Add support for libassuan file sockets (WinGnuPG support)

npiperelay.go

@@ -1,10 +1,13 @@
 package main
 
 import (
+	"bufio"
+	"errors"
 	"flag"
 	"io"
 	"log"
 	"os"
+	"strconv"
 	"sync"
 	"syscall"
 	"time"
@@ -14,30 +17,65 @@ import (
 
 const cERROR_PIPE_NOT_CONNECTED syscall.Errno = 233
 
+const WSAECONNREFUSED syscall.Errno = 10061
+const WSAENETUNREACH syscall.Errno = 10051
+const WSAETIMEDOUT syscall.Errno = 10060
+const ERROR_CONNECTION_REFUSED syscall.Errno = 1225
+
 var (
 	poll            = flag.Bool("p", false, "poll until the the named pipe exists")
 	closeWrite      = flag.Bool("s", false, "send a 0-byte message to the pipe after EOF on stdin")
 	closeOnEOF      = flag.Bool("ep", false, "terminate on EOF reading from the pipe, even if there is more data to write")
 	closeOnStdinEOF = flag.Bool("ei", false, "terminate on EOF reading from stdin, even if there is more data to write")
 	verbose         = flag.Bool("v", false, "verbose output on stderr")
+	assuan          = flag.Bool("a", false, "treat the target as a libassuan file socket (Used by GnuPG)")
 )
 
 func dialPipe(p string, poll bool) (*overlappedFile, error) {
 	p16, err := windows.UTF16FromString(p)
 	if err != nil {
 		return nil, err
 	}
-	for {
-		h, err := windows.CreateFile(&p16[0], windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil, windows.OPEN_EXISTING, windows.FILE_FLAG_OVERLAPPED, 0)
-		if err == nil {
-			return newOverlappedFile(h), nil
-		}
-		if poll && os.IsNotExist(err) {
-			time.Sleep(200 * time.Millisecond)
-			continue
-		}
-		return nil, &os.PathError{Path: p, Op: "open", Err: err}
+
+	h, err := windows.CreateFile(&p16[0], windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil, windows.OPEN_EXISTING, windows.FILE_FLAG_OVERLAPPED, 0)
+	if err == nil {
+		return newOverlappedFile(h), nil
 	}
+
+	return nil, err
+}
+
+func dialPort(p int, poll bool) (*overlappedFile, error) {
+	if p < 0 || p > 65535 {
+		return nil, errors.New("Invalid port value")
+	}
+
+	h, err := windows.Socket(windows.AF_INET, windows.SOCK_STREAM, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	// Create a SockaddrInet4 for connecting to
+	sa := &windows.SockaddrInet4{Addr: [4]byte{0x7F, 0x00, 0x00, 0x01}, Port: p}
+
+	// Bind to a randomly assigned local port
+	err = windows.Bind(h, &windows.SockaddrInet4{})
+	if err != nil {
+		return nil, err
+	}
+
+	// Wrap our socket up to be properly handled
+	conn := newOverlappedFile(h)
+
+	// Connect to the LibAssuan socket using overlapped ConnectEx operation
+	_, err = conn.asyncIo(func(h windows.Handle, n *uint32, o *windows.Overlapped) error {
+		return windows.ConnectEx(h, sa, nil, 0, nil, o)
+	})
+	if err == nil {
+		return conn, nil
+	}
+
+	return nil, err
 }
 
 func underlyingError(err error) error {
@@ -59,9 +97,73 @@ func main() {
 		log.Println("connecting to", args[0])
 	}
 
-	conn, err := dialPipe(args[0], *poll)
-	if err != nil {
-		log.Fatalln(err)
+	var conn *overlappedFile
+	var err error
+
+	// Loop only if we're polling the named pipe or socket
+	for {
+		conn, err = dialPipe(args[0], *poll)
+
+		if *poll && os.IsNotExist(err) {
+			time.Sleep(200 * time.Millisecond)
+			continue
+		}
+
+		if err != nil {
+			err = &os.PathError{Path: args[0], Op: "open", Err: err}
+			log.Fatalln(err)
+		}
+
+		// LibAssaaun file socket: Attempt to read contents of the target file and connect to a TCP port
+		if *assuan {
+			var port int
+			var nonce [16]byte
+
+			reader := bufio.NewReader(conn)
+
+			// Read the target port number from the first line
+			tmp, _, err := reader.ReadLine()
+			port, err = strconv.Atoi(string(tmp))
+			if err != nil {
+				log.Fatalln(err)
+			}
+
+			// Read the rest of the nonce from the file
+			n, err := reader.Read(nonce[:])
+			if err != nil {
+				log.Fatalln(err)
+			}
+
+			if n != 16 {
+				log.Fatalf("Read incorrect number of bytes for nonce. Expected 16, got %d (0x%X)", n, nonce)
+			}
+
+			if *verbose {
+				log.Printf("Port: %d, Nonce: %X", port, nonce)
+			}
+
+			_ = conn.Close()
+
+			// Try to connect to the libassaun TCP socket hosted on localhost
+			conn, err = dialPort(port, *poll)
+
+			if *poll && (err == WSAETIMEDOUT || err == WSAECONNREFUSED || err == WSAENETUNREACH || err == ERROR_CONNECTION_REFUSED) {
+				time.Sleep(200 * time.Millisecond)
+				continue
+			}
+
+			err = os.NewSyscallError("ConnectEx", err)
+
+			if err != nil {
+				log.Fatal(err)
+			}
+
+			_, err = conn.Write(nonce[:])
+			if err != nil {
+				log.Fatal(err)
+			}
+		}
+		break
 	}
 
 	if *verbose {

scripts/gpg-relay

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+exec socat UNIX-LISTEN:/home/<your-username>/.gnupg/S.gpg-agent,fork, EXEC:'npiperelay.exe -ei -ep -s -a "C:/Users/<your-user-folder>/AppData/Roaming/gnupg/S.gpg-agent"',nofork