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/*
* Packet interface
* Copyright (C) 1999 Kunihiro Ishiguro
*
* This file is part of GNU Zebra.
*
* GNU Zebra is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* GNU Zebra is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Zebra; see the file COPYING. If not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#ifndef _ZEBRA_STREAM_H
#define _ZEBRA_STREAM_H
#include "prefix.h"
/*
* A stream is an arbitrary buffer, whose contents generally are assumed to
* be in network order.
*
* A stream has the following attributes associated with it:
*
* - size: the allocated, invariant size of the buffer.
*
* - getp: the get position marker, denoting the offset in the stream where
* the next read (or 'get') will be from. This getp marker is
* automatically adjusted when data is read from the stream, the
* user may also manipulate this offset as they wish, within limits
* (see below)
*
* - endp: the end position marker, denoting the offset in the stream where
* valid data ends, and if the user attempted to write (or
* 'put') data where that data would be written (or 'put') to.
*
* These attributes are all size_t values.
*
* Constraints:
*
* 1. getp can never exceed endp
*
* - hence if getp is equal to endp, there is no more valid data that can be
* gotten from the stream (though, the user may reposition getp to earlier in
* the stream, if they wish).
*
* 2. endp can never exceed size
*
* - hence, if endp is equal to size, then the stream is full, and no more
* data can be written to the stream.
*
* In other words the following must always be true, and the stream
* abstraction is allowed internally to assert that the following property
* holds true for a stream, as and when it wishes:
*
* getp <= endp <= size
*
* It is the users responsibility to ensure this property is never violated.
*
* A stream therefore can be thought of like this:
*
* ---------------------------------------------------
* |XXXXXXXXXXXXXXXXXXXXXXXX |
* ---------------------------------------------------
* ^ ^ ^
* getp endp size
*
* This shows a stream containing data (shown as 'X') up to the endp offset.
* The stream is empty from endp to size. Without adjusting getp, there are
* still endp-getp bytes of valid data to be read from the stream.
*
* Methods are provided to get and put to/from the stream, as well as
* retrieve the values of the 3 markers and manipulate the getp marker.
*
* Note:
* At the moment, newly allocated streams are zero filled. Hence, one can
* use stream_forward_endp() to effectively create arbitrary zero-fill
* padding. However, note that stream_reset() does *not* zero-out the
* stream. This property should **not** be relied upon.
*
* A Good stream user should ensure it writes all bytes. (the zero-fill
* guarantee may be removed in future, however, the zero-filling may
* possibly be moved to stream_forward_endp() instead, maybe..)
*/
/* Stream buffer. */
struct stream
{
struct stream *next;
/* Remainder is ***private*** to stream
* direct access is frowned upon!
* Use the appropriate functions/macros
*/
size_t getp; /* next get position */
size_t endp; /* last valid data position */
size_t size; /* size of data segment */
unsigned char data[0]; /* data pointer */
};
/* First in first out queue structure. */
struct stream_fifo
{
size_t count;
struct stream *head;
struct stream *tail;
};
/* Utility macros. */
#define STREAM_SIZE(S) ((S)->size)
/* number of bytes which can still be written */
#define STREAM_WRITEABLE(S) ((S)->size - (S)->endp)
/* number of bytes still to be read */
#define STREAM_READABLE(S) ((S)->endp - (S)->getp)
/* deprecated macros - do not use in new code */
#define STREAM_PNT(S) stream_pnt((S))
#define STREAM_DATA(S) ((S)->data)
#define STREAM_REMAIN(S) STREAM_WRITEABLE((S))
/* Stream prototypes. */
struct stream *stream_new (size_t);
void stream_free (struct stream *);
struct stream * stream_copy (struct stream *new, struct stream *src);
struct stream *stream_dup (struct stream *);
size_t stream_get_getp (struct stream *);
size_t stream_get_endp (struct stream *);
size_t stream_get_size (struct stream *);
u_char *stream_get_data (struct stream *);
void stream_set_getp (struct stream *, size_t);
void stream_forward_getp (struct stream *, size_t);
void stream_forward_endp (struct stream *, size_t);
void stream_put (struct stream *, void *, size_t);
int stream_putc (struct stream *, u_char);
int stream_putc_at (struct stream *, size_t, u_char);
int stream_putw (struct stream *, u_int16_t);
int stream_putw_at (struct stream *, size_t, u_int16_t);
int stream_putl (struct stream *, u_int32_t);
int stream_putl_at (struct stream *, size_t, u_int32_t);
int stream_put_ipv4 (struct stream *, u_int32_t);
int stream_put_in_addr (struct stream *, struct in_addr *);
int stream_put_prefix (struct stream *, struct prefix *);
void stream_get (void *, struct stream *, size_t);
u_char stream_getc (struct stream *);
u_char stream_getc_from (struct stream *, size_t);
u_int16_t stream_getw (struct stream *);
u_int16_t stream_getw_from (struct stream *, size_t);
u_int32_t stream_getl (struct stream *);
u_int32_t stream_getl_from (struct stream *, size_t);
u_int32_t stream_get_ipv4 (struct stream *);
#undef stream_read
#undef stream_write
/* Deprecated: assumes blocking I/O. Will be removed.
Use stream_read_try instead. */
int stream_read (struct stream *, int, size_t);
/* Deprecated: all file descriptors should already be non-blocking.
Will be removed. Use stream_read_try instead. */
int stream_read_unblock (struct stream *, int, size_t);
/* Read up to size bytes into the stream.
Return code:
>0: number of bytes read
0: end-of-file
-1: fatal error
-2: transient error, should retry later (i.e. EAGAIN or EINTR)
This is suitable for use with non-blocking file descriptors.
*/
extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
int stream_recvmsg (struct stream *s, int fd, struct msghdr *,
int flags, size_t size);
int stream_write (struct stream *, u_char *, size_t);
void stream_reset (struct stream *); /* reset the stream. See Note above */
int stream_flush (struct stream *, int);
int stream_empty (struct stream *); /* is the stream empty? */
/* deprecated */
u_char *stream_pnt (struct stream *);
/* Stream fifo. */
struct stream_fifo *stream_fifo_new (void);
void stream_fifo_push (struct stream_fifo *fifo, struct stream *s);
struct stream *stream_fifo_pop (struct stream_fifo *fifo);
struct stream *stream_fifo_head (struct stream_fifo *fifo);
void stream_fifo_clean (struct stream_fifo *fifo);
void stream_fifo_free (struct stream_fifo *fifo);
#endif /* _ZEBRA_STREAM_H */
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