[tor-commits] [obfs4/master] Simplify some err and return logic
yawning at torproject.org
yawning at torproject.org
Sun Mar 22 13:03:55 UTC 2015
commit 398b795c87387d25c889a3bf700b387cd120520e
Author: Daniel Martà <mvdan at mvdan.cc>
Date: Sat Mar 21 21:48:36 2015 +0100
Simplify some err and return logic
---
transports/obfs2/obfs2.go | 70 ++++++++++++++++++------------------
transports/obfs3/obfs3.go | 54 ++++++++++++++--------------
transports/obfs4/handshake_ntor.go | 5 ++-
transports/obfs4/obfs4.go | 63 +++++++++++++++-----------------
transports/obfs4/packet.go | 17 ++++-----
transports/obfs4/statefile.go | 6 ++--
transports/scramblesuit/conn.go | 32 +++++++++--------
7 files changed, 118 insertions(+), 129 deletions(-)
diff --git a/transports/obfs2/obfs2.go b/transports/obfs2/obfs2.go
index f8efac1..bc2532b 100644
--- a/transports/obfs2/obfs2.go
+++ b/transports/obfs2/obfs2.go
@@ -187,7 +187,7 @@ func newObfs2ServerConn(conn net.Conn) (c *obfs2Conn, err error) {
return
}
-func (conn *obfs2Conn) handshake() (err error) {
+func (conn *obfs2Conn) handshake() error {
// Each begins by generating a seed and a padding key as follows.
// The initiator generates:
//
@@ -202,8 +202,8 @@ func (conn *obfs2Conn) handshake() (err error) {
// Each then generates a random number PADLEN in range from 0 through
// MAX_PADDING (inclusive).
var seed [seedLen]byte
- if err = csrand.Bytes(seed[:]); err != nil {
- return
+ if err := csrand.Bytes(seed[:]); err != nil {
+ return err
}
var padMagic []byte
if conn.isInitiator {
@@ -218,8 +218,8 @@ func (conn *obfs2Conn) handshake() (err error) {
binary.BigEndian.PutUint32(hsBlob[0:4], magicValue)
binary.BigEndian.PutUint32(hsBlob[4:8], padLen)
if padLen > 0 {
- if err = csrand.Bytes(hsBlob[8:]); err != nil {
- return
+ if err := csrand.Bytes(hsBlob[8:]); err != nil {
+ return err
}
}
@@ -230,25 +230,25 @@ func (conn *obfs2Conn) handshake() (err error) {
// and the responder sends:
//
// RESP_SEED | E(RESP_PAD_KEY, UINT32(MAGIC_VALUE) | UINT32(PADLEN) | WR(PADLEN))
- var txBlock cipher.Block
- if txBlock, err = aes.NewCipher(padKey); err != nil {
- return
+ txBlock, err := aes.NewCipher(padKey)
+ if err != nil {
+ return err
}
txStream := cipher.NewCTR(txBlock, padIV)
conn.tx = &cipher.StreamWriter{S: txStream, W: conn.Conn}
- if _, err = conn.Conn.Write(seed[:]); err != nil {
- return
+ if _, err := conn.Conn.Write(seed[:]); err != nil {
+ return err
}
- if _, err = conn.Write(hsBlob); err != nil {
- return
+ if _, err := conn.Write(hsBlob); err != nil {
+ return err
}
// Upon receiving the SEED from the other party, each party derives
// the other party's padding key value as above, and decrypts the next
// 8 bytes of the key establishment message.
