355 lines
11 KiB
Go
355 lines
11 KiB
Go
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package olm
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// #cgo LDFLAGS: -lolm -lstdc++
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// #include <olm/olm.h>
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// #include <stdlib.h>
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// #include <stdio.h>
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// void olm_session_describe(OlmSession * session, char *buf, size_t buflen) __attribute__((weak));
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// void meowlm_session_describe(OlmSession * session, char *buf, size_t buflen) {
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// if (olm_session_describe) {
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// olm_session_describe(session, buf, buflen);
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// } else {
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// sprintf(buf, "olm_session_describe not supported");
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// }
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// }
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import "C"
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import (
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"crypto/rand"
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"unsafe"
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"maunium.net/go/mautrix/id"
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)
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// Session stores an end to end encrypted messaging session.
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type Session struct {
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int *C.OlmSession
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mem []byte
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}
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// sessionSize is the size of a session object in bytes.
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func sessionSize() uint {
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return uint(C.olm_session_size())
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}
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// SessionFromPickled loads a Session from a pickled base64 string. Decrypts
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// the Session using the supplied key. Returns error on failure. If the key
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// doesn't match the one used to encrypt the Session then the error will be
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// "BAD_SESSION_KEY". If the base64 couldn't be decoded then the error will be
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// "INVALID_BASE64".
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func SessionFromPickled(pickled, key []byte) (*Session, error) {
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if len(pickled) == 0 {
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return nil, EmptyInput
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}
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s := NewBlankSession()
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return s, s.Unpickle(pickled, key)
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}
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func NewBlankSession() *Session {
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memory := make([]byte, sessionSize())
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return &Session{
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int: C.olm_session(unsafe.Pointer(&memory[0])),
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mem: memory,
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}
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}
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// lastError returns an error describing the most recent error to happen to a
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// session.
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func (s *Session) lastError() error {
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return convertError(C.GoString(C.olm_session_last_error((*C.OlmSession)(s.int))))
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}
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// Clear clears the memory used to back this Session.
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func (s *Session) Clear() error {
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r := C.olm_clear_session((*C.OlmSession)(s.int))
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if r == errorVal() {
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return s.lastError()
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}
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return nil
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}
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// pickleLen returns the number of bytes needed to store a session.
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func (s *Session) pickleLen() uint {
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return uint(C.olm_pickle_session_length((*C.OlmSession)(s.int)))
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}
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// createOutboundRandomLen returns the number of random bytes needed to create
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// an outbound session.
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func (s *Session) createOutboundRandomLen() uint {
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return uint(C.olm_create_outbound_session_random_length((*C.OlmSession)(s.int)))
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}
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// idLen returns the length of the buffer needed to return the id for this
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// session.
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func (s *Session) idLen() uint {
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return uint(C.olm_session_id_length((*C.OlmSession)(s.int)))
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}
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// encryptRandomLen returns the number of random bytes needed to encrypt the
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// next message.
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func (s *Session) encryptRandomLen() uint {
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return uint(C.olm_encrypt_random_length((*C.OlmSession)(s.int)))
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}
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// encryptMsgLen returns the size of the next message in bytes for the given
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// number of plain-text bytes.
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func (s *Session) encryptMsgLen(plainTextLen int) uint {
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return uint(C.olm_encrypt_message_length((*C.OlmSession)(s.int), C.size_t(plainTextLen)))
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}
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// decryptMaxPlaintextLen returns the maximum number of bytes of plain-text a
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// given message could decode to. The actual size could be different due to
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// padding. Returns error on failure. If the message base64 couldn't be
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// decoded then the error will be "INVALID_BASE64". If the message is for an
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// unsupported version of the protocol then the error will be
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// "BAD_MESSAGE_VERSION". If the message couldn't be decoded then the error
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// will be "BAD_MESSAGE_FORMAT".
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func (s *Session) decryptMaxPlaintextLen(message string, msgType id.OlmMsgType) (uint, error) {
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if len(message) == 0 {
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return 0, EmptyInput
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}
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r := C.olm_decrypt_max_plaintext_length(
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(*C.OlmSession)(s.int),
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C.size_t(msgType),
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unsafe.Pointer(C.CString(message)),
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C.size_t(len(message)))
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if r == errorVal() {
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return 0, s.lastError()
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}
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return uint(r), nil
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}
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// Pickle returns a Session as a base64 string. Encrypts the Session using the
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// supplied key.
