lib/stream.h

   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 along
  18  * with this program; see the file COPYING; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #ifndef _ZEBRA_STREAM_H
  23 #define _ZEBRA_STREAM_H
  24
  25 #include "prefix.h"
  26
  27 /*
  28  * A stream is an arbitrary buffer, whose contents generally are assumed to
  29  * be in network order.
  30  *
  31  * A stream has the following attributes associated with it:
  32  *
  33  * - size: the allocated, invariant size of the buffer.
  34  *
  35  * - getp: the get position marker, denoting the offset in the stream where
  36  *         the next read (or 'get') will be from. This getp marker is
  37  *         automatically adjusted when data is read from the stream, the
  38  *         user may also manipulate this offset as they wish, within limits
  39  *         (see below)
  40  *
  41  * - endp: the end position marker, denoting the offset in the stream where
  42  *         valid data ends, and if the user attempted to write (or
  43  *         'put') data where that data would be written (or 'put') to.
  44  *
  45  * These attributes are all size_t values.
  46  *
  47  * Constraints:
  48  *
  49  * 1. getp can never exceed endp
  50  *
  51  * - hence if getp is equal to endp, there is no more valid data that can be
  52  *   gotten from the stream (though, the user may reposition getp to earlier in
  53  *   the stream, if they wish).
  54  *
  55  * 2. endp can never exceed size
  56  *
  57  * - hence, if endp is equal to size, then the stream is full, and no more
  58  *   data can be written to the stream.
  59  *
  60  * In other words the following must always be true, and the stream
  61  * abstraction is allowed internally to assert that the following property
  62  * holds true for a stream, as and when it wishes:
  63  *
  64  *        getp <= endp <= size
  65  *
  66  * It is the users responsibility to ensure this property is never violated.
  67  *
  68  * A stream therefore can be thought of like this:
  69  *
  70  *      ---------------------------------------------------
  71  *      |XXXXXXXXXXXXXXXXXXXXXXXX                         |
  72  *      ---------------------------------------------------
  73  *               ^               ^                        ^
  74  *               getp            endp                     size
  75  *
  76  * This shows a stream containing data (shown as 'X') up to the endp offset.
  77  * The stream is empty from endp to size. Without adjusting getp, there are
  78  * still endp-getp bytes of valid data to be read from the stream.
  79  *
  80  * Methods are provided to get and put to/from the stream, as well as
  81  * retrieve the values of the 3 markers and manipulate the getp marker.
  82  *
  83  * Note:
  84  * At the moment, newly allocated streams are zero filled. Hence, one can
  85  * use stream_forward_endp() to effectively create arbitrary zero-fill
  86  * padding. However, note that stream_reset() does *not* zero-out the
  87  * stream. This property should **not** be relied upon.
  88  *
  89  * Best practice is to use stream_put (<stream *>, NULL, <size>) to zero out
  90  * any part of a stream which isn't otherwise written to.
  91  */
  92
  93 /* Stream buffer. */
  94 struct stream
  95 {
  96   struct stream *next;
  97
  98   /* Remainder is ***private*** to stream
  99    * direct access is frowned upon!
 100    * Use the appropriate functions/macros
 101    */
 102   size_t getp;          /* next get position */
 103   size_t endp;          /* last valid data position */
 104   size_t size;          /* size of data segment */
 105   unsigned char *data; /* data pointer */
 106 };
 107
 108 /* First in first out queue structure. */
 109 struct stream_fifo
 110 {
 111   size_t count;
 112
 113   struct stream *head;
 114   struct stream *tail;
 115 };
 116
 117 /* Utility macros. */
 118 #define STREAM_SIZE(S)  ((S)->size)
 119   /* number of bytes which can still be written */
 120 #define STREAM_WRITEABLE(S) ((S)->size - (S)->endp)
 121   /* number of bytes still to be read */
 122 #define STREAM_READABLE(S) ((S)->endp - (S)->getp)
 123
 124 #define STREAM_CONCAT_REMAIN(S1, S2, size) \
 125   ((size) - (S1)->endp - (S2)->endp)
 126
 127 /* deprecated macros - do not use in new code */
 128 #define STREAM_PNT(S)   stream_pnt((S))
 129 #define STREAM_DATA(S)  ((S)->data)
 130 #define STREAM_REMAIN(S) STREAM_WRITEABLE((S))
 131
 132 /* Stream prototypes.
 133  * For stream_{put,get}S, the S suffix mean:
 134  *
 135  * c: character (unsigned byte)
 136  * w: word (two bytes)
 137  * l: long (two words)
 138  * q: quad (four words)
 139  */
 140 extern struct stream *stream_new (size_t);
 141 extern void stream_free (struct stream *);
 142 extern struct stream * stream_copy (struct stream *, struct stream *src);
 143 extern struct stream *stream_dup (struct stream *);
 144 extern size_t stream_resize (struct stream *, size_t);
 145 extern size_t stream_get_getp (struct stream *);
 146 extern size_t stream_get_endp (struct stream *);
 147 extern size_t stream_get_size (struct stream *);
 148 extern u_char *stream_get_data (struct stream *);
 149
 150 /**
 151  * Create a new stream structure; copy offset bytes from s1 to the new
 152  * stream; copy s2 data to the new stream; copy rest of s1 data to the
 153  * new stream.
