From 6948f5a30dbabf0659b369c1d1006d2e4e5040fe Mon Sep 17 00:00:00 2001
From: Kioubit <kioubit@localhost.invalid>
Date: Sat, 25 Dec 2021 09:28:59 -0500
Subject: [PATCH] Support modules

---
 README.md                  |  5 ++++-
 config.go                  | 26 +++++++++++++++++++++++---
 main.go                    | 14 ++++++++++++++
 modules/example/example.go | 25 +++++++++++++++++++++++++
 modules/modules.go         | 21 +++++++++++++++++++++
 pndp/process.go            |  4 ++--
 6 files changed, 89 insertions(+), 6 deletions(-)
 create mode 100644 modules/example/example.go
 create mode 100644 modules/modules.go

diff --git a/README.md b/README.md
index 6c3d6a1..a8f460e 100644
--- a/README.md
+++ b/README.md
@@ -32,7 +32,8 @@ pndpd proxy <interface1> <interface2> <optional whitelist of CIDRs separated by
 ````
 More options and additional documentation in the example config file (pndpd.conf).
 
-### Developing
+## Developing
+### Adding Modules 
 It is easy to add functionality to PNDPD. For additions outside the core functionality you only need to keep the following methods in mind:
 ```` 
 package main
@@ -48,4 +49,6 @@ proxyInstance := pndp.NewProxy(iface1 string, iface2 string, filter []*net.IPNet
 proxyInstance.Start()
 proxyInstance.Stop()
 ````
+New functionality should be implemented as a module. You will find an example module under ``modules/example/``. 
+
 Pull requests are welcome for any functionality you add.
diff --git a/config.go b/config.go
index 7fec5dd..b988e71 100644
--- a/config.go
+++ b/config.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"pndpd/modules"
 	"pndpd/pndp"
 	"strings"
 )
@@ -40,7 +41,7 @@ func readConfig(dest string) {
 
 	for scanner.Scan() {
 		line := scanner.Text()
-		if strings.HasPrefix(line, "//") {
+		if strings.HasPrefix(line, "//") || strings.TrimSpace(line) == "" {
 			continue
 		}
 		if strings.HasPrefix(line, "debug") {
@@ -50,6 +51,7 @@ func readConfig(dest string) {
 			}
 			continue
 		}
+
 		if strings.HasPrefix(line, "responder") && strings.Contains(line, "{") {
 			obj := configResponder{}
 			filter := ""
@@ -75,8 +77,7 @@ func readConfig(dest string) {
 			}
 
 			allResponders = append(allResponders, &obj)
-		}
-		if strings.HasPrefix(line, "proxy") && strings.Contains(line, "{") {
+		} else if strings.HasPrefix(line, "proxy") && strings.Contains(line, "{") {
 			obj := configProxy{}
 			filter := ""
 			for {
@@ -106,6 +107,25 @@ func readConfig(dest string) {
 				}
 			}
 			allProxies = append(allProxies, &obj)
+		} else if strings.Contains(line, "{") {
+			option := strings.TrimSuffix(strings.TrimSpace(line), "{")
+			option = strings.TrimSpace(option)
+			if modules.ModuleList != nil {
+				for i := range modules.ModuleList {
+					if (*modules.ModuleList[i]).Option == option {
+						var lines []string
+						for {
+							scanner.Scan()
+							line = strings.TrimSpace(scanner.Text())
+							lines = append(lines, line)
+							if strings.HasPrefix(line, "}") {
+								break
+							}
+						}
+						(*modules.ModuleList[i]).ConfigCallback(lines)
+					}
+				}
+			}
 		}
 	}
 
diff --git a/main.go b/main.go
index 248b72e..b8d0b21 100644
--- a/main.go
+++ b/main.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"os/signal"
+	"pndpd/modules"
 	"pndpd/pndp"
 	"syscall"
 )
@@ -18,6 +19,13 @@ func WaitForSignal() {
 
 func main() {
 	fmt.Println("PNDPD Version 1.0 - Kioubit 2021")
+	if modules.ModuleList != nil {
+		fmt.Print("Loaded Modules: ")
+		for i := range modules.ModuleList {
+			fmt.Print((*modules.ModuleList[i]).Name + " ")
+		}
+		fmt.Println()
+	}
 
 	if len(os.Args) <= 2 {
 		printUsage()
@@ -47,6 +55,12 @@ func main() {
 	case "config":
 		readConfig(os.Args[2])
 	default:
+		for i := range modules.ModuleList {
+			if (*modules.ModuleList[i]).Option == os.Args[1] {
+				(*modules.ModuleList[i]).CommandLineCallback(os.Args)
+				return
+			}
+		}
 		printUsage()
 		return
 	}
diff --git a/modules/example/example.go b/modules/example/example.go
new file mode 100644
index 0000000..83b8221
--- /dev/null
+++ b/modules/example/example.go
@@ -0,0 +1,25 @@
+package example
+
+import (
+	"fmt"
+	"pndpd/modules"
+)
+
+// This is an example module that is not imported by the main program
+func init() {
+	modules.RegisterModule("Example", "example", "example <parameter 1> <parameter 2>", commandLineRead, configRead)
+}
+
+func configRead(s []string) {
+	// Prints out the contents of the config file that are relevant for this module (that are inside the example{} option)
+	for _, n := range s {
+		fmt.Println(n)
+	}
+}
+
+func commandLineRead(s []string) {
+	// Prints out the command line options given to the program if the command starts with "example"
+	for _, n := range s {
+		fmt.Println(n)
+	}
+}
diff --git a/modules/modules.go b/modules/modules.go
new file mode 100644
index 0000000..0993a9d
--- /dev/null
+++ b/modules/modules.go
@@ -0,0 +1,21 @@
+package modules
+
+var ModuleList []*Module
+
+type Module struct {
+	Name                string
+	Option              string
+	OptionDescription   string
+	CommandLineCallback func([]string)
+	ConfigCallback      func([]string)
+}
+
+func RegisterModule(name string, option string, description string, commandLineCallback func([]string), configCallback func([]string)) {
+	ModuleList = append(ModuleList, &Module{
+		Name:                name,
+		Option:              option,
+		OptionDescription:   description,
+		CommandLineCallback: commandLineCallback,
+		ConfigCallback:      configCallback,
+	})
+}
diff --git a/pndp/process.go b/pndp/process.go
index 9b24d1b..47a2dad 100644
--- a/pndp/process.go
+++ b/pndp/process.go
@@ -57,7 +57,7 @@ func (obj *ResponderObj) start() {
 	}()
 	go respond(obj.iface, requests, ndp_ADV, nil, obj.filter, obj.autosense, obj.stopWG, obj.stopChan)
 	go listen(obj.iface, requests, ndp_SOL, obj.stopWG, obj.stopChan)
-	fmt.Println("Started responder instance on interface ", obj.iface)
+	fmt.Println("Started responder instance on interface", obj.iface)
 	<-obj.stopChan
 }
 
@@ -128,7 +128,7 @@ func (obj *ProxyObj) start() {
 	go listen(obj.iface2, req_iface2_adv_iface1, ndp_ADV, obj.stopWG, obj.stopChan)
 	go respond(obj.iface1, req_iface2_adv_iface1, ndp_ADV, out_iface2_sol_questions_iface1_adv, nil, "", obj.stopWG, obj.stopChan)
 
-	fmt.Println("Started Proxy instance for interfaces: ", obj.iface1, " and ", obj.iface2)
+	fmt.Println("Started Proxy instance for interfaces:", obj.iface1, "and", obj.iface2)
 	<-obj.stopChan
 }