var peerSeed [seedLen]byte
- if _, err = io.ReadFull(conn.Conn, peerSeed[:]); err != nil {
- return
+ if _, err := io.ReadFull(conn.Conn, peerSeed[:]); err != nil {
+ return err
}
var peerPadMagic []byte
if conn.isInitiator {
@@ -257,46 +257,44 @@ func (conn *obfs2Conn) handshake() (err error) {
peerPadMagic = []byte(initiatorPadString)
}
peerKey, peerIV := hsKdf(peerPadMagic, peerSeed[:], !conn.isInitiator)
- var rxBlock cipher.Block
- if rxBlock, err = aes.NewCipher(peerKey); err != nil {
- return
+ rxBlock, err := aes.NewCipher(peerKey)
+ if err != nil {
+ return err
}
rxStream := cipher.NewCTR(rxBlock, peerIV)
conn.rx = &cipher.StreamReader{S: rxStream, R: conn.Conn}
hsHdr := make([]byte, hsLen)
- if _, err = io.ReadFull(conn, hsHdr[:]); err != nil {
- return
+ if _, err := io.ReadFull(conn, hsHdr[:]); err != nil {
+ return err
}
// If the MAGIC_VALUE does not match, or the PADLEN value is greater than
// MAX_PADDING, the party receiving it should close the connection
// immediately.
if peerMagic := binary.BigEndian.Uint32(hsHdr[0:4]); peerMagic != magicValue {
- err = fmt.Errorf("invalid magic value: %x", peerMagic)
- return
+ return fmt.Errorf("invalid magic value: %x", peerMagic)
}
padLen = binary.BigEndian.Uint32(hsHdr[4:8])
if padLen > maxPadding {
- err = fmt.Errorf("padlen too long: %d", padLen)
- return
+ return fmt.Errorf("padlen too long: %d", padLen)
}
// Otherwise, it should read the remaining PADLEN bytes of padding data
// and discard them.
tmp := make([]byte, padLen)
- if _, err = io.ReadFull(conn.Conn, tmp); err != nil { // Note: Skips AES.
- return
+ if _, err := io.ReadFull(conn.Conn, tmp); err != nil { // Note: Skips AES.
+ return err
}
// Derive the actual keys.
- if err = conn.kdf(seed[:], peerSeed[:]); err != nil {
- return
+ if err := conn.kdf(seed[:], peerSeed[:]); err != nil {
+ return err
}
- return
+ return nil
}
-func (conn *obfs2Conn) kdf(seed, peerSeed []byte) (err error) {
+func (conn *obfs2Conn) kdf(seed, peerSeed []byte) error {
// Additional keys are then derived as:
//
// INIT_SECRET = MAC("Initiator obfuscated data", INIT_SEED|RESP_SEED)
@@ -315,16 +313,16 @@ func (conn *obfs2Conn) kdf(seed, peerSeed []byte) (err error) {
}
initKey, initIV := hsKdf([]byte(initiatorKdfString), combSeed, true)
- var initBlock cipher.Block
- if initBlock, err = aes.NewCipher(initKey); err != nil {
- return
+ initBlock, err := aes.NewCipher(initKey)
+ if err != nil {
+ return err
}
initStream := cipher.NewCTR(initBlock, initIV)
respKey, respIV := hsKdf([]byte(responderKdfString), combSeed, false)
- var respBlock cipher.Block
- if respBlock, err = aes.NewCipher(respKey); err != nil {
- return
+ respBlock, err := aes.NewCipher(respKey)
+ if err != nil {
+ return err
}
respStream := cipher.NewCTR(respBlock, respIV)
@@ -336,7 +334,7 @@ func (conn *obfs2Conn) kdf(seed, peerSeed []byte) (err error) {
conn.rx.S = initStream
}
- return
+ return nil
}
func hsKdf(magic, seed []byte, isInitiator bool) (padKey, padIV []byte) {
diff --git a/transports/obfs3/obfs3.go b/transports/obfs3/obfs3.go
index 53409db..d215c49 100644
--- a/transports/obfs3/obfs3.go
+++ b/transports/obfs3/obfs3.go
@@ -166,56 +166,56 @@ func newObfs3ServerConn(conn net.Conn) (c *obfs3Conn, err error) {
return
}
-func (conn *obfs3Conn) handshake() (err error) {
+func (conn *obfs3Conn) handshake() error {
// The party who opens the connection is the 'initiator'; the one who
// accepts it is the 'responder'. Each begins by generating a
// UniformDH keypair, and a random number PADLEN in [0, MAX_PADDING/2].
