.gitignore

@@ -25,3 +25,4 @@
 go.work
 
 # End of https://www.toptal.com/developers/gitignore/api/go
+build/

cmd/agent/main.go

@@ -1,11 +1,15 @@
 package main
 
 import (
+	"bufio"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log"
+	"net"
 	"net/http"
 	"os"
+	"os/exec"
 
 	"git.mziesel.nl/mans/lg/internal/socket"
 )
@@ -63,7 +67,7 @@ func isAuthenticated(r *http.Request) bool {
 func ensureAuthenticatedMiddleware(next http.HandlerFunc) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if !isAuthenticated(r) {
-			http.Error(w, `{"error": "Unauthorized access"}`, http.StatusUnauthorized)
+			http.Error(w, "Unauthorized access", http.StatusUnauthorized)
 			return
 		}
 		next.ServeHTTP(w, r)
@@ -77,14 +81,7 @@ func plainTextMiddleware(next http.HandlerFunc) http.HandlerFunc {
 	}
 }
 
-func jsonMiddleware(next http.HandlerFunc) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/json")
-		next(w, r)
-	}
-}
-
-func apiMiddlewareChain(h http.HandlerFunc) http.HandlerFunc {
+func middlewareChain(h http.HandlerFunc) http.HandlerFunc {
 	return plainTextMiddleware(ensureAuthenticatedMiddleware(h))
 }
 
@@ -134,6 +131,87 @@ func birdCommandHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func createCommand(tool string, target string) (*exec.Cmd, error) {
+	commands := map[string][]string{
+		"ping":        {"ping", "-4", "-c", "4", "--", target},
+		"ping6":       {"ping", "-6", "-c", "4", "--", target},
+		"mtr":         {"mtr", "--show-ips", "--aslookup", "--report-wide", "-c", "10", "-4", target},
+		"mtr6":        {"mtr", "--show-ips", "--aslookup", "--report-wide", "-c", "10", "-6", target},
+		"traceroute":  {"traceroute", "-n", "-4", "--", target},
+		"traceroute6": {"traceroute", "-n", "-6", "--", target},
+	}
+	if cmdArgs, exists := commands[tool]; exists {
+		path, err := exec.LookPath(cmdArgs[0])
+		if err != nil {
+			return nil, err
+		}
+		cmd := exec.Command(path, cmdArgs[1:]...)
+		return cmd, nil
+	}
+	return nil, errors.New("Command is not allowed")
+}
+
+func isValidTarget(target string) error {
+	addr, err := net.ResolveIPAddr("ip", target)
+	if err != nil {
+		return err
+	}
+	if addr.IP.IsPrivate() {
+		return errors.New("RFC 1918 and RFC 4193 address space is not allowed")
+	}
+	return nil
+}
+
+func executeStreaming(w http.ResponseWriter, r *http.Request) {
+	tool := r.URL.Query().Get("tool")
+	target := r.URL.Query().Get("target")
+
+	err := isValidTarget(target)
+
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Bad Target: %s", err), http.StatusBadRequest)
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Connection", "keep-alive")
+
+	cmd, err := createCommand(tool, target)
+	if err != nil {
+		http.Error(w, "Internal Server Error: failed to create command", http.StatusInternalServerError)
+		log.Printf("ERROR: Failed to create command: %s\n", err)
+		return
+	}
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		http.Error(w, "Internal Server Error: failed to open pipe to CMD output", http.StatusInternalServerError)
+		log.Printf("ERROR: Failed to open pipe to CMD output: %s\n", err)
+		return
+	}
+	cmd.Stderr = cmd.Stdout
+	err = cmd.Start()
+	if err != nil {
+		http.Error(w, "Internal Server Error: failed to start command", http.StatusInternalServerError)
+		log.Printf("ERROR: Failed to start command: %s\n", err)
+		return
+	}
+
+	scanner := bufio.NewScanner(stdout)
+	scanner.Split(bufio.ScanLines)
+
+	_, pw, _ := os.Pipe()
+	cmd.Stdout = pw
+	cmd.Stdout = pw
+
+	for scanner.Scan() {
+		fmt.Fprintf(w, "%s\n", scanner.Bytes())
+		if f, ok := w.(http.Flusher); ok {
+			f.Flush()
+		}
+	}
+}
+
 func main() {
 	config := loadConfig()
 	formattedConfig, err := json.MarshalIndent(config, "", "  ")
@@ -144,9 +222,10 @@ func main() {
 
 	mux := http.NewServeMux()
 
-	mux.HandleFunc("/health", apiMiddlewareChain(healthHandler))
-	mux.HandleFunc("/bird/status", apiMiddlewareChain(birdStatusHandler))
-	mux.HandleFunc("/bird/command", apiMiddlewareChain(birdCommandHandler))
+	mux.HandleFunc("/health", middlewareChain(healthHandler))
+	mux.HandleFunc("/bird/status", middlewareChain(birdStatusHandler))
+	mux.HandleFunc("/bird/command", middlewareChain(birdCommandHandler))
+	mux.HandleFunc("/exec", middlewareChain(executeStreaming))
 
 	log.Printf("starting listner on %s:%d\n", config.Host, config.Port)