diff options
author | Daniel Martà <mvdan@mvdan.cc> | 2015-03-21 21:48:36 +0100 |
---|---|---|
committer | Daniel Martà <mvdan@mvdan.cc> | 2015-03-22 00:24:44 +0100 |
commit | 398b795c87387d25c889a3bf700b387cd120520e (patch) | |
tree | a79b76cdcf4aab33c75ac330b3539b330bf1be58 /transports/obfs2/obfs2.go | |
parent | ced244c09f46d60715d17b8e09c609e08cac87ae (diff) |
Simplify some err and return logic
Diffstat (limited to 'transports/obfs2/obfs2.go')
-rw-r--r-- | transports/obfs2/obfs2.go | 70 |
1 files changed, 34 insertions, 36 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) { |