1/*
2 * Packet interface
3 * Copyright (C) 1999 Kunihiro Ishiguro
4 *
5 * This file is part of GNU Zebra.
6 *
7 * GNU Zebra is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the
9 * Free Software Foundation; either version 2, or (at your option) any
10 * later version.
11 *
12 * GNU Zebra is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Zebra; see the file COPYING.  If not, write to the Free
19 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
20 * 02111-1307, USA.
21 */
22
23#ifndef _ZEBRA_STREAM_H
24#define _ZEBRA_STREAM_H
25
26#include "prefix.h"
27
28/*
29 * A stream is an arbitrary buffer, whose contents generally are assumed to
30 * be in network order.
31 *
32 * A stream has the following attributes associated with it:
33 *
34 * - size: the allocated, invariant size of the buffer.
35 *
36 * - getp: the get position marker, denoting the offset in the stream where
37 *         the next read (or 'get') will be from. This getp marker is
38 *         automatically adjusted when data is read from the stream, the
39 *         user may also manipulate this offset as they wish, within limits
40 *         (see below)
41 *
42 * - endp: the end position marker, denoting the offset in the stream where
43 *         valid data ends, and if the user attempted to write (or
44 *         'put') data where that data would be written (or 'put') to.
45 *
46 * These attributes are all size_t values.
47 *
48 * Constraints:
49 *
50 * 1. getp can never exceed endp
51 *
52 * - hence if getp is equal to endp, there is no more valid data that can be
53 *   gotten from the stream (though, the user may reposition getp to earlier in
54 *   the stream, if they wish).
55 *
56 * 2. endp can never exceed size
57 *
58 * - hence, if endp is equal to size, then the stream is full, and no more
59 *   data can be written to the stream.
60 *
61 * In other words the following must always be true, and the stream
62 * abstraction is allowed internally to assert that the following property
63 * holds true for a stream, as and when it wishes:
64 *
65 *        getp <= endp <= size
66 *
67 * It is the users responsibility to ensure this property is never violated.
68 *
69 * A stream therefore can be thought of like this:
70 *
71 * 	---------------------------------------------------
72 * 	|XXXXXXXXXXXXXXXXXXXXXXXX                         |
73 * 	---------------------------------------------------
74 *               ^               ^                        ^
75 *               getp            endp                     size
76 *
77 * This shows a stream containing data (shown as 'X') up to the endp offset.
78 * The stream is empty from endp to size. Without adjusting getp, there are
79 * still endp-getp bytes of valid data to be read from the stream.
80 *
81 * Methods are provided to get and put to/from the stream, as well as
82 * retrieve the values of the 3 markers and manipulate the getp marker.
83 *
84 * Note:
85 * At the moment, newly allocated streams are zero filled. Hence, one can
86 * use stream_forward_endp() to effectively create arbitrary zero-fill
87 * padding. However, note that stream_reset() does *not* zero-out the
88 * stream. This property should **not** be relied upon.
89 *
90 * Best practice is to use stream_put (<stream *>, NULL, <size>) to zero out
91 * any part of a stream which isn't otherwise written to.
92 */
93
94/* Stream buffer. */
95struct stream
96{
97  struct stream *next;
98
99  /* Remainder is ***private*** to stream
100   * direct access is frowned upon!
101   * Use the appropriate functions/macros
102   */
103  size_t getp; 		/* next get position */
104  size_t endp;		/* last valid data position */
105  size_t size;		/* size of data segment */
106  unsigned char *data; /* data pointer */
107};
108
109/* First in first out queue structure. */
110struct stream_fifo
111{
112  size_t count;
113
114  struct stream *head;
115  struct stream *tail;
116};
117
118/* Utility macros. */
119#define STREAM_SIZE(S)  ((S)->size)
120  /* number of bytes which can still be written */
121#define STREAM_WRITEABLE(S) ((S)->size - (S)->endp)
122  /* number of bytes still to be read */
123#define STREAM_READABLE(S) ((S)->endp - (S)->getp)
124
125#define STREAM_CONCAT_REMAIN(S1, S2, size) \
126  ((size) - (S1)->endp - (S2)->endp)
127
128/* deprecated macros - do not use in new code */
129#define STREAM_PNT(S)   stream_pnt((S))
130#define STREAM_DATA(S)  ((S)->data)
131#define STREAM_REMAIN(S) STREAM_WRITEABLE((S))
132
133/* Stream prototypes.
