: %w", err))
 		}
@@ -40,22 +50,6 @@ Example Usage:
 
 func init() {
 	rootCmd.AddCommand(serverCmd)
-	/*
-		viper.SetConfigName("hypconfig")
-		viper.SetConfigType("yaml")
-		viper.AddConfigPath("/etc/hyp/")
-		viper.AddConfigPath("$HOME/.hyp")
-		viper.AddConfigPath(".")
-		viper.SetDefault("RefreshInterval", 7200)
-
-		if err := viper.ReadInConfig(); err != nil {
-			if _, ok := err.(viper.ConfigFileNotFoundError); ok {
-				// Config file not found
-				// TBD: Implement
-			} else {
-				// Config file was found, but another error was produced
-				panic(fmt.Errorf("failed reading existing config file: %w", err))
-			}
-		}*/
+	serverCmd.PersistentFlags().String("configfile", "", "Path to the file containing the hypd configuration.")
 
 }

hypd/configuration/configuration.go

@@ -0,0 +1,64 @@
+package configuration
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+)
+
+type HypdConfiguration struct {
+	PreSharedKeyDirectory string `json:"preSharedKeyDirectory"` // hypd will load all *.secret files from this directory
+	SuccessAction         string `json:"successAction"`         // The action to take
+	TimeoutSeconds        int    `json:"timeoutSeconds"`        // If > 0, once a knock sequence has been successful this value will count down and when it reaches 0, it will perform the TimeoutAction on the client.
+	TimeoutAction         string `json:"timeoutAction"`         // The action to take after TimeoutSeconds has elapsed.  only applicable if TimeoutSeconds is > 0
+
+}
+
+// LoadConfiguration opens and parses the configuration file into a HypdConfiguration struct
+// If a configFilePath is not specified, it will search in common locations
+func LoadConfiguration(configFilePath string) (*HypdConfiguration, error) {
+	if configFilePath == "" {
+		commonLocations := []string{"hypdconfig.json",
+			"~/.config/hyp/hypdConfig.json",
+			"/etc/hyp/hypdConfig.json",
+			"/usr/local/etc/hyp/hypdConfig.json",
+		}
+
+		for _, loc := range commonLocations {
+			if _, err := os.Stat(loc); err == nil {
+				configFilePath = loc
+				break
+			}
+		}
+	}
+	// if it's still not found after checking common locations, load default config
+	if configFilePath == "" {
+		return DefaultConfig(), nil
+	}
+
+	// Otherwise if a config is specified, try to load it and error if it fails.
+	// I think it's better to error here if a config was intended and failed
+	// rather than failing back to default
+
+	b, err := os.ReadFile(configFilePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read config file '%s': %w", configFilePath, err)
+	}
+
+	var hypdConfiguration *HypdConfiguration
+	err = json.Unmarshal(b, hypdConfiguration)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal config file json to HypdConfiguration (is the config file malformed?): %w", err)
+	}
+
+	return nil, nil
+}
+
+func DefaultConfig() *HypdConfiguration {
+	return &HypdConfiguration{
+		PreSharedKeyDirectory: "./secrets/",
+		SuccessAction:         "iptables -A INPUT -p tcp -s %s --dport 22 -j ACCEPT",
+		TimeoutSeconds:        1440,
+		TimeoutAction:         "iptables -D INPUT -p tcp -s %s --dport 22 -j ACCEPT",
+	}
+}

hypd/server/packet.go

@@ -15,6 +15,7 @@ import (
 	"os/exec"
 	"time"
 
+	"deadbeef.codes/steven/hyp/hypd/configuration"
 	"deadbeef.codes/steven/hyp/otphyp"
 	"github.com/cilium/ebpf/link"
 	"github.com/cilium/ebpf/ringbuf"
@@ -48,7 +49,7 @@ var (
 // PacketServer is the main function when operating in server mode
 // it sets up the pcap on the capture device and starts a goroutine
 // to rotate the knock sequence
-func PacketServer(captureDevice string) error {
+func PacketServer(captureDevice string, config *configuration.HypdConfiguration) error {
 
 	iface, err := net.InterfaceByName(captureDevice)
 	if err != nil {