135 lines
3.5 KiB
Go
135 lines
3.5 KiB
Go
// Package pageant provides an interface to PyTTY pageant.exe utility.
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// This package is windows-only
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package pageant
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// see https://github.com/Yasushi/putty/blob/master/windows/winpgntc.c#L155
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// see https://github.com/paramiko/paramiko/blob/master/paramiko/win_pageant.py
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"sync"
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"syscall"
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"unsafe"
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)
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// MaxMessageLen defines maximum size of message can be sent to pageant
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const MaxMessageLen = 8192
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var (
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// ErrPageantNotFound returns when pageant process not found
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ErrPageantNotFound = errors.New("pageant process not found")
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// ErrSendMessage returns when message to pageant cannt be sent
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ErrSendMessage = errors.New("error sending message")
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// ErrMessageTooLong returns when message is too long (see MaxMessageLen)
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ErrMessageTooLong = errors.New("message too long")
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// ErrInvalidMessageFormat returns when message have invalid fomat
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ErrInvalidMessageFormat = errors.New("invalid message format")
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// ErrResponseTooLong returns when response from pageant is too long
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ErrResponseTooLong = errors.New("response too long")
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)
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/////////////////////////
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const (
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agentCopydataID = 0x804e50ba
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wmCopydata = 74
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)
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type copyData struct {
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dwData uintptr
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cbData uint32
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lpData unsafe.Pointer
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}
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var (
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lock sync.Mutex
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winFindWindow = winAPI("user32.dll", "FindWindowW")
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winGetCurrentThreadID = winAPI("kernel32.dll", "GetCurrentThreadId")
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winSendMessage = winAPI("user32.dll", "SendMessageW")
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)
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func winAPI(dllName, funcName string) func(...uintptr) (uintptr, uintptr, error) {
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proc := syscall.MustLoadDLL(dllName).MustFindProc(funcName)
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return func(a ...uintptr) (uintptr, uintptr, error) { return proc.Call(a...) }
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}
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// Available returns true if Pageant is started
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func Available() bool { return pageantWindow() != 0 }
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// Query sends message msg to Pageant and returns response or error.
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// 'msg' is raw agent request with length prefix
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// Response is raw agent response with length prefix
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func query(msg []byte) ([]byte, error) {
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if len(msg) > MaxMessageLen {
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return nil, ErrMessageTooLong
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}
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msgLen := binary.BigEndian.Uint32(msg[:4])
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if len(msg) != int(msgLen)+4 {
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return nil, ErrInvalidMessageFormat
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}
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lock.Lock()
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defer lock.Unlock()
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paWin := pageantWindow()
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if paWin == 0 {
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return nil, ErrPageantNotFound
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}
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thID, _, _ := winGetCurrentThreadID()
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mapName := fmt.Sprintf("PageantRequest%08x", thID)
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pMapName, _ := syscall.UTF16PtrFromString(mapName)
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mmap, err := syscall.CreateFileMapping(syscall.InvalidHandle, nil, syscall.PAGE_READWRITE, 0, MaxMessageLen+4, pMapName)
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if err != nil {
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return nil, err
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}
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defer syscall.CloseHandle(mmap)
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ptr, err := syscall.MapViewOfFile(mmap, syscall.FILE_MAP_WRITE, 0, 0, 0)
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if err != nil {
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return nil, err
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}
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defer syscall.UnmapViewOfFile(ptr)
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mmSlice := (*(*[MaxMessageLen]byte)(unsafe.Pointer(ptr)))[:]
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copy(mmSlice, msg)
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mapNameBytesZ := append([]byte(mapName), 0)
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cds := copyData{
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dwData: agentCopydataID,
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cbData: uint32(len(mapNameBytesZ)),
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lpData: unsafe.Pointer(&(mapNameBytesZ[0])),
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}
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resp, _, _ := winSendMessage(paWin, wmCopydata, 0, uintptr(unsafe.Pointer(&cds)))
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if resp == 0 {
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return nil, ErrSendMessage
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}
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respLen := binary.BigEndian.Uint32(mmSlice[:4])
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if respLen > MaxMessageLen-4 {
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return nil, ErrResponseTooLong
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}
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respData := make([]byte, respLen+4)
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copy(respData, mmSlice)
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return respData, nil
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}
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func pageantWindow() uintptr {
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nameP, _ := syscall.UTF16PtrFromString("Pageant")
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h, _, _ := winFindWindow(uintptr(unsafe.Pointer(nameP)), uintptr(unsafe.Pointer(nameP)))
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return h
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}
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