Edit File: writer.h
/* * Copyright (c) 2014, 2018 by Farsight Security, Inc. * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * */ #ifndef FSTRM_WRITER_H #define FSTRM_WRITER_H /** * \defgroup fstrm_writer fstrm_writer * * `fstrm_writer` is an interface for writing Frame Streams data into a byte * stream. The underlying byte stream I/O operations are abstracted by the * \ref fstrm_rdwr interface. Thus, the `fstrm_writer` interface can be used to * write Frame Streams data to any type of output whose read/write operations * are wrapped by an `fstrm_rdwr` object. * * Some basic `fstrm_writer` implementations are already provided in the `fstrm` * library. See fstrm_file_writer_init() for an implementation that writes to * a regular file, fstrm_tcp_writer_init() for an implementation that writes to * a TCP socket, and fstrm_unix_writer_init() for an implementation that writes * to a Unix socket. * * @{ */ /** * Initialize an `fstrm_writer_options` object. * * \return * `fstrm_writer_options` object. */ struct fstrm_writer_options * fstrm_writer_options_init(void); /** * Destroy an `fstrm_writer_options` object. * * \param wopt * Pointer to `fstrm_writer_options` object. */ void fstrm_writer_options_destroy( struct fstrm_writer_options **wopt); /** * Add a "Content Type" value to the set of content types that can be negotiated * by the writer. This function makes a copy of the provided string. This * function may be called multiple times, in which case multiple "Content Type" * values will be accepted by the reader. * * For uni-directional streams like regular files, the negotiated content type * will simply be the first content type provided to this function. For * bi-directional streams like sockets, a handshake occurs and the remote end * determines which content type should be sent. In the latter case, after the * writer has been successfully opened with a call to fstrm_writer_open(), the * fstrm_writer_get_control() function should be called with `type` set to * `FSTRM_CONTROL_ACCEPT` and the control frame queried in order to determine * the negotiated content type. * * \param wopt * `fstrm_writer_options` object. * \param content_type * The "Content Type" string to copy. Note that this string is not * NUL-terminated and may contain embedded NULs. * \param len_content_type * The number of bytes in `content_type`. * * \retval #fstrm_res_success * The "Content Type" field was successfully added. * \retval #fstrm_res_failure * The "Content Type" string is too long. */ fstrm_res fstrm_writer_options_add_content_type( struct fstrm_writer_options *wopt, const void *content_type, size_t len_content_type); /** * Initialize a new `fstrm_writer` object based on an underlying `fstrm_rdwr` * object and an `fstrm_writer_options` object. * * The underlying `fstrm_rdwr` object MUST have a `write` method. It MAY * optionally have a `read` method, in which case the stream will be treated as * a bi-directional, handshaked stream. Otherwise, if there is no `read` method * the stream will be treated as a uni-directional stream. * * This function is useful for implementing functions that return new types of * `fstrm_writer` objects, such as fstrm_file_writer_init() and * fstrm_unix_writer_init(). * * After a successful call to this function, the ownership of the `fstrm_rdwr` * object passes from the caller to the `fstrm_writer` object. The caller * should perform no further calls on the `fstrm_rdwr` object. The `fstrm_rdwr` * object will be cleaned up on a call to fstrm_writer_destroy(). * * \param wopt * `fstrm_writer_options` object. May be NULL, in which case default values * will be used. * * \param rdwr * Pointer to `fstrm_rdwr` object. Must be non-NULL. The `fstrm_rdwr` * object must have a `write` method, and may optionally have a `read` * method. * * \return * `fstrm_writer` object. * \retval * NULL on failure. */ struct fstrm_writer * fstrm_writer_init( const struct fstrm_writer_options *wopt, struct fstrm_rdwr **rdwr); /** * Destroy an `fstrm_writer` object. This implicitly calls fstrm_writer_close() * if necessary. * * \param w * Pointer to `fstrm_writer` object. * * \retval #fstrm_res_success * \retval #fstrm_res_failure */ fstrm_res fstrm_writer_destroy(struct fstrm_writer **w); /** * Open an `fstrm_writer` object and prepare it to write data. For * bi-directional writer implementations, this performs content type * negotiation. * * This function may fail if there was an underlying problem opening the output * stream. * * \param w * `fstrm_writer` object. * * \retval #fstrm_res_success * \retval #fstrm_res_failure */ fstrm_res fstrm_writer_open(struct fstrm_writer *w); /** * Close an `fstrm_writer` object. Open it has been closed, no data frames may * subsequently be written. * * Calling this function is optional; it may be implicitly invoked by a call to * fstrm_writer_destroy(). * * \param w * `fstrm_writer` object. * * \retval #fstrm_res_success * \retval #fstrm_res_failure */ fstrm_res fstrm_writer_close(struct fstrm_writer *w); /** * Write a data frame to an `fstrm_writer` object. * * This function implicitly calls fstrm_writer_open() if necessary. * * \param w * `fstrm_writer` object. * \param[in] data * Buffer containing the data frame payload. * \param[in] len_data * The number of bytes in `data`. * * \retval #fstrm_res_success * The data frame was successfully written. * \retval #fstrm_res_failure */ fstrm_res fstrm_writer_write( struct fstrm_writer *w, const void *data, size_t len_data); /** * Write multiple data frames to an `fstrm_writer` object. * * This function implicitly calls fstrm_writer_open() if necessary. * * Data frames are passed similarly to the `writev()` system call, with an array * of `struct iovec` objects describing the data frame payloads and their * lengths. The complete set of data frames will be written to the output * stream after a successful call. * * \param w * `fstrm_writer` object. * \param iov * Array of `struct iovec` objects. * \param iovcnt * Number of `struct iovec` objects in `iov`. * * \retval #fstrm_res_success * The data frames were successfully written. * \retval #fstrm_res_failure */ fstrm_res fstrm_writer_writev( struct fstrm_writer *w, const struct iovec *iov, int iovcnt); /** * Obtain a pointer to an `fstrm_control` object used during processing. Objects * returned by this function are owned by the `fstrm_reader` object and must not * be modified by the caller. After a call to fstrm_reader_destroy() these * pointers will no longer be valid. * * For example, with bi-directional streams this function can be used to obtain * a pointer to the ACCEPT control frame, which can be queried to see which * "Content Type" was negotiated during the opening of the writer. * * This function implicitly calls fstrm_writer_open() if necessary. * * \param w * `fstrm_writer` object. * \param type * Which control frame to return. * \param[out] control * The `fstrm_control` object. * * \retval #fstrm_res_success * If an `fstrm_control` object was returned. * \retval #fstrm_res_failure */ fstrm_res fstrm_writer_get_control( struct fstrm_writer *w, fstrm_control_type type, struct fstrm_control **control); /**@}*/ #endif /* FSTRM_WRITER_H */
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