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JS: make sure returned strings are null-terminated

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It turns out that the 'length' argument to 'Pointer_stringify' doesn't work if
the input includes characters >= 128.

Rather than try to figure out which methods can return UTF-8, and which always
return plain ascii, replace all uses of Pointer_stringify with a 'length'
argument with the version that expects a NULL-terminated input, and extend the
buffer by a byte to allow space for a null-terminator.

In the case of decrypt, we need to add the null ourself.

Fixes https://github.com/vector-im/vector-web/issues/1719.
This commit is contained in:
Richard van der Hoff 2016-07-05 23:01:23 +01:00
parent c8d00665b3
commit 939aa747dd
1 changed files with 38 additions and 18 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

56
javascript/olm_post.js
View file

@ -4,6 +4,16 @@ var free = Module['_free'];
var Pointer_stringify = Module['Pointer_stringify'];
var OLM_ERROR = Module['_olm_error']();
/* The 'length' argument to Pointer_stringify doesn't work if the input includes
* cahracters >= 128; we therefore need to add a NULL character to all of our
* strings. This acts as a symbolic constant to help show what we're doing.
*/
var NULL_BYTE_PADDING_LENGTH = 1;
/* allocate a number of bytes of storage on the stack.
*
* If size_or_array is a Number, allocates that number of zero-initialised bytes.
*/
function stack(size_or_array) {
return Module['allocate'](size_or_array, 'i8', Module['ALLOC_STACK']);
}
@ -68,11 +78,11 @@ Account.prototype['identity_keys'] = restore_stack(function() {
var keys_length = account_method(
Module['_olm_account_identity_keys_length']
)(this.ptr);
var keys = stack(keys_length);
var keys = stack(keys_length + NULL_BYTE_PADDING_LENGTH);
account_method(Module['_olm_account_identity_keys'])(
this.ptr, keys, keys_length
);
return Pointer_stringify(keys, keys_length);
return Pointer_stringify(keys);
});
Account.prototype['sign'] = restore_stack(function(message) {
@ -81,24 +91,24 @@ Account.prototype['sign'] = restore_stack(function(message) {
)(this.ptr);
var message_array = array_from_string(message);
var message_buffer = stack(message_array);
var signature_buffer = stack(signature_length);
var signature_buffer = stack(signature_length + NULL_BYTE_PADDING_LENGTH);
account_method(Module['_olm_account_sign'])(
this.ptr,
message_buffer, message_array.length,
signature_buffer, signature_length
);
return Pointer_stringify(signature_buffer, signature_length);
return Pointer_stringify(signature_buffer);
});
Account.prototype['one_time_keys'] = restore_stack(function() {
var keys_length = account_method(
Module['_olm_account_one_time_keys_length']
)(this.ptr);
var keys = stack(keys_length);
var keys = stack(keys_length + NULL_BYTE_PADDING_LENGTH);
account_method(Module['_olm_account_one_time_keys'])(
this.ptr, keys, keys_length
);
return Pointer_stringify(keys, keys_length);
return Pointer_stringify(keys);
});
Account.prototype['mark_keys_as_published'] = restore_stack(function() {
@ -135,11 +145,11 @@ Account.prototype['pickle'] = restore_stack(function(key) {
Module['_olm_pickle_account_length']
)(this.ptr);
var key_buffer = stack(key_array);
var pickle_buffer = stack(pickle_length);
var pickle_buffer = stack(pickle_length + NULL_BYTE_PADDING_LENGTH);
account_method(Module['_olm_pickle_account'])(
this.ptr, key_buffer, key_array.length, pickle_buffer, pickle_length
);
return Pointer_stringify(pickle_buffer, pickle_length);
return Pointer_stringify(pickle_buffer);
});
Account.prototype['unpickle'] = restore_stack(function(key, pickle) {
@ -183,11 +193,11 @@ Session.prototype['pickle'] = restore_stack(function(key) {
Module['_olm_pickle_session_length']
)(this.ptr);
var key_buffer = stack(key_array);
var pickle_buffer = stack(pickle_length);
var pickle_buffer = stack(pickle_length + NULL_BYTE_PADDING_LENGTH);
session_method(Module['_olm_pickle_session'])(
this.ptr, key_buffer, key_array.length, pickle_buffer, pickle_length
);
return Pointer_stringify(pickle_buffer, pickle_length);
return Pointer_stringify(pickle_buffer);
});
Session.prototype['unpickle'] = restore_stack(function(key, pickle) {
@ -246,11 +256,11 @@ Session.prototype['create_inbound_from'] = restore_stack(function(
Session.prototype['session_id'] = restore_stack(function() {
var id_length = session_method(Module['_olm_session_id_length'])(this.ptr);
var id_buffer = stack(id_length);
var id_buffer = stack(id_length + NULL_BYTE_PADDING_LENGTH);
session_method(Module['_olm_session_id'])(
this.ptr, id_buffer, id_length
);
return Pointer_stringify(id_buffer, id_length);
return Pointer_stringify(id_buffer);
});
Session.prototype['matches_inbound'] = restore_stack(function(
@ -292,7 +302,7 @@ Session.prototype['encrypt'] = restore_stack(function(
)(this.ptr, plaintext_array.length);
var random = random_stack(random_length);
var plaintext_buffer = stack(plaintext_array);
var message_buffer = stack(message_length);
var message_buffer = stack(message_length + NULL_BYTE_PADDING_LENGTH);
session_method(Module['_olm_encrypt'])(
this.ptr,
plaintext_buffer, plaintext_array.length,
@ -301,7 +311,7 @@ Session.prototype['encrypt'] = restore_stack(function(
);
return {
"type": message_type,
"body": Pointer_stringify(message_buffer, message_length)
"body": Pointer_stringify(message_buffer)
};
});
@ -316,13 +326,23 @@ Session.prototype['decrypt'] = restore_stack(function(
// caculating the length destroys the input buffer.
// So we copy the array to a new buffer
var message_buffer = stack(message_array);
var plaintext_buffer = stack(max_plaintext_length);
var plaintext_buffer = stack(
max_plaintext_length + NULL_BYTE_PADDING_LENGTH
);
var plaintext_length = session_method(Module["_olm_decrypt"])(
this.ptr, message_type,
message_buffer, message.length,
plaintext_buffer, max_plaintext_length
);
return Pointer_stringify(plaintext_buffer, plaintext_length);
// Pointer_stringify requires a null-terminated argument (the optional
// 'len' argument doesn't work for UTF-8 data).
Module['setValue'](
plaintext_buffer+plaintext_length,
0, "i8"
);
return Pointer_stringify(plaintext_buffer);
});
function Utility() {
@ -353,13 +373,13 @@ Utility.prototype['sha256'] = restore_stack(function(input) {
var output_length = utility_method(Module['_olm_sha256_length'])(this.ptr);
var input_array = array_from_string(input);
var input_buffer = stack(input_array);
var output_buffer = stack(output_length);
var output_buffer = stack(output_length + NULL_BYTE_PADDING_LENGTH);
utility_method(Module['_olm_sha2516'])(
this.ptr,
input_buffer, input_array.length(),
output_buffer, output_length
);
return Pointer_stringify(output_buffer, output_length);
return Pointer_stringify(output_buffer);
});
Utility.prototype['ed25519_verify'] = restore_stack(function(