Incomplete Windows daemon support

daemon/2serverUNIXGeneric.go

@@ -0,0 +1,81 @@
+//go:build !windows
+
+package daemon
+
+import (
+	"bytes"
+	"log"
+	"net"
+	"net/rpc"
+	"os"
+	"strconv"
+	"time"
+
+	peercred "github.com/rwinkhart/peercred-mini"
+)
+
+// Run should be called to start an RPC server.
+func Run() {
+	// register RCWService with the RPC package
+	if err := rpc.Register(&RCWService{}); err != nil {
+		log.Fatalf("Error registering RPC service: %v", err)
+	}
+
+	// store the hash of the daemon binary
+	daemonHash = getFileHash(binPath)
+
+	// remove the socket file if it already exists
+	if _, err := os.Stat(socketPath); err == nil {
+		if err := os.Remove(socketPath); err != nil {
+			log.Fatalf("Failed to remove existing socket: %v", err)
+		}
+	}
+
+	// listen on the Unix domain socket
+	listener, err := net.Listen("unix", socketPath)
+	if err != nil {
+		log.Fatalf("Failed to listen on UNIX socket %s: %v", socketPath, err)
+	}
+	defer listener.Close()
+	log.Printf("RPC daemon listening on unix://%s", socketPath)
+
+	// accept connections (timeout after 3 minutes of inactivity)
+	for {
+		listener.(*net.UnixListener).SetDeadline(time.Now().Add(3 * time.Minute))
+
+		conn, err := listener.Accept()
+		if err != nil {
+			if err.(net.Error).Timeout() {
+				log.Println("Three minutes have passed without any connections. Exiting...")
+				os.Exit(0)
+			}
+			log.Printf("Accept error: %v", err)
+			continue
+		}
+		// use a goroutine to check the client's identity
+		go handleConn(conn)
+	}
+}
+
+// handleConn verifies the identity of the client.
+// It uses the file descriptor of the connection to get the PID of the client,
+// which is then used to get the path of the client's executable and calculate its hash.
+// The passphrase is only returned if the client's executable hash matches the daemon's hash
+// and if the request is coming from the same user.
+// This ensures that only the binary the daemon is embedded in can retrieve the passphrase.
+func handleConn(conn net.Conn) {
+	ucred := peercred.Get(conn)
+
+	// check if the RPC call is coming from an identical binary and from the same user
+	callingBinPath := pidToPath(ucred.PID)
+	if ucred.UID == strconv.Itoa(os.Getuid()) && bytes.Equal(getFileHash(callingBinPath), daemonHash) {
+		// valid client; hand off the connection to the RPC server
+		rpc.ServeConn(conn)
+	} else {
+		// invalid client; close the connection w/o a response,
+		// log the client's path, and kill the daemon
+		conn.Close()
+		log.Printf("Request received from invalid client: PID(%d), UID(%s), Path(%s)", ucred.PID, ucred.UID, callingBinPath) // TODO log to file
+		os.Exit(2)
+	}
+}