// Both parties then send:
//
// PUB_KEY | WR(PADLEN)
- var privateKey *uniformdh.PrivateKey
- if privateKey, err = uniformdh.GenerateKey(csrand.Reader); err != nil {
- return
+ privateKey, err := uniformdh.GenerateKey(csrand.Reader)
+ if err != nil {
+ return err
}
padLen := csrand.IntRange(0, maxPadding/2)
blob := make([]byte, uniformdh.Size+padLen)
- var publicKey []byte
- if publicKey, err = privateKey.PublicKey.Bytes(); err != nil {
- return
+ publicKey, err := privateKey.PublicKey.Bytes()
+ if err != nil {
+ return err
}
copy(blob[0:], publicKey)
- if err = csrand.Bytes(blob[uniformdh.Size:]); err != nil {
- return
+ if err := csrand.Bytes(blob[uniformdh.Size:]); err != nil {
+ return err
}
- if _, err = conn.Conn.Write(blob); err != nil {
- return
+ if _, err := conn.Conn.Write(blob); err != nil {
+ return err
}
// Read the public key from the peer.
rawPeerPublicKey := make([]byte, uniformdh.Size)
- if _, err = io.ReadFull(conn.Conn, rawPeerPublicKey); err != nil {
- return
+ if _, err := io.ReadFull(conn.Conn, rawPeerPublicKey); err != nil {
+ return err
}
var peerPublicKey uniformdh.PublicKey
- if err = peerPublicKey.SetBytes(rawPeerPublicKey); err != nil {
- return
+ if err := peerPublicKey.SetBytes(rawPeerPublicKey); err != nil {
+ return err
}
// After retrieving the public key of the other end, each party
// completes the DH key exchange and generates a shared-secret for the
// session (named SHARED_SECRET).
- var sharedSecret []byte
- if sharedSecret, err = uniformdh.Handshake(privateKey, &peerPublicKey); err != nil {
- return
+ sharedSecret, err := uniformdh.Handshake(privateKey, &peerPublicKey)
+ if err != nil {
+ return err
}
- if err = conn.kdf(sharedSecret); err != nil {
- return
+ if err := conn.kdf(sharedSecret); err != nil {
+ return err
}
- return
+ return nil
}
-func (conn *obfs3Conn) kdf(sharedSecret []byte) (err error) {
+func (conn *obfs3Conn) kdf(sharedSecret []byte) error {
// Using that shared-secret each party derives its encryption keys as
// follows:
//
@@ -248,14 +248,14 @@ func (conn *obfs3Conn) kdf(sharedSecret []byte) (err error) {
//
// Note: To have this be the last place where the shared secret is used,
// also generate the magic value to send/scan for here.
- var initBlock cipher.Block
- if initBlock, err = aes.NewCipher(initSecret[:keyLen]); err != nil {
+ initBlock, err := aes.NewCipher(initSecret[:keyLen])
+ if err != nil {
return err
}
initStream := cipher.NewCTR(initBlock, initSecret[keyLen:])
- var respBlock cipher.Block
- if respBlock, err = aes.NewCipher(respSecret[:keyLen]); err != nil {
+ respBlock, err := aes.NewCipher(respSecret[:keyLen])
+ if err != nil {
return err
}
respStream := cipher.NewCTR(respBlock, respSecret[keyLen:])
@@ -272,7 +272,7 @@ func (conn *obfs3Conn) kdf(sharedSecret []byte) (err error) {
conn.rxMagic = initMagic
}
- return
+ return nil
}
func (conn *obfs3Conn) findPeerMagic() error {
diff --git a/transports/obfs4/handshake_ntor.go b/transports/obfs4/handshake_ntor.go
index 8dcf0c8..57de460 100644
--- a/transports/obfs4/handshake_ntor.go
+++ b/transports/obfs4/handshake_ntor.go
@@ -417,10 +417,9 @@ func findMarkMac(mark, buf []byte, startPos, maxPos int, fromTail bool) (pos int
func makePad(padLen int) ([]byte, error) {
pad := make([]byte, padLen)
- err := csrand.Bytes(pad)
- if err != nil {
+ if err := csrand.Bytes(pad); err != nil {
return nil, err
}
- return pad, err
+ return pad, nil
}
diff --git a/transports/obfs4/obfs4.go b/transports/obfs4/obfs4.go
index 256f549..07af9ab 100644
--- a/transports/obfs4/obfs4.go
+++ b/transports/obfs4/obfs4.go
@@ -105,16 +105,15 @@ func (t *Transport) ClientFactory(stateDir string) (base.ClientFactory, error) {
// ServerFactory returns a new obfs4ServerFactory instance.
