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recv.go
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recv.go
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package wormhole
import (
"bytes"
"context"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"hash"
"io"
"log"
"github.com/psanford/wormhole-william/internal/crypto"
"github.com/psanford/wormhole-william/rendezvous"
)
// Receive receives a message sent by a wormhole client.
//
// It returns an IncomingMessage with metadata about the payload being sent.
// To read the contents of the message call IncomingMessage.Read().
func (c *Client) Receive(ctx context.Context, code string) (fr *IncomingMessage, returnErr error) {
sideID := crypto.RandSideID()
appID := c.appID()
rc := rendezvous.NewClient(c.url(), sideID, appID)
defer func() {
mood := rendezvous.Errory
if returnErr == nil {
// don't close our connection in this case
// wait until the user actually accepts the transfer
return
} else if returnErr == errDecryptFailed {
mood = rendezvous.Scary
}
rc.Close(ctx, mood)
}()
_, err := rc.Connect(ctx)
if err != nil {
return nil, err
}
nameplate, err := nameplaceFromCode(code)
if err != nil {
return nil, err
}
err = rc.AttachMailbox(ctx, nameplate)
if err != nil {
return nil, err
}
clientProto := newClientProtocol(ctx, rc, sideID, appID)
err = clientProto.WritePake(ctx, code)
if err != nil {
return nil, err
}
err = clientProto.ReadPake()
if err != nil {
return nil, err
}
err = clientProto.WriteVersion(ctx)
if err != nil {
return nil, err
}
_, err = clientProto.ReadVersion()
if err != nil {
return nil, err
}
if c.VerifierOk != nil {
verifier, err := clientProto.Verifier()
if err != nil {
return nil, err
}
if ok := c.VerifierOk(hex.EncodeToString(verifier)); !ok {
errMsg := "sender rejected verification check, abandoned transfer"
writeErr := clientProto.WriteAppData(ctx, &genericMessage{
Error: &errMsg,
})
if writeErr != nil {
return nil, writeErr
}
return nil, errors.New(errMsg)
}
}
collector, err := clientProto.Collect(collectOffer, collectTransit)
if err != nil {
return nil, err
}
defer collector.close()
var offer offerMsg
err = collector.waitFor(&offer)
if err != nil {
return nil, err
}
fr = &IncomingMessage{}
if offer.Message != nil {
answer := genericMessage{
Answer: &answerMsg{
MessageAck: "ok",
},
}
err = clientProto.WriteAppData(ctx, &answer)
if err != nil {
return nil, err
}
rc.Close(ctx, rendezvous.Happy)
fr.Type = TransferText
fr.textReader = bytes.NewReader([]byte(*offer.Message))
return fr, nil
} else if offer.File != nil {
fr.Type = TransferFile
fr.Name = offer.File.FileName
fr.TransferBytes = int(offer.File.FileSize)
fr.UncompressedBytes = int(offer.File.FileSize)
fr.FileCount = 1
} else if offer.Directory != nil {
fr.Type = TransferDirectory
fr.Name = offer.Directory.Dirname
fr.TransferBytes = int(offer.Directory.ZipSize)
fr.UncompressedBytes = int(offer.Directory.NumBytes)
fr.FileCount = int(offer.Directory.NumFiles)
} else {
return nil, errors.New("Got non-file transfer offer")
}
var gotTransitMsg transitMsg
err = collector.waitFor(&gotTransitMsg)
if err != nil {
return nil, err
}
transitKey := deriveTransitKey(clientProto.sharedKey, appID)
transport := newFileTransport(transitKey, appID, c.relayAddr())
transitMsg, err := transport.makeTransitMsg()
if err != nil {
return nil, fmt.Errorf("Make transit msg error: %s", err)
}
err = clientProto.WriteAppData(ctx, &genericMessage{
Transit: transitMsg,
})
if err != nil {
return nil, err
}
reject := func() (initErr error) {
defer func() {
mood := rendezvous.Errory
if returnErr == nil {
mood = rendezvous.Happy
} else if returnErr == errDecryptFailed {
mood = rendezvous.Scary
}
rc.Close(ctx, mood)
}()
var errStr = "transfer rejected"
answer := &genericMessage{
Error: &errStr,
}
ctx := context.Background()
err = clientProto.WriteAppData(ctx, answer)
if err != nil {
return err
}
return nil
}
// defer actually sending the "ok" message until
// the caller does a read on the IncomingMessage object.