134 * For stream_{put,get}S, the S suffix mean:
135 *
136 * c: character (unsigned byte)
137 * w: word (two bytes)
138 * l: long (two words)
139 * q: quad (four words)
140 */
141extern struct stream *stream_new (size_t);
142extern void stream_free (struct stream *);
143extern struct stream * stream_copy (struct stream *, struct stream *src);
144extern struct stream *stream_dup (struct stream *);
145extern size_t stream_resize (struct stream *, size_t);
146extern size_t stream_get_getp (struct stream *);
147extern size_t stream_get_endp (struct stream *);
148extern size_t stream_get_size (struct stream *);
149extern u_char *stream_get_data (struct stream *);
150
151/**
152 * Create a new stream structure; copy offset bytes from s1 to the new
153 * stream; copy s2 data to the new stream; copy rest of s1 data to the
154 * new stream.
155 */
156extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2,
157				    size_t offset);
158
159extern void stream_set_getp (struct stream *, size_t);
160extern void stream_set_endp (struct stream *, size_t);
161extern void stream_forward_getp (struct stream *, size_t);
162extern void stream_forward_endp (struct stream *, size_t);
163
164/* steam_put: NULL source zeroes out size_t bytes of stream */
165extern void stream_put (struct stream *, const void *, size_t);
166extern int stream_putc (struct stream *, u_char);
167extern int stream_putc_at (struct stream *, size_t, u_char);
168extern int stream_putw (struct stream *, u_int16_t);
169extern int stream_putw_at (struct stream *, size_t, u_int16_t);
170extern int stream_putl (struct stream *, u_int32_t);
171extern int stream_putl_at (struct stream *, size_t, u_int32_t);
172extern int stream_putq (struct stream *, uint64_t);
173extern int stream_putq_at (struct stream *, size_t, uint64_t);
174extern int stream_put_ipv4 (struct stream *, u_int32_t);
175extern int stream_put_in_addr (struct stream *, struct in_addr *);
176extern int stream_put_prefix (struct stream *, struct prefix *);
177
178extern void stream_get (void *, struct stream *, size_t);
179extern u_char stream_getc (struct stream *);
180extern u_char stream_getc_from (struct stream *, size_t);
181extern u_int16_t stream_getw (struct stream *);
182extern u_int16_t stream_getw_from (struct stream *, size_t);
183extern u_int32_t stream_getl (struct stream *);
184extern u_int32_t stream_getl_from (struct stream *, size_t);
185extern uint64_t stream_getq (struct stream *);
186extern uint64_t stream_getq_from (struct stream *, size_t);
187extern u_int32_t stream_get_ipv4 (struct stream *);
188
189#undef stream_read
190#undef stream_write
191
192/* Deprecated: assumes blocking I/O.  Will be removed.
193   Use stream_read_try instead.  */
194extern int stream_read (struct stream *, int, size_t);
195
196/* Read up to size bytes into the stream.
197   Return code:
198     >0: number of bytes read
199     0: end-of-file
200     -1: fatal error
201     -2: transient error, should retry later (i.e. EAGAIN or EINTR)
202   This is suitable for use with non-blocking file descriptors.
203 */
204extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
205
206extern ssize_t stream_recvmsg (struct stream *s, int fd, struct msghdr *,
207                               int flags, size_t size);
208extern ssize_t stream_recvfrom (struct stream *s, int fd, size_t len,
209                                int flags, struct sockaddr *from,
210                                socklen_t *fromlen);
211extern size_t stream_write (struct stream *, const void *, size_t);
212
213/* reset the stream. See Note above */
214extern void stream_reset (struct stream *);
215extern int stream_flush (struct stream *, int);
216extern int stream_empty (struct stream *); /* is the stream empty? */
217
218/* deprecated */
219extern u_char *stream_pnt (struct stream *);
220
221/* Stream fifo. */
222extern struct stream_fifo *stream_fifo_new (void);
223extern void stream_fifo_push (struct stream_fifo *fifo, struct stream *s);
224extern struct stream *stream_fifo_pop (struct stream_fifo *fifo);
225extern struct stream *stream_fifo_head (struct stream_fifo *fifo);
226extern void stream_fifo_clean (struct stream_fifo *fifo);
227extern void stream_fifo_free (struct stream_fifo *fifo);
228
229#endif /* _ZEBRA_STREAM_H */
230