 154  */
 155 extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2,
 156                                     size_t offset);
 157
 158 extern void stream_set_getp (struct stream *, size_t);
 159 extern void stream_set_endp (struct stream *, size_t);
 160 extern void stream_forward_getp (struct stream *, size_t);
 161 extern void stream_forward_endp (struct stream *, size_t);
 162
 163 /* steam_put: NULL source zeroes out size_t bytes of stream */
 164 extern void stream_put (struct stream *, const void *, size_t);
 165 extern int stream_putc (struct stream *, u_char);
 166 extern int stream_putc_at (struct stream *, size_t, u_char);
 167 extern int stream_putw (struct stream *, u_int16_t);
 168 extern int stream_putw_at (struct stream *, size_t, u_int16_t);
 169 extern int stream_put3 (struct stream *, u_int32_t);
 170 extern int stream_put3_at (struct stream *, size_t, u_int32_t);
 171 extern int stream_putl (struct stream *, u_int32_t);
 172 extern int stream_putl_at (struct stream *, size_t, u_int32_t);
 173 extern int stream_putq (struct stream *, uint64_t);
 174 extern int stream_putq_at (struct stream *, size_t, uint64_t);
 175 extern int stream_put_ipv4 (struct stream *, u_int32_t);
 176 extern int stream_put_in_addr (struct stream *, struct in_addr *);
 177 extern int stream_put_in_addr_at (struct stream *, size_t, struct in_addr *);
 178 extern int stream_put_in6_addr_at (struct stream *, size_t, struct in6_addr *);
 179 extern int stream_put_prefix_addpath (struct stream *, struct prefix *,
 180                                       int addpath_encode,
 181                                       u_int32_t addpath_tx_id);
 182 extern int stream_put_prefix (struct stream *, struct prefix *);
 183 extern int stream_put_labeled_prefix (struct stream *, struct prefix *,
 184                                       u_char *);
 185 extern void stream_get (void *, struct stream *, size_t);
 186 extern void stream_get_from (void *, struct stream *, size_t, size_t);
 187 extern u_char stream_getc (struct stream *);
 188 extern u_char stream_getc_from (struct stream *, size_t);
 189 extern u_int16_t stream_getw (struct stream *);
 190 extern u_int16_t stream_getw_from (struct stream *, size_t);
 191 extern u_int32_t stream_get3 (struct stream *);
 192 extern u_int32_t stream_get3_from (struct stream *, size_t);
 193 extern u_int32_t stream_getl (struct stream *);
 194 extern u_int32_t stream_getl_from (struct stream *, size_t);
 195 extern uint64_t stream_getq (struct stream *);
 196 extern uint64_t stream_getq_from (struct stream *, size_t);
 197 extern u_int32_t stream_get_ipv4 (struct stream *);
 198
 199 /* IEEE-754 floats */
 200 extern float stream_getf (struct stream *);
 201 extern double stream_getd (struct stream *);
 202 extern int stream_putf (struct stream *, float);
 203 extern int stream_putd (struct stream *, double);
 204
 205 #undef stream_read
 206 #undef stream_write
 207
 208 /* Deprecated: assumes blocking I/O.  Will be removed.
 209    Use stream_read_try instead.  */
 210 extern int stream_read (struct stream *, int, size_t);
 211
 212 /* Read up to size bytes into the stream.
 213    Return code:
 214      >0: number of bytes read
 215      0: end-of-file
 216      -1: fatal error
 217      -2: transient error, should retry later (i.e. EAGAIN or EINTR)
 218    This is suitable for use with non-blocking file descriptors.
 219  */
 220 extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
 221
 222 extern ssize_t stream_recvmsg (struct stream *s, int fd, struct msghdr *,
 223                                int flags, size_t size);
 224 extern ssize_t stream_recvfrom (struct stream *s, int fd, size_t len,
 225                                 int flags, struct sockaddr *from,
 226                                 socklen_t *fromlen);
 227 extern size_t stream_write (struct stream *, const void *, size_t);
 228
 229 /* reset the stream. See Note above */
 230 extern void stream_reset (struct stream *);
 231 extern int stream_flush (struct stream *, int);
 232 extern int stream_empty (struct stream *); /* is the stream empty? */
 233
 234 /* deprecated */
 235 extern u_char *stream_pnt (struct stream *);
 236
 237 /* Stream fifo. */
 238 extern struct stream_fifo *stream_fifo_new (void);
 239 extern void stream_fifo_push (struct stream_fifo *fifo, struct stream *s);
 240 extern struct stream *stream_fifo_pop (struct stream_fifo *fifo);
 241 extern struct stream *stream_fifo_head (struct stream_fifo *fifo);
 242 extern void stream_fifo_clean (struct stream_fifo *fifo);
 243 extern void stream_fifo_free (struct stream_fifo *fifo);
 244
 245 #endif /* _ZEBRA_STREAM_H */