mirror of
https://github.com/rclone/rclone.git
synced 2024-12-02 21:50:33 +08:00
330 lines
7.1 KiB
Go
330 lines
7.1 KiB
Go
package mega
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"encoding/base64"
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"encoding/binary"
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"encoding/json"
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"errors"
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"math/big"
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"net"
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"net/http"
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"strings"
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"time"
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)
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func newHttpClient(timeout time.Duration) *http.Client {
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// TODO: Need to test this out
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// Doesn't seem to work as expected
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c := &http.Client{
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Transport: &http.Transport{
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Dial: func(netw, addr string) (net.Conn, error) {
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c, err := net.DialTimeout(netw, addr, timeout)
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if err != nil {
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return nil, err
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}
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return c, nil
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},
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Proxy: http.ProxyFromEnvironment,
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},
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}
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return c
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}
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// bytes_to_a32 converts the byte slice b to uint32 slice considering
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// the bytes to be in big endian order.
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func bytes_to_a32(b []byte) []uint32 {
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length := len(b) + 3
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a := make([]uint32, length/4)
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buf := bytes.NewBuffer(b)
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for i, _ := range a {
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_ = binary.Read(buf, binary.BigEndian, &a[i])
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}
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return a
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}
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// a32_to_bytes converts the uint32 slice a to byte slice where each
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// uint32 is decoded in big endian order.
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func a32_to_bytes(a []uint32) []byte {
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buf := new(bytes.Buffer)
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buf.Grow(len(a) * 4) // To prevent reallocations in Write
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for _, v := range a {
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_ = binary.Write(buf, binary.BigEndian, v)
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}
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return buf.Bytes()
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}
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// base64urlencode encodes byte slice b using base64 url encoding.
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// It removes `=` padding when necessary
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func base64urlencode(b []byte) []byte {
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enc := base64.URLEncoding
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encSize := enc.EncodedLen(len(b))
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buf := make([]byte, encSize)
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enc.Encode(buf, b)
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paddSize := 3 - len(b)%3
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if paddSize < 3 {
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encSize -= paddSize
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buf = buf[:encSize]
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}
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return buf
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}
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// base64urldecode decodes the byte slice b using base64 url decoding.
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// It adds required '=' padding before decoding.
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func base64urldecode(b []byte) []byte {
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enc := base64.URLEncoding
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padSize := 4 - len(b)%4
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switch padSize {
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case 1:
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b = append(b, '=')
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case 2:
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b = append(b, '=', '=')
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}
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decSize := enc.DecodedLen(len(b))
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buf := make([]byte, decSize)
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n, _ := enc.Decode(buf, b)
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return buf[:n]
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}
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// base64_to_a32 converts base64 encoded byte slice b to uint32 slice.
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func base64_to_a32(b []byte) []uint32 {
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return bytes_to_a32(base64urldecode(b))
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}
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// a32_to_base64 converts uint32 slice to base64 encoded byte slice.
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func a32_to_base64(a []uint32) []byte {
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return base64urlencode(a32_to_bytes(a))
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}
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// paddnull pads byte slice b such that the size of resulting byte
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// slice is a multiple of q.
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func paddnull(b []byte, q int) []byte {
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if rem := len(b) % q; rem != 0 {
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l := q - rem
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for i := 0; i < l; i++ {
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b = append(b, 0)
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}
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}
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return b
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}
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// password_key calculates password hash from the user password.
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func password_key(p string) []byte {
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a := bytes_to_a32(paddnull([]byte(p), 4))
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pkey := a32_to_bytes([]uint32{0x93C467E3, 0x7DB0C7A4, 0xD1BE3F81, 0x0152CB56})
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n := (len(a) + 3) / 4
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ciphers := make([]cipher.Block, n)
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for j := 0; j < len(a); j += 4 {
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key := []uint32{0, 0, 0, 0}
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for k := 0; k < 4; k++ {
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if j+k < len(a) {
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key[k] = a[k+j]
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}
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}
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ciphers[j/4], _ = aes.NewCipher(a32_to_bytes(key)) // Uses AES in ECB mode
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}
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for i := 65536; i > 0; i-- {
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for j := 0; j < n; j++ {
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ciphers[j].Encrypt(pkey, pkey)
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}
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}
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return pkey
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}
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// stringhash computes generic string hash. Uses k as the key for AES
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// cipher.
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func stringhash(s string, k []byte) []byte {
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a := bytes_to_a32(paddnull([]byte(s), 4))
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h := []uint32{0, 0, 0, 0}
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for i, v := range a {
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h[i&3] ^= v
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}
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hb := a32_to_bytes(h)
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cipher, _ := aes.NewCipher(k)
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for i := 16384; i > 0; i-- {
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cipher.Encrypt(hb, hb)
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}
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ha := bytes_to_a32(paddnull(hb, 4))
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return a32_to_base64([]uint32{ha[0], ha[2]})
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}
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// getMPI returns the length encoded Int and the next slice.