func (t *Transport) ServerFactory(stateDir string, args *pt.Args) (base.ServerFactory, error) {
- var err error
-
- var st *obfs4ServerState
- if st, err = serverStateFromArgs(stateDir, args); err != nil {
+ st, err := serverStateFromArgs(stateDir, args)
+ if err != nil {
return nil, err
}
var iatSeed *drbg.Seed
if st.iatMode != iatNone {
iatSeedSrc := sha256.Sum256(st.drbgSeed.Bytes()[:])
+ var err error
iatSeed, err = drbg.SeedFromBytes(iatSeedSrc[:])
if err != nil {
return nil, err
@@ -152,8 +151,6 @@ func (cf *obfs4ClientFactory) Transport() base.Transport {
}
func (cf *obfs4ClientFactory) ParseArgs(args *pt.Args) (interface{}, error) {
- var err error
-
var nodeID *ntor.NodeID
var publicKey *ntor.PublicKey
@@ -161,8 +158,8 @@ func (cf *obfs4ClientFactory) ParseArgs(args *pt.Args) (interface{}, error) {
// for the Node ID and Public Key.
certStr, ok := args.Get(certArg)
if ok {
- var cert *obfs4ServerCert
- if cert, err = serverCertFromString(certStr); err != nil {
+ cert, err := serverCertFromString(certStr)
+ if err != nil {
return nil, err
}
nodeID, publicKey = cert.unpack()
@@ -173,6 +170,7 @@ func (cf *obfs4ClientFactory) ParseArgs(args *pt.Args) (interface{}, error) {
if !ok {
return nil, fmt.Errorf("missing argument '%s'", nodeIDArg)
}
+ var err error
if nodeID, err = ntor.NodeIDFromHex(nodeIDStr); err != nil {
return nil, err
}
@@ -191,8 +189,7 @@ func (cf *obfs4ClientFactory) ParseArgs(args *pt.Args) (interface{}, error) {
if !ok {
return nil, fmt.Errorf("missing argument '%s'", iatArg)
}
- var iatMode int
- iatMode, err = strconv.Atoi(iatStr)
+ iatMode, err := strconv.Atoi(iatStr)
if err != nil || iatMode < iatNone || iatMode > iatParanoid {
return nil, fmt.Errorf("invalid iat-mode '%d'", iatMode)
}
@@ -343,16 +340,15 @@ func (conn *obfs4Conn) clientHandshake(nodeID *ntor.NodeID, peerIdentityKey *nto
// Consume the server handshake.
var hsBuf [maxHandshakeLength]byte
for {
- var n int
- if n, err = conn.Conn.Read(hsBuf[:]); err != nil {
+ n, err := conn.Conn.Read(hsBuf[:])
+ if err != nil {
// The Read() could have returned data and an error, but there is
// no point in continuing on an EOF or whatever.
return err
}
conn.receiveBuffer.Write(hsBuf[:n])
- var seed []byte
- n, seed, err = hs.parseServerHandshake(conn.receiveBuffer.Bytes())
+ n, seed, err := hs.parseServerHandshake(conn.receiveBuffer.Bytes())
if err == ErrMarkNotFoundYet {
continue
} else if err != nil {
@@ -369,39 +365,38 @@ func (conn *obfs4Conn) clientHandshake(nodeID *ntor.NodeID, peerIdentityKey *nto
}
}
-func (conn *obfs4Conn) serverHandshake(sf *obfs4ServerFactory, sessionKey *ntor.Keypair) (err error) {
+func (conn *obfs4Conn) serverHandshake(sf *obfs4ServerFactory, sessionKey *ntor.Keypair) error {
if !conn.isServer {
return fmt.Errorf("serverHandshake called on client connection")
}
// Generate the server handshake, and arm the base timeout.
hs := newServerHandshake(sf.nodeID, sf.identityKey, sessionKey)
- if err = conn.Conn.SetDeadline(time.Now().Add(serverHandshakeTimeout)); err != nil {
- return
+ if err := conn.Conn.SetDeadline(time.Now().Add(serverHandshakeTimeout)); err != nil {
+ return err
}
// Consume the client handshake.
var hsBuf [maxHandshakeLength]byte
for {
- var n int
- if n, err = conn.Conn.Read(hsBuf[:]); err != nil {
+ n, err := conn.Conn.Read(hsBuf[:])
+ if err != nil {
// The Read() could have returned data and an error, but there is
// no point in continuing on an EOF or whatever.
