add user configurable commands that can be run on events

cmds.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+)
+
+type Command struct {
+	Path          string   `json:"command_path"`
+	Args          []string `json:"command_args"`
+	AllowExitCode int      `json:"exit_code"`
+	Event         string   `json:"event"`
+	MsgFormat     string   `json:"msg_format"`
+}
+
+func (c *Command) Run(fp string) bool {
+	cmd := &exec.Cmd{}
+	if len(c.Args) == 0 {
+		cmd = exec.Command(c.Path, fmt.Sprintf(c.MsgFormat, fp))
+	} else {
+		cmd = exec.Command(c.Path, c.Args...)
+	}
+
+	err := cmd.Start()
+	if err != nil {
+		log.Println(err)
+		return false
+	}
+
+	err = cmd.Wait()
+	if err != nil {
+		exit, ok := err.(*exec.ExitError)
+		if !ok {
+			return false
+		}
+		if exit.ExitCode() == c.AllowExitCode {
+			return true
+		}
+	}
+
+	return true
+}
+
+type Commands []Command
+
+func (cs Commands) Get(event string) *Command {
+	for _, c := range cs {
+		if c.Event == event {
+			return &c
+		}
+	}
+	return nil
+}
+
+func LoadCommands(p string) Commands {
+	cmds := Commands{}
+	data, err := os.ReadFile(p)
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = json.Unmarshal(data, &cmds)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	return cmds
+}

main.go

@@ -1,15 +1,11 @@
 package main
 
 import (
-	"bufio"
 	"flag"
-	"fmt"
 	"log"
 	"net"
 	"net/http"
 	"net/http/pprof"
-	"os"
-	"strings"
 	"time"
 
 	"golang.org/x/crypto/ssh"
@@ -19,6 +15,7 @@ import (
 func main() {
 	dbg := flag.Bool("debug", false, "Enable pprof debugging")
 	sock := flag.String("s", "/tmp/traygent", "Socket path to create")
+	cmdList := flag.String("c", "/etc/traygent.json", "List of commands to execute")
 	flag.Parse()
 
 	if *dbg {
@@ -60,25 +57,36 @@ func main() {
 		}
 	}()
 
+	cmds := LoadCommands(*cmdList)
+
 	for {
 		select {
 		case added := <-tagent.addChan:
-			fmt.Printf("NOTICE: added %q\n", ssh.FingerprintSHA256(added))
+			fp := ssh.FingerprintSHA256(added)
+			log.Printf("NOTICE: added %q\n", fp)
+			c := cmds.Get("added")
+			if c != nil {
+				c.Run(fp)
+			}
 		case rm := <-tagent.rmChan:
-			fmt.Printf("NOTICE: removed %q\n", rm)
+			log.Printf("NOTICE: removed %q\n", rm)
+			c := cmds.Get("removed")
+			if c != nil {
+				c.Run(rm)
+			}
 		case pub := <-tagent.sigReq:
-			r := bufio.NewReader(os.Stdin)
-
-			fmt.Printf("NOTICE: Allow access to %q?: ", ssh.FingerprintSHA256(pub))
-			resp, _ := r.ReadString('\n')
-			resp = strings.Trim(resp, "\n")
-
-			if resp == "yes" {
+			fp := ssh.FingerprintSHA256(pub)
+			log.Printf("NOTICE: access request for: %q?\n", fp)
+			c := cmds.Get("sign")
+			if c != nil {
+				if c.Run(fp) {
 					go func() { tagent.sigResp <- true }()
 				} else {
 					go func() { tagent.sigResp <- false }()
 				}
-			fmt.Printf("%q\n", resp)
+			} else {
+				panic("nope")
+			}
 		}
 	}
 }