Session login, not fully working yet

mega.go

@@ -417,6 +417,7 @@ func (m *Mega) api_request(r []byte) (buf []byte, err error) {
 			m.debugf("Retry API request %d/%d: %v", i, m.retries, err)
 			backOffSleep(&sleepTime)
 		}
+
 		resp, err = m.client.Post(url, "application/json", bytes.NewBuffer(r))
 		if err != nil {
 			continue
@@ -510,7 +511,7 @@ func (m *Mega) prelogin(email string) error {
 }
 
 // Authenticate and start a session
-func (m *Mega) login(email string, passwd string) error {
+func (m *Mega) login(email string, passwd string, multiFactor string) error {
 	var msg [1]LoginMsg
 	var res [1]LoginResp
 	var err error
@@ -531,6 +532,10 @@ func (m *Mega) login(email string, passwd string) error {
 
 	msg[0].Cmd = "us"
 	msg[0].User = email
+	if multiFactor != "" {
+		msg[0].Mfa = multiFactor
+	}
+
 	if m.accountVersion == 1 {
 		msg[0].Handle = uhandle
 	} else {
@@ -585,7 +590,32 @@ func (m *Mega) Login(email string, passwd string) error {
 		return err
 	}
 
-	err = m.login(email, passwd)
+	err = m.login(email, passwd, "")
+	if err != nil {
+		return err
+	}
+
+	waitEvent := m.WaitEventsStart()
+
+	err = m.getFileSystem()
+	if err != nil {
+		return err
+	}
+
+	// Wait until the all the pending events have been received
+	m.WaitEvents(waitEvent, 5*time.Second)
+
+	return nil
+}
+
+// MultiFactorLogin - Authenticate and start a session with 2FA
+func (m *Mega) MultiFactorLogin(email, passwd, multiFactor string) error {
+	err := m.prelogin(email)
+	if err != nil {
+		return err
+	}
+
+	err = m.login(email, passwd, multiFactor)
 	if err != nil {
 		return err
 	}
@@ -603,6 +633,74 @@ func (m *Mega) Login(email string, passwd string) error {
 	return nil
 }
 
+// SessionLogin - Authenticate and resume a session with session key
+func (m *Mega) SessionLogin(sessionKey string) error {
+	var msg [1]SessionLoginMsg
+	var res [1]LoginResp
+	var err error
+	var result []byte
+
+	var sessionVersion uint8 = 0
+	USERHANDLE := 8
+	SIDLEN := 2*aes.BlockSize + USERHANDLE*4/3 + 1
+	if len(sessionKey) == aes.BlockSize+SIDLEN+1 {
+		sessionVersion = sessionKey[0]
+		if sessionVersion != 1 {
+			return EARGS
+		}
+
+		sessionKey = sessionKey[1:]
+	}
+
+	var sek []byte
+	var buf []byte
+	if len(sessionKey) == aes.BlockSize+SIDLEN {
+		m.k = []byte(sessionKey[:aes.BlockSize])
+
+		sid := sessionKey[aes.BlockSize:]
+		sida := string(megaBtoa(sid[:SIDLEN]))
+		m.sid = sida[:len(sida)-3]
+		sek = make([]byte, aes.BlockSize)
+		rand.Read(sek)
+
+		buf = megaBtoa(string(sek))
+		// TODO: fetch timezone
+	} else if len(sessionKey) > 0 && sessionKey[0] == 2 {
+		return fmt.Errorf("the session key passed is a folder link")
+	} else {
+		return EARGS
+	}
+
+	msg[0].Cmd = "us"
+	msg[0].SessionKey = string(buf[:len(buf)-3])
+
+	req, err := json.Marshal(msg)
+	if err != nil {
+		return err
+	}
+	result, err = m.api_request(req)
+	if err != nil {
+		return err
+	}
+
+	err = json.Unmarshal(result, &res)
+	if err != nil {
+		return err
+	}
+
+	waitEvent := m.WaitEventsStart()
+
+	err = m.getFileSystem() // FIXME: We need to fetch masterkey in some way in order to decrypt node attributes
+	if err != nil {
+		return err
+	}
+
+	// Wait until the all the pending events have been received
+	m.WaitEvents(waitEvent, 5*time.Second)
+
+	return nil
+}
+
 // WaitEventsStart - call this before you do the action which might
 // generate events then use the returned channel as a parameter to
 // WaitEvents to wait for the event(s) to be received.

