Commit 1b15465c authored by Richard van der Hoff's avatar Richard van der Hoff
Browse files

Separate base64ing from the rest of msg encoding

Factor the actual message encoding/decoding and encrypting/decrypting out to
separate functions from the top-level functions which do the base64-wrangling.

This is particularly helpful in the 'outbound' code-path where the offsets
required to allow room to base64-encode make the flow hard to see when it's all inline.
parent a919a149
......@@ -53,8 +53,10 @@ size_t _olm_encode_group_message_length(
* olm_encode_group_message_length() bytes long.
* ciphertext_ptr: returns the address that the ciphertext
* should be written to, followed by the MAC.
*
* Returns the size of the message, up to the MAC.
*/
void _olm_encode_group_message(
size_t _olm_encode_group_message(
uint8_t version,
const uint8_t *session_id,
size_t session_id_length,
......
......@@ -163,19 +163,15 @@ size_t olm_unpickle_inbound_group_session(
return pickled_length;
}
size_t olm_group_decrypt_max_plaintext_length(
/**
* get the max plaintext length in an un-base64-ed message
*/
static size_t _decrypt_max_plaintext_length(
OlmInboundGroupSession *session,
uint8_t * message, size_t message_length
) {
size_t r;
struct _OlmDecodeGroupMessageResults decoded_results;
r = _olm_decode_base64(message, message_length, message);
if (r == (size_t)-1) {
session->last_error = OLM_INVALID_BASE64;
return r;
}
_olm_decode_group_message(
message, message_length,
megolm_cipher->ops->mac_length(megolm_cipher),
......@@ -195,25 +191,38 @@ size_t olm_group_decrypt_max_plaintext_length(
megolm_cipher, decoded_results.ciphertext_length);
}
size_t olm_group_decrypt_max_plaintext_length(
OlmInboundGroupSession *session,
uint8_t * message, size_t message_length
) {
size_t raw_length;
size_t olm_group_decrypt(
raw_length = _olm_decode_base64(message, message_length, message);
if (raw_length == (size_t)-1) {
session->last_error = OLM_INVALID_BASE64;
return (size_t)-1;
}
return _decrypt_max_plaintext_length(
session, message, raw_length
);
}
/**
* decrypt an un-base64-ed message
*/
static size_t _decrypt(
OlmInboundGroupSession *session,
uint8_t * message, size_t message_length,
uint8_t * plaintext, size_t max_plaintext_length
) {
struct _OlmDecodeGroupMessageResults decoded_results;
size_t max_length, raw_message_length, r;
size_t max_length, r;
Megolm *megolm;
Megolm tmp_megolm;
raw_message_length = _olm_decode_base64(message, message_length, message);
if (raw_message_length == (size_t)-1) {
session->last_error = OLM_INVALID_BASE64;
return (size_t)-1;
}
_olm_decode_group_message(
message, raw_message_length,
message, message_length,
megolm_cipher->ops->mac_length(megolm_cipher),
&decoded_results);
......@@ -259,7 +268,7 @@ size_t olm_group_decrypt(
r = megolm_cipher->ops->decrypt(
megolm_cipher,
megolm_get_data(megolm), MEGOLM_RATCHET_LENGTH,
message, raw_message_length,
message, message_length,
decoded_results.ciphertext, decoded_results.ciphertext_length,
plaintext, max_plaintext_length
);
......@@ -272,3 +281,22 @@ size_t olm_group_decrypt(
return r;
}
size_t olm_group_decrypt(
OlmInboundGroupSession *session,
uint8_t * message, size_t message_length,
uint8_t * plaintext, size_t max_plaintext_length
) {
size_t raw_message_length;
raw_message_length = _olm_decode_base64(message, message_length, message);
if (raw_message_length == (size_t)-1) {
session->last_error = OLM_INVALID_BASE64;
