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#ifndef SESSION_BUILDER_H
#define SESSION_BUILDER_H
#include <stdint.h>
#include "axolotl_types.h"
#ifdef __cplusplus
extern "C" {
#endif
/*
* Session builder is responsible for setting up encrypted sessions.
* Once a session has been established, session_cipher
* can be used to encrypt/decrypt messages in that session.
*
* Sessions are built from one of three different possible vectors:
* - A session_pre_key_bundle retrieved from a server
* - A pre_key_whisper_message received from a client
* - A key_exchange_message sent to or received from a client
*
* Sessions are constructed per AXOLOTL address
* (recipient name + device ID tuple). Remote logical users are identified by
* their recipient name, and each logical recipient can have multiple
* physical devices.
*/
/**
* Constructs a session builder.
*
* The store and global contexts must remain valid for the lifetime of the
* session builder.
*
* When finished, free the returned instance by calling session_builder_free().
*
* @param builder set to a freshly allocated session builder instance
* @param store the axolotl_store_context to store all state information in
* @param remote_address the address of the remote user to build a session with
* @param global_context the global library context
* @return 0 on success, or negative on failure
*/
int session_builder_create(session_builder **builder,
axolotl_store_context *store, const axolotl_address *remote_address,
axolotl_context *global_context);
/**
* Build a new session from a received pre_key_whisper_message.
*
* After a session is constructed in this way, the embedded whisper_message
* can be decrypted.
*
* @param message The received pre_key_whisper_message.
* @param unsigned_pre_key_id set to the unsigned pre key ID, if available.
* Return value indicates whether or not this value is available.
* @retval 0 Success, no unsigned pre key value available
* @retval 1 Success, an unsigned pre key is available
* @retval AX_ERR_INVALID_KEY_ID when there is no local pre_key_record that
* corresponds to the PreKey ID in the message.
* @retval AX_ERR_INVALID_KEY when the message is formatted incorrectly.
* @retval AX_ERR_UNTRUSTED_IDENTITY when the identity key of the sender is untrusted.
*/
int session_builder_process_pre_key_whisper_message(session_builder *builder,
session_record *record, pre_key_whisper_message *message, uint32_t *unsigned_pre_key_id);
/**
* Build a new session from a session_pre_key_bundle retrieved from a server.
*
* @param bundle A pre key bundle for the destination recipient, retrieved from a server.
* @retval AX_SUCCESS Success
* @retval AX_ERR_INVALID_KEY when the session_pre_key_bundle is badly formatted.
* @retval AX_ERR_UNTRUSTED_IDENTITY when the sender's identity key is not trusted.
*/
int session_builder_process_pre_key_bundle(session_builder *builder, session_pre_key_bundle *bundle);
/**
* Build a new session from a key_exchange_message received from a remote client.
*
* @param message The received key_exchange_message.
* @param response_message Set to the key_exchange_message to respond with,
* or set to 0 if no response is necessary.
* @retval AX_SUCCESS Success
* @retval AX_ERR_INVALID_KEY if the received key_exchange_message is badly formatted.
* @retval AX_ERR_UNTRUSTED_IDENTITY
* @retval AX_ERR_STALE_KEY_EXCHANGE
*/
int session_builder_process_key_exchange_message(session_builder *builder, key_exchange_message *message, key_exchange_message **response_message);
/**
* Initiate a new session by sending an initial key_exchange_message to the recipient.
*
* @param message Set to the key_exchange_message to deliver.
* @return AX_SUCCESS on success, negative on error
*/
int session_builder_process(session_builder *builder, key_exchange_message **message);
void session_builder_free(session_builder *builder);
#ifdef __cplusplus
}
#endif
#endif /* SESSION_BUILDER_H */
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