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authorRichard van der Hoff <github@rvanderhoff.org.uk>2016-12-15 16:54:39 +0000
committerGitHub <noreply@github.com>2016-12-15 16:54:39 +0000
commit7fd63bcac7110abd5a1eef927abc3184da68a35c (patch)
tree4f273f56830ef78ee42e954ab514df8d0471dd34 /javascript/olm_post.js
parent2e04868c468ba4d0362a209f8f261df649598a07 (diff)
parent09b3e1eecdd83c738a1bcd1aca7319206eaf7091 (diff)
Merge pull request #39 from matrix-org/rav/messages_on_heap
Allocate memory for message blobs on the heap
Diffstat (limited to 'javascript/olm_post.js')
-rw-r--r--javascript/olm_post.js144
1 files changed, 94 insertions, 50 deletions
diff --git a/javascript/olm_post.js b/javascript/olm_post.js
index 54e42c5..3e80c0b 100644
--- a/javascript/olm_post.js
+++ b/javascript/olm_post.js
@@ -4,9 +4,11 @@ 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
- * characters >= 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.
+/* The 'length' argument to Pointer_stringify doesn't work if the input
+ * includes characters >= 128, which makes Pointer_stringify unreliable. We
+ * could use it on strings which are known to be ascii, but that seems
+ * dangerous. Instead we add a NULL character to all of our strings and just
+ * use UTF8ToString.
*/
var NULL_BYTE_PADDING_LENGTH = 1;
@@ -40,6 +42,13 @@ function restore_stack(wrapped) {
}
}
+/* set a memory area to zero */
+function bzero(ptr, n) {
+ while(n-- > 0) {
+ Module['HEAP8'][ptr++] = 0;
+ }
+}
+
function Account() {
var size = Module['_olm_account_size']();
this.buf = malloc(size);
@@ -297,59 +306,94 @@ Session.prototype['matches_inbound_from'] = restore_stack(function(
Session.prototype['encrypt'] = restore_stack(function(
plaintext
) {
- var random_length = session_method(
- Module['_olm_encrypt_random_length']
- )(this.ptr);
- var message_type = session_method(
- Module['_olm_encrypt_message_type']
- )(this.ptr);
- var plaintext_array = array_from_string(plaintext);
- var message_length = session_method(
- Module['_olm_encrypt_message_length']
- )(this.ptr, plaintext_array.length);
- var random = random_stack(random_length);
- var plaintext_buffer = stack(plaintext_array);
- var message_buffer = stack(message_length + NULL_BYTE_PADDING_LENGTH);
- session_method(Module['_olm_encrypt'])(
- this.ptr,
- plaintext_buffer, plaintext_array.length,
- random, random_length,
- message_buffer, message_length
- );
- return {
- "type": message_type,
- "body": Pointer_stringify(message_buffer)
- };
+ var plaintext_buffer, message_buffer, plaintext_length;
+ try {
+ var random_length = session_method(
+ Module['_olm_encrypt_random_length']
+ )(this.ptr);
+ var message_type = session_method(
+ Module['_olm_encrypt_message_type']
+ )(this.ptr);
+
+ plaintext_length = Module['lengthBytesUTF8'](plaintext);
+ var message_length = session_method(
+ Module['_olm_encrypt_message_length']
+ )(this.ptr, plaintext_length);
+
+ var random = random_stack(random_length);
+
+ // need to allow space for the terminator (which stringToUTF8 always
+ // writes), hence + 1.
+ plaintext_buffer = malloc(plaintext_length + 1);
+ Module['stringToUTF8'](plaintext, plaintext_buffer, plaintext_length + 1);
+
+ message_buffer = malloc(message_length + NULL_BYTE_PADDING_LENGTH);
+
+ session_method(Module['_olm_encrypt'])(
+ this.ptr,
+ plaintext_buffer, plaintext_length,
+ random, random_length,
+ message_buffer, message_length
+ );
+ return {
+ "type": message_type,
+ "body": Module['UTF8ToString'](message_buffer),
+ };
+ } finally {
+ if (plaintext_buffer !== undefined) {
+ // don't leave a copy of the plaintext in the heap.
+ bzero(plaintext_buffer, plaintext_length + 1);
+ free(plaintext_buffer);
+ }
+ if (message_buffer !== undefined) {
+ free(message_buffer);
+ }
+ }
});
Session.prototype['decrypt'] = restore_stack(function(
message_type, message
) {
- var message_array = array_from_string(message);
- var message_buffer = stack(message_array);
- var max_plaintext_length = session_method(
- Module['_olm_decrypt_max_plaintext_length']
- )(this.ptr, message_type, message_buffer, message_array.length);
- // 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 + 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
- );
-
- // 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"
- );
+ var message_buffer, plaintext_buffer, max_plaintext_length;
+
+ try {
+ message_buffer = malloc(message.length);
+ Module['writeAsciiToMemory'](message, message_buffer, true);
+
+ max_plaintext_length = session_method(
+ Module['_olm_decrypt_max_plaintext_length']
+ )(this.ptr, message_type, message_buffer, message.length);
+
+ // caculating the length destroys the input buffer, so we need to re-copy it.
+ Module['writeAsciiToMemory'](message, message_buffer, true);
+
+ plaintext_buffer = malloc(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
+ );
+
+ // UTF8ToString requires a null-terminated argument, so add the
+ // null terminator.
+ Module['setValue'](
+ plaintext_buffer+plaintext_length,
+ 0, "i8"
+ );
+
+ return UTF8ToString(plaintext_buffer);
+ } finally {
+ if (message_buffer !== undefined) {
+ free(message_buffer);
+ }
+ if (plaintext_buffer !== undefined) {
+ // don't leave a copy of the plaintext in the heap.
+ bzero(plaintext_buffer, max_plaintext_length + NULL_BYTE_PADDING_LENGTH);
+ free(plaintext_buffer);
+ }
+ }
- return Pointer_stringify(plaintext_buffer);
});
function Utility() {