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func (s *Session) Pickle(key []byte) []byte {
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if len(key) == 0 {
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panic(NoKeyProvided)
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}
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pickled := make([]byte, s.pickleLen())
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r := C.olm_pickle_session(
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(*C.OlmSession)(s.int),
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unsafe.Pointer(&key[0]),
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C.size_t(len(key)),
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unsafe.Pointer(&pickled[0]),
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C.size_t(len(pickled)))
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if r == errorVal() {
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panic(s.lastError())
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}
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return pickled[:r]
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}
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func (s *Session) Unpickle(pickled, key []byte) error {
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if len(key) == 0 {
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return NoKeyProvided
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}
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r := C.olm_unpickle_session(
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(*C.OlmSession)(s.int),
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unsafe.Pointer(&key[0]),
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C.size_t(len(key)),
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unsafe.Pointer(&pickled[0]),
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C.size_t(len(pickled)))
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if r == errorVal() {
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return s.lastError()
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}
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return nil
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}
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func (s *Session) GobEncode() ([]byte, error) {
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pickled := s.Pickle(pickleKey)
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length := unpaddedBase64.DecodedLen(len(pickled))
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rawPickled := make([]byte, length)
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_, err := unpaddedBase64.Decode(rawPickled, pickled)
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return rawPickled, err
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}
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func (s *Session) GobDecode(rawPickled []byte) error {
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if s == nil || s.int == nil {
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*s = *NewBlankSession()
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}
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length := unpaddedBase64.EncodedLen(len(rawPickled))
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pickled := make([]byte, length)
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unpaddedBase64.Encode(pickled, rawPickled)
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return s.Unpickle(pickled, pickleKey)
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}
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func (s *Session) MarshalJSON() ([]byte, error) {
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pickled := s.Pickle(pickleKey)
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quotes := make([]byte, len(pickled)+2)
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quotes[0] = '"'
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quotes[len(quotes)-1] = '"'
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copy(quotes[1:len(quotes)-1], pickled)
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return quotes, nil
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}
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func (s *Session) UnmarshalJSON(data []byte) error {
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if len(data) == 0 || len(data) == 0 || data[0] != '"' || data[len(data)-1] != '"' {
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return InputNotJSONString
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}
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if s == nil || s.int == nil {
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*s = *NewBlankSession()
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}
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return s.Unpickle(data[1:len(data)-1], pickleKey)
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}
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// Id returns an identifier for this Session. Will be the same for both ends
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// of the conversation.
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func (s *Session) ID() id.SessionID {
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sessionID := make([]byte, s.idLen())
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r := C.olm_session_id(
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(*C.OlmSession)(s.int),
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unsafe.Pointer(&sessionID[0]),
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C.size_t(len(sessionID)))
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if r == errorVal() {
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panic(s.lastError())
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}
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return id.SessionID(sessionID)
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}
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// HasReceivedMessage returns true if this session has received any message.
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func (s *Session) HasReceivedMessage() bool {
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switch C.olm_session_has_received_message((*C.OlmSession)(s.int)) {
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case 0:
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return false
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default:
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return true
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}
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}
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// MatchesInboundSession checks if the PRE_KEY message is for this in-bound
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// Session. This can happen if multiple messages are sent to this Account
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// before this Account sends a message in reply. Returns true if the session
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// matches. Returns false if the session does not match. Returns error on
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// failure. If the base64 couldn't be decoded then the error will be
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// "INVALID_BASE64". If the message was for an unsupported protocol version
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// then the error will be "BAD_MESSAGE_VERSION". If the message couldn't be
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// decoded then then the error will be "BAD_MESSAGE_FORMAT".
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func (s *Session) MatchesInboundSession(oneTimeKeyMsg string) (bool, error) {
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if len(oneTimeKeyMsg) == 0 {
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return false, EmptyInput
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}
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r := C.olm_matches_inbound_session(
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(*C.OlmSession)(s.int),
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unsafe.Pointer(&([]byte(oneTimeKeyMsg))[0]),
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C.size_t(len(oneTimeKeyMsg)))
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if r == 1 {
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return true, nil
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} else if r == 0 {
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return false, nil
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} else { // if r == errorVal()
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return false, s.lastError()
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}
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}
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// MatchesInboundSessionFrom checks if the PRE_KEY message is for this in-bound
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// Session. This can happen if multiple messages are sent to this Account
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// before this Account sends a message in reply. Returns true if the session
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// matches. Returns false if the session does not match. Returns error on
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// failure. If the base64 couldn't be decoded then the error will be
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// "INVALID_BASE64". If the message was for an unsupported protocol version
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// then the error will be "BAD_MESSAGE_VERSION". If the message couldn't be
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// decoded then then the error will be "BAD_MESSAGE_FORMAT".