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func getMPI(b []byte) (*big.Int, []byte) {
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p := new(big.Int)
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plen := (uint64(b[0])*256 + uint64(b[1]) + 7) >> 3
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p.SetBytes(b[2 : plen+2])
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b = b[plen+2:]
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return p, b
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}
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// getRSAKey decodes the RSA Key from the byte slice b.
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func getRSAKey(b []byte) (*big.Int, *big.Int, *big.Int) {
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p, b := getMPI(b)
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q, b := getMPI(b)
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d, _ := getMPI(b)
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return p, q, d
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}
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// decryptRSA decrypts message m using RSA private key (p,q,d)
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func decryptRSA(m, p, q, d *big.Int) []byte {
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n := new(big.Int)
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r := new(big.Int)
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n.Mul(p, q)
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r.Exp(m, d, n)
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return r.Bytes()
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}
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// blockDecrypt decrypts using the block cipher blk in ECB mode.
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func blockDecrypt(blk cipher.Block, dst, src []byte) error {
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if len(src) > len(dst) || len(src)%blk.BlockSize() != 0 {
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return errors.New("Block decryption failed")
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}
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l := len(src) - blk.BlockSize()
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for i := 0; i <= l; i += blk.BlockSize() {
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blk.Decrypt(dst[i:], src[i:])
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}
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return nil
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}
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// blockEncrypt encrypts using the block cipher blk in ECB mode.
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func blockEncrypt(blk cipher.Block, dst, src []byte) error {
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if len(src) > len(dst) || len(src)%blk.BlockSize() != 0 {
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return errors.New("Block encryption failed")
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}
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l := len(src) - blk.BlockSize()
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for i := 0; i <= l; i += blk.BlockSize() {
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blk.Encrypt(dst[i:], src[i:])
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}
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return nil
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}
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// decryptSeessionId decrypts the session id using the given private
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// key.
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func decryptSessionId(privk []byte, csid []byte, mk []byte) ([]byte, error) {
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block, _ := aes.NewCipher(mk)
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pk := base64urldecode(privk)
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err := blockDecrypt(block, pk, pk)
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if err != nil {
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return nil, err
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}
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c := base64urldecode(csid)
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m, _ := getMPI(c)
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p, q, d := getRSAKey(pk)
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r := decryptRSA(m, p, q, d)
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return base64urlencode(r[:43]), nil
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}
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// chunkSize describes a size and position of chunk
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type chunkSize struct {
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position int64
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size int
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}
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func getChunkSizes(size int64) (chunks []chunkSize) {
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p := int64(0)
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for i := 1; size > 0; i++ {
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var chunk int
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if i <= 8 {
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chunk = i * 131072
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} else {
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chunk = 1048576
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}
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if size < int64(chunk) {
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chunk = int(size)
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}
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chunks = append(chunks, chunkSize{position: p, size: chunk})
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p += int64(chunk)
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size -= int64(chunk)
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}
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return chunks
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}
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func decryptAttr(key []byte, data []byte) (attr FileAttr, err error) {
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err = EBADATTR
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block, err := aes.NewCipher(key)
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if err != nil {
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return attr, err
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}
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iv := a32_to_bytes([]uint32{0, 0, 0, 0})
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mode := cipher.NewCBCDecrypter(block, iv)
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buf := make([]byte, len(data))
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mode.CryptBlocks(buf, base64urldecode([]byte(data)))
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if string(buf[:4]) == "MEGA" {
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str := strings.TrimRight(string(buf[4:]), "\x00")
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err = json.Unmarshal([]byte(str), &attr)
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}
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return attr, err
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}
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func encryptAttr(key []byte, attr FileAttr) (b []byte, err error) {
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err = EBADATTR
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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data, err := json.Marshal(attr)
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if err != nil {
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return nil, err
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}
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attrib := []byte("MEGA")
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attrib = append(attrib, data...)
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attrib = paddnull(attrib, 16)
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iv := a32_to_bytes([]uint32{0, 0, 0, 0})
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mode := cipher.NewCBCEncrypter(block, iv)
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mode.CryptBlocks(attrib, attrib)
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b = base64urlencode(attrib)
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return b, nil
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}
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func randString(l int) (string, error) {
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encoding := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789AB"
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b := make([]byte, l)
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_, err := rand.Read(b)
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if err != nil {
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return "", err
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}
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enc := base64.NewEncoding(encoding)
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d := make([]byte, enc.EncodedLen(len(b)))
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enc.Encode(d, b)
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d = d[:l]
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return string(d), nil
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}
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