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//
// Copyright (c) 2014 David Mzareulyan
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software
// and associated documentation files (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge, publish, distribute,
// sublicense, and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial
// portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
// BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// +build windows
package sshagent
// see https://github.com/Yasushi/putty/blob/master/windows/winpgntc.c#L155
// see https://github.com/paramiko/paramiko/blob/master/paramiko/win_pageant.py
import (
"encoding/binary"
"errors"
"fmt"
"sync"
"syscall"
"unsafe"
)
// Maximum size of message can be sent to pageant
const MaxMessageLen = 8192
var (
ErrPageantNotFound = errors.New("pageant process not found")
ErrSendMessage = errors.New("error sending message")
ErrMessageTooLong = errors.New("message too long")
ErrInvalidMessageFormat = errors.New("invalid message format")
ErrResponseTooLong = errors.New("response too long")
)
const (
agentCopydataID = 0x804e50ba
wmCopydata = 74
)
type copyData struct {
dwData uintptr
cbData uint32
lpData unsafe.Pointer
}
var (
lock sync.Mutex
winFindWindow = winAPI("user32.dll", "FindWindowW")
winGetCurrentThreadID = winAPI("kernel32.dll", "GetCurrentThreadId")
winSendMessage = winAPI("user32.dll", "SendMessageW")
)
func winAPI(dllName, funcName string) func(...uintptr) (uintptr, uintptr, error) {
proc := syscall.MustLoadDLL(dllName).MustFindProc(funcName)
return func(a ...uintptr) (uintptr, uintptr, error) { return proc.Call(a...) }
}
// Available returns true if Pageant is running
func Available() bool { return pageantWindow() != 0 }
// Query sends message msg to Pageant and returns response or error.
// 'msg' is raw agent request with length prefix
// Response is raw agent response with length prefix
func query(msg []byte) ([]byte, error) {
if len(msg) > MaxMessageLen {
return nil, ErrMessageTooLong
}
msgLen := binary.BigEndian.Uint32(msg[:4])
if len(msg) != int(msgLen)+4 {
return nil, ErrInvalidMessageFormat
}
lock.Lock()
defer lock.Unlock()
paWin := pageantWindow()
if paWin == 0 {
return nil, ErrPageantNotFound
}
thID, _, _ := winGetCurrentThreadID()
mapName := fmt.Sprintf("PageantRequest%08x", thID)
pMapName, _ := syscall.UTF16PtrFromString(mapName)
mmap, err := syscall.CreateFileMapping(syscall.InvalidHandle, nil, syscall.PAGE_READWRITE, 0, MaxMessageLen+4, pMapName)
if err != nil {
return nil, err
}
defer syscall.CloseHandle(mmap)
ptr, err := syscall.MapViewOfFile(mmap, syscall.FILE_MAP_WRITE, 0, 0, 0)
if err != nil {
return nil, err
}
defer syscall.UnmapViewOfFile(ptr)
mmSlice := (*(*[MaxMessageLen]byte)(unsafe.Pointer(ptr)))[:]
copy(mmSlice, msg)
mapNameBytesZ := append([]byte(mapName), 0)
cds := copyData{
dwData: agentCopydataID,
cbData: uint32(len(mapNameBytesZ)),
lpData: unsafe.Pointer(&(mapNameBytesZ[0])),
}
resp, _, _ := winSendMessage(paWin, wmCopydata, 0, uintptr(unsafe.Pointer(&cds)))
if resp == 0 {
return nil, ErrSendMessage
}
respLen := binary.BigEndian.Uint32(mmSlice[:4])
if respLen > MaxMessageLen-4 {
return nil, ErrResponseTooLong
}
respData := make([]byte, respLen+4)
copy(respData, mmSlice)
return respData, nil
}
func pageantWindow() uintptr {
nameP, _ := syscall.UTF16PtrFromString("Pageant")
h, _, _ := winFindWindow(uintptr(unsafe.Pointer(nameP)), uintptr(unsafe.Pointer(nameP)))
return h
}
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