messages.go

@@ -30,10 +30,19 @@ type LoginResp struct {
 	U          string `json:"u"`
 }
 
+type SessionLoginMsg struct {
+	Cmd        string `json:"a"`
+	SessionKey string `json:"sek,omitempty"`
+	Si         string `json:"si,omitempty"`
+}
+
 type UserMsg struct {
 	Cmd string `json:"a"`
 }
 
+type KeyResp struct {
+}
+
 type UserResp struct {
 	U     string `json:"u"`
 	S     int    `json:"s"`

utils.go

@@ -374,3 +374,157 @@ func randString(l int) (string, error) {
 	d = d[:l]
 	return string(d), nil
 }
+
+// megaAtob - Mega custom base64 encoding
+func megaAtob(in string) []byte {
+	out := make([]byte, len(in)*3/4)
+	atob([]byte(in), &out, len(out))
+	return out
+}
+
+// Do not call this function directly, use megaAtob instead
+func atob(a []byte, buf *[]byte, blen int) int {
+	c := make([]byte, 4)
+	var i int
+	p := 0
+
+	c[3] = 0
+
+	for j := 0; j < len(a); j += 4 {
+		b := 4
+		if len(a)-j < 4 {
+			b = len(a) - j
+		}
+		for i = 0; i < b; i++ {
+			c[i] = from64(a[i+j])
+			if (c[i]) == 255 {
+				break
+			}
+		}
+
+		if p >= blen || i == 0 {
+			return p
+		}
+
+		(*buf)[p] = (c[0] << 2) | ((c[1] & 0x30) >> 4)
+		p++
+
+		if (p >= blen) || (i < 3) {
+			return p
+		}
+
+		(*buf)[p] = (c[1] << 4) | ((c[2] & 0x3c) >> 2)
+		p++
+
+		if (p >= blen) || (i < 4) {
+			return p
+		}
+
+		(*buf)[p] = (c[2] << 6) | c[3]
+		p++
+	}
+
+	return p
+}
+
+func from64(c byte) uint8 {
+	if (c >= 'A') && (c <= 'Z') {
+		return c - 'A'
+	}
+
+	if (c >= 'a') && (c <= 'z') {
+		return c - 'a' + 26
+	}
+
+	if (c >= '0') && (c <= '9') {
+		return c - '0' + 52
+	}
+
+	if c == '-' || c == '+' {
+		return 62
+	}
+
+	if c == '_' || c == '/' {
+		return 63
+	}
+
+	return 255
+}
+
+// megaBtoa - Mega custom base64 decoding
+func megaBtoa(in string) []byte {
+	out := make([]byte, len(in)*4/3+4)
+	btoa([]byte(in), len(in), &out)
+	return out
+}
+
+// Do not call this function directly, use megaBtoa instead
+func btoa(buf []byte, blen int, a *[]byte) int {
+	p := 0
+	index := 0
+
+	for {
+		if blen <= 0 {
+			break
+		}
+
+		(*a)[p] = to64(buf[index] >> 2)
+		p++
+
+		var tmp uint8
+		if blen > 1 {
+			tmp = buf[index+1]
+		} else {
+			tmp = 0
+		}
+		(*a)[p] = to64((buf[index] << 4) | (tmp >> 4))
+		p++
+
+		if blen < 2 {
+			break
+		}
+
+		if blen > 2 {
+			tmp = buf[index+2]
+		} else {
+			tmp = 0
+		}
+		(*a)[p] = to64(buf[index+1]<<2 | (tmp >> 6))
+		p++
+
+		if blen < 3 {
+			break
+		}
+
+		(*a)[p] = to64(buf[index+2])
+		p++
+
+		blen -= 3
+		index += 3
+	}
+
+	(*a)[p] = 0
+	return p
+}
+
+func to64(c byte) uint8 {
+	c &= 63
+
+	if c < 26 {
+		return c + 'A'
+	}
+
+	if c < 52 {
+		return c - 26 + 'a'
+	}
+
+	if c < 62 {
+		return c - 52 + '0'
+	}
+
+	if c == 62 {
+		return '-'
+	}
+
+	return '_'
+}