return (size_t)-1;
}
return _decrypt(
session, message, raw_message_length,
plaintext, max_plaintext_length
);
}
......@@ -347,7 +347,7 @@ size_t _olm_encode_group_message_length(
}
void _olm_encode_group_message(
size_t _olm_encode_group_message(
uint8_t version,
const uint8_t *session_id,
size_t session_id_length,
......@@ -364,6 +364,7 @@ void _olm_encode_group_message(
std::memcpy(session_id_pos, session_id, session_id_length);
pos = encode(pos, GROUP_MESSAGE_INDEX_TAG, message_index);
pos = encode(pos, GROUP_CIPHERTEXT_TAG, *ciphertext_ptr, ciphertext_length);
return pos-output;
}
void _olm_decode_group_message(
......
......@@ -199,51 +199,41 @@ size_t olm_group_encrypt_message_length(
return _olm_encode_base64_length(message_length);
}
size_t olm_group_encrypt(
OlmOutboundGroupSession *session,
uint8_t const * plaintext, size_t plaintext_length,
uint8_t * message, size_t max_message_length
/** write an un-base64-ed message to the buffer */
static size_t _encrypt(
OlmOutboundGroupSession *session, uint8_t const * plaintext, size_t plaintext_length,
uint8_t * buffer
) {
size_t ciphertext_length;
size_t rawmsglen;
size_t ciphertext_length, mac_length, message_length;
size_t result;
uint8_t *ciphertext_ptr, *message_pos;
rawmsglen = raw_message_length(session, plaintext_length);
if (max_message_length < _olm_encode_base64_length(rawmsglen)) {
session->last_error = OLM_OUTPUT_BUFFER_TOO_SMALL;
return (size_t)-1;
}
uint8_t *ciphertext_ptr;
ciphertext_length = megolm_cipher->ops->encrypt_ciphertext_length(
megolm_cipher,
plaintext_length
);
/* we construct the message at the end of the buffer, so that
* we have room to base64-encode it once we're done.
*/
message_pos = message + _olm_encode_base64_length(rawmsglen) - rawmsglen;
mac_length = megolm_cipher->ops->mac_length(megolm_cipher);
/* first we build the message structure, then we encrypt
* the plaintext into it.
*/
_olm_encode_group_message(
message_length = _olm_encode_group_message(
OLM_PROTOCOL_VERSION,
session->session_id, GROUP_SESSION_ID_LENGTH,
session->ratchet.counter,
ciphertext_length,
message_pos,
buffer,
&ciphertext_ptr);
message_length += mac_length;
result = megolm_cipher->ops->encrypt(
megolm_cipher,
megolm_get_data(&(session->ratchet)), MEGOLM_RATCHET_LENGTH,
plaintext, plaintext_length,
ciphertext_ptr, ciphertext_length,
message_pos, rawmsglen
buffer, message_length
);
if (result == (size_t)-1) {
......@@ -252,6 +242,37 @@ size_t olm_group_encrypt(
megolm_advance(&(session->ratchet));
return result;
}
size_t olm_group_encrypt(
OlmOutboundGroupSession *session,
uint8_t const * plaintext, size_t plaintext_length,
uint8_t * message, size_t max_message_length
) {
size_t rawmsglen;
size_t result;
uint8_t *message_pos;
rawmsglen = raw_message_length(session, plaintext_length);
if (max_message_length < _olm_encode_base64_length(rawmsglen)) {
session->last_error = OLM_OUTPUT_BUFFER_TOO_SMALL;
return (size_t)-1;
}
/* we construct the message at the end of the buffer, so that
* we have room to base64-encode it once we're done.
*/
message_pos = message + _olm_encode_base64_length(rawmsglen) - rawmsglen;
/* write the message, and encrypt it, at message_pos */
result = _encrypt(session, plaintext, plaintext_length, message_pos);
if (result == (size_t)-1) {
return result;
}
/* bas64-encode it */
return _olm_encode_base64(
message_pos, rawmsglen, message
);
......
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