1b15465c42
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.
98 lines
2.6 KiB
C
98 lines
2.6 KiB
C
/* Copyright 2016 OpenMarket Ltd
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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* functions for encoding and decoding messages in the Olm protocol.
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*
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* Some of these functions have only C++ bindings, and are declared in
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* message.hh; in time, they should probably be converted to plain C and
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* declared here.
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*/
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#ifndef OLM_MESSAGE_H_
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#define OLM_MESSAGE_H_
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#include <stdint.h>
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* The length of the buffer needed to hold a group message.
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*/
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size_t _olm_encode_group_message_length(
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size_t group_session_id_length,
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uint32_t chain_index,
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size_t ciphertext_length,
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size_t mac_length
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);
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/**
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* Writes the message headers into the output buffer.
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*
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* version: version number of the olm protocol
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* session_id: group session identifier
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* session_id_length: length of session_id
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* message_index: message index
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* ciphertext_length: length of the ciphertext
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* output: where to write the output. Should be at least
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* olm_encode_group_message_length() bytes long.
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* ciphertext_ptr: returns the address that the ciphertext
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* should be written to, followed by the MAC.
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*
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* Returns the size of the message, up to the MAC.
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*/
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size_t _olm_encode_group_message(
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uint8_t version,
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const uint8_t *session_id,
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size_t session_id_length,
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uint32_t message_index,
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size_t ciphertext_length,
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uint8_t *output,
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uint8_t **ciphertext_ptr
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);
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struct _OlmDecodeGroupMessageResults {
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uint8_t version;
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const uint8_t *session_id;
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size_t session_id_length;
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uint32_t message_index;
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int has_message_index;
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const uint8_t *ciphertext;
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size_t ciphertext_length;
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};
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/**
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* Reads the message headers from the input buffer.
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*/
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void _olm_decode_group_message(
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const uint8_t *input, size_t input_length,
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size_t mac_length,
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/* output structure: updated with results */
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struct _OlmDecodeGroupMessageResults *results
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);
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif /* OLM_MESSAGE_H_ */
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