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 "mpls.h"
  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. */
  95 struct stream {
  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         size_t count;
 111
 112         struct stream *head;
 113         struct stream *tail;
 114 };
 115
 116 /* Utility macros. */
 117 #define STREAM_SIZE(S)  ((S)->size)
 118 /* number of bytes which can still be written */
 119 #define STREAM_WRITEABLE(S) ((S)->size - (S)->endp)
 120 /* number of bytes still to be read */
 121 #define STREAM_READABLE(S) ((S)->endp - (S)->getp)
 122
 123 #define STREAM_CONCAT_REMAIN(S1, S2, size) ((size) - (S1)->endp - (S2)->endp)
 124
 125 /* deprecated macros - do not use in new code */
 126 #if CONFDATE > 20181128
 127 CPP_NOTICE("lib: time to remove deprecated stream.h macros")
 128 #endif
 129 #define STREAM_PNT(S)   stream_pnt((S))
 130 #define STREAM_REMAIN(S) STREAM_WRITEABLE((S))
 131
 132 /* this macro is deprecated, but not slated for removal anytime soon */
 133 #define STREAM_DATA(S)  ((S)->data)
 134
 135 /* Stream prototypes.
 136  * For stream_{put,get}S, the S suffix mean:
 137  *
 138  * c: character (unsigned byte)
 139  * w: word (two bytes)
 140  * l: long (two words)
 141  * q: quad (four words)
 142  */
 143 extern struct stream *stream_new(size_t);
 144 extern void stream_free(struct stream *);
 145 extern struct stream *stream_copy(struct stream *, struct stream *src);
 146 extern struct stream *stream_dup(struct stream *);
 147 extern size_t stream_resize(struct stream *, size_t);
 148 extern size_t stream_get_getp(struct stream *);
 149 extern size_t stream_get_endp(struct stream *);
 150 extern size_t stream_get_size(struct stream *);
 151 extern u_char *stream_get_data(struct stream *);
 152
 153 /**
 154  * Create a new stream structure; copy offset bytes from s1 to the new
 155  * stream; copy s2 data to the new stream; copy rest of s1 data to the
 156  * new stream.
 157  */
 158 extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2,
 159                                     size_t offset);
 160
 161 extern void stream_set_getp(struct stream *, size_t);
 162 extern void stream_set_endp(struct stream *, size_t);
 163 extern void stream_forward_getp(struct stream *, size_t);
 164 extern void stream_forward_endp(struct stream *, size_t);
 165
 166 /* steam_put: NULL source zeroes out size_t bytes of stream */
 167 extern void stream_put(struct stream *, const void *, size_t);
 168 extern int stream_putc(struct stream *, u_char);
 169 extern int stream_putc_at(struct stream *, size_t, u_char);
 170 extern int stream_putw(struct stream *, u_int16_t);
 171 extern int stream_putw_at(struct stream *, size_t, u_int16_t);
 172 extern int stream_put3(struct stream *, u_int32_t);
 173 extern int stream_put3_at(struct stream *, size_t, u_int32_t);
 174 extern int stream_putl(struct stream *, u_int32_t);
 175 extern int stream_putl_at(struct stream *, size_t, u_int32_t);
 176 extern int stream_putq(struct stream *, uint64_t);
 177 extern int stream_putq_at(struct stream *, size_t, uint64_t);
 178 extern int stream_put_ipv4(struct stream *, u_int32_t);
 179 extern int stream_put_in_addr(struct stream *, struct in_addr *);
 180 extern int stream_put_in_addr_at(struct stream *, size_t, struct in_addr *);
 181 extern int stream_put_in6_addr_at(struct stream *, size_t, struct in6_addr *);
 182 extern int stream_put_prefix_addpath(struct stream *, struct prefix *,
 183                                      int addpath_encode,
 184                                      u_int32_t addpath_tx_id);
 185 extern int stream_put_prefix(struct stream *, struct prefix *);
 186 extern int stream_put_labeled_prefix(struct stream *, struct prefix *,
 187                                      mpls_label_t *);
 188 extern void stream_get(void *, struct stream *, size_t);
 189 extern bool stream_get2(void *data, struct stream *s, size_t size);
 190 extern void stream_get_from(void *, struct stream *, size_t, size_t);
 191 extern u_char stream_getc(struct stream *);
 192 extern bool stream_getc2(struct stream *s, u_char *byte);
 193 extern u_char stream_getc_from(struct stream *, size_t);
 194 extern u_int16_t stream_getw(struct stream *);
 195 extern bool stream_getw2(struct stream *s, uint16_t *word);
 196 extern u_int16_t stream_getw_from(struct stream *, size_t);
 197 extern u_int32_t stream_get3(struct stream *);
 198 extern u_int32_t stream_get3_from(struct stream *, size_t);
 199 extern u_int32_t stream_getl(struct stream *);
 200 extern bool stream_getl2(struct stream *s, uint32_t *l);
 201 extern u_int32_t stream_getl_from(struct stream *, size_t);
 202 extern uint64_t stream_getq(struct stream *);
 203 extern uint64_t stream_getq_from(struct stream *, size_t);
 204 extern u_int32_t stream_get_ipv4(struct stream *);
 205
 206 /* IEEE-754 floats */
 207 extern float stream_getf(struct stream *);
 208 extern double stream_getd(struct stream *);
 209 extern int stream_putf(struct stream *, float);
 210 extern int stream_putd(struct stream *, double);
 211
 212 #undef stream_read
 213 #undef stream_write
 214
 215 /* Deprecated: assumes blocking I/O.  Will be removed.