acceptAndInitialize := func() (initErr error) {
defer func() {
mood := rendezvous.Errory
if returnErr == nil {
mood = rendezvous.Happy
} else if returnErr == errDecryptFailed {
mood = rendezvous.Scary
}
rc.Close(ctx, mood)
}()
answer := &genericMessage{
Answer: &answerMsg{
FileAck: "ok",
},
}
ctx := context.Background()
err = clientProto.WriteAppData(ctx, answer)
if err != nil {
return err
}
conn, err := transport.connectDirect(&gotTransitMsg)
if err != nil {
return err
}
if conn == nil {
conn, err = transport.connectViaRelay(&gotTransitMsg)
if err != nil {
return err
}
}
if conn == nil {
return errors.New("Failed to establish connection")
}
cryptor := newTransportCryptor(conn, transitKey, "transit_record_sender_key", "transit_record_receiver_key")
fr.cryptor = cryptor
fr.sha256 = sha256.New()
return nil
}
fr.initializeTransfer = acceptAndInitialize
fr.rejectTransfer = reject
return fr, nil
}
// A IncomingMessage contains information about a payload sent to this wormhole client.
//
// The Type field indicates if the sender sent a single file or a directory.
// If the Type is TransferDirectory then reading from the IncomingMessage will
// read a zip file of the contents of the directory.
type IncomingMessage struct {
Name string
Type TransferType
TransferBytes int
UncompressedBytes int
FileCount int
textReader io.Reader
transferInitialized bool
initializeTransfer func() error
rejectTransfer func() error
cryptor *transportCryptor
buf []byte
readCount int
sha256 hash.Hash
readErr error
}
// Read the decripted contents sent to this client.
func (f *IncomingMessage) Read(p []byte) (int, error) {
if f.readErr != nil {
return 0, f.readErr
}
switch f.Type {
case TransferText:
return f.readText(p)
case TransferFile, TransferDirectory:
return f.readCrypt(p)
default:
return 0, fmt.Errorf("Unknown Receiver type %d", f.Type)
}
}
func (f *IncomingMessage) readText(p []byte) (int, error) {
return f.textReader.Read(p)
}
// Reject an incoming file or directory transfer. This must be
// called before any calls to Read. This does nothing for
// text message transfers.
func (f *IncomingMessage) Reject() error {
switch f.Type {
case TransferFile, TransferDirectory:
default:
return errors.New("Can only reject File and Directory transfers")
}
if f.readErr != nil {
return f.readErr
}
if f.transferInitialized {
return errors.New("Cannot Reject after calls to Read")
}
f.transferInitialized = true
f.rejectTransfer()
return nil
}
func (f *IncomingMessage) readCrypt(p []byte) (int, error) {
if f.readErr != nil {
return 0, f.readErr
}
if !f.transferInitialized {
f.transferInitialized = true
err := f.initializeTransfer()
if err != nil {
return 0, err
}
}
if len(f.buf) == 0 {
rec, err := f.cryptor.readRecord()
if err == io.EOF {
log.Printf("unexpected eof! reclen=%d totallen=%d", len(rec), f.readCount)
f.readErr = io.ErrUnexpectedEOF
return 0, f.readErr
} else if err != nil {
f.readErr = err
return 0, err
}
f.buf = rec
}
n := copy(p, f.buf)
f.buf = f.buf[n:]
f.readCount += n
f.sha256.Write(p[:n])
if f.readCount >= f.TransferBytes {
f.readErr = io.EOF
sum := f.sha256.Sum(nil)
ack := fileTransportAck{
Ack: "ok",
SHA256: fmt.Sprintf("%x", sum),
}
msg, _ := json.Marshal(ack)
f.cryptor.writeRecord(msg)
f.cryptor.Close()
}
return n, nil
}