Merge pull request #1 from svanharmelen/dev

Initial commit
diff --git a/README.md b/README.md
index b19b49c..d93af40 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,23 @@
 # ssh-agent
-Create a new [agent.Agent](https://godoc.org/golang.org/x/crypto/ssh/agent#Agent) on any type of OS (so including Windows)
+
+Create a new [agent.Agent](https://godoc.org/golang.org/x/crypto/ssh/agent#Agent) on any type of OS (so including Windows) from any [Go](https://golang.org) application.
+
+## Limitations
+
+When compiled for Windows, it will only support [Pageant](http://the.earth.li/~sgtatham/putty/0.66/htmldoc/Chapter9.html#pageant) as the SSH authentication agent.
+
+## Credits
+
+Big thanks to [Давид Мзареулян (David Mzareulyan)](https://github.com/davidmz) for creating the [go-pageant](https://github.com/davidmz/go-pageant) package!
+
+## Issues
+
+If you have an issue: report it on the [issue tracker](https://github.com/xanzy/ssh-agent/issues)
+
+## Author
+
+Sander van Harmelen (<sander@xanzy.io>)
+
+## License
+
+The files `pageant_windows.go` and `sshagent_windows.go` have their own license (see file headers). The rest of this package is licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at <http://www.apache.org/licenses/LICENSE-2.0>
diff --git a/pageant_windows.go b/pageant_windows.go
new file mode 100644
index 0000000..3507b02
--- /dev/null
+++ b/pageant_windows.go
@@ -0,0 +1,146 @@
+//
+// 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 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 := 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, _ := UTF16PtrFromString(mapName)
+
+	mmap, err := CreateFileMapping(InvalidHandle, nil, PAGE_READWRITE, 0, MaxMessageLen+4, pMapName)
+	if err != nil {
+		return nil, err
+	}
+	defer CloseHandle(mmap)
+
+	ptr, err := MapViewOfFile(mmap, FILE_MAP_WRITE, 0, 0, 0)
+	if err != nil {
+		return nil, err
+	}
+	defer UnmapViewOfFile(ptr)
+
+	mmSlice := (*(*[MaxMessageLen]byte)(Pointer(ptr)))[:]
+
+	copy(mmSlice, msg)
+
+	mapNameBytesZ := append([]byte(mapName), 0)
+
+	cds := copyData{
+		dwData: agentCopydataID,
+		cbData: uint32(len(mapNameBytesZ)),
+		lpData: Pointer(&(mapNameBytesZ[0])),
+	}
+
+	resp, _, _ := winSendMessage(paWin, wmCopydata, 0, uintptr(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, _ := UTF16PtrFromString("Pageant")
+	h, _, _ := winFindWindow(uintptr(Pointer(nameP)), uintptr(Pointer(nameP)))
+	return h
+}
diff --git a/sshagent.go b/sshagent.go
new file mode 100644
index 0000000..259fea2
--- /dev/null
+++ b/sshagent.go
@@ -0,0 +1,49 @@
+//
+// Copyright 2015, Sander van Harmelen
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+// +build !windows
+
+package sshagent
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os"
+
+	"golang.org/x/crypto/ssh/agent"
+)
+
+// New returns a new agent.Agent that uses a unix socket
+func New() (agent.Agent, net.Conn, error) {
+	if !Available() {
+		return nil, nil, errors.New("SSH agent requested but SSH_AUTH_SOCK not-specified")
+	}
+
+	sshAuthSock := os.Getenv("SSH_AUTH_SOCK")
+
+	conn, err := net.Dial("unix", sshAuthSock)
+	if err != nil {
+		return nil, nil, fmt.Errorf("Error connecting to SSH_AUTH_SOCK: %v", err)
+	}
+
+	return agent.NewClient(conn), conn, nil
+}
+
+// Available returns true is a auth socket is defined
+func Available() bool {
+	return os.Getenv("SSH_AUTH_SOCK") != ""
+}
diff --git a/sshagent_windows.go b/sshagent_windows.go
new file mode 100644
index 0000000..c46710e
--- /dev/null
+++ b/sshagent_windows.go
@@ -0,0 +1,80 @@
+//
+// 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
+
+import (
+	"errors"
+	"io"
+	"net"
+	"sync"
+
+	"golang.org/x/crypto/ssh/agent"
+)
+
+// New returns a new agent.Agent and the (custom) connection it uses
+// to communicate with a running pagent.exe instance (see README.md)
+func New() (agent.Agent, net.Conn, error) {
+	if !Available() {
+		return nil, nil, errors.New("SSH agent requested but Pageant not running")
+	}
+
+	return agent.NewClient(&conn{}), nil, nil
+}
+
+type conn struct {
+	sync.Mutex
+	buf []byte
+}
+
+func (c *conn) Close() {
+	c.Lock()
+	defer c.Unlock()
+	c.buf = nil
+}
+
+func (c *conn) Write(p []byte) (int, error) {
+	c.Lock()
+	defer c.Unlock()
+
+	resp, err := query(p)
+	if err != nil {
+		return 0, err
+	}
+
+	c.buf = append(c.buf, resp...)
+
+	return len(p), nil
+}
+
+func (c *conn) Read(p []byte) (int, error) {
+	c.Lock()
+	defer c.Unlock()
+
+	if len(c.buf) == 0 {
+		return 0, io.EOF
+	}
+
+	n := copy(p, c.buf)
+	c.buf = c.buf[n:]
+
+	return n, nil
+}