 216    Use stream_read_try instead.  */
 217 extern int stream_read(struct stream *, int, size_t);
 218
 219 /* Read up to size bytes into the stream.
 220    Return code:
 221      >0: number of bytes read
 222      0: end-of-file
 223      -1: fatal error
 224      -2: transient error, should retry later (i.e. EAGAIN or EINTR)
 225    This is suitable for use with non-blocking file descriptors.
 226  */
 227 extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
 228
 229 extern ssize_t stream_recvmsg(struct stream *s, int fd, struct msghdr *,
 230                               int flags, size_t size);
 231 extern ssize_t stream_recvfrom(struct stream *s, int fd, size_t len, int flags,
 232                                struct sockaddr *from, socklen_t *fromlen);
 233 extern size_t stream_write(struct stream *, const void *, size_t);
 234
 235 /* reset the stream. See Note above */
 236 extern void stream_reset(struct stream *);
 237 extern int stream_flush(struct stream *, int);
 238 extern int stream_empty(struct stream *); /* is the stream empty? */
 239
 240 /* deprecated */
 241 extern u_char *stream_pnt(struct stream *);
 242
 243 /* Stream fifo. */
 244 extern struct stream_fifo *stream_fifo_new(void);
 245 extern void stream_fifo_push(struct stream_fifo *fifo, struct stream *s);
 246 extern struct stream *stream_fifo_pop(struct stream_fifo *fifo);
 247 extern struct stream *stream_fifo_head(struct stream_fifo *fifo);
 248 extern void stream_fifo_clean(struct stream_fifo *fifo);
 249 extern void stream_fifo_free(struct stream_fifo *fifo);
 250
 251 /* This is here because "<< 24" is particularly problematic in C.
 252  * This is because the left operand of << is integer-promoted, which means
 253  * an uint8_t gets converted into a *signed* int.  Shifting into the sign
 254  * bit of a signed int is theoretically undefined behaviour, so - the left
 255  * operand needs to be cast to unsigned.
 256  *
 257  * This is not a problem for 16- or 8-bit values (they don't reach the sign
 258  * bit), for 64-bit values (you need to cast them anyway), and neither for
 259  * encoding (because it's downcasted.)
 260  */
 261 static inline uint8_t *ptr_get_be32(uint8_t *ptr, uint32_t *out)
 262 {
 263         uint32_t tmp;
 264         memcpy(&tmp, ptr, sizeof(tmp));
 265         *out = ntohl(tmp);
 266         return ptr + 4;
 267 }
 268
 269 /*
 270  * so Normal stream_getX functions assert.  Which is anathema
 271  * to keeping a daemon up and running when something goes south
 272  * Provide a stream_getX2 functions that do not assert.
 273  * In addition provide these macro's that upon failure
 274  * goto stream_failure.  This is modeled upon some NL_XX
 275  * macros in the linux kernel.
 276  *
 277  * This change allows for proper memory freeing
 278  * after we've detected an error.
 279  *
 280  * In the future we will be removing the assert in
 281  * the stream functions but we need a transition
 282  * plan.
 283  */
 284 #define STREAM_GETC(S, P)                       \
 285         do {                                    \
 286                 uint8_t _pval;                  \
 287                 if (!stream_getc2((S), &_pval)) \
 288                         goto stream_failure;    \
 289                 (P) = _pval;                    \
 290         } while (0)
 291
 292 #define STREAM_GETW(S, P)                       \
 293         do {                                    \
 294                 uint16_t _pval;                 \
 295                 if (!stream_getw2((S), &_pval)) \
 296                         goto stream_failure;    \
 297                 (P) = _pval;                    \
 298         } while (0)
 299
 300 #define STREAM_GETL(S, P)                               \
 301         do {                                            \
 302                 uint32_t _pval;                         \
 303                 if (!stream_getl2((S), &_pval))         \
 304                         goto stream_failure;            \
 305                 (P) = _pval;                            \
 306         } while (0)
 307
 308 #define STREAM_GET(P, STR, SIZE)                        \
 309         do {                                            \
 310                 if (!stream_get2((P), (STR), (SIZE)))   \
 311                         goto stream_failure;            \
 312         } while (0)
 313
 314 #endif /* _ZEBRA_STREAM_H */