- return
+ return err
}
conn.receiveBuffer.Write(hsBuf[:n])
- var seed []byte
- seed, err = hs.parseClientHandshake(sf.replayFilter, conn.receiveBuffer.Bytes())
+ seed, err := hs.parseClientHandshake(sf.replayFilter, conn.receiveBuffer.Bytes())
if err == ErrMarkNotFoundYet {
continue
} else if err != nil {
- return
+ return err
}
conn.receiveBuffer.Reset()
- if err = conn.Conn.SetDeadline(time.Time{}); err != nil {
- return
+ if err := conn.Conn.SetDeadline(time.Time{}); err != nil {
+ return nil
}
// Use the derived key material to intialize the link crypto.
@@ -422,26 +417,24 @@ func (conn *obfs4Conn) serverHandshake(sf *obfs4ServerFactory, sessionKey *ntor.
// handshake_ntor.go.
// Generate/send the response.
- var blob []byte
- blob, err = hs.generateHandshake()
+ blob, err := hs.generateHandshake()
if err != nil {
- return
+ return err
}
var frameBuf bytes.Buffer
- _, err = frameBuf.Write(blob)
- if err != nil {
- return
+ if _, err = frameBuf.Write(blob); err != nil {
+ return err
}
// Send the PRNG seed as the first packet.
- if err = conn.makePacket(&frameBuf, packetTypePrngSeed, sf.lenSeed.Bytes()[:], 0); err != nil {
- return
+ if err := conn.makePacket(&frameBuf, packetTypePrngSeed, sf.lenSeed.Bytes()[:], 0); err != nil {
+ return err
}
if _, err = conn.Conn.Write(frameBuf.Bytes()); err != nil {
- return
+ return err
}
- return
+ return nil
}
func (conn *obfs4Conn) Read(b []byte) (n int, err error) {
diff --git a/transports/obfs4/packet.go b/transports/obfs4/packet.go
index 9865c82..461ad54 100644
--- a/transports/obfs4/packet.go
+++ b/transports/obfs4/packet.go
@@ -69,7 +69,7 @@ func (e InvalidPayloadLengthError) Error() string {
var zeroPadBytes [maxPacketPaddingLength]byte
-func (conn *obfs4Conn) makePacket(w io.Writer, pktType uint8, data []byte, padLen uint16) (err error) {
+func (conn *obfs4Conn) makePacket(w io.Writer, pktType uint8, data []byte, padLen uint16) error {
var pkt [framing.MaximumFramePayloadLength]byte
if len(data)+int(padLen) > maxPacketPayloadLength {
@@ -93,22 +93,19 @@ func (conn *obfs4Conn) makePacket(w io.Writer, pktType uint8, data []byte, padLe
// Encode the packet in an AEAD frame.
var frame [framing.MaximumSegmentLength]byte
- frameLen := 0
- frameLen, err = conn.encoder.Encode(frame[:], pkt[:pktLen])
+ frameLen, err := conn.encoder.Encode(frame[:], pkt[:pktLen])
if err != nil {
// All encoder errors are fatal.