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func (s *Session) MatchesInboundSessionFrom(theirIdentityKey, oneTimeKeyMsg string) (bool, error) {
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if len(theirIdentityKey) == 0 || len(oneTimeKeyMsg) == 0 {
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return false, EmptyInput
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}
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r := C.olm_matches_inbound_session_from(
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(*C.OlmSession)(s.int),
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unsafe.Pointer(&([]byte(theirIdentityKey))[0]),
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C.size_t(len(theirIdentityKey)),
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unsafe.Pointer(&([]byte(oneTimeKeyMsg))[0]),
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C.size_t(len(oneTimeKeyMsg)))
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if r == 1 {
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return true, nil
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} else if r == 0 {
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return false, nil
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} else { // if r == errorVal()
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return false, s.lastError()
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}
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}
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// EncryptMsgType returns the type of the next message that Encrypt will
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// return. Returns MsgTypePreKey if the message will be a PRE_KEY message.
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// Returns MsgTypeMsg if the message will be a normal message. Returns error
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// on failure.
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func (s *Session) EncryptMsgType() id.OlmMsgType {
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switch C.olm_encrypt_message_type((*C.OlmSession)(s.int)) {
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case C.size_t(id.OlmMsgTypePreKey):
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return id.OlmMsgTypePreKey
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case C.size_t(id.OlmMsgTypeMsg):
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return id.OlmMsgTypeMsg
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default:
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panic("olm_encrypt_message_type returned invalid result")
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}
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}
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// Encrypt encrypts a message using the Session. Returns the encrypted message
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// as base64.
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func (s *Session) Encrypt(plaintext []byte) (id.OlmMsgType, []byte) {
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if len(plaintext) == 0 {
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panic(EmptyInput)
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}
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// Make the slice be at least length 1
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random := make([]byte, s.encryptRandomLen()+1)
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_, err := rand.Read(random)
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if err != nil {
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panic(NotEnoughGoRandom)
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}
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messageType := s.EncryptMsgType()
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message := make([]byte, s.encryptMsgLen(len(plaintext)))
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r := C.olm_encrypt(
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(*C.OlmSession)(s.int),
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unsafe.Pointer(&plaintext[0]),
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C.size_t(len(plaintext)),
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unsafe.Pointer(&random[0]),
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C.size_t(len(random)),
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unsafe.Pointer(&message[0]),
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C.size_t(len(message)))
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if r == errorVal() {
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panic(s.lastError())
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}
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return messageType, message[:r]
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}
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// Decrypt decrypts a message using the Session. Returns the the plain-text on
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// success. Returns error on failure. If the base64 couldn't be decoded then
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// the error will be "INVALID_BASE64". If the message is for an unsupported
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// version of the protocol then the error will be "BAD_MESSAGE_VERSION". If
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// the message couldn't be decoded then the error will be BAD_MESSAGE_FORMAT".
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// If the MAC on the message was invalid then the error will be
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// "BAD_MESSAGE_MAC".
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func (s *Session) Decrypt(message string, msgType id.OlmMsgType) ([]byte, error) {
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if len(message) == 0 {
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return nil, EmptyInput
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}
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decryptMaxPlaintextLen, err := s.decryptMaxPlaintextLen(message, msgType)
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if err != nil {
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return nil, err
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}
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plaintext := make([]byte, decryptMaxPlaintextLen)
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r := C.olm_decrypt(
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(*C.OlmSession)(s.int),
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C.size_t(msgType),
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unsafe.Pointer(&([]byte(message))[0]),
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C.size_t(len(message)),
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unsafe.Pointer(&plaintext[0]),
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C.size_t(len(plaintext)))
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if r == errorVal() {
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return nil, s.lastError()
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}
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return plaintext[:r], nil
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}
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// https://gitlab.matrix.org/matrix-org/olm/-/blob/3.2.8/include/olm/olm.h#L392-393
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const maxDescribeSize = 600
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// Describe generates a string describing the internal state of an olm session for debugging and logging purposes.
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func (s *Session) Describe() string {
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desc := (*C.char)(C.malloc(C.size_t(maxDescribeSize)))
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defer C.free(unsafe.Pointer(desc))
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C.meowlm_session_describe(
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(*C.OlmSession)(s.int),
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desc,
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C.size_t(maxDescribeSize))
|
||
|
|
return C.GoString(desc)
|
||
|
|
}
|