- return
+ return err
}
- var wrLen int
- wrLen, err = w.Write(frame[:frameLen])
+ wrLen, err := w.Write(frame[:frameLen])
if err != nil {
- return
+ return err
} else if wrLen < frameLen {
- err = io.ErrShortWrite
- return
+ return io.ErrShortWrite
}
- return
+ return nil
}
func (conn *obfs4Conn) readPackets() (err error) {
diff --git a/transports/obfs4/statefile.go b/transports/obfs4/statefile.go
index 0838180..6c34f35 100644
--- a/transports/obfs4/statefile.go
+++ b/transports/obfs4/statefile.go
@@ -183,7 +183,7 @@ func jsonServerStateFromFile(stateDir string, js *jsonServerState) error {
return err
}
- if err = json.Unmarshal(f, js); err != nil {
+ if err := json.Unmarshal(f, js); err != nil {
return fmt.Errorf("failed to load statefile '%s': %s", fPath, err)
}
@@ -227,7 +227,7 @@ func newJSONServerState(stateDir string, js *jsonServerState) (err error) {
return nil
}
-func newBridgeFile(stateDir string, st *obfs4ServerState) (err error) {
+func newBridgeFile(stateDir string, st *obfs4ServerState) error {
const prefix = "# obfs4 torrc client bridge line\n" +
"#\n" +
"# This file is an automatically generated bridge line based on\n" +
@@ -244,7 +244,7 @@ func newBridgeFile(stateDir string, st *obfs4ServerState) (err error) {
st.clientString())
tmp := []byte(prefix + bridgeLine)
- if err = ioutil.WriteFile(path.Join(stateDir, bridgeFile), tmp, 0600); err != nil {
+ if err := ioutil.WriteFile(path.Join(stateDir, bridgeFile), tmp, 0600); err != nil {
return err
}
diff --git a/transports/scramblesuit/conn.go b/transports/scramblesuit/conn.go
index b77bc5f..b8a27c7 100644
--- a/transports/scramblesuit/conn.go
+++ b/transports/scramblesuit/conn.go
@@ -441,20 +441,23 @@ handshakeUDH:
}
}
-func (conn *ssConn) initCrypto(seed []byte) (err error) {
+func (conn *ssConn) initCrypto(seed []byte) error {
// Use HKDF-SHA256 (Expand only, no Extract) to generate session keys from
// initial keying material.
okm := hkdfExpand(sha256.New, seed, nil, kdfSecretLength)
- if conn.txCrypto, err = newCryptoState(okm[0:32], okm[32:40], okm[80:112]); err != nil {
- return
+ var err error
+ conn.txCrypto, err = newCryptoState(okm[0:32], okm[32:40], okm[80:112])
+ if err != nil {
+ return err
}
- if conn.rxCrypto, err = newCryptoState(okm[40:72], okm[72:80], okm[112:144]); err != nil {
- return
+ conn.rxCrypto, err = newCryptoState(okm[40:72], okm[72:80], okm[112:144])
+ if err != nil {
+ return err
}
- return
+ return nil
}
-func (conn *ssConn) padBurst(burst *bytes.Buffer, sampleLen int) (err error) {
+func (conn *ssConn) padBurst(burst *bytes.Buffer, sampleLen int) error {
// Burst contains the fully encrypted+MACed outgoing payload that will be
// written to the network. Pad it out so that the last segment (based on
// the ScrambleSuit MTU) is sampleLen bytes.
@@ -473,18 +476,17 @@ func (conn *ssConn) padBurst(burst *bytes.Buffer, sampleLen int) (err error) {
}
if padLen == 0 {
- return
- } else if padLen > maxSegmentLength {
+ return nil
+ }
+ if padLen > maxSegmentLength {
// Note: packetmorpher.py: getPadding is slightly wrong and only
// accounts for one of the two packet headers.
- if err = conn.makePacket(burst, pktPayload, nil, 700-pktOverhead); err != nil {
- return
+ if err := conn.makePacket(burst, pktPayload, nil, 700-pktOverhead); err != nil {
+ return err
}
- err = conn.makePacket(burst, pktPayload, nil, padLen-(700+2*pktOverhead))
- } else {
- err = conn.makePacket(burst, pktPayload, nil, padLen-pktOverhead)
+ return conn.makePacket(burst, pktPayload, nil, padLen-(700+2*pktOverhead))
}
- return
+ return conn.makePacket(burst, pktPayload, nil, padLen-pktOverhead)
}
func newScrambleSuitClientConn(conn net.Conn, tStore *ssTicketStore, ca *ssClientArgs) (net.Conn, error) {
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